VCCA Home Forums TECHNICAL - GENERAL Trucks and Vans Differential work

I am currently restoring a 38 Chevy 1/2 ton pickup. It sat for years in a field and during the tear down phase, I noted that the ring gear is rusted and pitted on the teeth that were above the oil level in the differential. I would like to replace the ring gear and pinion. I figured I'd rebuild the whole thing while I'm at it. Some say that I should hire a pro to do it, and they may be correct, but I'd like to do as much of this restoration as possible myself. It is all original and I plan to keep it that way. Does anyone know of a good source with pictures that will show me step by step what I need to do to properly perform this job? I am willing to obtain the tools I need to do it and I am not completely in the dark as I have rebuilt the outdrive on an old Mercruiser I/O on a boat. It's just that these torque tubes are something I've never worked on before and I have never rebuilt an automobile differential.

Also, I see an add in G&D occasionally for ring and pinion gears that will increase the ratio. This will not be a daily driver. Do you guys think those gears are worth the investment when all I plan to do is cruise up to the local Sonics on Saturday nights? Will this modification take away from the value of my truck?

Thanks

First item of business is you need to own a repair manual. You may also find that a Motors Manual of that vintage or later will prove valuable. If you follow the instructions fully you should not have any trouble.

The new gears that are available are nice for a cruiser, however with your planned use I would stay with the standard gears.

If you have any problems, just rush back here for help.

The complete operation will be described in the shop manual....Manuals are available from ....www.fillingstation.com....for $20.00 in reprint.Worth hundreds :)

The only special tool you will need is a dial indicator.

If you're going to replace the ring and pinion, you might as well get Larry Jackson's 3.36 ratio replacements. If you drive farther than on to a trailer, you'll appreciate it.
. You know your skill level. The bearings usually need to be pressed, Riveting equipment is not in everyones toolbox, and setting the lash is best done with a dial indicator.

OK, I'll say it. For the use you describe, how about polishing the teeth with emory paper. In a few years, when all else is done and if there's trouble, you can do the rebuild. You're going to go slow, not far, and not be pulling a heavy load. I'd bet that if you shine it up you'll be fine. Just wash out all the dust.

Thanks everybody for the help. Each of you has given good advice. Chevradioman and Chevgene, I got the Chevrolet shop manual as you recommended and I have to say that after reading it a few times this operation is not intuitive at best and at worst is hard to follow...for a novice like me anyway. They seem have written this for an experienced Chevy mechanic and leave steps out and do not show a lot of pics. But as you said, this book is filled with valuable info and I'm glad you enlightened me. I have not located a Motors Manual yet, but I' still looking.

Lou, you and others say if one is to go to the trouble and expense of a total rebuild, then one would be remiss not to change the gear ratio while in the midst of this major project. I tend to agree, but I have never heard of Larry Jackson or a 3.36 gear. All I could find are 3.55 gears and typically I would have to change the rear end to install those because they only go back to 1940.

Wilson, I also can understand your position. Although I have never heard of the emory cloth option (they say the teeth are too hard and therefore impossible to remove the pits...who is THEY, anyway?), folks in this corner say for my use the gears should be fine. And I thought it interesting to note that the shop manual says that one of the advantages of Hypoid Gears is that gears which have been slightly scored due to the use of improper lubricant may still be used. The manual says that after about 1000 miles with proper lubricant the gears will smooth themselves out due to the sliding contact between them. Maybe the high spots will work themselves smooth and the pits will be insignificant if the teeth mesh well?

These points are all interesting and I will take them all into consideration as I make my final decision on the best course of action.

Thanks again everyone!

Chevytrkmn

Chevytrkmn
If you go the emery cloth way be careful not to go too deep or you will take the hard facing of the teeth. Also you will need to do all teeth the same or you can end up with more backlash on some teeth than others leaving uneven operation and eventually broken teeth.
There are workshops that will "relap" crown wheel and pinion sets. You may need to remove the wheel from the centre casing for this procedure though.
Tony

I think that any rust on the teeth would quickly wear off while driving down the road. You may need to change the gear lube again after a few hundred miles if the rear end lasts that long.

The chevy shop manual is indeed vague. Call Patrick's and request a copy of their instructions to install one of thier ring and pinions...it was very helpful for me, and showing what tools will work instead of the cumbersome and rare tools shown in the shop manual. Email me if you need any instructions.

I installed Larry Jackson's 3.36 ring/pinion. Not enough miles driven yet to give honest feedback. Cost was $900 plus shipping, plus new bearings, and seals. Figure I have about $1300 into rebuilt torque tube assembly.

It is a job you can do. The only thing I hired was to have the side bearings pressed on the differential carrier.