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help diagnosing a '29 std powertrain problem


jps
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My car was running OK until  3 weeks ago when I stopped at a light and put it in neutral.  When the light went green, I tried shifting into 1st, but heard a loud "pop" or "bang", and afterwards thr car would not move (it seemed to be stuck in neutral - it could be pushed).  I could put the car into any gear but none  of them worked.  So it was towed home.  

 

Yesterday I opened up the transmission cover and could see nothing wrong.  All the gears slide as they should and look to be in really nice condition, and I see nothing broken.  The clutch feels the same as before, and when I removed the inspection cover on the top just above the transmission I could see the main or end plate moving in/out as I pushed in and released the clutch, but I can't actually see the multi-disk plates  behind the end plate via the inspection hole.

 

So I am guessing that the clutch is OK and the transmission is OK.  That leaves the universal joint or the point where the engine connects to the clutch.  I have a few of the basic manuals but they don't show much detail about how this is all connected or how to diagnose what is wrong.  Is there any book or manual, or are there any service bulletins that might help me figure out what to do next?  I don't have experience fixing this but would like to try regardless of the difficulty because I can't do anything with the car now except run the engine.  I am OK with doing whatever is necessary as long as I know what that is and how to do it.

 

Thanks

 

John

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Might try jacking up a rear wheel. It should not turn with the transmission in gear.  I would think with the transmission in neutral one, or ones helper, should be able to see the output shaft/gear move with the top off the transmission.  If one cannot see the shaft/gear turn, suspect the U-joint. Same if the wheel turns with transmission in gear.

 

 Just saw Grimey's post. Very well could be.

  Ben

Edited by Ben Bruce aka First Born (see edit history)
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John,

  The Drive train is designed with a shear key between the tapered axle and hub on the rear wheels. The key  helps protect the other components.   It is most likely that you have sheared one those keys.  If you broke a ring or piñon gear  or universal joint there would likely be quite a bit of chatter when towing the car.  I would check both sides for a sheared key first, a relatively  easy fix.  

 

Glenn Manes

Wheat Ridge CO

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  • 2 weeks later...

It looks like the rear passenger-side axle is broken, but I need to do a few more things before I can be sure.  I can't work on it this weekend but the following weekend should be when I know for sure.  The hub key on the driver's side is mis-shaped also, and the wheel hub has burrs along the keyway, so I will at least need a new key for that side.  I can spin the rear wheel by hand in one direction with it jacked up while in gear.  And the axle shaft on the passenger side will slide out very easily (it shouldn't do that) but I can't get it all the way out to see where it broke until I can move the car away from the garage wall (tight garage).

 

I also took off the differential cover, but could see no damage.  In the process I noticed something odd on only one side of the axle housing, just inside of the brake drum.  It looks like someone added an odd-shaped "patch" or cover (for lack of a better term) on the bottom half of the shaft.  This probably is unrelated to my problem, and probably was added by the guy that restored the car before I bought it, but it looks weird and I wonder why it is there.

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On ‎10‎/‎4‎/‎2018 at 12:19 AM, jps said:

 In the process I noticed something odd on only one side of the axle housing, just inside of the brake drum.  It looks like someone added an odd-shaped "patch" or cover (for lack of a better term) on the bottom half of the shaft.  This probably is unrelated to my problem, and probably was added by the guy that restored the car before I bought it, but it looks weird and I wonder why it is there.

 

I would guess that what you see is shim stock.  If the axle wore down some because it was loose at one time, the taper would be too small for the wheel to be tightened onto the axle.  The shim stock would move the wheel outboard so the nut would tighten the wheel to the axle.

 

If you can post some pictures, I can confirm what you have or maybe there is something else that the rest of us can analyze.

 

PS: I have heard of all kinds of material used as shim stock including beer cans. :-)

Edited by Larry Schramm (see edit history)
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12 hours ago, Larry Schramm said:

I would guess that what you see is shim stock.

I agree.  I used a soda pop can to field repair a friend's worn axle taper on a brass era car.  That car is still on the road with that repair because making new axles is labor intensive and expensive for a machinist to do it for you.

Edited by Mark Shaw (see edit history)
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  • 4 weeks later...

Sorry this took so long, but here are photos from my car of what might be shim stock as Larry suggested.  Can you confirm from the pictures that the left side has shim stock (I show both sides for reference):

 

DSC03444.JPG

DSC03448.JPG

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Has that shim slipped out of the spring hanger mounting? Maybe it is needed because the axle housing is very slightly smaller than the ID of the hanger housing when it it clamped up and it should not rotate there? Or are they trying to bog up some wear (keep the grease in) by shoving something in the edge?

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If the keyway is damaged on the LHS hub such that the key is a loose fit, you can fix it by cutting the slot wider to make it straight and have a stepped key made. I did this for my car. The axle nut was not tight enough and the hub was moving, so slogged it out. I used to hear it go "clunk" when I started to back out of the garage, as the hub turned very slightly on the tapered axle.

Edited by Spinneyhill (see edit history)
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