monte383sbc

iTrader: (15)

had anyone deleted there 3rd accumulator? i was reading off a different forum and a few people siad they removed it and did not re-install the 3rd accumulator... so i belive they are talkng about the 3rd accumulator/ check ball which tends to leak? also is this the check ball thats located in the bottom of the servo bore? also if they do delete it do they plug it or jut leave the accumulator bore open? thanks for any info, matt

mrvedit

Yes, the check ball in the case at the bottom of the servo is part of the 3rd accumulator. It is important to make sure it does not leak as it is likely a top-3 reason that the 3/4 clutch fails and probably the top-1 reason when it repeatedly fails within a few miles.

I have spoken to a dozen+ performance trans builders and none has ever mentioned deleting/blocking this check ball. The purpose for this check ball, and those in the pump and input housing, is to bleed off air so that the hydraulic fluid can apply solidly. (Perhaps a bad analogy, but think of air in your hydraulic brakes.)

When considering any mod to the trans, I also ask "why didn't GM do this"? Often it is to make a soft shifting trans for many applications; other times to save a few dollars. I think GM had a good reason to add the cost of this check valve.

monte383sbc

iTrader: (15)

http://www.pacificp.com/forum/viewto...7235&view=next. Check this out

mrvedit

That is a good summary with many good suggestions. My comments on it:
1. The check ball in the input shaft can be removed as suggested (but questioned by the OP).
2. I don't have the experience to say whether blocking the 3rd accumulator check ball is a good idea. Any pros here have comments on that?
3. The Alto Red frictions were popular when that thread was written 5 years ago, but have not held up well. However, I use the Red frictions for the forward and overrun clutches.
4. Nice that the Transgo separator plate and various Sonnax parts were recommended. That still is true today.

monte383sbc

iTrader: (15)

http://www.camaroz28.com/forums/driv...-4l60e-420697/

here's another post from another forum, its a good read

mrvedit

Much of that thread is 8 years old now and newer products and new information and experience supersede some of those recommendations.

Sorry, but I just don't have the experience or information on whether blocking the 3rd accumulator check ball is currently considered a good idea.

monte383sbc

iTrader: (15)

Thanks for all the help on all my post. You helped me out allot. Hey do you recomend the sonnax 3rd accumulator? I dont wana chance the old check ball leaking or getting stuck

mrvedit

Hmmm, not sure what you mean by the "Sonnax 3rd accumulator".
Perhaps you mean the Sonnax servo release check valve, part # 77701-076 and only $12. Yes, I am many others (including the last link you posted) recommend this.

BTW, the part number for the check ball is ACDelco #8634400, just a few dollars at the dealer. It is a bit tricky to install though.

And you are welcome - I learned from the links you posted and from my research while answering your questions.

Jake's Performance

iTrader: (2)

Technically the 3rd accumulator on a 4L60E is the oil that releases the 2nd gear band by pushing the servo off. It would take significant hydraulic changes to delete this in the trans and to my knowledge nobody has ever tried it on the 4L60E.
It could be done, and it may solve some issues with 3-4 clutch pack failures, but it would be a big undertaking.

monte383sbc

iTrader: (15)

thanks, for the info, iam jus gunna replace the check *****

performabuilt

iTrader: (25)

My question would be if you were to delete the "3rd accum" exactly how would the band be released on the 2-3 shift as the 2nd oil remains applied . As mentioned the 3rd clutch oil releases the band but against the 2nd oil. You would not only have to block the accumulator you would need to dump the 2nd clutch oil and stop its feed

Jake's Performance

iTrader: (2)

And like I said, it would be a big undertaking. I've studied it, and I can do it, but the R&D time isn't something I'm willing to take on right now.
It will completely change everything we know about orifice sizing for 3rd feed, etc.

You would release the band with a heavier spring on the servo.
It's commonly done on C4's with aftermarket valve bodies. It is also similar to many transbrakes on a TH400 where 2nd gear oil isn't used on the backside of the low servo, so release is done by the spring only.

performabuilt

iTrader: (25)

oh yes I'm sure it can be done and could see real advantages but would be a good undertaking for sure.

Jake's Performance

iTrader: (2)

I think that properly executed, and using the Sonnax input drum to maximize strength and clutch area, it would make the 3-4 clutch pack failures almost non-existent.

Part of the issue with the 2-3 shift on the 4L60 series units (as Frank well knows so I'm posting for the benefit of others) is that on a 2-3 shift MOST of the oil to make the shift is used to release the servo, and while that is happening, simultaneously, the 3-4 clutches are being engaged.
The 3-4 apply piston area is too small and the 3-4 clutch friction area is also borderline, but combined with the apply oil getting robbed to release the servo, it's hard to make it work at elevated HP levels.
You can cheat the apply and friction area with more pressure to a point.

Eliminating 3rd oil from releasing the servo would allow all the oil to instantly go to apply the 3-4 clutches and what we've seen on other units where we eliminating accumulators is that we had to reduce orifice sizing a HUGE amount to keep the shifts from being too harsh. It would be the same on the 4L60E.

If I did more 4L60E's I would spend the time on development to do this but ultimately it's not my market and I have other projects in the works.

mrvedit

This got me studying the hydraulic diagrams in the 4L60E Technician's Guide. Again. Correct me if I am wrong, but it appears the 2nd clutch circuit is fully applied in 3rd gear. The 3rd clutch has a larger surface area on the 2nd servo piston and can therefore push it back, but it is pushing again significant force, especially when using a Vette or Billet servo. For just a spring to disengage the band, the 2nd clutch circuit would need to exhaust in 3rd gear.

Back to the OP's earlier posts, I think when those links say to "plug the accumulator" they only meant the tiny bleed hole. I don't see much value to that, especially when the 3rd feed hole is enlarged. In other words, those links are NOT saying to disable the entire 3rd accumulator, just clogging the 1/100" bleed hole.

Jake's Performance

iTrader: (2)

Correct.