4.11 and 3.78 pinion difference?

[thunderbirdesq]

Is there a difference between the pinion gears for these two gearsets? I know they're both 9 tooth.... Having trouble setting carrier bearing preload/gear mesh on a supposed 3.78 gearset, thinking meybe I have a mismatched set...

[ford38v8]

Yes, they are different. Also can be diferent even if correct tooth count. Every set was lapped in at the factory, and etched with it's own serial number per each set.

Hint on the preload: Don't mess with the KRW spring loaded gage, it's not nearly as accurate as you'd think it to be. A fast, easy, and really much more accurate method... Using a large bench vise, clamp the spline in the vise pointing down. Take the banjo in both hands and spin it hard and fast. When you have the preload right, it will make less than one complete turn and stop.

[thunderbirdesq]

Wonderful. That's what I figured...

Even with all the paper shims installed, as the side bolts are tightened, the pinion gets progressively harder to turn, and feels sorta lumpy as it tightens up. Pretty sure it's not the bearings...

Never encountered this problem before.

Thanks for the tip too!

Originally Posted by ford38v8

Yes, they are different. Also can be diferent even if correct tooth count. Every set was lapped in at the factory, and etched with it's own serial number per each set.

Hint on the preload: Don't mess with the KRW spring loaded gage, it's not nearly as accurate as you'd think it to be. A fast, easy, and really much more accurate method... Using a large bench vise, clamp the spline in the vise pointing down. Take the banjo in both hands and spin it hard and fast. When you have the preload right, it will make less than one complete turn and stop.

[ford38v8]

The pinion preload must be done before the axle housings are installed. That's the preload I thought you meant?

[thunderbirdesq]

Pinion preload is already set, I'm talking about the carrier bearing setting. I think I'm having gear tooth interference because I have a mismatched gearset. Either that or I neglected to remove a carrier bearing shim when pressing on the new bearings, but I doubt that... Feels like gear teeth.

[JM 35 Sedan]

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What is the history on this gear set you are trying to use? Did you remove them from a rear as a set, did you buy them as a set, or? ? Are they original Ford gears or newly manufactured reproduction gears? Look for the number on the small bearing end of the pinion opposite the splined end. Is this same number etched into the back surface of the ring gear?
As Alan said you can not mix ring/pinion gears from different ratio sets even when tooth count is the same BECAUSE the cut gear profiles are usually different.

[thunderbirdesq]

Well then... we've got a problem. They're definitely NOT a matched set, this is a quickchange that I bought from a speed shop that only came with the pinion. To be honest this is not even close to the first problem I've encountered with this deal...

damn.

[JM 35 Sedan]

I'm wondering if your QC will accept stock Early Ford V8, '35-'48, banjo rear gears? If so it would not be very difficult to remedy your situation with a good matched set of used gears. What does the spline count need to be on the pinion gear for your QC? Which of the two ratios mentioned in your initial post would you prefer to have? Good used 4.11 ten spline sets are easy to find (I have 3 of 4 good used sets that I have no use for). 3.78 ten spline sets are more difficult to find. 3.78 six spline sets are easy to find used or buy new if you can use a six spline set in your QC. Just some random thoughts.

[thunderbirdesq]

Either set would work, I don't really have a preference, yes it does use early ford gears, six splines, the only modification would be to turn down the end of the pinion to the id of the rear cover bearing. It's actually a welded unit built from a ford banjo center.

The MAIN problem is that I was hoping to get this under the car before a trip to bonneville that I leave for on Saturday. Unfortunately, that doesn't look like its going to happen at this point. The car currently has 3.54 gears in it so it's not too terrible, but a little more leg on a 5000 mile round trip would make the journey a bit more pleasant.

[JM 35 Sedan]

Maybe finding a good used set of 3.78 six spline gears in your neck of the woods and getting it together by Sat. is doable but watch out for old Murphy and his Laws throwing a wrench in those gears during that 5k mile run. Charlie ny who posts here is up near you and could possibly help you find the gears you need and maybe get that rear together properly and on time to make the switch. We will be at Bonneville on the 11th....maybe see you there?

[thunderbirdesq]

I've got a phone message into Charlie already, if anyone can help, it'll be him. Yea, I would have MUCH, much, MUCH rather preferred doing this job about 5 months ago, but despite my best intentions and planning, here I am in the eleventh hour doing my best to keep from tearing all my hair out.

I just fooled with it some more, it's definitely NOT a bearing crush issue, there seems to be a spot in the rotation where I can turn the pinion by hand pretty freely, but it quickly becomes notchy and difficult. If I center the pinion in the free area, I can turn both axle shafts with no drag by hand. Again, confirming my suspicions that it's a gear mesh problem... Egad...

See you there for sure, Look for the much-chopped, Yblock powered, 34 5w in grey primer running with the Rolling Bones crew. It may or may not have a QC under it, haha!

