Mechanical brakes, what i did

[CWPASADENA]

In an attempt to make the Mechanical Brakes work the good when I restored My Tudor, this is what I did:

Per Les Andrews Book, I rebuilt or replaced EVERY component.

I TIG welded and re-machined the tracks insted of replacing them.

I installed new Cast Iron Drums and properly turned them.

I used Scandinavian Woven Lining.

I arced the linings to the drums.

I "Centered" the linings when installing them on the backing plates.

I installed "Floaters" in the fronts.

ADDITIONAL MODIFICATION

I lengthened the front levers by 50%.

Reason for this;

As designed , as close as I can figure, the Front/Rear Brake Bias on a Model A is 40%Front/60% Rear.

Most modern Front Engine, Rear Drive Automobiles will have a Brake Bias in the range of 60%F/40%R to 70%F/30%R. This is because under hard braking, with weight transfer, weight if the car will be shifted more to the front wheels and the car will not have a tendency to lock up the rear wheels under hard braking.

By increasing the length of the front levers by 50%, I added 50% more brakes to the front which results in a 50/50 brake balance. This is a lot better but could be better yet. This also adds 20% additional overall total braking effort for the same pedal pressure.

RESULTS,

I have about 150 Miles on the car. When I first drove it out of the shop, I wanted to be VERY careful to be sure the brakes worked. After a few easy trips around the block, it was time to really try the brakes. Under moderate braking, it does not take a great deal of pedal effort, stops nice and straight. Under heaver braking, you can now see the radiator start to dip down and it really feels like the fronts are working.

Yesterday, I was running along about 45 MPH and was hurrying to make a green light up ahead. It turned yellow too soon and I had to stop in a short distance. I applied the brakes to the point where I started where I could hear the front brakes just want to start to lock up. Actually I applied more brake then necessary for the situation but wanted to see what a panic stop may be like. You could feel the weight transfer to the front and I was easily able to stop well short of the intersection. It really gives you a very comfortable feeling that you really have good brakes.

The woven linings with the Cast Iron drums are quiet and do not "Growl" or make noise when coming to a stop, even with the wheels not in the straight ahead position.

I am not saying this is what any one else should do, it is just what I did and the results I had.

My Experience.

Chris

[BRENT in 10-uh-C]

Actually, I am of the opinion that you took away front braking instead of increasing it due to the amount of travel it now requires vs. the normal amount of rear arm travel. The brake pedal now must pull the arm further to apply the same amount of brakes on the front.

.

[Mike V. Florida]

Is it the picture or are you missing grease fittings on the spring shackels?

[Bob C]

I was thinking the same as Brent when reading what you did to the arms.

Bob

[Jason in TX]

I'm going to also agree with decreasing the breaking action. By adding a longer arm, you decrease the force needed, but you have to also apply more movement.

Perhaps this would make more sense if you had lengthened the levers on the brake cross shaft. that would have pulled the stock lever further back. Or you could have also lengthened the push rod inside that pushes on the wedge.

[Bob Johnson]

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What did you do about the brake rod adjustment? To get the results you want you would have to loosen up the rear brake rods. The front to rear ratio is usually adjusted by the brake rods. If you shorten the front rods or lengthen the rear rods you get more front brakes. to get more rear brakes shorten the rear rods or lengthen the front rods. By lengthening the levers you have changed the distance that the break pedal has to move to to lock up the front brakes. Lets say it took 2" of travel for the brake pedal to go from a slight drag on the all 4 brakes to lockup. Now it will take 4" of travel to do the same for the front bakes. However the rears will lock up at 2" and the fronts will not be locked up. But if you lengthen the rear brake rods so the rear brakes do not start to drag until the pedal is 2" down. Then all 4 brakes will lock at 4" pedal movement.

Bob

[CWPASADENA]

Originally Posted by Mike V. Florida

Is it the picture or are you missing grease fittings on the spring shackels?

Good eye,

I took this picture before I had all the details finished. It now has grease fittings.

Chris

[fritznbud]

CW, I'd eat my lunch off your car so clean, i adjusted my brakes to work the way you have, the fronts doing more than before. They work great and i have to watch when stopping too quick, like i'm in my conventional car. I can forget what i'm driving sometimes. But i'm real happy with my adjustment.

[1931 flamingo]

How did you "safely" increase the length of the front levers.
paul in CT

[CWPASADENA]

Originally Posted by BRENT in 10-uh-C

Actually, I am of the opinion that you took away front braking instead of increasing it due to the amount of travel it now requires vs. the normal amount of rear arm travel. The brake pedal now must pull the arm further to apply the same amount of brakes on the front.

.

Originally Posted by Bob C

I was thinking the same as Brent when reading what you did to the arms.

Bob

Originally Posted by Jason in TX

I'm going to also agree with decreasing the breaking action. By adding a longer arm, you decrease the force needed, but you have to also apply more movement.

Perhaps this would make more sense if you had lengthened the levers on the brake cross shaft. that would have pulled the stock lever further back. Or you could have also lengthened the push rod inside that pushes on the wedge.

Originally Posted by Bob Johnson

What did you do about the brake rod adjustment? To get the results you want you would have to loosen up the rear brake rods. The front to rear ratio is usually adjusted by the brake rods. If you shorten the front rods or lengthen the rear rods you get more front brakes. to get more rear brakes shorten the rear rods or lengthen the front rods. By lengthening the levers you have changed the distance that the break pedal has to move to to lock up the front brakes. Lets say it took 2" of travel for the brake pedal to go from a slight drag on the all 4 brakes to lockup. Now it will take 4" of travel to do the same for the front bakes. However the rears will lock up at 2" and the fronts will not be locked up. But if you lengthen the rear brake rods so the rear brakes do not start to drag until the pedal is 2" down. Then all 4 brakes will lock at 4" pedal movement.

