TH350 transbrake stuck

[fuzzyGN]

I have a newly rebuild TH350 with a Hipster transbrake installed. The problem I am having is the trans appears to be stuck in brake mode even with power completely disconnected from the solenoid. I have a solid park , then reverse, then reverse, brake, second and direct. No neutral and reverse is always engaged. Obviously it is a mechanical issue but what? I have yet to get it on the lift but is there anything obvious I should look for? I plan on pulling the solenoid out and test it for function and then peak inside the VB at the valve to see if it may be stuck. Other than that I have no idea where to look. VB gasket? Drum not releasing? Help?

 

[lilbowtie]

Make sure the return spring is on the right of the valve for the trans brake.

 

[fuzzyGN]

OK, pulled the solenoid and checked out what I could. The valve moves freely and the spring is in the correct position. The solenoid was weak so I plugged it off to hold the valve in the "off" position to test trans function. Still it acts like it is stuck on. So, even with the solenoid totally out of the picture the trans brake acts like it is stuck on. Park, reverse, reverse, brake, 2nd, 3rd. What is even left at this point? Could the VB be faulty? It is a Hipster.

 

[GNeric]

Ok. Any ideas out there for this brake? We have the valve body out and checked passages but have no reference as to what needed to be machined out compared to stock. No check balls installed into case. Manual valve and modulator valve modified as per instructions. Cup plug into case where servo goes. No band installed. No 2-3 accumulator piston. 2-3 shift valve train is non existant. Bushing held in place in vb with roll pin and in place of what would be the 2-3 shift valve is a "ball bearing" that looks to be able to seal off the governor to reverse passage of vb. Detent regulator valve train is removed as well. Detent valve train is also removed. 1-2 assembly is fixed in it's bore. No debris in pan to indicate that clutches are being missapplied. We still have Park, 2 reverses, (no neutral), brake, 2nd and direct. I have a pic of the channels of the vb if anyone who has dealt with TH350 brakes before can maybe point to something I haven't seen before. Even checked to make sure manual valve is positioned correctly. All is good in that respect.

 

[GNeric]

I am pretty sure I found it. Short of pulling trans completely out, I decided to get it down to fluid passages (separator plate out of the way) and install the solenoid and modulator valve and spring. As soon as I even get the tension of the Oring holding the solenoid in, the solenoid wedges against the first land of the mod valve and pushes it to the applied position. Tried mounting the solenoid "level" along with the valve and I am pretty sure the solenoid outer diameter is not on center with the inner diameter where the plunger contacts the land of the modulator, in this case. Took modulator valve out and ground .020" off the outer diameter (red box) and reinstalled. Valve moves as it should and as soon as new solenoid shows up, it should kick ass now. No outer edge contact and no binding. Fluid in tomorrow after work and test. Should have NO reverse and NO brake in Low.

 

[fuzzyGN]

We (GNeric) fixed it! It was the valve pictured above. Originally, I mistaken thought the applied position on the solenoid was when the solenoid was "out." This was wrong. I thought that because even with the solenoid burned out and floppy as all get out, the solenoid always was in the "in" position. That was due to the binding between the valve and the solenoid. So, after we got that part figured out with was much easier to determine the valve center line and the solenoid centerline were not matching up. After a little careful grinding as pictured above, it works as it should. I just don't have reverse until the new solenoid shows up so I have to be careful as to where I park