TH-350 splines shreading and noises!

[Heckeng]

Ok, I had a noise that SOUNDS kind of like intermittant valves out of adjustment. I thought coming from my engine or trans and have been trying to find it. I've replaced tons of stuff such as the roller lifters, valve springs, put in a newly rebuilt (different) th-350, adjusted the valve springs to different lash recommendations. Nothing has changed the noise.

 

I think I've narrowed it down to the converter so I have a new ATI converter and flexplate waiting to be put in.

 

The new transmission had a couple issues of it's own. It was shifting softly, and at first, very strange rpms of shifting so. . .

 

We took the transmission out and apart. The governor valve was sticking so that is the shifting rpm issue. We also found two different sets of splines almost sheared off! The larger splined portion of the pump that goes into the converter was in horrible shape, and the internal (towards rear of car) portion of the small input shaft had it's splines nearly completely sheared off. The rebuild kit was a B&M full kit with a shift kit and it was put in by a very qualified GM mechanic that does that for a living and also builds racing transmissions for people. Point being that it's possible, but not probably that it's an error on his part! Do any of you know what could cause this? Just curious. I'd like to think that my engine was putting out that much power, but really don't think that's the case. My friend races an all steel camaro with a th-350 that he built and it does mid tens with no problems, so I think my th350 should handle a monte doing 12s.

 

I'll post an update once we get some new parts in the tranny and get the new converter installed as far as the noise goes.

 

Any input would be appreciated!

[Guest]

Typical of a sloppy spline fit of a B&M,and many others as well, converter behind any good amount of torque. They are really worn off, when the spline fit is loose it allows the stator and turbine splines to walk side to side on the input shaft and the stator collar shaft wearing the spline away over time.

In a way you beat the averages, the converter (b&m's) normanlly die long before you see the problem you have now.

The only other cause could be improper heat treat of the spline shafts.

Don

[Heckeng]

It did look like that on the splines that went into the converter, I didn't know how to describe it though! Good call. I guess I should put that in the converter thread too! As far as the smaller input shaft, do you have any ideas on that one? It's not touching the converter, so I can't blame that one on them! Probably just a poor fit to begin with I'm guessing. This was a core I bought from a local salvage yard, it probably had the issue started before I had it built and just didn't get caught.

 

Don, on a side note, I appreciate you posting! When I fully expected NOBODY to answer this one, or others, you always surprise me. I appreciate your input. Thanks!

[Heckeng]

Update time

 

The soft shifting was an accumulator seal that had cracked. . . fixed now.

 

Also, I had a stuck 2-3 shift valve causing it to shift from first to 3rd and massively bog

 

AND had a gov valve that was sticking. That has been replaced also.

 

These are all the reasons that the transmission was in the junk yard in the first place! I usually pick up cores and get them up to running condition, never had this much trouble though!

 

Got the converter and flexplate in too. Noises are still there. I'm either hearing my valves more easily through my "Cheverolet" tall cast valve covers which is something alot of the older rodders have been telling me, or it's just some vibration in the body somewhere that I haven't isolated yet! I've replaced everything else!!!

 

I guess now, I will just run it. I think I've regained faith in the motor and tranny now!