Bob

I KNEW THIS ONE WOULD BE LOTS OF FUN !!!!!


Lengthing the FRONT actuating lever will result in greater torque at the pivot of the lever for the same force (pull by the brake rod) on the end of the lever. With greater torque at the pivot (in this case the actuator shaft), you have greater force at the end of the lever on the opposite side of the pivot (in this case, the little arm on the other end of the actuator shaft that pushes down on the push rod). You could also accomplish the same thing by SHORTENING the lever at the cross shaft. I found it easier to work with the front levers.

As originally designed, the front brakes contribute to apx 40% of the total braking of the car. By increasing the length of the front levers you do increase the FRONT braking by 50% but the total braking (Front plus Rear) by only 20% (beings the front brakes originally only contributed 40% of the total in the first place).

IE, As originally designed, if you applied a force (pushed on) the brake pedal to the point where you had 1000 Lbs. of total brake retarding force, 400 Lbs would be contributed by the front and 600 Lbs by the rear. (400+600=1000).

By increasing the length of the FRONT levers by 50%, you increase the amount of braking effort that the front brakes contribute to the total by 50%. Example, with the SAME PEDAL FORCE required to give a total of 1000 Lbs. in the above example, you still have 600 Lb of retarding force contributed by the rear brakes (because the pull on the brake rods has not changed and you have not changed anything on the rears), but now, with the 50% longer front levers, you have 600 Lbs (insted of 400 lbs) contributed by the front brakes (400+50% x 400=600) or (400 x 1.5 =600). Now you have 1200 lbs of total braking effort (600+600) for the SAME PEDAL FORCE as used in the first example (unmodified configuretion).

As far as adjustment is concerned. I adjusted the individual brakes in the conventional manner, THEN I equalized the side to side and front to rear braking by adjusting the length of the rods. I did this with the BRAKES WELL APPLIED but not locked up. I had the car up on my lift and the wheels off. I made an adaptor that will hook over the lug studs and used an old, beam style, torque wrench to measure the braking effort of each wheel. You can also do this by having the wheels off the ground and try to turn each wheel to check the drag of each brake. YOU HAVE TO ADJUST THE FRONT TO REAR BALANCE WITH THE BRAKES WELL APPLIED, just like you should do with an unmodified system.

It does take an additional 20% of pedal travle to achieve the same pedal force, BUT you also have 20% more TOTAL BRAKING.

If you were to lengthen the front push rods you are not changing any of the leverages. All that would accomplish is you would have to lengthen the front brake rods to rotate the levers further forward to be able to release the brakes fully. What you want to do is to have more force on the front push rods for any given pedal force.

My goal was to get the BRAKE BIAS closer to optiumun and also to increase TOTAL BRAKING EFFORT for a given pedal force.

Again, I am NOT saying everyone should do this BUT this is what I did and the results I got.

Chris

[CWPASADENA]

Originally Posted by 1931 flamingo

How did you "safely" increase the length of the front levers.
paul in CT

I used four levers total. I cut to top off of two and the bottom off of the other two so I could overlap them. I TIG Welded them together and normalized them. I am not concerned at all about failure BUT I will not do any for cars that are to be run on the street. I do fabrication work and will only do this kind of stuff on competition cars that only see track use or on my own cars. I also shortened my own steering arm BUT I will not do them for others.

AGAIN, I am NOT saying others should do this, This is just what I did.

Chris

[mrtexas]

Originally Posted by CWPASADENA

I KNEW THIS ONE WOULD BE LOTS OF FUN !!!!!

Lengthing the FRONT actuating lever will result in greater torque at the pivot of the lever for the same force (pull by the brake rod) on the end of the lever. With greater torque at the pivot (in this case the actuator shaft), you have greater force at the end of the lever on the opposite side of the pivot (in this case, the little arm on the other end of the actuator shaft that pushes down on the push rod). You could also accomplish the same thing by SHORTENING the lever at the cross shaft. I found it easier to work with the front levers.

Chris

You sure you got that right? For the same amount of pedal you are now moving the front brake only 2/3 as much. I didn't take statics and dynamics in school but....

[dr.j]

Very very interesting; I understand the concept that the longer arm would require less energy to pull it back and that the longer arm would increase the distance needed. Very very interesting

[Bob Johnson]

Chris,

Please give more details on

" I adjusted the individual brakes in the conventional manner"


Bob

[CWPASADENA]

Originally Posted by Bob Johnson

Chris,

Please give more details on

" I adjusted the individual brakes in the conventional manner"


Bob

With the brake rods not yet hooked up, I adjusted each individual brake to set the clearance between the drum and shoe using the adjuster in the backing plate. Tighten the adjuster until there is a heavy drag on the brake and then back off the adjuster until there is no drag (or a very slight drag with new linings).

Then, hook up the rods and with the brake pedal blocked about 1/2 way down, adjust the length of each pull rod until there is aproximately 150 Ft. Lbs of brake torque on each wheel. I use a beam type torque wrench and NOT a "Clicker" type wrench. The actual value is not too important but all wheels must be equal to each other. This will insure you have equal brakes side to side and a 50/50 bias under moderate braking.

