Does a mod using a ’39 clutch & brake pedal work correctly?

[Robert Dip]

The reason being is that a lot of guys ( gals are guys too ) use the '39 pedal set-up when updating the '35 - '38 brakes to hydraulics. I recently changed the clutch on my ’39 from a stock 9” to a 10”, which also includes using the flywheel from a ’48. In the adjustments, I now have almost no pedal play, and when shifting gears, I need to have the pedal down completely to the floor to prevent gear grinding. I measured the arm on the pedal, and it is short at 1 3/8" arc....and came to the conclusion that this is the one that needs to be increased to at least 1 3/4". The stock ’39 arm on the trans case is also shorter than most, so I would not touch this one. I am also presently doing this conversation on my '35 using the ‘original ’39 pedals. The '48 uses the 10" clutch, and that, to me, has always been the one to use. The question is…does the 10” PP need more travel than the 9” to release? The PP I use is the conventional 3 adjustable finger type. Thanks...Robert

[Mart]

In my experience, no. I have run my roadster (30A on 32 rails) with both 9" and 10" clutches and the clutch pedal operation is similar in both cases. If you are using a lot of travel to release your clutch (regardless of size) then you either have a mis-match in lever lengths, or there is a reason it is not releasing (warped disc or something)
Do you have a 39 lever on the gearbox?

I don't know the relative lengths, but if the 39 trans lever is shorter than a 35 and you're using a 35 (for example) then the pedal travel will be long (and light)

Mart.

[Barn Junk]

Here are some "approx" lever arm lengths (distance pivot point from shaft center):
1932 -- 4 3/4 inches
1933-34 -- 4 inches
1935-38 -- 3 !/4 inches
1939 -- 3 1/2 inches

Of course the pivot position varies also from left to right.

[George/Maine]

The 39 pedal has a very short throw making the pedal longer is no good.
The trans arm on 39 case is shorter.3 1/2" as above.
Lokking from side when making contact with presure plate my guess you lose the same contact point.Most throw would be 1 oclock to 11 oclock.
Make all adjustment with floor in place if removed.

[Robert Dip]

Mart...on the case of the '39, I used the same original '39 lever on the trans...in other words, no linkage was changed. The 10" disc is brand new and not warped.

George/Maine....the idea is not to make the pedal longer, but to modify the lower lever which only 1 3/8" arc. Increasing this would solve all issues...this would also increase the pedal pressure, but it's not that stiff to begin with. just curious what others have actually experienced.

Thanks guys...Robert

[George/Maine]

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If it worked good before,you changed the point of contact.
Say the pedal half way down,the fork should be 12 oclock.
You may need to changed pin location on lever.
If you made the shaft end longer would it hit the floor.
I had that problem on my 39 car,found out i had a 32 lever.Grind gears

[Pete]

I have always used the 9 inch clutch.
Smaller in diameter so less weight....easier to balance....less pedal pressure...engine spools up faster...easier shifting...can be made to handle 400 hp.

[DICK SPADARO]

The throw out lever on the transmission must be a 39 lever to work with the 39 pedals. You did not indicate what car this conversion is being done on so the pedal to trans rod length makes a big difference. If you are relocating the pedals, the stock rod may not be the correct length. Further explain your conversion to accurately get a solution to your issue.

[Robert Dip]

Dick S....As written in the initial wording, I changed from a 9" to a 10" in my '39 Coupe. Used the same trans clutch arm, and naturally, have not touched the clutch pedal, just re-adjusted the existing rod. The reason I also mention this is when one converts to hydraulics on '35 to '38 cars, does this short arc on the popular '39 pedals affect other setup, since it did affect mine, using all of the existing components. Hope I was clear on what I wrote.

Pete...400hp on a 9" clutch.....not in a million years in my books....just calculate the surface area on the disc and the pressure needed to handle that much power....must be close to the 'Theory of Relativity'.

[Bassman/NZ]

Uh.... dont doubt anything that Pete has to say.... he's been doing it all his life and has more knowledge than 20 of us mortals combined.

[Pete]

Originally Posted by Robert Dip

Dick S....As written in the initial wording, I changed from a 9" to a 10" in my '39 Coupe. Used the same trans clutch arm, and naturally, have not touched the clutch pedal, just re-adjusted the existing rod. The reason I also mention this is when one converts to hydraulics on '35 to '38 cars, does this short arc on the popular '39 pedals affect other setup, since it did affect mine, using all of the existing components. Hope I was clear on what I wrote.

Pete...400hp on a 9" clutch.....not in a million years in my books....just calculate the surface area on the disc and the pressure needed to handle that much power....must be close to the 'Theory of Relativity'.

You better go back to engineering school. You have been reading the wrong comic books.
I ran a 345 ci blown Olds at Bonneville with a 9 inch clutch. That engine made 430 on the dyno. I had several 315 ci and 324 ci flatheads in the 50's and 60's that made over 400 hp on 100% nitro and picric acid.
All had 9 inch clutches.....Granted they were not stock but they were single plate.

[DICK SPADARO]

Robert, I guess your question first started about 39 pedal conversions in 35-38 chassis so I assumed that you were doing a conversion with 39 pedal not having a 39 car with the correct pedal assembly already. Now you say its on your 39 then you revert to saying you are doing this conversion on a 35. Any way if you are having clutch adjustment difficulties with the stock parts in your 39 there is an issue.

Lets start over I'll be dense so which car is giving you trouble the 39 or the 35? If the 39 is giving you an issue with the release on the clutch with the stock parts something is installed or adjusted incorrectly. The pedal free play should be adjusted with the floorboard installed or a stop in place to replicated the floorboard position with the clutch pedal.

To adjust the pedal you should disconnect the pedal push rod from the clutch throw lever. Now rotate the clutch throw lever forward so you can feel the throw out bearing contact the pressure plate. With the bearing contacting the pressure plate and the clutch pedal in the up position, the pedal rod should be adjusted so the rod end aligns with the clevis pin hole and then turned back 2-3 complete revolutions to get a freeplay spacing. Your clutch should be full disengaged about 1 1/2" off the floor. If the clutch is fully disengaged at that distance and the input shaft still is driven by the clutch then there are additional issues. What do you have for distances?

