SM465 will not go into 2nd

[Jamesz]

Hello everyone!
I picked up a sm465 from a guy a while back and he claims that the transmission has been rebuilt a couple years ago and never put into a truck. After i put it into my truck and drove it i found that you can go from 1st (or low) to 2nd just fine and 3-4 are good as well but downshifting from any other gear into 2nd is actually impossible. There is no grinding when trying to put it in gear while moving it just won't drop into 2nd. Now after a while the transmission sounds like there is gravel in the bearings or something when it is in 2nd while driving. The transmission has also developed a loud rock crushing sound at idle with the clutch not pressed in. Has anyone had this issue or seen it before?
Thank you for your time.

 

[Tank6x2]

Pull it apart, something ain’t right there

 

[nvrenuf]

The gravel sound while moving in 2nd isn’t normal.

The very low volume rattling at idle with the clutch out could be the throw out bearing moving a bit (my 06 Dodge does this sometimes) however if it’s loud it’s a problem.

The sm465 transmission does not like or want to downshift into 2nd unless you are just rolling very slow. Do not expect it to downshift into 2nd like it will from 4th to 3rd.

I’ve had several 465’s and they are typically VERY quiet in operation regardless of what gear or moving or not - of course, this is outside of the non syncro’d grinding of 1st and reverse.

 

[straydog371]

What gear oil is in it?

 

[Jamesz]

What gear oil is in it?

I had Triax 75w-90 GL-4 fluid in it before I took it apart

 

[Jamesz]

The gravel sound while moving in 2nd isn’t normal.

The very low volume rattling at idle with the clutch out could be the throw out bearing moving a bit (my 06 Dodge does this sometimes) however if it’s loud it’s a problem.

The sm465 transmission does not like or want to downshift into 2nd unless you are just rolling very slow. Do not expect it to downshift into 2nd like it will from 4th to 3rd.

I’ve had several 465’s and they are typically VERY quiet in operation regardless of what gear or moving or not - of course, this is outside of the non syncro’d grinding of 1st and reverse.

I apologize for the late response, for some reason I wasn't notified!

I took it apart and I found a bearing inside the front input shaft completely tore itself apart. So I replaced it and the noise went away for a little while but now I faintly hear it again. It did not fix the not going into 2nd problem.

I finally got the truck registered so I've been driving it a couple of times and if I'm sitting at a red light occasionally it will not go into second at all and just grind with the clutch all the way in so I'll have to put it in 1st (if it will go in) or 3rd.

Now I'm wondering is the main shaft supposed to be able to move forwards and backwards about a half inch? I'll try to figure out a way to post that video I took here in a little while.

 

[Jamesz]

The gravel sound while moving in 2nd isn’t normal.

The very low volume rattling at idle with the clutch out could be the throw out bearing moving a bit (my 06 Dodge does this sometimes) however if it’s loud it’s a problem.

The sm465 transmission does not like or want to downshift into 2nd unless you are just rolling very slow. Do not expect it to downshift into 2nd like it will from 4th to 3rd.

I’ve had several 465’s and they are typically VERY quiet in operation regardless of what gear or moving or not - of course, this is outside of the non syncro’d grinding of 1st and reverse.

One more oddity about this transmission or drivetrain is that when I'm in reverse if the truck is rolling backwards and I press the clutch in the rear tires will completely lock up. once the truck is hot it doesn't do it that often. But I have not read anyone having a transmission binding problem in reverse.

I

 

[nvrenuf]

The input shaft should only have a few thousandths of end play so 1/2" is definitely a problem.

 

[nvrenuf]

With that much end play of the input shaft, I'd bet the wheels locking up is the result of parts moving out of position and locking / binding up the transmission itself.

I'd dig into it a lot sooner than later while it's still (hopefully) rebuildable.

 

[SquareRoot]