VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1929-1932 1931 Rear dif isn't transfering power.

Gentlemen.
I got my 31 running but it will not move under it's own power.

After checking my gearbox I pulled the diff cover, lifted the rear wheels off the ground and I have power getting to the ring gear but nothing to the rear wheel. The spider gears spin but the wheels won't when I turn the engine with the hand crank with the car in gear.

I stuck a thin screwdriver between the axle spider gear and the diff carrier and was able to get the wheel to turn when the engine was cranked.

The rear gear looks perfect, no chips or missing teeth, everything moves smooth. The diff has probably been rebuilt in the past.

Heres my question.
Is there a washer or clutch that is supposed to go between all or some of the spider gears and the carrier?
How much clearance should there be between the gears and the carrier?
Could it be degraded or incorrect rear fluid that is causing this?
Can one of ya'll post a pic of a properly functioning rear ends gears with the spider gears visible?


Thanks

What happens if you jack the rear up and try to turn both of the wheels, The axles have a common problem of shearing in two if force is applied to hard. New axles are available from the FS in Lebanon OR.

That was one of my first thoughts to but I am pretty sure they're not snapped I'll pull them tomorrow to be sure.

I jacked the rear up and had my buddy watch the diff as I turned both wheels. Both wheels turn the axle gears and spider gears but the ring/pinion gear wont turn.

same in reverse if I turn the engine. The ring/pinion gear turns and the spider gears go around but the axle gears wont turn. unless I shove something between the carrier and the axle gear. I can create roughly a .040 gap between the carrier and the axle gear when I pry it.

Also of note is when I turn a wheel the other wheel doesn't turn like it does in rear ends that I'm used to where they spin opposite ways.

There is also some keyways on the outer end of the axle, which drive the hubs and wheels , maybe one of those is Missing? both missing? does the axle spin at the hub nut when trying to drive the car?

Also spotted those when I pulled the hubcap off. They are there on both sides. there not sheared and the holes are tight. axle spins with the hubs

Based on your description the problem appears to be between the ring gear and axle gears. 0.040 gap does not seem to be enough to permit total slip. I am just wondering if one of the pins has fallen out or bearing balls missing. A close inspection of all the parts should find the problem.

This reminds me of an old joke.... but does yours look like this?

The problem is that it has all slip and no grip.

Bill thats how my rear looks. can you get a shot of the planetary gears, spider and axle gears?
Thanks

Maybe this illustration from a 1941 Chevy parts book will help. Differential exploded The center sections of most Chevys are basically the same. It is the smaller internal gears that apparently are your problem. Click on "Differential exploded" above to open the webpage.

That does help.

The passenger vehicle disection is pretty vague but If you click next 3 times you come to the "truck rear axle exploded veiw. It shows an exploded veiw of the planitary and there are washers between the axle gear and carrier. Part 5.543 Thrust washer. If my axle does not have these and it is supposed to that would probably cause my problem.

I apologize for intruding, but I think and agree with Chipper. Since this is not a limited slip diff and the washers are for shimming the space between the spider gears and the ring gear, I would think that an axle is buggered up or a pin is loose and causing the ring gear not to drive the spider gears and therefore the axles. I hope the water is not muddied too much....

Mac

No muddy water here. Like i said I don't think the axles are snapped but I'm still going to pull them and check them out. Actually in about an hour or so.
If I can't figure it out I'll post a bunch of pix.

When you drained the oil was it full of metal? If an axle isn't snapped then perhaps the spider gears are stripped out.

Found the answer. Axle snapped on the driver side. It was a over cleanshear but had a small nub that caused enough friction to turn the spider gears from hand turning the wheel but not enough friction to turn the wheel through the ring gear turning.. no I have my answer as to why the car was left to rust in pieces. Lol.

Thanks again ya'll

d

For peace of mind , it might be a good idea to fit 2 new axles. The modern material is a lot improved.

Think I'd change out both axles if it were/was me. Especially as it has been a tough week for anyone with a '31 Chevy? Just ask Blaine!!!! He may have one he can sell you - then you'd have a pair. Oh, especially change out both if you're planning a '31 Chevy Cross Country Excursion!!!!

I think that down deep most of us suspected that you probably had a broken axle since that is a fairly common problem with that vintage of vehicle. And, your detailed description pretty much supported a broken axle as well. No problem though since you can get brand new axle shafts from TFS.

Wow, 2 broken axles in the same month... I know what I should have invested in!!! Ha!!

What I learned from this is that under some circumstances, you can still turn the wheel with the broken axel by hand, but it won't turn from the engine. Interesting.....

Sorry about your problem -- but the good news is that it's only about $300 (unless you replace both), and you can do it in under an hour!!!

And... in a motel parking lot!!!!!!!!!

Sorry about the axle....In any case, you found the problem and it can be fixed. Have a safe, peaceful and wonderful Christmas.

While it may seem that broken axles is a common problem, that is not the case. Many years ago particularly with washboard dirt roads they were much more common. The bumps created significant stress on the drive line parts, particularly axles. Some of that damage may still be present in some of our old Chevys. With today's road system drive line shock is much reduced. Mileage driven, loads, speeds today also reduce axle breakage. I have driven '31 Chevrolets for over 40 years and only broken one axle. It was 3/4 broken when I bought the car. Only found out when it finally broke.

Modern axles are definitely over kill but will make sure that you break something other than the axle.