[russcc]

Doubt the ability of 9"clutch to handle anything, read "Flathead Introduction" on this site. You will come away convinced that Pete is dead on. No need to go to 10". Not sure about the leverage, but if something changed, that likely is the problem, if worked before. Unless we are using a Chinese clutch versus a Fort Wayne rebuilt Ford clutch. Than all bets are off.

[Robert Dip]

Pete....I've been at it for 50 years....been there done that too....but i'm not a Bonneville guy just going in a straight line, cause that's another story on using a clutch. In drag racing, with even as low as a E stock with 300 horses, a 10" racing clutch with 3,800 lbs pressure, it was the only set up that let me run without blowing the clutch due to slippage and overheating....and making holy messes out of stock alum bellhousings...went immediately to NHRA certified scattershields before loosing my toes. ( before going onto C/MP and Alterds. Not only am I an engineer, but real life experiences does not place me in your ballpark on using clutches. I guess Ford engineers were also out to lunch when they decided to go to the 10" clutch on the '41 to '48 models. Anyway, we could debate this for many years to come, but that is not the issue. The question still remains is that why is the exact same setup giving me this situation that was not there with the 9". There is always a simple explanation somewhere, just trying to identify it.
The PP i am using is a Ford unit that ran in a '48 very well. The disc is new and no Chinese junk is ever used by me...goes against my principles.....but who knows, the PP could be a potential problem, however doubtful. Today, I sat down and 'designed' a modification piece that can be added to the original '39 lever, increasing it from 1 3/8" to 2 1/8" to give me that extra throw.

Dick S....Yes, the issue is only with the '39 and using all of the same hardware. The '35 is a work in progress, and not an issue today. My question is simply put in this manner...I do not have enough throw now having installed the 10" clutch. I did not have a chance to measure the different PP arms to see if the 9" and the 10" are the same. Maybe it does take more throw on the 10" and making the geometry different. I am sure there are lots of guys using the '39 pedals with the 10" PP, so it would be nice to get some reference feedback here.
Presently, I drive the '39 as is without a big concern, but, it is still not the way it should be....and that's what we are here for....to uncover this little mystery on my end.
Pete...your comments are also welcomed.......Robert

[George/Maine]

I had a 10" clutch in my 39 with a 51 engine 8ba,PP mercury 1949,and with the 39 pedal stock and 39 lever worked ok.
My guess the flywheel maybe thicker, or disk,PP
When the lever makes contact at PP,the lever on trans should be to back say 1 oclock pedal all way down say 11 oclock.
Those trans are you looks not raceing.

[Robert Dip]

George/Maine....thanks for the input. It would not make a difference on the flywheel thickness or throw-out bearing, that's what the adjustment rod does. I used the 10" wide disc. ( probably a HD police or ambulance unit that was originally commented on by a F Barner ) as it uses the total surface of the PP, as compared to the standard size. I also miked it to check the thickness, and it compared to within .015" of other brand new discs. Photo shows the difference of the wider disc as compared to the standard one. And yes, modifying the pedal clutch lever are to a longer throw will bring it very close to the floorboard, but manageable. I wanted a more durable clutch, especially with the 25T L-Z gears, as a 'get going' from a dead stop requires a little more 'clutch work'. It's all a matter of getting use to it...works out fine. Robert

[DICK SPADARO]

Robert, Just a question did you remove the throw out lever on the clutch shaft or replace it at any time? If you did, did you re install it with the correct orientation? The shaft pin hole is indexed to the clutch rod hole and if installed backwards changes the angle of the clutch throw arm relationship to the pedal arm.

[Robert Dip]

Dick S.....as seen in the photo ( hope it's clear enough ) the clutch arm was placed back in the exact same position as when I removed it to re-build the transmission. It is also in the correct 1 o'clock position. Curious situation, is it not ? Robert

[TomT/Williamsburg]

OK - I'm no guru but I will weigh in here just by my experience using a 39 pedal setup with a T5 adapter but I had the same issue(s). Here's what I did:

1 - I got longer adjustable arms from the clutch pedal to the 39 clutch arm on the tranny
2 - readjusted things with the new items and still had issues although it was better.
3 - the piece you pictured, Robert Dip: I actually modified it and cocked it further toeards teh back of the car, making for a longer throw and was then able to properly adjust the arm to get good clutch pedal throw. We did this by welding a piece into the slot where the adjusting arm would reside. Since at rest it's already slight pointing towards the back, this worked out very well.

Now, this is a non-stock solution for a non-stock setup but perhaps something here will trigger something and get 'er done for you.

I've posted the only picture I have for my setup and it really does not show too much but I add it for reference ....

Good luck ....

[George/Maine]

Tom thats one way,mine had a 32 lever over 4" on trans.I shorten mine to about 39 lenght.Just think 39 is a one year lever and only so many to go around.
With a new cutch there could be some drag till worn in,also splines want to be clean and not binding.When I had my problem i was going to make pedal longer but it would hit my exhaust pipe.

[DICK SPADARO]

Robert, something looks odd about the arm you have here are pictures of a 39 arm , black, and a 35-8 rusty they have different index. here are a couple pictures of the arms

[Robert Dip]

TomT.....I guess you and I are in the same boat. ( thought I was alone there for a while ) and yes, your mods on the pedal arm is the direction I am headed for a cure. What PP did you install in this set-up, was it a long type 10" ??

Dick....thanks for the photos...my arm is in an 'S' form for the offset, but I believe that the end result is the same. I measured my arm at exactly 3" hole c/c. What distance do you have on the arms you displayed? Over the years, I have never seen an arm shorter in c/c hole distance than this 3" piece. Robert

[DICK SPADARO]

Robert, Somebody screwed with your arm. The black arm in the picture is correct and
unaltered c-c measurement is 3.5" 35-38 arm measures 3.25, your measurement is 3" with that "S" bend in your set up you cant get enough throw. The correct 39 arm has the throw lever positioned to the outer portion of the casting almost right above the pin holes. refer back to the pictures because your part doesnt match.