Release the brake pedal and check to see that all the brakes are fully released. If the brakes do fully release, check to see if you can shorten the rods just a little more before the brakes start to apply. If so, repeat the above step with a little less pedal travel. Idealy, you want the highest brake pedal with the brakes applied BUT you also want to insure the brakes will fully release and do not drag.

Even with the longer front levers, with the brakes adjusted in this manner, there is actually little additional movement of all the levers required to apply the brakes from a moderate level of braking on to where the brakes start will start to lock up.

After the brakes are initially set up, future adjustments to compensate for wear can be made with the backing plate adjusters only.

PLEASE UNDERSTAND, THIS IS WHAT I DID BUT I AM NOT TELLING ANYONE ELSE THAT THIS IS WHAT THEY SHOULD DO.

Chris

[CWPASADENA]

Originally Posted by dr.j

Very very interesting; I understand the concept that the longer arm would require less energy to pull it back and that the longer arm would increase the distance needed. Very very interesting

The brakes are adjusted to a 50/50 bias when moderately applied. The longer front levers insure this bias is maintained as braking effort is increased. After the brakes are applied to a moderate level, the shoes are fully seated against the drums, and it takes very little additional rotation of the levers (and therefore movement of the rods) to increase brake application. You are escentially just increasing the pull on the operating levers.

AGAIN, THIS IS THE WAY I DID IT AND I AM NOT SUGGESTING OTHERS DO THE SAME.

Chris

[Tibor]

I understand what your saying im only an enigneering student but I did make it to staticts, dynamics, and physics. You are saying is that by lengthing the front brake arms you trade force for distance. Simple mechanics, Like using a pully set up. You have a longer arm so you have more torque but you have to increase the distance in pedal throw.
just out of curiosity what feild of engineering were you in?
Tibor

[tiquer]

Originally Posted by CWPASADENA

The brakes are adjusted to a 50/50 bias when moderately applied. The longer front levers insure this bias is maintained as braking effort is increased. After the brakes are applied to a moderate level, the shoes are fully seated against the drums, and it takes very little additional rotation of the levers (and therefore movement of the rods) to increase brake application. You are escentially just increasing the pull on the operating levers.

AGAIN, THIS IS THE WAY I DID IT AND I AM NOT SUGGESTING OTHERS DO THE SAME.

Chris

I have to agree with you Chris in that if the brakes are adjusted to a close fit to the drum very little extra rotation is required and the length is mainly to increase the pulling power of the brake pedal. Seems to me the actual results speak for them selves. Engineer or not.

[Bob Johnson]

OK now I get it. Once the shoes engage the drums there is very little movement of the levers. Thus the extra length of the front brake levers does not make much difference and the front brake shoes "see" a greater pressure than the rears. Thanks for the explanation.

Bob

[James Rogers]

So, let me get this straight. You lengthened the front levers to get more force and leverage to the front brakes but shortened the steering (pitman) arm to get more force and leverage to the steering? Seems like a contradiction here.

[Ron Lachniet]

When I started working on my model A and read how the brakes were set up with more braking on the rear I was of the understanding that they did this so under normal braking you would not lose steering control while braking. With that in mind, I think that was some of the reason for ABS brakes in modern systems. Just a thought.

[Tom Wesenberg]

Originally Posted by James Rogers

So, let me get this straight. You lengthened the front levers to get more force and leverage to the front brakes but shortened the steering (pitman) arm to get more force and leverage to the steering? Seems like a contradiction here.

Not really, because the pitman arm APPLIES the force, and the brake shaft arm RECIEVES the force.

I understand the idea of the longer brake arm multiplying the force, but with the shorter brake arm movement, the brakes would need to be kept in closer adjustment; ie, if the brake shoe wear is allowed to accumulate before readjusting, it seems any leverage advantage would soon be lost. I haven't taken much time to think this modified brake arm theory through because I'm satisfied with my stock brakes.

If you want more braking from the front brakes, then it seems installing floaters on the fronts ONLY would be an easier way to go, and it would be easily reversible if it didn't work to your satisfaction.

[Marco Tahtaras]

I started to write this yesterday morning but was pulled away. Since then some have thought through the concept.

What Chris did was increase the leverage to the fronts which were technically under leveraged compared to later cars when Ford finally understood the reality of front versus rear needs. Yes, this does slow the actuation of the front brakes. That is normal and unavoidable. Look at the ratios of any block and tackle. The lift capacity is not determined by the size of the cable or rope (although it must be suitably sized), but the the capacity is determined by the ratio or number of wraps of the cable. The more wraps, the slower it lifts but the more it lifts with the same applied force.

Everyone assumes the Model A front brakes actuate or engage at the same rate as the rears. This is not the case. The topic came up about ten years ago regarding an article written suggesting the brakes could be adjusted 50-50 or 60-40 front-rear. I explained at that time it was simply a fallacy. In doing so you are simply reducing the function of the rear brakes and FORCING the much stiffer (less leverage) front brakes to do more of the work. Think of it this way, shortening the front brake rods to make the front brakes come on earlier is the same as lengthening the rear rods to come on later (reducing rear brake function) except the latter lowers the functional height of the brake pedal. I further explained that to even equalize the braking force at the drum (front to rear) you must actually equalize the leverage. This essentially also means making the brakes actuate at the same rate.

