Technical > Dan Dishon's Transmission Den

Trans brake Problem

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grapro:
Dan
i have a power glide in my fed built by a local race transmission builder and we have been having a strange problem with the trans brake. The brake is a brand new TSI package we put in last year and it has been doing some strange things. I only ended up using the brake 6 times last year because it would never release quickly, it started off with a delay of 4 seconds when i released it first time and after the next times i tried it it got better to a 2 second delay after releasing it before it took off, we went through it just recently and added heavy springs  and removed a reverse disc hoping it will be better.  We went through everything and everything else looked good inside.Talked to the people at TSI and they had no ideas. I met someone at the track and they said they the same problem and they thought it was the converter but my transmission guru doesn't think so. He has done a lot of transmissions and has never seen this before. we cleaned up the reverse piston and it moves freely. I'm going to try this in the spring and see if this works and if not i will have to change out the brake. have you ever encountered anything like this?

bikeguy307:
My first question is it a pro brake if so do you have the delay when backing up? If its not a pro brake is there a delay in the reverse release when taking the shifter out of reverse? There are 3 thing need to activate the brake, button, solenoid, and the valve. I would start with the button and a test light, then move to testing the solenoid on the bench, replacing it with a know good one is another test. Last would be the valve sticking, as things tend to swell when hot it needs to be checked hot, either in the car or on the bench. I had a TSI pro brake stick a few years back. TSI has a step on the valve where it meets the casting and there was just enough mis machining that it would stick when at operating temp, but function fine cold. We took the valve and placed it in a drill, used valve lapping on the step area and lapped it in till the sticking went away. I avoided using sand paper for fear of taking to much. I used a heat gun on the bench to heat the valve body to simulate the operating temp.

Hope this helps,
Dan

grapro:
Dan
thanks for the quick reply. It is not a pro brake and it seems to disengage fine when shifting out of reverse. One of the things you said caught me which was the mis match of the reverse piston. I have tried the brake cold in the car in my garage without a burnout and it released immediately. But on the track after the burnout it seemed to be the problem. I will check the assembly and see if it is binding.

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