1-2 Accumulator Assy ?

[HellOnWheels]

Should the 1-2 accumulator piston, and spring be left out of a trans that has over 400 hp and a lockup converter with a stall of 32-3400 rpm??




TIA
HOW

 

[HellOnWheels]

....anyone?


I'm asking this question based on what I read in the CK manual on page 114, where it pertains to the 1-2 accumulator assembly.

"Also if the engine produces in excess of 400hp the shift cushioning effect of the 1-2 accumulator assembly should be deleted" Then it goes on to describe how to plug off the feed hole, then "When performing this modification you can omit the 1-2 piston (61) and spring (59).

Am I reading this right? Anyone did this mod to their trans??

TIA
HOW

 

[Blazer406]

IMHO deleting the 1-2 accumulator should be for strip only cars... the 1-2 shift becomes so violent... that you can forget ever drinking a cup of coffee in your car if you drive it on the street much..... it will rattle the dash when it shifts......

At least that is my experience on a 700R4 when blocking the 1-2 accumulator feed.


HTH

 

[Firechicken]

I blocked off the 1-2 accumulator and omitted the piston and spring in mine. I love the hard shift this mod produces. Not everyone will however.

 

[jakeshoe]

I did it to mine.

I have a ~2500 converter that actually footbrakes to 2800 behind my 427 in the heavy Chevelle, so with the slightly loose converter it isn't a killer hard shift at low rpm, it gets pretty firm at 1/2 throttle an higher.

I think converter selection and personal preference dictates this more than HP rating etc..

My trans doesn't shift killer hard even at WOT though... even with the accum blocked. Maybe my seperator plate holes are more conservative.

A 700-R4 is a completely different animal so I wouldn't compare the two for purposes of this discussion.

Also the 200-4R, if you retain the cushion spring on the servo, it acts as a secondary accumulator, and IMO should always be retained to prevent band lug failure.

Many builders omit this spring, but leave the 1-2 accumulator partially functioning...
I would rather block the 1-2 and retain the cushion spring....

 

[HellOnWheels]

IMHO deleting the 1-2 accumulator should be for strip only cars... the 1-2 shift becomes so violent... that you can forget ever drinking a cup of coffee in your car if you drive it on the street much..... it will rattle the dash when it shifts......

At least that is my experience on a 700R4 when blocking the 1-2 accumulator feed.


HTH

Even with 32-3400 stall?

 

[HellOnWheels]

I blocked off the 1-2 accumulator and omitted the piston and spring in mine. I love the hard shift this mod produces. Not everyone will however.

What size and stall is your converter?

Thanks
HOW

 

[Blazer406]

Even with 32-3400 stall?

Well.... I had a switch on my T/C lockup. Yes my stall was 3500+ (at least where it was flashing behind my smallblock). I will clarify my above statement that when the converter was set to lock-up as soon as it went into second (just like a turbo Buick when the ALDL wires tcc lockup are shorted together)... the shift was alot more violent at part throttle.... like you would normally drive on the street..... but with the converter unlocked... it was much more liveable.... I ran my lockup switch in the locked position all the time... so I remember the dash shaking


HTH

 

[Firechicken]

Right now my converter is a stock D5 and so I have quite firm shifts. I don't have my new PTC one installed yet. However, like Jakeshoe, when I had my old loose 10/12 converter installed the shifts were not hard at all as the converter slop ate the firmness up.

I expect that when I install my new converter the shifts will lose some of their firmness, but will still be a bit firm at part throttle.

 

[HellOnWheels]

Okay, thanks guys. I'm gonna try it without the 1-2 accumulator and see what happens, seems that the bottom line here is that the converter will determine how firm the shift will be. Mine is a 32-3400 stall, so hopefully it will work okay.



Thanks again,
HOW

 

[jakeshoe]

For what it's worth,
I had the D5 converter and my flexplate cracked taking out the pump and converter hub.
I fixed the trans, and replaced the converter with a re-stalled stocker to get me back close to the D5 since I have a mild BBC combo and the D5 was about perfect.

The replacement converter seems to have the same characteristics as the D5. My shifts are reasonable to me. If the converter was any tighter I would say retain the accumulator.
If you have a 3000+ converter, just block it and be done with it.