Now it's important to note that the simpler linkage of the rear brakes DOES provide a slight mechanical advantage due to efficiency but not nearly to the extent that the the added leverage (and slower actuation) does. Adding leverage to the fronts will similarly slow the actuation which can then be adjusted to engage at the proper time. Wear will not cause any future adjustment issues assuming the modification is not too extreme.

[JoeWay]

Like Marco, I have been composing a reply in my mind; in my case, from my perspective as a professional restorer of vintage brake parts. Marco's comments are as usual excellent and on the money, so I won't try to duplicate them.

The only downside to this change is the slight increase in pedal travel, but it is IMO insignificant compared to the increased braking response and the improvement in braking bias. As Marco mentions, even Ford soon realized he had the ratio wrong. It's much safer for the fronts to lock up first than the rears.

Sure would be nice to see these arms show up in the repop market with the short pitman arms.

Joe

[hardtimes]

somethings wrong here ? see if i got this worng !
at least more than a few (hundred) discussions here over the years. have most concluding/procliaming....Ford got it right, leave it alone stock with mechanicals...yada,etc!
now..'experts' are claiming ford got it wrong and that he realized it! then some A owner comes along with a homebrew mod and its proclaimed that that mod should be offered on the market for general consumption, to 'improve' (correct) fords mistake....'for improved' mechanical brake use. look out floaters...hereyecom!
Q... if improving model A brakes is truly the goal, why not just do the hydraulic bendix system? even ford knew that hydraulics system was the best..and eventually went with that ? yikes...would/could this be considered (gulp)rodding? no pun intended!

[James Rogers]

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Originally Posted by hardtimes

somethings wrong here ? See if i got this worng !
At least more than a few (hundred) discussions here over the years. Have most concluding/procliaming....ford got it right, leave it alone stock with mechanicals...yada,etc!
Now..'experts' are claiming ford got it wrong and that he realized it! Then some a owner comes along with a homebrew mod and its proclaimed that that mod should be offered on the market for general consumption, to 'improve' (correct) fords mistake....'for improved' mechanical brake use. Look out floaters...hereyecom!
Q... If improving model a brakes is truly the goal, why not just do the hydraulic bendix system? Even ford knew that hydraulics system was the best..and eventually went with that ? Yikes...would/could this be considered (gulp)rodding? No pun intended!

Exactly!

[CWPASADENA]

Originally Posted by Tibor

I understand what your saying im only an enigneering student but I did make it to staticts, dynamics, and physics. You are saying is that by lengthing the front brake arms you trade force for distance. Simple mechanics, Like using a pully set up. You have a longer arm so you have more torque but you have to increase the distance in pedal throw.
just out of curiosity what feild of engineering were you in?
Tibor

You have the picture, Actually, it is a very simple basic concept.

I am a Mechanical Engineer and have worked in the automotive field for about 50 years.

Good luck with your schooling. I found Mechanical Engineering to be a very interesting field, especially if you are into cars.

Chris

[CWPASADENA]

Originally Posted by James Rogers

So, let me get this straight. You lengthened the front levers to get more force and leverage to the front brakes but shortened the steering (pitman) arm to get more force and leverage to the steering? Seems like a contradiction here.

Steering is the opposite case of brakes. With steering, it takes a fixed amount of force (push or pull) on the drag link to turn the front wheels. To DECREASE the torque of the pitman arm (which is directly related to steering effort) required to produce that fixed amount of force at the end of the steering arm, you SHORTEN the length of the steering arm. Force x Length = Torque. For a given force, as the length decreases, the torque decreases.

With brakes, if you want to INCREASE the torque of the operating shaft without increasing the pulling force on the end of the lever, you INCREASE the length of the lever. Force x Length = Torque. For a given force, as you increase the length of the lever, you increase the torque. Increasing the torque of the operating shaft will increase the braking effort (apply the brakes harder).

It is all mechanics.

Chris

[MikeK]

A non-mechanical mod to shift braking to the front is to use woven linings in the front only, harder molded in the rear. Worked for me.

[CWPASADENA]

Ford went from Model T Brakes, (Rear brakes only) to Four wheel Brakes with the Model A and a 40/60 Front to Rear Bias. This was a BIG STEP. From 32-38, I am not sure if Ford maintained a 40/60 Bias but I suspect they started to shift to more front bias. By 1939 the went to Hydraulics which had a design bias of closer to 60/40. I believe by 1946, they even increased the size of the front wheel cylinders and were probably closer to 65/35.

In 1928, I do not think Ford had a real good understanding of brake bias (no body did) and they felt they did not want to lock up the fronts so as not to loose steering. In actuality, locking up the rears well before the fronts can cause the vehicle to "swap Ends". Have you ever driven an old Pick-up with no load in the rear on a wet winding road and have it turn around on you for what you thought was no reason. The rear brakes locked with light applicatiion and you lost all control.

All I have done, is used a little more modern thinking to improve the operation of the Model A Ford Brakes. This is a VERY simple modification and it really works well. I have another Model A with original brakes in good working order to compair it to.

I guess this is sort of like the shortened steering arms, some of us enjoy easier steering.

Again, This is what I did and I am not suggesting others do the same.

Chris

[Tibor]

Originally Posted by CWPASADENA

You have the picture, Actually, it is a very simple basic concept.

I am a Mechanical Engineer and have worked in the automotive field for about 50 years.

Good luck with your schooling. I found Mechanical Engineering to be a very interesting field, especially if you are into cars.