[Robert Dip]

Dick..."Somebody screwed with your arm"....I won't doubt that, since I am reviving a 50's built Hot Rod, but, having a shorter arm down to 3" is beneficial for my problem, and not the other way round. Having a 3.5" c/c arm requires even more clutch pedal travel to disengage the clutch, which I don't have. Whatever someone did in the past, this set-up was good with the 9" clutch..????? Go figure??

[Robert Dip]

Dick...after looking into more detail on your photos, it looks like my arm is the '38 on your photo, reversed and bent back outward for proper rod alignment....IF, that's the case. Interesting, but still at the correct clock position and I'm still better off with the 3" arc.

[DICK SPADARO]

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Nope, your problem is disengaging the clutch so it doesnt drag on the flywheel when shifting, as you decrease the length of the throw arm it requires a longer stroke to make the pedal operate the required distance. Its distance travel required to disengage the clutch. A 3" lever will only travel xxx inches of the pedal stroke, using a longer clutch lever will now generate a stroke travel of yyy inches. You have three lever arms, one the stock pedal arm, one the clutch arm and one the throw out fork. The pedal arm and the throw out arm are fixed so the only variable is the clutch arm and that is too small to match the required throw distance to fully disengage the clutch. The reason you didnt notice it before with the 9" disc was probably due to the slippage due to the lesser contact area. With the 10" plate there is more area and less slip. Just change the arm to the correct one and jobs done. They are about $20.00

[V8COOPMAN]

Originally Posted by DICK SPADARO

Nope, your problem is disengaging the clutch so it doesnt drag on the flywheel when shifting, as you decrease the length of the throw arm it requires a longer stroke to make the pedal operate the required distance. Its distance travel required to disengage the clutch. A 3" lever will only travel xxx inches of the pedal stroke, using a longer clutch lever will now generate a stroke travel of yyy inches. You have three lever arms, one the stock pedal arm, one the clutch arm and one the throw out fork. The pedal arm and the throw out arm are fixed so the only variable is the clutch arm and that is too small to match the required throw distance to fully disengage the clutch. The reason you didnt notice it before with the 9" disc was probably due to the slippage due to the lesser contact area. With the 10" plate there is more area and less slip. Just change the arm to the correct one and jobs done. They are about $20.00

Dick....SHORTER the clutch release arm on the trans, the higher number of degrees of clutch release shaft rotation, considering the same amount of PEDAL lever input. Shortening the TRANS arm promotes GREATER fork travel. Sometimes when I don't hold my tongue just right, stuff works-out backwards, too. DD

[Robert Dip]

Dick...Sorry, your formulae does not equate...the longer the trans clutch shaft arm is, the more travel is needed....not good. If, for example, if I need to rotate the clutch shaft 30 degrees, as per the sketch, I would need more travel with the longer arm.

[V8COOPMAN]

Originally Posted by Robert Dip

Dick...Sorry, your formulae does not equate...the longer the trans clutch shaft arm is, the more travel is needed....not good. If, for example, if I need to rotate the clutch shaft 30 degrees, as per the sketch, I would need more travel with the longer arm.

Robert...I think Dick's just having a bad day. He'll come-around...he DOES know better. DD

[Robert Dip]

DD....I know that.....and I know Dick, we go back a long ways....but I don't think he's figured out yet who I am.....hell, all of our brains do work backwards at time....How often do I question my own. Are we having fun yet! Robert

[George/Maine]

To get the max throw, the trans lever has to be at 12 oclock,and the pedal 1/2 way down.
To contact the throwout bearing to soon or late you loose throw.
True short lever more throw.
The arm you have is most likely off location because of the bolt.

[DICK SPADARO]

If this is the only mistake I make today I view it as a good day. You Guys you are looking at it the wrong way, your math is correct for a single point but we are dealing with more than one point operation. Robert you answered your problem in post #28.

The Clutch arm is too short to completely disengage the clutch. Maybe I need to explain it as a measure of degrees of rotation not distance traveled. If you need 40 degrees of rotation to disengage the clutch you need 40 degrees. The pedal is hitting the floor and not allowing the clutch to disengage because it is not allowing the clutch shaft to rotate enough. Like you are getting 37 degrees of rotation and then the pedal bottoms. It needs the longer arm to completely disengage the clutch not a shorter one. The shorter arm moves a shorter distance but it means the clutch pedal moves a longer distance during operation, it would be fine if you didn't have a floor board. With your arm the pedal bottoms out on the floor board sooner than it should.

Going to a longer arm on the clutch shaft changes the ratio so the pedal arm has a longer stroke and increases the pedal throw so doesnt bottom out so quick and completes the clutch relaese.

[V8COOPMAN]

OK Folks, this ain't rocket science. Robert Dip...Let's start over, just to be clear. '39 Ford, right? '39 pedal assembly, right? 9" clutch worked properly before you decided to change to a 10" for some reason, correct so far? Is it a fact that the ONLY thing that has changed here is that you've replaced a 9" clutch/PP with a 10" clutch/PP? That's what I get out of all this. I also understand that your clutch release arm is not stock, but I BELIEVE it is the same one that was being used BEFORE the clutch swap......CORRECT?

With ALL these questions answered and confirmed by you ROBERT, we ought to be able to get somewhere without any confusion. IF you had it all working with the 9", and that's ALL that you've changed, I would also have to question SOMETHING being dimensionally and significantly different with the 10" clutch cover/actuating levers as I THINK you seem to be asking. DD

[Robert Dip]

Dick, this is getting funny, and I am not laughing at you, just with you. V8 COOPMAN and I are going to have to sit down with you on this one. What I will be doing to solve this at present, is to leave the clutch shaft arm as is, and increase the pedal lever arm from 1 3/8” to approx. 2”. This will give me the extra throw length needed.
Having said that, it still does not give me an explanation on why there has become a difference going from a 9” to a 10”. Yes, there may an additional frictional difference using a wider surface disc, but not to that degree.
This has me very curious, because so many out there are using the ’39 pedal set-up when converting to hydraulics. Even B. Drake has made available a repop of these pedals. It is just in my professional nature to find the reasons behind this situation. TomT seemed to have this predicament also. I am sure that our discussions here will help others using this set-up….as so many other forums have assisted me in the past.

