1935 rear end with 378 gears

[epw1949]

i would like to put 378's gears in my 34 rear end,but no one makes them,i do have a 35 rear with 378's. My question is: Has anyone used 35 gears in a 34? I know the banjo is wider on the 35,but can the ring and pinon be machine to fit the 34? Thanks for any help in advance.e.p.w.

[deuce lover]

They will fit (10 spline)except the pinion shaft is longer than a 34 so the hole for the shear pin is moved up maybe an inch.You can either cut the drive shaft or redrill the pin hole (on the drive shaft)to line up with the pinion.

[35fordtn]

Try reading through this thread
https://www.fordbarn.com/forum/showth...ght=1935+gears

[Mart]

There is a vendor that sells 3.78s and 3.54s already modified to fit the earlier 32-34 V8 rear end housing. They are 6 spline though, so a relatively minor mod to the driveshaft will be required.

99% sure on this, can't remember the vendor though.

Mart.

[Terry,OH]

Beside the 35 pinion being slightly longer and having 6 spline VS 10 on the 33-34 pinion, the diameter of the pinion gear is a bit large to fit in the 33-34 housing without slight modification and there is a possibility the ring could hit some of the banjo casting (minor) all can be corrected for a proper fit.

[JM 35 Sedan]

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Early Ford V-8 Sales, Inc. sells new 3.54 & 3.25 gear sets for '32-'34 passenger cars & pickups that have 10 spline pinions. Cost is $495.00/set. They also sell the installation kits with all new bearings, gaskets, etc.

[rockfla]

If you don't end up using the 35 w/378 gears, PM me and I would maybe interested in relieving you of that rear end if you wish?

[JM 35 Sedan]

Originally Posted by rockfla

If you don't end up using the 35 w/378 gears, PM me and I would maybe interested in relieving you of that rear end if you wish?

Likewise EPW. I have a wanted ad here now looking for 3.78 or 3.54 gears and buying a complete '35-'36 rear with one of those two gear sets in it would be even better.

[bobH]

I've put 35-38, 10-spline, 3.78 gears in a 34 rear end. There are numerous articles on how to do this. I would expect an internet search would produce info, or refer to above posts. The info has also been in an old V8 Times. Also, Richard, EV8G, has posted on this forum, how to do it. A short version... find a crankshaft grinder who knows his flathead stuff, have the pinion bearing surface ground to the proper 34 dimensions. This is a 'stepped' surface, by only about a thou. A sharp machinist will note this, and duplicate it. Then deal with the fitting of the pinion gear teeth to fit through the hole in the 34 banjo - the same crankshaft grinder will grind a small amount off the outer diameter of the teeth. Make, or buy, the required (approx 1/2-in-long) spacer for the pinion shaft (the 35-up pinion is that much longer than L32-34). (Some rear end guru's have found that the 34 steering gear bearing race is the correct dimension to serve as this spacer. I looked through a source of front wheel bearing races to find this spacer.) Then assemble as normal for 34. Then deal with change in driveshaft length - it needs to be approx 1/2-in shorter. The idea is to compensate for the 1/2-in longer pinion, and end up with the speedo drive gear centered where it belongs, in its 'hole' in the torque tube.
For me, it was not a big deal. I have a crank grinder in my area that knows his stuff, and is also a flathead guy, so this part was easy. As for the driveshaft, I used the regular, local driveshaft guy. I had a little trouble convincing him that the 1/2-in difference was important, but, beyond that, no problem.
In some situations, it will be found that the outer, backside diameter, of the ring gear, will touch the axle housing (bell). If so, a small amount of material (very small) needs to be removed from the backside, outer diameter, of the ring gear. I did not need to do this, but I believe Richard has run into this minor problem.
Please PM me, if you want more info.
(ps... BTW, the last time I talked to the rear end guru listed in the V8 Times, he told me that he has a source for the machinist (crankshaft grinder) that he sends the gears to, to modify for this conversion. If you don't find someone locally, you might contact him for help.)
(pps... I'll also mention, the crank grinder charged me 25 bucks. My point is, at this price, the pinion mod is quick and easy. Take him a 34 pinion to duplicate, and a 34 banjo housing to verify fit of pinion teeth through the hole.)
(ppps... Going back to deuce lovers suggestion, I did not investigate the simple idea of moving the driveshaft, and re-drilling the pin hole to compensate for the change in driveshaft length. It would be worthwhile to check this - I might have saved a trip to the driveshaft shop.)

[JSeery]

Very informative and interesting response!!

[Ol' Ron]

You couls always install a Michael.

[epw1949]

Thanks Barner's,what I did not tell you was three years ago,I took the 411's out of my 34,replaced them with a new 6 spline set of 354's using the spline coupler 6 to 10,and cutting the drive shaft. I am not happy with the 354's,because I feel its too higher gear for my stock engine.I do have another 34 with 354's,but the engine is 276 ci,and they are great. Now the whole reason I started this post was,to find out how hard it would be to use 35-378's in my 34,because I already have a 35 rear with 378's which I think would being my stock engine alive. You guys are great,and you have answer my question.Thank you & take care.E.P.Williams

[Lawrie]

I put a 46 3.78 into my 33 with a standard bore 33 babbit engine, it was a really good modification,great on the hi way.
The 33 towed our caravan great with the 3.78 .
I have a stock 34 3w with the 3.54 and a bit tired engine,the 33 with the babbit eng and 3.78 gears would leave it for dead.
PM me if you want any info on fitting the later gears .
Lawrie