BamaTony

Hey everyone! I got a question. If using a pinless piston on 3-4 accumulator, has anyone ever turned the piston with dome against the plate rather than spring against the plate? How would this affect 3-4 shift? Thanks for responses!

MaroonMonsterLS1

Block the 4th accumulator feed hole with a checkball. Don't bother leaving that accumulator functional.
It's nearly impossible to make 4th too firm on this trans.
If you're still using that part...just use it like sonnax tells you to.

PBA

If you block the feed hole, then you do not install anything here. If you use the Sonnax pinless setup, install the spring first and then the piston, so it sits against the separator plate.

MaroonMonsterLS1

Thanks for mentioning leaving the piston out Dana. I forgot to say that when I mentioned blocking the feed!

BamaTony

Thanks for the info!

vorteciroc

Should your 4L60 family transmission have the original 4th servo and 2-4 band; please follow what MaroonMonsta and PBA have told you.

I am one of the less common builders that will most often use the accumulator circuits as mush as possible.

For the 4L60 family transmissions; especially with a Sonnax or Superior 4th servo and extra-wide 2-4 band... I prefer to keep the 4th accumulator circuit alive.
I keep all of the accumulator circuits alive and I like to make changes to the accumulator valve-train as well.

I usually do the following (see photo below):



-Use the Sonnax accumulator piston set #77998-03K (Pinless/ dual seal)
-Use the Sonnax outside accumulator spring #77704S (Firmest spring that is not bound before compression)
-Use GM/ ACDelco inside accumulator spring #24220146 (Firmest spring that is not bound before compression)

-Use "B" or "BX" stamped accumulator valve-train (should your unit not already possess it)
-Use a longer/ stiffer accumulator valve spring from a Superior shift correction set #K-700-R4 or other cheap shift kit (This one is about $35)

I also at times make orifice changes to these circuits both at the valve-train end and at the piston end of the circuits... I will not be getting into details on this, sorry.

MaroonMonsterLS1

For anyone reading...here's a simple explanation. the longer an accumulator takes to stroke...the firmer the shift.
Yes...i know that sounds backwards...just trust me. I've gotten into the details of it before in grainy detail, you can search and find my posts.

vorteciroc

LMAO!

Thanks ;-)

vorteciroc

;-) what do they say about skinning a cat?

You don't mess with the accumulator valve spring or orificing on the C or D valve-trains, do you?

sjsingle1

iTrader: (1)

ok.....my old TG 4L60 kit had instructions and plug to block the 4 accumulator......but why ? its effect after blocking is.....

is this still a mod for the E ....or just the old 4L60.....

MaroonMonsterLS1

Yes, always mess with the accumulator valve spring.
17g
20b
20e

can all be used together to change shift feel in the accumulator circuit.
making 17g larger will firm shifts...feeds more oil from d4 into the accum circuit
making 20b larger will soften shifts...gives more oil to the feedback side of the valve...stroking it inboard...reducing the oil delivered to the accum circuit
making the spring stiffer will firm shifts...stiffer spring strokes the valve outboard and lets more d4 oil into the accum circuit
making 20b larger only affects the 3/4 shift...and I block that accumulator in 95% of builds so it's usually a moot point. but in practice it is an orifice for 3/4 accum feed.

Many ways to skin a cat...

Jays_SSZ28

iTrader: (2)

Why do you need to leave the piston out when blocking the feed?

I'm assuming you don't have to, I ran one for a long time (30k miles) with the feed blocked (from 700R4 kit) and the piston installed. It's in my spare parts pile now because I don't need it but it's always worked great.

sjsingle1

iTrader: (1)

even tho no one has answered my question....

as a general mod......what does eliminating the accumulator do ?

I see in the CK performance kits most of them eliminate every accumulator possible

I mean the purpose of the accumulator is to soften the shift transition ? right ?

vorteciroc

Accumulator deletion will speed-up and firm-up a shift occurrence.
However, it also can be too harsh for the transmission under the right circumstances.
These statements refer to hydraulic actions via a non-electronic transmission, because with electronics... the "tune" is also a factor.

When using an electronic automatic transmission... Software is a big factor here in shift firmness.
The "tune" for the transmission will affect how soft or firm a shift will be.

Shift firmness is dependent on overlapping factors... Line pressure, accumulators, and programming/ tune.