[Robert Dip]

V8COOPMAN....well said....correct on all counts.....took the words right out of me....it's gotta be the PP...there is nothing else. Now for the million $$ question....is my 10" PP a weirdo one....or is there really a difference in throw from a 9 to a 10????? Amen.

[V8COOPMAN]

Robert...You and I are on the same page. IF I were in your shoes, I'd be asking the same question about the PP. What's really interesting here is the fact that your clutch release arm is ALREADY shortened effectively from a stock '39 arm (effectively the same direction you would need to go to fix your problem...just not enough YET). I understand that you intend to correct this fiasco by lengthening the arm on the PEDAL (effectively the same as shortening the clutch release arm).

Since I think you seemed to indicate that you can "kind of" drive the car the way it is, I'd bet you do not need to lengthen the pedal arm to any more than 1 3/4" effective length. Remember, the longer that PEDAL lever gets, the more "leg" it'll take to push that pedal. You know what to do...you're headed in the correct direction. I'd like to hear of your progress. DD

[bbrocksr]

If both pressure plates are working correctly they require the same amount of travel to release. If the 9" released correctly and the 10" doesn't you have a defective 10" pressure plate or disc.
I think Dick is misunderstanding which lever you are talking about.
The pedal lever has to be longer or the release shaft lever has to be shorter to get more travel of the throwout fork.
Bill

[DICK SPADARO]

Ok I'll concede you guys are correct I'm wrong. Ford made the throw lever specifically for that combination. Yours is not the correct one its too short and it doesnt work correctly in this application. Does that give you a hint that something might be wrong parts wise. Rather than question my poor math skills and the pressure plate quality look at what you have starting with the situation that the pedal assembly botttoms out on the floor preventing complete release of the clutch!

The clutch should be in full disengagement way before the pedal bottoms on the floor board out. Since the limit factor is the floor board you have to initiate a longer travel in the clutch throw out shaft to increase the distance travel by the throw out fork. You math guys are assuming that the clutch pivot and the trans pivot are on the same plain , they are not, the trans clutch arm pivot point is below the axis of the pedal, the linkage points are at the same plain. Shortening the clutch throw arm moves the linkage points so the throw initiated becomes smaller not larger and requires more clutch pedal input to travel the same distance however the pedal hits the floor before achieving the necessary the throw. The shorter arm cannot rotate far enough to release the clutch.

Additionally making the clutch throw arm arm shorter makes it move more rapidly so you have less of a sweet spot and a hair trigger clutch release with a chatter potential. As I said before the issue was already there just masked by the slippage in the smaller clutch disc. Put the longer correct arm on readjust the pedal to arm rod and problem solved.

[Robert Dip]

V8COO........Yes, 1 3/4" on the pedal lever arm would be good, amd the reason I mentioned 2" is because I have designed a piece to add to the existing than can be placed directly in place without taking anything off the car or welding under the car. The slot fork at the pedals is 0.312" ( 5/16" ) and I can fab a piece that will slip in place. This now means that the pedal side will use a fork piece on each end of the adjust rod. ( I am not going to take this engine out again, at least not for a while ) The existing hole in the pedal will be used as one of the bolting points and the existing grease thread centered in the piviting shaft, now a 1/8 NPT can be used and modified to hold as a second mounting point. The .312 thick flat horseshoe style piece will have the hole machined above the existing one, but it needs room for the fork to pivot. Yes, this will bring me close to the floorpan....but we'll see. In this manner, I can experiment on how it works out. Everything I do in building a car goes on the drawing board....I never fit & fiddle....that's me.....design to exact needs and install.
Dick, the next time we meet at a car show....we'll go to the bar and discuss this in-depth...drinks are on me.

[George/Maine]

I think we all know you have the wrong lever and the shaft has been drilled.
Now the point i,m trying to make is the pin location is very close 1/8" could fix the problem.
Say the lever started at 3 oclock to 1 oclock the movemnet is less, then at 1-11 oclock. this is max travel.
If you look at the lever the pin lacation is not the same. as stock 39.
being the 39 pedal works ok for others,try your idea trial and errror.
Also make sure your pedal is hitting the floor underside for max travel.

[Robert Dip]

George/Maine.....thanks, but we all know that the 11 - 1 o'clock position is the best scenario, and that is exactly where my lever on the '39 is at. And, NO, the shaft was not drilled....it is in an untouched condition. My pedals are also at max on the floorboard underside....cannot any closer unless I raise the floor. All said and being equal as before on clearance and parts, the mystery still seems to be with the PP. It is the only part that was changed.

[DICK SPADARO]

Robert there is nothing to be discussed except the missalignment angle of your contraption and the choice of brand of your Free Beer offer.

Increasing the length of the pedal lever is the same as installing the correct length clutch lever and leaving the pedal lever stock. By the time you junk rig some adjuster adapter up you could have unbolted the too short clutch arm and bolted the correct replacement arm back on and hardly got your hands dirty.

I thought about the reason the 9" worked and the 10" didn't work as well and came up with the conclusion the the pressure plate arm height is different between the two. The PP arms dont have to be exact matches because the pedal rod adjustment is used to take up minor differences in arm height. If you have your pedal adjusted all the way out and the pedal is bumping the bottom of the floor board but when depressed still not releasing completely you dont have enough throw in the clutch shaft arm( due to the short homemade arm) thus you need a longer arm on the clutch shaft.

[Robert Dip]

Dick..."I thought about the reason the 9" worked and the 10" didn't work as well and came up with the conclusion the the pressure plate arm height is different between the two."...yes, and that is the only thing left to do. I shall get from my stash, a '48 flywheel and 10" disc & PP assembly, have right beside it the '39 flywheel and 9" clutch assembly, and in my press, measure the travel required to release the disc.