-andy

[thunderbirdesq]

Figured out my ratchety clunking problem, turns out the pinion support bearing wasn't quite seated as far as it could be and the inside edge of the ring gear was contacting the edge closest to the pinion teeth... Seated it a little further and reinstalled the pinion, reset the preload... seems to set up nicely now, gear mesh contact pattern looks nice @ .006" lash. I'm gonna give this a whirl... knowing full well I may be swapping it out in a hotel parking lot somewhere in the midwest. Definitely bringing my 3.54 gears/center/loaded carrier along for the ride as a spare. Keep your fingers crossed and say a little prayer for me please!

cheers and thanks fellas!

[SUHRsc]

Phew... cuttin' it close Andy.... You'll make it... the whole car seems to have been a whirlwind of gettin' it done with positive results!

Safe travels!
Have fun!
Zach

[cvstl]

Just a question, but why not leave the 3.54s in for a 5k mile run? (Other than the obvious coolness of the QC.... but your car has plenty of cool without a QC)

You're running a '39 trans right, or do you have an O.D.?

Just seems like a few less revs on that long of a trip would be a little more pleasant

[thunderbirdesq]

Originally Posted by SUHRsc

Phew... cuttin' it close Andy.... You'll make it... the whole car seems to have been a whirlwind of gettin' it done with positive results!

Safe travels!
Have fun!
Zach

Thanks Zach, let's hope the trend continues! While installing the QC yesterday we found a cracked rear drum, a crumbling rear brake shoe, and while pulling the trans to replace the noisy throwout bearing that you may have heard groaning a bit when I pulled into your place the other day, I found it wasn't the throwout bearing at all, but a broken pressure plate... Jeez, this thing is FIGHTING me every step of the way! I had 16 hours of whirlwind yesterday with only a 15 minute break for a spam sandwich and I've been at it all day so far today doing routine maintenance bs... packing bearings, greasing things, changing the oil, tightening bolts, topping things off, and checking things over etc... Ugh... I'm tired.

I joked with my navigator for the trip, Dave, that after busting our humps like crazy to get this thing in shape it would probably throw a rod through the block halfway through OH, hahaha!

Originally Posted by cvstl

Just a question, but why not leave the 3.54s in for a 5k mile run? (Other than the obvious coolness of the QC.... but your car has plenty of cool without a QC)

You're running a '39 trans right, or do you have an O.D.?

Just seems like a few less revs on that long of a trip would be a little more pleasant

Yea, it's a '39 trans, no od, the wheel bearing surfaces on the rear that I've been driving around are probably as bad as any I've ever seen, I didn't trust them so a rearend rebuild was in order either way. With the QC spur gears I have I can run an effective ratio of 3.00:1, much nicer than even a 3.54 set. I was going to bring my old banjo center and gearset in case of catastrophic results on the way, but I found this when I cracked it open!!! The missing tooth was NOT in the case! I've been driving this dang thing ALL over the place, 2500 miles so far and never noticed anything!

My pal Jim is letting me borrow a nice 3.54 gearset for spare parts, although the thought of rebuilding a rear end in a hotel parking lot is not something I relish the thought of...

[cvstl]

Originally Posted by thunderbirdesq

Yea, it's a '39 trans, no od, the wheel bearing surfaces on the rear that I've been driving around are probably as bad as any I've ever seen, I didn't trust them so a rearend rebuild was in order either way. With the QC spur gears I have I can run an effective ratio of 3.00:1, much nicer than even a 3.54 set. I was going to bring my old banjo center and gearset in case of catastrophic results on the way, but I found this when I cracked it open!!! The missing tooth was NOT in the case! I've been driving this dang thing ALL over the place, 2500 miles so far and never noticed anything!

My pal Jim is letting me borrow a nice 3.54 gearset for spare parts, although the thought of rebuilding a rear end in a hotel parking lot is not something I relish the thought of...

Dohhh .....I forgot about the whole benefit of the QC.

Considering what you started with a few months ago, changing out a gear set in a parking lot is a piece of cake. Hope you don't have to do it though.

Safe Travels & Smooth Sailing.... and don't forget pics for us back home.

[thunderbirdesq]

Well, this mismatched set ran just fine the whole way out to the salt flats and back, almost 5k miles. I'm going to disassemble in a week or so to check everything out and add a pinion seal as it did shove lube up the TT with its lower driveshaft input... every 500 miles or so I'd drain a cup out of the trans and pour it back in the rear. Aside from that it worked out great.

[uncle max]

Originally Posted by thunderbirdesq

Well, this mismatched set ran just fine the whole way out to the salt flats and back, almost 5k miles. I'm going to disassemble in a week or so to check everything out and add a pinion seal as it did shove lube up the TT with its lower driveshaft input... every 500 miles or so I'd drain a cup out of the trans and pour it back in the rear. Aside from that it worked out great.

"She's about a Mover"...

[thunderbirdesq]

Originally Posted by uncle max

"She's about a Mover"...

Haha, you heard them playing that Sir Douglas Quintet hit on the casino "muzak" too, huh Max? BTW, had a chance to check out your cool car in the lot but didn't see you around it, next time...

[4ford]

With all that was said in the posts about gears, is it advisable to get a set of gears from speedway and have no problems. Or get a set that is used that match? Iam thinking about changeling to 354 or 378s. But would like to know a good sorce for them. It's a 1941 coupe a few guys say speedways are ok.? Any input? Or thoughts

Thanks mike