People used to and still do to some extent... delete accumulators because they did not know any other way to increase shift firmness.
For your situation... the 4th accumulator does not have a huge affect... so as most do, you can delete it without concern.

MaroonMonsterLS1

Don't cop an attitude...your question has been answered. Look at post #7. It says how it would affect the 3-4 shift.
look at how the oil flows...it flows in from the top of the bore. pushing the piston towards the separator plate...sooo...if you flip that setup over and install the spring into the case first...that will stroke the accumulator faster...meaning the shift will be softer.
You DO NOT want a softer 3-4 shift. Even with accumulator blocked the shift is usually never ever too firm.

Eliminating the accumulator altogether makes a shift as firm as it can get (excluding feed hole size, clutch count/clearance, etc)



Jays...when you block the accum, you omit the piston to ensure the rear geartrain still gets lube. You can see the orifice in the end of the bore...little cup plug with a hole in it. That orifice normally sees 4th gear oil and it sprays into the case.
When you block 4th accum...that orifice no longer sees any oil UNLESS you leave the piston out. Then the orifice sees accumulator oil in all gear ranges. Better lube.

Jays_SSZ28

iTrader: (2)

Hmm, good point. Glad it has 30k miles on it without that lube LOL.
I thought about that back in the 90's with the 700 kit. Doesn't look like the piston does anything anymore, back then while installing it in the case with the trans in the car I thought how nice it would be to not have it fall in my face, but no transgo says put it back in.

sjsingle1

iTrader: (1)

my cop has has a attitude !

I was kinda confused .....I know I have read or mis read ( by you or ? ) that the 60 and 80 have different results from the use of stiffer or softer springs in accumulators

and while I have heard of blocking the 4th accum....never have heard or blocking the 1-2 accum .....to harsh ?

would a stiffer spring in the 4th almost to the point of not stroking the piston be more desirable than blocking ?

my only experience i can add was thinking that the springs that come in the sonnax kit for the 1-2 accum as being to stiff resulting in a 1-2 shift to firm for my liking....i simply replaced them with softer GM springs and the shift is now perfect for me

when i first hear of a mod my first question is why is it necessary and does it extend tranny life or make shift quality better or worse ....and I like knowing that a mod can be tailored to my shift taste

MaroonMonsterLS1

1-2 shift becomes WAY too firm with a blocked 1-2 accumulator.
the 3-4 shift does not.

blocking the 4th accumulator does something big in my eyes...cures a large potential leak in the circuit. The piston gets worn and wallered out around the pin and leaks 4th gear oil into the accumulator fluid circuit...this can cause loss of 4th gear, overheating of oil, etc.
This is the reason the sonnax pinless accumulators were made. To cure the leaky pin.

BUT...if I can cure the problem, and get a beneficial shift feel by blocking...and also increase the amount of lube oil...then its an all around win in my book. I don't think the 4th gear shift is ever too firm with a blocked 3-4 accum.

Kfxguy

iTrader: (1)

I'm the odd man out. I always use the sonnax pinless accumulators and I never block the circuit. I may be wrong, but I feel like 1) the accumulators were put there for a reason 2) the reason is the weak *** marshmallow metal parts in this transmission need some sort of shock absorber to live under any kind of decent power.

I try to keep it simple. I do fix all the leaks I can, enlarge the feed hole(s) and upgrade whatever parts I can. Btw, turbo car is still going strong (knock on wood). Drove it to work today. I have beat the **** out of it on many occasions and lots of back to back passes. On 13 psi and climbing.

I dont ever want the 3-4 to shift firm and I'll never shift full throttle to 4th. You do that and you are asking for trouble. I use this trans as a three speed with an overdrive.

MaroonMonsterLS1

The reason is that GM copied much of the 200-4r ideas into the 700
Another reason is because grandma in her buick might have noticed 4th gear...ever felt a stock as they come 700? Damn thing is almost a CVT how it slides between gears.
the 3-2 downshift timing valves were great on paper and bad in practice on the 2004r and the 700r4

the 1-2 accum I 100% agree KFX...needs to be functional and needs to protect the internals.
But the 3-4 accum I disagree...not needed for protection there. You'll be hard pressed to make 4th too firm...especially too firm to hurt something.

And IDK anyone that needs 4th gear WOT shifts...60e I built for a foxbody with 4.30's and a 26" tire might make a 3-4 WOT in the 1/4...but that would be at 120mph+
anybody with 3.73's or less likely won't need a 3-4 shift at WOT