As for your first paragraph, the beer is only going to be a chaser....a double scotch is in order....the clutch shaft still has to be shorter, not longer. We may have to empty the bar...it's going to be a long night. Cheers.

[Matt in Alameda]

OK guys, this may have nothing to do with nothing.....but in 39 the clutch (and Brake) pedal had a rather thick rubber bumper ( Mac's # 91A-2476/7527.....page 19 in my catalog) in place under the floor board. The pedal would be "down" farther initially with this bumper on it and it should be able to stroke the clutch arm farther forward since more adjustment is available on the threaded rod. In other words, you are shortening the relationship of the clutch pedal bracket to the clutch arm on the bell housing.....this should leave more threads available for adjustment and the adjustment is longer, which is what you want I think............or am I more confused than everyone else here today? ......Matt in Alameda

[Robert Dip]

Matt....a good one....the thick rubber bumpers.....however, I modified the wood floor board...they are now deep set in the wood for that added throw. How much more throw do I need with this clutch ?....Thanks...Robert

[V8COOPMAN]

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Mr. Dip...You seem like the type of guy that I would enjoy sitting and consuming a beer or three with, given the chance, but we're on opposite ends of this continent and we ain't likely to meet any time soon. Nevertheless, I would have thought Dick's recall of 10th grade geometry would have surfaced by now. Yup Robert, you've got a couple of oddball parts there, especially that short arm on the trans. You suspected it was short and Barn Junk confirmed that with his measurements for a '39 arm. You've shared some interesting circumstances here. Man, this is the stuff that ALL can learn something from while playing with these old cars, IF they'll just listen and think. Unfortunately, you've gotten 40+ replies so far, quite a few of which are quick shots from the hip, and a couple that don't agree with the laws of physics. Annnnnnnd, we still don't have an answer to your basic question which essentially was..."is there any difference in height between a 9" and a 10" PP assembly?". Obviously, you have a handle on the physics of what's actually goin' on here. I've enjoyed having the opportunity to kick this around with ya. Let us know when ya have it fine-tuned. DD

[Robert Dip]

DD.....I had you in mind to join in at the 'Bar' session.....needed back-up here....BUT, you never know, the world is getting smaller, and I have gathered friends form all over the US and Canada. We enjoy our pastime tinkering around with these ole Fords...and discussions like this are fun....it's part of us, even if we happen to agree to disagree. The passion lives on...Robert

PS....I am now committed to get back to this at one time or another...Las Vegas calls...wife's idea of a 45 year anniversary....Cheers.

[DICK SPADARO]

Good morning Friends, neighbors and countryman, Since I have been providing the entertainment for the past couple days on my math ability and I agree its not great because I was in shop class more than math. This is my latest attempt to solve Roberts clutch disengagement issue.

To back up my theory and allow my friends to follow I have provided a diagram of the issue. First the clutch will not completely release with the pedal at its highest travel and its lowest depress. The clutch arm has been converted to a shorter throw arm 3" than the stock 3.5" arm. The pedal travel is approximately 6" from top to bottom out and the pedal ratio is 6 x1 (approx) and 20* of rotation gives about 1/2" of pedal throw. The throw out fork is 3.5" long.

Now with this information we are changing rotary motion into lateral motion because we have to move the throw out bearing. When comparing the stroke range of the short arm Robert has installed on his car it shows that the pedal is bottoming out on the floor board before effectively disengaging the clutch disc as the movement is stopped by the floor board due to the short throw of the 3" arm( covers 20* quicker). The longer clutch stock arm has additional pedal travel because it has not reached the 20* rotation point where the pedal would bottom on the floor board. The distance differential between the throws is the distance necessary to disengage the clutch. Therefore the shorter arm does not allow the clutch to disengage because it needs a longer rotation and cant because the pedal is bottomed out. Reverting back to the original stock arm will give the necessary travel distance in the pedal to prevent bottoming out before the clutch disc is released. Making a longer pedal arm will increase the rotation but that not the best solution. Note the throw out fork leads the clutch arm by 10* so although the intersection points are similar the clutch pedal has not reached full depression with the stock clutch arm at point B and it is at this point the additional throw releases the clutch disc. Spacing of a-b is the distance the pedal must move to disengage. Its not real as big as the diagram but its easy to reference.

The main issue is to keep the pedal from bottoming on the floor to complete the required travel and that what is happening with the short arm. It worked before but probably really not at 100% and the thickness of the clutch disc or finger height is a variable with the 10" unit.

[bbrocksr]

Originally Posted by DICK SPADARO

Good morning Friends, neighbors and countryman, Since I have been providing the entertainment for the past couple days on my math ability and I agree its not great because I was in shop class more than math. This is my latest attempt to solve Roberts clutch disengagement issue.

To back up my theory and allow my friends to follow I have provided a diagram of the issue. First the clutch will not completely release with the pedal at its highest travel and its lowest depress. The clutch arm has been converted to a shorter throw arm 3" than the stock 3.5" arm. The pedal travel is approximately 6" from top to bottom out and the pedal ratio is 6 x1 (approx) and 20* of rotation gives about 1/2" of pedal throw. The throw out fork is 3.5" long.

Now with this information we are changing rotary motion into lateral motion because we have to move the throw out bearing. When comparing the stroke range of the short arm Robert has installed on his car it shows that the pedal is bottoming out on the floor board before effectively disengaging the clutch disc as the movement is stopped by the floor board due to the short throw of the 3" arm( covers 20* quicker). The longer clutch stock arm has additional pedal travel because it has not reached the 20* rotation point where the pedal would bottom on the floor board. The distance differential between the throws is the distance necessary to disengage the clutch. Therefore the shorter arm does not allow the clutch to disengage because it needs a longer rotation and cant because the pedal is bottomed out. Reverting back to the original stock arm will give the necessary travel distance in the pedal to prevent bottoming out before the clutch disc is released. Making a longer pedal arm will increase the rotation but that not the best solution. Note the throw out fork leads the clutch arm by 10* so although the intersection points are similar the clutch pedal has not reached full depression with the stock clutch arm at point B and it is at this point the additional throw releases the clutch disc. Spacing of a-b is the distance the pedal must move to disengage. Its not real as big as the diagram but its easy to reference.

