No accumalator spring.. do or dont

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Terry Markwart

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Ok, i finally got around to pulling out the Cheetah valvebody out of my 727, to no surprise the accumalator spring was not in the transmision, it was left to float in the bore. I just got my TF2 transgo kit and before i install it i am windering if i should install the blocker rod 2.85" 1/2" diameter in the bore first, let it float again or find a spring... i do want firm snappy shifts ( its a hotrod after all), any thoughts and comments are welcome.
Thanks in-advance. Terry
20220404_185643.jpg
 
Back in the 60's the first thing I did was to remove
the spring and turn up the line pressure about 5 turns.
I drove the one 67 GTX about 100,000 miles in two years and
never seem to hurt anything.
 
It does not "float". The purpose of the accumulator is to soften the shifts for little old ladies. When removed it bottoms out against the valve body and remains there, firming up all the shifts.
 
Ok, i finally got around to pulling out the Cheetah valvebody out of my 727, to no surprise the accumalator spring was not in the transmision, it was left to float in the bore. I just got my TF2 transgo kit and before i install it i am windering if i should install the blocker rod 2.85" 1/2" diameter in the bore first, let it float again or find a spring... i do want firm snappy shifts ( its a hotrod after all), any thoughts and comments are welcome.
Thanks in-advance. TerryView attachment 1715902064
Remove the accumulator spring and install the blocker rod. That is part of the shift kit recommendations I've used for decades now.
 
Put the spring in, I think you will find that Transgo now does not tell you to discard it.
 
I used the trans go kit and left it in and mine does not shift hard at all, next time I’m in there it’s going and I’m installing a blocker rod.
 
OK, whatever.. I install it so it has a cushioning effect on the rear clutch to help prevent damage to the Bevel spring. Modern day shift kits, make the mod mute in my opinion. Also the Accumulator does not function between the 2-3rd shifts.

Here's some info on the subject.

"The accumulator spring is the subject of much myth, and the myth just keeps getting repeated (even by people with SAE behind their name).

The sole purpose of the outer spring is to position the accumulator piston at the end of its bore when there is no pressure on the system; when the trans is initially placed in a forward gear, fluid pressure forces the piston against the spring which offers a cushioning effect to the application of the rear clutch. This is the only time the spring cushions anything and it's done with the car at a standstill.

When the 1-2 upshift occurs the piston moves in the opposite direction, (AWAY from the spring) so the spring has absolutely no cushioning affect on the shift. The cushioning that the accumulator supplies on the 1-2 upshift is strictly a hydraulic function, it "accumulates" fluid to slow down the application of the kickdown band.

For those who care to do a little research on the subject, grab any Factory Service Manual from the late sixties-on and study the fluid flow diagrams in the Torqueflite section. It will become quite apparent that the accumulator piston never moves toward the spring on upshifts, it actually moves AWAY from the spring on the 1-2 upshift and stays in that position during the 2-3 upshift. The spring can offer no cushioning to the upshift unless the piston moves toward it, it doesn't. The only accumulator modification that will affect the upshift is to block the piston; this is why a stuck accumulator will cause a harsh 1-2 shift as the FSM states.

The spring myth probably arose from the known fact that the accumulator cushions the 1-2 upshift. Knowing this fact and observing the presence of a spring easily leads to the assumption that the spring is the cushioning agent when, in reality, the cushioning is a strictly hydraulic function (similar to a suspension hydraulic shock absorber).

The often repeated "poor man's shift kit" advice in MA and elsewhere to crank the line pressure adjuster to the max and toss the spring produces a noticeable result solely because of the raised line pressure, not the spring removal.

For those who are still not convinced, ask yourself this question: if simply removing the spring eliminates the cushioning effect why do most of the reprogramming kits include a blocker rod to block the piston's movement?"
 
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Well, i did stick a blocker rod in, followed the transgo instructions to a tee and am hoping both shifts break the tires loose on wot 6000rpm shifts. Thanks to everyone and their points of view and experience
 
OK, whatever.. I install it so it has a cushioning effect on the rear clutch to help prevent damage to the Bevel spring. Modern day shift kits, make the mod mute in my opinion. Also the Accumulator does not function between the 2-3rd shifts.

Here's some info on the subject.

"The accumulator spring is the subject of much myth, and the myth just keeps getting repeated (even by people with SAE behind their name).

The sole purpose of the outer spring is to position the accumulator piston at the end of its bore when there is no pressure on the system; when the trans is initially placed in a forward gear, fluid pressure forces the piston against the spring which offers a cushioning effect to the application of the rear clutch. This is the only time the spring cushions anything and it's done with the car at a standstill.

When the 1-2 upshift occurs the piston moves in the opposite direction, (AWAY from the spring) so the spring has absolutely no cushioning affect on the shift. The cushioning that the accumulator supplies on the 1-2 upshift is strictly a hydraulic function, it "accumulates" fluid to slow down the application of the kickdown band.

For those who care to do a little research on the subject, grab any Factory Service Manual from the late sixties-on and study the fluid flow diagrams in the Torqueflite section. It will become quite apparent that the accumulator piston never moves toward the spring on upshifts, it actually moves AWAY from the spring on the 1-2 upshift and stays in that position during the 2-3 upshift. The spring can offer no cushioning to the upshift unless the piston moves toward it, it doesn't. The only accumulator modification that will affect the upshift is to block the piston; this is why a stuck accumulator will cause a harsh 1-2 shift as the FSM states.

The spring myth probably arose from the known fact that the accumulator cushions the 1-2 upshift. Knowing this fact and observing the presence of a spring easily leads to the assumption that the spring is the cushioning agent when, in reality, the cushioning is a strictly hydraulic function (similar to a suspension hydraulic shock absorber).

The often repeated "poor man's shift kit" advice in MA and elsewhere to crank the line pressure adjuster to the max and toss the spring produces a noticeable result solely because of the raised line pressure, not the spring removal.

For those who are still not convinced, ask yourself this question: if simply removing the spring eliminates the cushioning effect why do most of the reprogramming kits include a blocker rod to block the piston's movement?"
I have 2 questions 4 ya. The Hemi and 440-6 transmissions had a spring on the inside to keep the accumulator at the top of its bore against the valve body. Why do u think Mopar did that? Does the accumulator really move back and forth on the shifts. Thanks. Kim
 
Kim, If you look at the fluid flow diagrams for the TF, they will answer your questions.
 
Shocks don't cushion?? Good ta no..
Sure.. whatever.
Question is, when you select 2nd gear, how long does it take to move the accumulator in the other direction, especially when the valve body has been modified to facilitate oil flow and it's aided by a spring?
How far does it move? How much oil does it take to fill it and dump from the other side?
If the restriction in the accumulator oil circuit is more than the ones in the 1st to 2nd shift circuit of a modified valve body would that also reduce it's influence on the shift quality. Would the 1st to 2nd circuit go to full pressure before the accumulator gets a chance to cushion it?
These are things to consider.
 
Well, there is that saying.
"If you don't understand it, then just kill it".
I like to know why I'm doing something.
 
Well, some people come up with what works and some just follow along.
 
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