Chris

But remeber engineers arn't allowed to no anything about cars especially about fixing them. Just ask someone from the general public and they will tell you.

I like what you did, Im going to consider doing this modification to my A. Thanks for the luck ill take all i can get.

[Mike V. Florida]

I don't get it? I put my foot on the brake pedal and the cars slows to a stop. I slam on the brakes all four wheels lock up. No spinning around, no sideways sliding.

I guess this whole thread to me falls under it's your car do to it what you want.

[CWPASADENA]

Originally Posted by hardtimes

somethings wrong here ? see if i got this worng !
at least more than a few (hundred) discussions here over the years. have most concluding/procliaming....Ford got it right, leave it alone stock with mechanicals...yada,etc!
now..'experts' are claiming ford got it wrong and that he realized it! then some A owner comes along with a homebrew mod and its proclaimed that that mod should be offered on the market for general consumption, to 'improve' (correct) fords mistake....'for improved' mechanical brake use. look out floaters...hereyecom!
Q... if improving model A brakes is truly the goal, why not just do the hydraulic bendix system? even ford knew that hydraulics system was the best..and eventually went with that ? yikes...would/could this be considered (gulp)rodding? no pun intended!

I am NOT saying "Ford got it wrong". I am saying "Ford did the best they could with the knowledge they had at the time".

Hopefully, the understanding of brake dynamics has increased in the past 80 years. Adding more front bias definately will improve the overall performance of the braking system.

NOW;

This is NOT some "Homebrew Mod".

This is a well engineered, well designed and well executed modification.

I WAS NOT GOING TO GET INTO THIS BUT:

MY BACKGROUND IS:

I am a Degreed Mechanical Engineer.

I have worked in some facet of the Automotive Industry for more then 50 years.

For many years, I was in charge of the Brake Test Division of Clayton Mfg. Co. having designed Dynamic Brake Test Equiptment and Research Brake Dynamometers powered by motors as large as 400 HP.

I have Worked with the major Auto Manufacturers regarding "End of the Assembly Line" and "In the Field" Dynamic Brake Testing Equiptment.

I have worked with the US Goverment and several of the States regarding Brake testing and inspection for "In Service Vehicles".

I have been involved with Motorsports for many years and Vintage Road Racing where I have restored, and competed in Race cars equipted with both Disc and Drum Brakes. If you want to have a challange, try to get a Road Race Car with Drum Brakes to stop consistantly from the start of the race to the end.

I have worked on everything from an early '30s Indianapolis Race Car to a Modern Ferrari.

This is my background, what is yours????

AGAIN, I AM NOT SAYING ANYONE ELSE SHOULD DO THIS, THIS IS WHAT I DID AND THE RESULTS I GOT.

Chris

[CWPASADENA]

Originally Posted by MikeK

A non-mechanical mod to shift braking to the front is to use woven linings in the front only, harder molded in the rear. Worked for me.

This is certainly one way of improving the front to rear bias but in doing so, you have lost some of the rear brake performance and therefore you have less total brake effort for a given brake pedal force.

By increasing the length of the front levers, you not only improve bias BUT you also increase total braking effort for a given brake pedal force.

Again, This is just what I did and am not suggesting other also do the same. (Sorry, but I have to put a "Disclamer" in all my comments)

Chris

[Mike V. Florida]

Originally Posted by CWPASADENA

I WAS NOT GOING TO GET INTO THIS BUT:


Chris

Glad you did!

It's always good to see where someones point of view comes from!!!

[CWPASADENA]

Originally Posted by mike v. Florida

i guess this whole thread to me falls under it's your car do to it what you want.

yes!!!!!

[Bob Johnson]

Chris,

I for one thank you for the information. I learned some things.

Bob

[john in illinois]

Thanks for the discussion Chris.

[Kevin in NJ]

Before anyone jumps out and just starts modifying their cars let us think a bit about this.

Disclaimer: I am not saying this lever mod is good or bad. It certainly has technical merit, but I think it is not something the average guy wants to do as the brakes have to be done with attention to details as the front brake shoes have to be set up tight to the drums.

My first question comes from the comparison of any mod to original.
Does it really get you any worthwhile advantage in real life?

Do they really work better than factory?
We do not know for fact if any mods are better then factory.

We do know properly restored to original brakes work great.

There needs to be a quantitative set of data to determine if the changes are really anything good. Not just someone who thinks it works better then what they previously had experienced.

For example, using the same body or same type of body (weight distribution is important) one would first restore the brakes back to factory.
Then using a repeatable technique measure the brake power. The car would have to be run until the shoes were fully wore in to the drums. Once max braking is achieved with the factory set up, record the numbers.
Then change the levers and re run the tests.
Then change to the floaters.

Until these types of tests are run the ideas of changing the brake system are a nice novelty. All we know is a person changed the brakes and found them to work great- but compared to what? How much had the pedal travel and effort changed? Saying "it seems to be less pressure" is not very good, the person is comparing against what?

When compared to the fact just properly restoring the factory tolerances is known to give great brakes why complicate matters?
Lets be real. Many have troubles with just bringing the brakes back to factory. Most are doing band aid repairs and then throwing in some mods in hopes of better brakes. In the process skipping steps.


If real science was applied we might find the modified brakes are 10% less braking or only 5% more braking under certain conditions like running 65 MPH. At what point is it worth making the changes given how cars are driven?

Of course, the science may also find the mod significantly improves the brakes.

Again, I am not trying to knock CW's idea as it may be a very good idea.