The main issue is to keep the pedal from bottoming on the floor to complete the required travel and that what is happening with the short arm. It worked before but probably really not at 100% and the thickness of the clutch disc or finger height is a variable with the 10" unit.

With all due respect Dick You've still got it wrong. A shorter lever on the throwout shaft will move the throwout fork farther.
The longer the throwout shaft lever the less the travel of the throwout fork.
Bill

[George/Maine]

I,ll second that shorter more throw.
On my 39 I had a 32 trans and was having same problem about 4" and shorted it and worked better.
If the screws on the pp are not even could cause wobble,or not adjusted right.
It has a open drive trans best remove it,check loose pin on fork,shaft, and make sure you have a return spring and up tight to floor.You want it to just about touch the throw bears don,t go for 1" play.With 3" laver you should have plenty of travel.

[Mart]

This is kind of going around in circles.

The 10" and 9" clutch assemblies should be interchangeable. The release mechanism should work the same for both. One should not require more throw than the other.

If your 10" clutch is not releasing, and your 9" was, there is something wrong with your 10" clutch assembly. If the 10" does not release and neither did the 9" then there is something wrong with your lever ratios.

I repeat - in my car I have used both 9" and 10" clutches and have only had to make a minor adjustment to the push rod.

Mart.

[Robert Dip]

I'm afraid to comment....glad to see I have back-up. For the sake of the archives, I measured the clutch bearing fork arm, and the c/c is at 3 1/8". It can increase slightly as the fork moves forward, but now we may be splitting hairs. All this to say that I have practically a 1/1 ratio on the outer clutch shaft arm as to the actual inner bearing fork.
This bar bill is gonna cost me plenty....it's now triple scotch with multiple chasers and a very, very long night.
Are we having fun yet!

[Fordors]

I was going to stay out of this one, but here goes anyway. There are two different lever ratios commonly used on Long style PP's, the 5.1-1 and a 4.7-1. A PP using the 4.7-1 levers will require more force at the pedal but it will move the pressure ring faster and would release the disc where a lever ratio of 5.1-1 might not. With no change to the linkage lever ratios (with t/o bearing travel remaining constant) 4.7-1 levers would "help" the situation.
When Ford went to the 10" clutch did they at the same time increase the static load of the pressure plate by changing the springs, or at least setting them tighter? Greater friction surface alone would not help transfer the torque but more static spring pressure would. More spring pressure makes for a stiffer pedal and Ford may have felt that undesirable so the question is this- is there a difference in lever ratios between the 9" and 10" PP's? Throwing a value out there of .100 (the amount of pressure ring travel needed) the 4.7 lever needs a t/o travel (once the fingers are contacted) of .470 to release the disc and the 5.1 needs .040 more t/o travel. Can anyone compare levers on a 9" and 10" PP?

[Robert Dip]

Fordors.....glad you did not stay out of this one....what you are saying about the different PP levers could be a problem solver here on this forever question of is there a difference between the 9 and the 10. From all of the geometry lessons we have seen here, it does not take much to make a big enough of a difference. I will definitely have to make the comparison of throw from a 9 to a 10.....at least, with the ones that i have...and who knows what has been done in the past with the different PP levers. One may have thought that they are all the same. Your input may be quite valuable....thanks for sharing this.....Robert

[George/Maine]

I think if you bend the trans lever and make 1/4 shorter you will be ok.
I had a mercury 10" on mine fingers different and made the lever on mine shorter.
The 39 big trucks used a 10" but think the pedals are not the same but also had bigger frame and may have used another shaft end.
39 pedels work but need some tweeking for other cars.
If you add on the end of shaft would need about 1/2" would buy you about 1/4" travel.I had another car and used a11" truck clutch would snap the theet trying to get 2nd gear rubber. The good old days That trans in a 51 ford car.

[DICK SPADARO]

OK This is my almost last post on this science project, I'm going to have so much free beer that I'll have to purchase a cooler.. This is whats up.. All you guys that are telling me I'm wrong are assuming the pivot points for the pedal shaft and the clutch shaft rotation are on the same plain thus the reason you believe I'm wrong and you are correct, that is not the case.

With the pivot points at the level, the rotation is as you state it, the short lever moves the 10* while the long lever does not move that distance, only about 8* of rotation. You guys would be correct if the trans shaft/pedal shaft was aligned like that but it is NOT.

The pivot point for the transmission clutch shaft is approximately 1 1/2" below the pivot point of the pedal shaft. This offset of rotation centers almost reverses the math and the short arm travels about 8* while the longer arm travels the 10*. Thus making the longer arm necessary to disengage the clutch fully.

Time to pay up Robert, do Canadians have any good beer???

[bbrocksr]

Originally Posted by DICK SPADARO

OK This is my almost last post on this science project, I'm going to have so much free beer that I'll have to purchase a cooler.. This is whats up.. All you guys that are telling me I'm wrong are assuming the pivot points for the pedal shaft and the clutch shaft rotation are on the same plain thus the reason you believe I'm wrong and you are correct, that is not the case.

With the pivot points at the level, the rotation is as you state it, the short lever moves the 10* while the long lever does not move that distance, only about 8* of rotation. You guys would be correct if the trans shaft/pedal shaft was aligned like that but it is NOT.

The pivot point for the transmission clutch shaft is approximately 1 1/2" below the pivot point of the pedal shaft. This offset of rotation centers almost reverses the math and the short arm travels about 8* while the longer arm travels the 10*. Thus making the longer arm necessary to disengage the clutch fully.

Time to pay up Robert, do Canadians have any good beer???

