The Stovebolt Site Forums The Shop Area Engine Shop 4 speed tranny question

Pulled my SM420 out of my 51 3100 just to go through it. Shifting seems smooth and no known issues when I drove it including no leaking. I took the cover off and it looks pristine in there and well maintained. Having it out I notice that the input shaft wiggles a bit. Question is should I put in new bearings or just put new gaskets on and seal it back up leaving well enough alone?

Purney,

If it didn't howl, I would leave it alone. That ball bearing has to have clearance to operate, and when you vector (?) that to the end of the long input shaft, it will probably show up as a small amount of wiggle.

If you are still unsure, price the bearing and compare it to the amount of labor and mashed knuckles it took to remove the tranny...if the bearing price is cheaper than the peace of mind, stick a new one in.

That's my two cent take on the situation!

Stuart

Thanks Stuart. Tranny didnt howl, if the slight wiggle is normal then I think I will leave well enough alone. New gaskets and off I go!

Stuart is right. While you have the front retainer off take a bright light & shine it in the front bearing. Turn it slow & check for any pits or roughness in the races or balls. That is the part that wears the soonest & can cause the most noise. It can be replaced without tearing down the trans.

Will do, thanks Wrench.

Thanks Wrench. I have mine on an engine stand. I will check that before I put it in the truck.

That transmission is a rock crusher. In production for 30 years seeing duty in heavy trucks, busses and military vehicles.

Check the pilot bearing.