I am just adding some perspective for all to consider. We should not be running out and changing stuff willy nilly just because one person did a change and he thinks it works great. (I am not trying to put down CW, just put perspective on a larger issue)


From a historical context. We know the A brakes are the Fords first attempt at a 4 wheel brake system. There were several variations during production. If you take the time to surf through the 1928 to 1939 service bulletins you will see the evolution of the Ford mechanical brakes. Ford did go to a floating brake system using wedges front and rear by the end.

The A brakes certainly were not the best that Ford could have produced.
They were learning as they go.
We know for FACT that properly restored the brakes are only limited by the small tire contact patch of the original tires.


Finally,
My opinions based on some facts:
The original mechanical brake system is the best choice if you are using the original wheels and tires.
A car with more HP, 16" wheels and radial tires would make me think seriously about going to hydraulics.
Hydraulics are not the best choice for cars that are not driven much. They will fail if not used frequently.

[MikeK]

Thanks Chris for a thread about a totally new mod that stirs controversy. That's been missing here for a while. Now someone needs to start one about how they adapted a modern vacuum booster to the cross-shaft for mechanicals.

[CWPASADENA]

Originally Posted by Kevin in NJ

Before anyone jumps out and just starts modifying their cars let us think a bit about this.

Disclaimer: I am not saying this lever mod is good or bad. It certainly has technical merit, but I think it is not something the average guy wants to do as the brakes have to be done with attention to details as the front brake shoes have to be set up tight to the drums.

My first question comes from the comparison of any mod to original.
Does it really get you any worthwhile advantage in real life?

Do they really work better than factory?
We do not know for fact if any mods are better then factory.

We do know properly restored to original brakes work great.

There needs to be a quantitative set of data to determine if the changes are really anything good. Not just someone who thinks it works better then what they previously had experienced.

For example, using the same body or same type of body (weight distribution is important) one would first restore the brakes back to factory.
Then using a repeatable technique measure the brake power. The car would have to be run until the shoes were fully wore in to the drums. Once max braking is achieved with the factory set up, record the numbers.
Then change the levers and re run the tests.
Then change to the floaters.

Until these types of tests are run the ideas of changing the brake system are a nice novelty. All we know is a person changed the brakes and found them to work great- but compared to what? How much had the pedal travel and effort changed? Saying "it seems to be less pressure" is not very good, the person is comparing against what?

When compared to the fact just properly restoring the factory tolerances is known to give great brakes why complicate matters?
Lets be real. Many have troubles with just bringing the brakes back to factory. Most are doing band aid repairs and then throwing in some mods in hopes of better brakes. In the process skipping steps.


If real science was applied we might find the modified brakes are 10% less braking or only 5% more braking under certain conditions like running 65 MPH. At what point is it worth making the changes given how cars are driven?

Of course, the science may also find the mod significantly improves the brakes.

Again, I am not trying to knock CW's idea as it may be a very good idea.

I am just adding some perspective for all to consider. We should not be running out and changing stuff willy nilly just because one person did a change and he thinks it works great. (I am not trying to put down CW, just put perspective on a larger issue)


From a historical context. We know the A brakes are the Fords first attempt at a 4 wheel brake system. There were several variations during production. If you take the time to surf through the 1928 to 1939 service bulletins you will see the evolution of the Ford mechanical brakes. Ford did go to a floating brake system using wedges front and rear by the end.

The A brakes certainly were not the best that Ford could have produced.
They were learning as they go.
We know for FACT that properly restored the brakes are only limited by the small tire contact patch of the original tires.


Finally,
My opinions based on some facts:
The original mechanical brake system is the best choice if you are using the original wheels and tires.
A car with more HP, 16" wheels and radial tires would make me think seriously about going to hydraulics.
Hydraulics are not the best choice for cars that are not driven much. They will fail if not used frequently.

Kevin,

I will certainly agree with you that for a proper comparison, there needs to be a proper engineering study. Base line test information needs to be determined with a properly restored original brake system. Then change only the front levers and re-adjusted the brakes and repeat the tests. The "base line" test results and the "as modified" test results can then be compaired.

If someone would like to undertake this, I would be glad to assist.

Actually, it would be real easy to make up a set of levers with two holes in them, one for the "stock" length lever and one for the "Modified" length lever. This way, it would be very easy to switch back and forth between "stock" and "Modified".

I would never suggest someone put the longer levers on their car unless the complete original brake system is in very good condition. All the modifications in the world will not overcome a worn out brake system.

Again, This is just what I did and I am not suggesting anyone modify there brakes in this manner.

Chris

[CWPASADENA]

Originally Posted by MikeK

Thanks Chris for a thread about a totally new mod that stirs controversy. That's been missing here for a while. Now someone needs to start one about how they adapted a modern vacuum booster to the cross-shaft for mechanicals.

NOW, This is an interesting idea!!!!

Chris

[CWPASADENA]

Originally Posted by Marco Tahtaras

I started to write this yesterday morning but was pulled away. Since then some have thought through the concept.

What Chris did was increase the leverage to the fronts which were technically under leveraged compared to later cars when Ford finally understood the reality of front versus rear needs. Yes, this does slow the actuation of the front brakes. That is normal and unavoidable. Look at the ratios of any block and tackle. The lift capacity is not determined by the size of the cable or rope (although it must be suitably sized), but the the capacity is determined by the ratio or number of wraps of the cable. The more wraps, the slower it lifts but the more it lifts with the same applied force.