Still wrong.
Longer arm = less throwout fork travel.
Shorter arm = more throwout fork travel.
Lowering the throwout shaft1 1/2 " is not going to change this.
Bill

[George/Maine]

The 39 first year for hyd brakes needed new setup.I was only made for 9" clutch.
In 40 remade different setup.I don,t have one to look at but clutch arm must have been down so not hit floor.pivit for trans level to frame also lecer down.
Down makes trans shaft turn forward on top.They did away with arm.
So bend arm shorter,go with 40 pedals,or put the 9 back.
I was going to do same setup,and went with Flatomatic c4 and realy like it.
Have fun.

[Robert Dip]

George/Maine....glade you brought up the '40 scenario.....I just happen to have an entire '40 rolling chassis....another project of mine...don't ask....and dug out the trans pivoting arms. Yes, this is a different, however, the clutch pedal arm and the trans clutch shaft arms act in the same manner. Well, now it gets interesting....the '39 pedals arm is 1 3/8" c/c. The '40 is 1 5/8" c/c....1/4" increase in arc. Now for the clutch shaft arm that pivots on the frame....well, well, it measures 2 5/8"...yes shorter than the one I have which is at 3"...shorter by 3/8".....SO....we have more distance on the pedal arm, and less distance on the clutch shaft arm. This means that we have gained stroke on both counts.....and that....is self explanatory. I certainly would not have any issue with this geometry. Also for the record, I measured the difference of pedals itself, and they are exactly the same. They arcs at
11-1/4" and throws at 6"...which, when triangulated, converts to 30 degrees arcing.

Dick....we have to be careful with Canadian beer, the alcohol content is very high, but we could go with the Coronas. My army ( geometry supporters ) is increasing every day....but, we need you still alive to take care of our Flathead needs. Your loyal supporter, no matter what.... Robert

[Robert Dip]

OPPs I goofed.....the '40 pedal arm is at 1 1/8"....shorter than the '39....shoot first, ask questions after....but the '40 arm is definitely shorter by 3/8"....back to the drawing board.

[DICK SPADARO]

Ok I know I'm not a rocket scientist but I have stayed at the H Inn. All you guys say I'm wrong but never prove the point. If I'm doing something wrong I dont mind being told that, That is how you learn about anything. If I'm wrong I'll concede and say thanks for taking the time to explain my error. I know this is starting to get like a soap opera but the result will get Roberts car to shift correctly. The following is my ploting of the shift lever action that requires the longer lever to be used not the shorter or a shorter lever. If this is incorrect tell me why.

[George/Maine]

So what they did on the 40 was make the clutch shorter,This makes is eaiser
about 8 to 1,then the 40 shorter to 2 5/8" This fixed the problem with 39 clutch problems.Why take parts from the 40, just bend the arm shorter.
AS I have said because it have a 39 and had the same problem.
I had a 32 arm on mine , 4" plus and that was why mine had problems.
Shorter equals more travel.
If you had a large clock with 12" hands and moved the hands from 11 to 1 oclock,
then you had a pocket watch and moved the hands the same amount ,
witch would you have to move more from 11 to 1.
Shorter more travel.

[Mart]

I'm sorry, Dick, I can't understand your sketches.

The bottom line is that the clutch release shaft needs to achieve a certain degree of rotation to move the release fork tips far enough to get the required travel on the bearing.

If you don't want to change the pedals, you only have a certain amount of travel available at the pedal end of the push rod. The clutch lever end of the push rod will travel the same distance, it's travel guided by having to follow the arc of the lever.

Science tells us that there is a certain point along the length of that lever that the push rod needs to be attached at to achieve the shaft rotation required.

If you attach the push rod closer to the shaft you will get more rotation, if you attach it further away, you will get less rotation.

If Robert wants to use the pedals he has, without modifying them, and the clutch assembly he has, then to achieve release he needs to keep using a shorter lever until the required travel is achieved.

Ideally both levers should be at 90 degrees to the push rod at mid travel.

This is the most important point. But the setup is virtually factory correct, the chassis used is so similar to a 39 that it should all just bolt together.

I can do some diagrams, but it will take some time and may not be necessary.

Robert, why dont you make up a temporary clutch lever and drill it with a series of holes. find the one that does the trick and modify a genuine ford lever to that length.

That's what I would do if I didn't quite know what I wanted - just mock it up and see.

But the fact remains, there is something wrong with the 10" clutch assembly. It should release with the standard stroke available from a 39 pedal and release lever.

If the lever used is a genuine 39 lever then there is something wrong. If you want to go the route of a special shorter lever to make your clutch work, then that's ok, but it will end up being heavier than it should be.

I've had 40 years in the automotive industry and this sort of stuff is bread and butter to me.

Mart.

[junk yard kid]

On my 35 the frame had to be bent to clear the pedal and the then the exhaust pipe as well. I also have to have the pedal all the way to the floor to shift into second or first from a stop.

[bbrocksr]

Originally Posted by Mart

I'm sorry, Dick, I can't understand your sketches.

The bottom line is that the clutch release shaft needs to achieve a certain degree of rotation to move the release fork tips far enough to get the required travel on the bearing.

If you don't want to change the pedals, you only have a certain amount of travel available at the pedal end of the push rod. The clutch lever end of the push rod will travel the same distance, it's travel guided by having to follow the arc of the lever.

Science tells us that there is a certain point along the length of that lever that the push rod needs to be attached at to achieve the shaft rotation required.

If you attach the push rod closer to the shaft you will get more rotation, if you attach it further away, you will get less rotation.

If Robert wants to use the pedals he has, without modifying them, and the clutch assembly he has, then to achieve release he needs to keep using a shorter lever until the required travel is achieved.

Ideally both levers should be at 90 degrees to the push rod at mid travel.

This is the most important point. But the setup is virtually factory correct, the chassis used is so similar to a 39 that it should all just bolt together.

I can do some diagrams, but it will take some time and may not be necessary.

Robert, why dont you make up a temporary clutch lever and drill it with a series of holes. find the one that does the trick and modify a genuine ford lever to that length.

That's what I would do if I didn't quite know what I wanted - just mock it up and see.

But the fact remains, there is something wrong with the 10" clutch assembly. It should release with the standard stroke available from a 39 pedal and release lever.

