I think my th400 is making a grinding sound

[watertreatpete]

I am trying to narrow down this grinding sound my 1/2ton big bock truck is making. It is like a metal on metal sound, almost like brake pads that are worn out. It seems like it it is in the middle of the truck , that's why I am thinking the trans.

Here is some back ground: The th400 was a free bee from a diesel short bus. The th400 looked clean and rebuilt , the bus was rolled over so it was running when junked. It was a short tail shaft that had a bolt on yoke, I am running a slip yoke. I am getting a grinding sound at light throttle after the truck is driven a few miles and warmed up, If I shift in to neutral it goes away. If I put it in second the sound is still there. The trans shifts normal and is not slipping at all even under full throttle.

I noticed the rear yoke has some play if I push it side to side, not sure this is normal,

Any ideas?

 

[Honky Kong jr]

There is a special yoke needed to run a slip yoke on a fixed yoke trans. I hope that's what your using otherwise your gonna destroy that trans.

 

[watertreatpete]

I have the slip yoke conversion from Denny's drive shafts, It sounds like a bad bearing, Do torque converters make any strange sounds when going?