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Del in NE Ohio 04-10-2016 07:23 AM

Locked-up rear end

Went to help a Model A owner who has a major problem. The car won't move in any gear to the point of stalling the motor. Tranmission is in good shape. Before we go to remove the rear end for repair, Is there a way to tell if the problem is ring/pinion vs spider gears?

Tom Wesenberg 04-10-2016 07:27 AM

Re: Locked-up rear end

Put the rear end up on jack stands, put the tranny in gear, then turn one rear wheel by hand and see if the other rear wheel turns the opposite direction. It should turn smoothly without clunking and binding. If it does, then the spider gears are likely good.

BTW, I've seen brake lining bind up a rear end.

Does the gear shift feel normal as you move it through each gear?

harleytoprock 04-10-2016 07:33 AM

Re: Locked-up rear end

If the spyders were locked, car would still roll straight forward. I'm betting the trans is stuck in two gears. Just a guess really. Does the car move in reverse with shift lever in nuetral? It's time to remove the rer and trouble shoot.

harleytoprock 04-10-2016 07:43 AM

Re: Locked-up rear end

I had an E-brake so mangled it would not release.

Del in NE Ohio 04-10-2016 07:46 AM

Re: Locked-up rear end

Trans seems to shift smoothly through all gears. In 1st gear, it might move forward inch or two. Same thing in Reverse. Then with trans out of gear, will not roll in either direction.

Jerry Kzoo 04-10-2016 08:50 AM

Re: Locked-up rear end

Do what Tom says and put the rear end up on jack stands. Then try to spin the rear wheels on each side with the trans out of gear. If one will turn and not the other then one of the wheels is locked up. If neither will turn it could be the rear end. To get them to spin you might have to back off the brake adjustment wedges, but before you drive the car make sure they are adjusted back up.


Del in NE Ohio 04-10-2016 08:55 AM

Re: Locked-up rear end

Raised rear and both wheels/axles rotate as they should. Ring pinion problem? U-joint?

Tom Wesenberg 04-10-2016 09:07 AM

Re: Locked-up rear end

At this point I'd make sure the tranny isn't locked in two gears at the same time. You should be able to tell by the feel of the gear shift lever as it moves the gears, but you may want to remove the top of the tranny to be sure. This will also give you a chance to see if the problem could be in the tranny.

The engine runs OK as I recall, but I found a bolt in the bellhousing locking the flywheel from turning once.

BTW, how did this problem originate?

tbirdtbird 04-10-2016 09:31 AM

Re: Locked-up rear end

did this come on suddenly?
What was done to the car before this happened.
Did the owner drive over some RR tracks too fast? With wheel hop you can destroy the pinion if you do so.
How do we know the tranny is good? Did it work OK before the wheels locked?

Way more info is needed; this would be an unusual problem.

larrys40 04-10-2016 09:56 AM

Re: Locked-up rear end

I agree with Tom's assessment. To eliminate any e brake issues remove the drums and check rotation then .

Del in NE Ohio 04-10-2016 12:38 PM

Re: Locked-up rear end

Came on suddenly. Car is driven frequently. Owner reported hearing a "clunk" upon leaving a stop light. With floor jack under banjo, wheels rotate freely. Makes me think there is not a brake problem.

19tudor29 04-10-2016 01:13 PM

Re: Locked-up rear end

In reply 7, "they rotate as they should". In other words, rotate one side forward and other side rotates backward? Can both be rotated forward or backward with a person on each wheel and transmission in neutral? Success on these test should eliminate a differential and driveshaft problem.

harleytoprock 04-10-2016 06:47 PM

Re: Locked-up rear end

Will the wheels roll if pushing the car in neutral?

Mitch//pa 04-10-2016 07:20 PM

Re: Locked-up rear end

Look at the ring gear through the fill hole..

racingrufus 04-10-2016 07:48 PM

Re: Locked-up rear end

My 29 Special Coupe was trying to lock up when coasting, on acceleration it would pull with no problem but was making noise. When I disassembled rear I found the pinion bearing preload and lock nuts had come loose and traveled up drive shaft. I had to build rear with new ring gear and pinion, bearings and gaskets. The old ring and pinion looked ok but was a 4-11 ratio, I put in 3-54 and am very pleased. Dwayne

Del in NE Ohio 04-12-2016 04:56 PM

Re: Locked-up rear end

Update! Returned to the "A" in question today. With trans in nuetral, rear wheels off the ground, we each attempted to rotate rear wheels forward and then attempt to rotate to the rear. No dice. Locked up tight. So... I'll be returning on Sat AM where after consuming requisite coffee & donuts, the rear end assy is coming out!

29 model-a 04-12-2016 05:37 PM

Re: Locked-up rear end

I think before you do that< you should pull the trans tower. As tom mentioned, much easier job. pete

Mitch//pa 04-12-2016 05:43 PM

Re: Locked-up rear end

Did you peak in the fill hole??

Del in NE Ohio 04-12-2016 06:03 PM

Re: Locked-up rear end

Trans tower was removed and trans drained. No damaged gears. All seems to be in order. Every gear shifts as it should. Have not looked in the fill hole of rear end.
1. When clutch released, stalls engine, doesn't move.
2. With trans in nuetral, will not roll.
3. With rear wheels off ground, both wheels turn freely, in opposite direction as they should.
4. With rear wheels off ground, trans in nuetral, attempt to rotate both wheels same direction was not possible.

Mitch//pa 04-12-2016 06:10 PM

Re: Locked-up rear end

Look for metal in the diff oil when u drain it. If you see none or nothing when looking in the fill hole ,,, open the clamshell first when you go to drop the rear...

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