If the lever used is a genuine 39 lever then there is something wrong. If you want to go the route of a special shorter lever to make your clutch work, then that's ok, but it will end up being heavier than it should be.

I've had 40 years in the automotive industry and this sort of stuff is bread and butter to me.

Mart.

Good explanation!
Bill

[Robert Dip]

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Awareness.....a word, or a state of mind, that I have been preaching for years comes into play here. Are we aware that the clutch activation can be great or, rather poor, as in my case, or, even worse, not workable. Have we ever, really considered this in depth when mixing & matching parts? My issue ( not problem, because it is acceptable as-is ) will be solved by modifying one of the many arms I have found in my stash. ( yes, I am a hoarder ) In the attached photos, I have a perfect looking arm with # 01W 7524, and according to the green bible, it states '41 - '48 truck. It even has an elongated surface area that I can drill another hole which can be at 2.450" c/c ( really short ) The existing one is at 2.875" c/c. The only problem with this arm is that the mounting holes are indexed in the wrong location. ( angle ) I also have another one from an unknown application ( black one ) and measures at 3.375 c/c. If mine is a modified and bent to fit, it must have come from a similar # part. This one is indexed correctly, and I shall cut, weld, bend to fit to test. I will be shooting for 2.700” c/c. ( sorry Dick )

junk yard kid……and this is that awareness situation stated above. You have a similar problem, it seems, and I do not believe there are only a few of us here. Installing ’39 pedals in a ’35….well, this is next in line for me also with my ’35 3W project. My eye and ears are wide open once more with your input.

The interesting part about this discussion is not about competing math skills, but to properly identify the proper dimensions, angles, whatever, is needed to have a comfortable operation of our clutches. We have 9”, 10’ and 11” PP…. ( I see occasionally 9.5”…never seen one, nor does the green bible state such an animal ) I guess we will eventually have to have a chart on the throws required to release the disc on each one of these….are they the same or different??

[junk yard kid]

I didnt install my pedals but i did put in the 39 box and i put the arm that came with the car on the 39 box. I found it acceptable but wanted it better on a late night a few months ago and found the dent in the frame and a park on the exhaust pipe and heated it and then pushed the clutch down hard. That 1/8 -1/4 inch helped a lot. On a different car i had the pedal threads hitting the floor boards.

[Flat Ernie]

OK - how 'bout this: everyone is right...at some point.

I think what Dick may be trying to illustrate is when pushing that shorter lever with offset pivot points, you can, in some circumstances, get to a theoretical maximum deflection where you're not going to push the short lever any further, the pushrod just sort of goes up and down - think in terms of a connecting rod and how it quits moving the piston, yet the crank continues to turn a few degrees - you can actually increase the piston dwell at TDC by lengthening the rod and keeping all else equal. In the case of two levers, it's almost an over-center condition, or very near it.

I don't know that's what's happening here, and I rather doubt it, but I think that may be Dick's point - if this were the case, lengthening the clutch lever would actually help...to a point. Make no mistake, it's a pretty small window of tolerances that would have to stack up to find yourself here...

I think under most normal circumstances, if you want to achieve more throw, the other guys are correct: longer pedal lever, shorter clutch lever = more clutch fork travel. I also think it will solve this current problem. However, I think there's an issue with the 10" clutch or disk that needs to be ferreted out...

[Robert Dip]

Flat Ernie...Thank you for your input. I am more than curious on the 10" PP, if this is the issue or not. In the near future, I shall be making tests on the 9, 10, and 11" PP required travel to release... I have all of these here in my stash of parts, as well as quite a few 10" PP and flywheels to accomodtae both the 10 & 11".......for comparison sake.

Time to end this posts, before we get to dizzy.

Thanks all for your participation and future results will be posted by me.

THE END.......Robert

[Andy]

I just took my first ride in the 32 after the clutch disk replacement. It has all stock levers and other parts. Before, The clutch was chattering. I put in a new disk which is thicker than the old used up one. I also adjusted the clutch PP arms to make sure they were even. I used blocks under the PP and measured up from the flywheel face. I had to lengthen the clutch adjustment which is expected with a thicker disk. The supprise is the clutch must now be pushed in further to disengage. It must be in the operating angle of the PP arms. All the parts are the same except for the disk.

[Mart]

The new disc probably has more waviness in the metal layer between the friction surfaces, so it gives more during engagement to make it smoother. Consequently the travel to release may be a tad longer as the waviness adds to the travel. The old plate may have less waviness or none at all.

Obviously only theory, a bit of a guess, but one possible reason. There may be others too.

Mart.

[George/Maine]

I was looking for some Flathead info and came across this pic,

Ford new they had a problem with the 39 pedal,so the redesign shows what they did.
The pedal clutch lever was made longer by 1/4" and the trans lever was extended to frame and was made shorter. New lever was shorten to 2 5/8".
The adjustment should have 1" free play at pedal and maybe 1" or more off floor.
This must have been plenty as this setup was from 1940thur 1948.

[Barn Junk]

39 pedal linkage worked fine. The reason for 40 change was to clear up room for the column shift linkage.

Originally Posted by George/Maine

I was looking for some Flathead info and came across this pic,

Ford new they had a problem with the 39 pedal,so the redesign shows what they did.
The pedal clutch lever was made longer by 1/4" and the trans lever was extended to frame and was made shorter. New lever was shorten to 2 5/8".
The adjustment should have 1" free play at pedal and maybe 1" or more off floor.
This must have been plenty as this setup was from 1940thur 1948.

[911 STEVE]

Looking for some info from an old timer. A friend has a 34 Ford hot rod (sorry) with an unusual master cyl & pedal. His dad built the car in the late 50's so he has no idea where some of the parts came from. The brake master cylinder and pedal bracket are one entire cast unit. the pedal is pivoted in this bracket and has the usual pushrod going into the master cylinder. the top of this cylinder/bracket has 4 studs made into it facing up so it can be bolted to a horizontal bracket between the dash and firewall. He has one for the brakes and one for the hydraulic clutch, mounted right next to each other. We're thinking it might be early GMC truck but there are no numbers on it. Sound familiar to anyone?????