1-2 Accumulator piston Stuck
#1
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Car: 92 Z28
Engine: Ramjet 350
Transmission: T-56
Axle/Gears: 3.23 Torsen
1-2 Accumulator piston Stuck
So I'm tearing this 700r4 down for a rebuild and found the 1-2 Accumulator piston stuck in the bore. It's stuck in there pretty good. Anybody ever encounter this? Maybe this is why they junked the poor firebird I got it off of. If this is the case you have no second gear right?
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Car: Yes
Engine: Usually
Transmission: Sometimes
Axle/Gears: Behind me somewhere
Re: 1-2 Accumulator piston Stuck
No. If the accumulator is stuck, then it doesn't accumulate.
Its job is to absorb the first incremental bit of fluid being sent toward the band servo for the 1-2 shift, to cushion the shock. If it's stuck, i.e. not accumulating, 2nd gear probably slammed pretty hard.
Its job is to absorb the first incremental bit of fluid being sent toward the band servo for the 1-2 shift, to cushion the shock. If it's stuck, i.e. not accumulating, 2nd gear probably slammed pretty hard.
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Car: Yes
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Transmission: Sometimes
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Re: 1-2 Accumulator piston Stuck
Incidentally, you can eliminate the pin that it rides on, by getting "pinless" ones from Sonnax https://www.sonnax.com/parts/2520-pi...tor-piston-kit and maybe others. The same part fits both 1-2 & 3-4. Drill acoupla holes in the factory one(s) if you want, yank out with a dent puller or something, clean up the bore(s) if necessary (probably not but heh...), and put the better one(s) in instead.
The more usual way they fail is by wearing the pin bore to the point that the fluid all leaks out and no pressure every builds up. Hence the point of the "pinless" design.
The more usual way they fail is by wearing the pin bore to the point that the fluid all leaks out and no pressure every builds up. Hence the point of the "pinless" design.
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Car: 92 Z28
Engine: Ramjet 350
Transmission: T-56
Axle/Gears: 3.23 Torsen
Re: 1-2 Accumulator piston Stuck
Cool. Thanks for the info. Much appreciated. I'm gonna try swapping housings. Piston looks good, just gets stuck in the housing.
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Re: 1-2 Accumulator piston Stuck
The pin must be in there straight and tight. The piston must not wobble on the pin or replace it. Most of the time the pin is worn and the pin hole in the piston is worn out. Bore must mot have any scratches. If there is any scratches and they cannot easily be smoothed out, you will need another housing. If you are using a TransGo Shift kit, you will not be able to use the Sonnax pinless setup.
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