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Discussion Starter #1
So I have 18 or so passes on my glide since it was taken apart for recert in October of this last fall. When the trans was inspected (after damn near 150 trouble free passes) it looked absolutely mint and was put back together the way it was with the exception of a ATI wicked quick Valve body (it had always run the cast iron ATI pro brake deal before).... after our 18 hits in Vegas (and killing a planetary from tire shake) we found burnt reverse clutches. Most suspected a transbrake that was re-applied after the launch but none of the switch data or the output data from the ecu showed that? So this go around I put a reverse psi sensor in it. At first glance everything seemed normal, I did a couple spool tests on the converter and the release of the brake dropped the psi straight down, as I expected it should. Upon closer inspection it doesn’t drop back to zero, it’s only dropping back to 10 or so psi. Possibly more cuz when I’m releasing it in these logs I’m lifting and main line pressure isn’t bad high as it would be on an actual launch? Now obviously the only thing changed was the valve body, I haven’t spoken with ATI yet (will this morning) but is there any chance something like the plunger depth could just be a bit tight on the transbrake? I have heard of guys shimming the brake out but that was usually for reaction times? I can manually push the head of the brake all the way in (which is what ATI instructions say to check if the engagement is correct. I still have my other valve body, tommorow is a test day, so I may have to switch back tonight, just wondering if there could be a simple fix? Thanks
 

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It is very odd to have residual pressure considering the back of the brake valve should be beyond the valve body itself and that should have more than adequate exhaust even if there was a leak into that circuit.



Hutch
 

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Discussion Starter #3
I’m tempted for what it takes to switch VB out, to do nothing but switch it back to my cast one, and try the same test. It was a problem that we tried to find on the bench as it was on our radar from seeing burnt clutches in reverse. Absolutely nothing mechanically made sense...It certainly is a strange deal but I am trying to be logical in that the only change (switching VB) could likely be our problem... I’ll speak with ATI this morning, get their take on it, but I don’t know what else I could test to diagnose at this point aside from changing the VB back to rule out problems elsewhere ?
 

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Discussion Starter #5 (Edited)
........
 

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Discussion Starter #6
No; it’s a turbo car. I like to keep it running basically til the chutes are out and I’m slowed down.... nothing has changed in my top end procedure....
 

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Even with 10psi, I don't think that is enough to overcome the return springs on the reverse piston . Since its a turbo car and the VB was new , were you doing a bunch of testing to get the bump box working properly and possibly burnt them then? During the shake , do you see any signs that there was re-application of the brake? Do you run a delay box?

How badly burnt were they?


Hutch
 

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Discussion Starter #9
Sorry for the delay in response. I was testing on Friday after making an adjustment to my solenoid depth. It wasn’t allowing the transbrake plunger to come back far enough (although in the instructions ATI suggests to make sure your head of the transbrake can bottom out on the solenoid back when you push on it, and if it doesn’t, to shim it out at that point) .... in doing so, my bump box settings were much more aggressive due to it dumping much more fluid. I ended up having to really tone down the pwm on the bump.... on my first hit I had my best reaction time (with a shallow stage to boot)... the transmission operated very well, zero shift flare and pressures were good. Although my transbrake solenoid tester correct for the method they use for checking acceptable depth, shimming it out seemed to be the fix.
 
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