Blocking 3-2 valves
Thread Starter
TECH Enthusiast
Joined: Jan 2019
Posts: 677
Likes: 490
From: Roxana, IL
Blocking 3-2 valves Just wondering/curious if blocking the 3-2 downshift valve and 3-2 control valve would cause a really firm or hard 1-2 and 2-3 in a daily driver? Studying the book, I don't think they would. Should this mod be used in a performance application only or???
Does the Accumulator valve spring effect the 1-2 shift only or the 1-2 and the 2-3?
my GM tech guide say's it affects 1-2 & 3-4.
Accumulator Valve (371)
The accumulator valve is biased by torque signal fluid pressure,
spring force and orificed accumulator fluid pressure at the end
of the valve. The valve regulates D4 fluid into accumulator
fluid pressure in relation to engine torque, as determined by
torque signal fluid pressure. Accumulator fluid pressure is
used to control shift feel during the 1-2 and 3-4 shifts. During
the 1-2 and 3-4 upshifts, the valve regulates the exhaust of
accumulator fluid to help control shift feel.
I'm hoping that @vorteciroc or @MaroonMonster could weigh in on it.
I have a customer complaint of a hard 1-2, 2-3 shift & a normal 3-4.. It got a standard OH with a TransGo Box SK, corvette servo and a .500 boost valve. I did block both 3-2 valves and I do not usually do this on a Daily Driver...
Does the Accumulator valve spring effect the 1-2 shift only or the 1-2 and the 2-3?
my GM tech guide say's it affects 1-2 & 3-4.
Accumulator Valve (371)
The accumulator valve is biased by torque signal fluid pressure,
spring force and orificed accumulator fluid pressure at the end
of the valve. The valve regulates D4 fluid into accumulator
fluid pressure in relation to engine torque, as determined by
torque signal fluid pressure. Accumulator fluid pressure is
used to control shift feel during the 1-2 and 3-4 shifts. During
the 1-2 and 3-4 upshifts, the valve regulates the exhaust of
accumulator fluid to help control shift feel.
- A stuck accumulator valve could cause no 3-4 shift, slips or
I'm hoping that @vorteciroc or @MaroonMonster could weigh in on it.
I have a customer complaint of a hard 1-2, 2-3 shift & a normal 3-4.. It got a standard OH with a TransGo Box SK, corvette servo and a .500 boost valve. I did block both 3-2 valves and I do not usually do this on a Daily Driver...
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Joined: Dec 2012
Posts: 3,615
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From: Iowa
the blocked 3-2 valves aren't going to cause harsh upshifts like you are describing
we need way more info here.
What is line pressure
what were orifice sizes
what accumulator setups
etc etc
If there are codes for anything like a MAF or MAP sensor. Or if there were trans slip codes before overhaul that didn't get cleared. Etc...you need to address those otherwise there will be increased line pressure and overly harsh shifts.
we need way more info here.
What is line pressure
what were orifice sizes
what accumulator setups
etc etc
If there are codes for anything like a MAF or MAP sensor. Or if there were trans slip codes before overhaul that didn't get cleared. Etc...you need to address those otherwise there will be increased line pressure and overly harsh shifts.
Thread Starter
TECH Enthusiast
Joined: Jan 2019
Posts: 677
Likes: 490
From: Roxana, IL
Thank You, @MaroonMonsterLS1 I didn't think that they could. I just wanted a fresh opinion on that. Those are all path's i will head down once this is back in the vehicle. Right now I was not even given the opportunity to drive it or do a line pressure test. The customer just pulled it out and brought it back for an internal inspection. I spoke with him and he was supposed to bring it today for a road test. Some where between then an Monday he convinced himself that because the transmission had been overfilled it was destroyed inside because of the shifts.
sometimes you cant make them believe you until you show them... Today he comes by to see inside. He is a mechanic at a local shop, one of 9 mechanic's there.
sometimes you cant make them believe you until you show them... Today he comes by to see inside. He is a mechanic at a local shop, one of 9 mechanic's there.
