transmission noise for weeks now

[bdas]

My problem is I took my 1940 Cadillac to my mechanic to replace seals in the trans to clear up some leaks. When I got it back the trans was making noise and vibration only in second gear. It seemed okay if you didn't put pressure on the gas, but as soon as you did it would make this loud rumbling noise. It would also happen when down shifting into second. This was only in second gear. I took it back to the mechanic they took it all apart and couldn't find anything wrong. The car was then towed to a transmission shop and they can't find the problem. They sent the trans to their sister transmission shop and still no answers. Anybody run across something like this. It's going on three weeks now.

Thanks for any input:confused:

[Spinneyhill]

The 1939 Studebaker Commander has to have the bellhousing dial-indicated onto the engine to make sure the pinion shaft is parallel to the crankshaft and gearbox main shaft, otherwise the front bearing doesn't do well and the gears don't mesh properly. Does the Cadillac require this too? If they didn't do it, you may get noise.

[bdas]

The 1939 Studebaker Commander has to have the bellhousing dial-indicated onto the engine to make sure the pinion shaft is parallel to the crankshaft and gearbox main shaft, otherwise the front bearing doesn't do well and the gears don't mesh properly. Does the Cadillac require this too? If they didn't do it, you may get noise.

thanks Spinneyhill I never heard of that I will do some research and see

[dictator27]

The 1939 Studebaker Commander has to have the bellhousing dial-indicated onto the engine to make sure the pinion shaft is parallel to the crankshaft and gearbox main shaft, otherwise the front bearing doesn't do well and the gears don't mesh properly. Does the Cadillac require this too? If they didn't do it, you may get noise.

This applies to the installation of a replacement transmission. If the old transmission is being reinstalled it is not necessary.

Terry

[ricosan]

bdas,

 

This reads like a great mystery.  What was the cause of the noise and vibration?

 

ricosan

[JWLawrence]

Check transmission mounts and drive shaft joints. If it was not doing this before the work, then probably related to installation.

 

(o{}o)

[Matt Harwood]

If the '40 Cadillac transmission is anything like the transmission in my '41 Buick, there are roller bearings inside that are just loose and orbiting around the shaft, not retained by a cage. They need to be installed just so (I used heavy grease to hold them in place while I inserted the shaft) but I can see how it would be easy to not put them all in because it seems like they won't all fit. If I didn't know exactly how many bearings came out, I would have skipped one because at first glance, there was just no way that last one would or could fit. Of course, you need to know how to do it, but I can certainly see something like that causing a rumbling noise. It seems that all your mechanic did was seals, but if he did the front and rear seals, he might have pulled the main shaft or at least the retaining ring, and the bearings could spill out. Not saying he did anything of the sort, but I can see how it would happen.

 

Could be time for a second opinion?

Edited December 3, 2015 by Matt Harwood (see edit history)