Everyone assumes the Model A front brakes actuate or engage at the same rate as the rears. This is not the case. The topic came up about ten years ago regarding an article written suggesting the brakes could be adjusted 50-50 or 60-40 front-rear. I explained at that time it was simply a fallacy. In doing so you are simply reducing the function of the rear brakes and FORCING the much stiffer (less leverage) front brakes to do more of the work. Think of it this way, shortening the front brake rods to make the front brakes come on earlier is the same as lengthening the rear rods to come on later (reducing rear brake function) except the latter lowers the functional height of the brake pedal. I further explained that to even equalize the braking force at the drum (front to rear) you must actually equalize the leverage. This essentially also means making the brakes actuate at the same rate.

Now it's important to note that the simpler linkage of the rear brakes DOES provide a slight mechanical advantage due to efficiency but not nearly to the extent that the the added leverage (and slower actuation) does. Adding leverage to the fronts will similarly slow the actuation which can then be adjusted to engage at the proper time. Wear will not cause any future adjustment issues assuming the modification is not too extreme.

Marco,

Thanks for your input.

I tend to write like an Engineer and you have the ability to explain things in a very clear and easily understood manner.

Your comments are always valued and appreciated.

Chris

[Bob C]

Here is a picture of a vacuum setup
.

[Special Coupe Frank]

Originally Posted by MikeK

Thanks Chris for a thread about a totally new mod that stirs controversy. That's been missing here for a while. Now someone needs to start one about how they adapted a modern vacuum booster to the cross-shaft for mechanicals.

It's been did. Vacuum-boosted mechanical brakes were around in the early to mid 1930's... some of the big Lincolns used them, among others.

Maybe not "modern", but they existed.

[MikeK]

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Originally Posted by Special Coupe Frank

It's been did. Vacuum-boosted mechanical brakes were around in the early to mid 1930's... some of the big Lincolns used them, among others.

Maybe not "modern", but they existed.

Originally Posted by Bob C

Here is a picture of a vacuum setup
.

I never said there were no vacuum assists on mechanicals!
I pondered the idea of using a modern vacuum assist. THAT has never been done to my knowlwdge on an A. Brackets/ linkage/ leverage, etc. It would be a design challenge, as modern boosters are basically "push" operation, and mechanical brake systems are based on all "pull" rods.

It would be interesting if was worked out with a new available booster and parts. That would make a leverage change like Chris did to shift the front/rear bias a toe-tappin' delight.

[hardtimes]

chris,
i didnt say that YOU said that 'ford got it wrong'...reread the thread! it was said by other. impressive resume, indeed! 'homebrew' may have been a condensed description, certainly not meant to be derrogatory, which is apparenyly how you took it..and i now can see why knowing some of your history! i can appreciate your applying your expertise to improve the A mechanicals...and would be right in line to purchase any real improvement thereto!
mabe said wrong, and certainly not directed towards YOU, but i read over/over the same past imput to 'leave them there stock mechanicals alone as ford made them'. then some new /differing change idea comes along.....and out the window goes the leave them alone crowd!

btw chris,
i do not have as great a background as you , in this field. however, i see/understand your method/application! i also have 50 years of driving cars with mechanical and hydraulic brake systems, including fords...practical application! good luck with your efforts !
i'd be interested to hear from an engineer with your background, why a model A with bendix hydraulics and modern materials, i.e.- stainless line, synthetic fluids and PROPER installation/maintenance...why you think it wouldnt last?

[Special Coupe Frank]

I pondered the idea of using a modern vacuum assist. THAT has never been done to my knowlwdge on an A. Brackets/ linkage/ leverage, etc. It would be a design challenge, as modern boosters are basically "push" operation, and mechanical brake systems are based on all "pull" rods.

It would be interesting if was worked out with a new available booster and parts. That would make a leverage change like Chris did to shift the front/rear bias a toe-tappin' delight.

Whether it's a modern "co-axial" booster or a 1930's "pull-can", the effect is the same: a vacuum-assisted device, adding to the operators pedal effort to apply the brakes.

Adding a vacuum servo to the main pull rod of an otherwise-stock Model A braking system would not change any leverage or alter the front-rear brake bias; it would simply reduce the amount of pedal effort required on the part of the driver.

I guess it could be done; the tricky part would be setting-up the reaction valving.

The 1956-'62 MoPars did have a similar vacuum pedal-assist power brake: it was a big oval can or bellows mounted above the stock MC, and an operating rod that went through the firewall, acting on a lever attached to the brake pedal arm. Have them on my '60 Windsor... they work pretty well, but it's a real Rube Goldberg-looking set-up.
PITA to check the brake fluid in the MC too.

By 1963, MoPar came to its senses and adopted Bendix brakes, and coaxial power-brakes,like the rest of the industry.

[1931 flamingo]

On the idea of vac assisted mech brakes, It seems that many people are having enough trouble getting the vac w/shield wiper to work with the available vacuum, how big is the vac resevoir going to have to be to get anny vac assist to work?
Paul in CT

[Glenn of northport]

30 years ago i bought longer arms used them for many years last year i redid my brakes took off the arms,i just checked them and they are 5 inches long .I was happy with them and also with orginal ones,

[MikeK]

Originally Posted by 1931 flamingo

On the idea of vac assisted mech brakes, It seems that many people are having enough trouble getting the vac w/shield wiper to work with the available vacuum, how big is the vac resevoir going to have to be to get anny vac assist to work?
Paul in CT

The reservoir is built into the modern assist units, and generally holds sufficient vacuum for 2 complete applications. An A will produce plenty of vacuum to "charge" the unit while driving, more than many modern cars. Vacuum wipers suffer during acceleration, and speed up during deceleration, exactly the time an assist unit will get it's vacuum topped off. What will be needed is a larger fitting and hose to the intake manifold, something like 3/8" I.D.

This is a small diameter (about 6") dual diaphragm unit.

[1931 flamingo]

Thanks Mike!!! Love this place, so much info right at our finger tips.
Paul in CT

[Special Coupe Frank]

Originally Posted by MikeK

This is a small diameter (about 6") dual diaphragm unit.

Could it be as simple "inserting" this booster into the middle of the main pedal to cross-shaft rod ? ( Conceptually, at least? )

The stock battery location would cause some issues...

Someone could make it work...

[CWPASADENA]

Originally Posted by hardtimes

chris,
i didnt say that YOU said that 'ford got it wrong'...reread the thread! it was said by other. impressive resume, indeed! 'homebrew' may have been a condensed description, certainly not meant to be derrogatory, which is apparenyly how you took it..and i now can see why knowing some of your history! i can appreciate your applying your expertise to improve the A mechanicals...and would be right in line to purchase any real improvement thereto!
mabe said wrong, and certainly not directed towards YOU, but i read over/over the same past imput to 'leave them there stock mechanicals alone as ford made them'. then some new /differing change idea comes along.....and out the window goes the leave them alone crowd!

btw chris,
i do not have as great a background as you , in this field. however, i see/understand your method/application! i also have 50 years of driving cars with mechanical and hydraulic brake systems, including fords...practical application! good luck with your efforts !
i'd be interested to hear from an engineer with your background, why a model A with bendix hydraulics and modern materials, i.e.- stainless line, synthetic fluids and PROPER installation/maintenance...why you think it wouldnt last?

Thanks for your comments,

I am not looking for everyone to agree with me, or anyone for that manner. I am open to a constructive discussion. If I came down on you a little hard, I appologize. I try to be very careful about labling people or ideas. Certainly no body knows everything, all of us have some area of expertise and we can all learn.

As far as re-working the model A Brakes as Self energizing Hydraulics, I think someone is selling a kit to do this. There is nothing wrong with converting a Model A to Hydraulics but for this car, my personal preference was to leave the mechanicals and see if I can make them a little better.

I also understand there is a kit that converts the mechanicals to self energizing. I built this chassis about 6 years ago and this kit was not available or prehaps I would have considered that approach. I also have read on The Barn where some are very satisfied with this modification while others could not get the adjustment right and went back to the original configuration. I am not familiar with this modification so I would not have an opinion.

What I did is just a little different approach. This modification is simple, easy to install and adjust. Personally, I like how it works.

Again, I am not suggesting anyone else does this, this is just what I did.

Chris

[Bob C]

Probably need to find a booster like these.
http://www.pbr.com.au/products/heavy...erChambers.pdf

Bob

[CWPASADENA]

Originally Posted by Glenn of northport

30 years ago i bought longer arms used them for many years last year i redid my brakes took off the arms,i just checked them and they are 5 inches long .I was happy with them and also with orginal ones,

I was not aware that longer arms were made and sold 30 years ago but I am not supprised. There is really not much that is actually new.

Somewhere, I have an old kit that re-works the internals of the Model A front brakes. I think the idea was along the lines of making the fronts self energizing. This is an old kit that was sold back '30s or '40s. I will have to dig it out and see what it is all about.

Chris

[BCCHOPIT]

Originally Posted by 1931 flamingo

On the idea of vac assisted mech brakes, It seems that many people are having enough trouble getting the vac w/shield wiper to work with the available vacuum, how big is the vac resevoir going to have to be to get anny vac assist to work?
Paul in CT

You don't need brakes going up hill

[fiftyv8]

I have this question about an after market brake boosting product I've seen mentioned on the HAMB but at that time did not need to know about.

Who makes or sells this item that attachs to the main brake rod bar under the center crossmember and provides braking assistance to mechanical rod brakes.

I believe they are made especially for Model A Fords.

I've done a search here but come up with nothing.
It could have been they were mentioned in a thread about something else.

Any help or links would be much appreciated.

I am wondering if it is related to the folks in CA doing hydraulic brake conversions for Model A's.

Does anybody know where to start looking???

[PetesPonies]

I like what you did. It is basic mechanical advantage engineering and to me seems to be a good change. I assume you all are familar with this change that is available too ?

https://www.youtube.com/watch?v=2EjRe411l3M

[BILL WILLIAMSON]

Very good thread! Lots of info to ponder.
I once fabricated a new diaphragm for the vacuum booster on a '36 Lincoln Model "K." Car weighed 5,990 lbs, 16 inch brakes, built like a ton and a half TRUCK! Stopping was only a FANTASY without the booster!! The booster was gigantic! WAY too big for a light car. Bill W.

[jerry rose]

I haven't been here for a while. I see we can talk modifications and not be brow beat and told to go to the hamb board.

[BILL WILLIAMSON]

Jerry,
Could this mean that we're MATURING a bit & not being so MEAN spirited? Bill W.

[Will Kimble]

How about lengthening the arm on the cross shaft as well? Am I right to think it would increase leverage and make the front brakes come on sooner?

I think this is where I would attempt to adjust the front to rear ratio.