4L60E

Rodeo · October 31, 2004

I have a '95 GMC Sierra with a 350 and a 4L60E tranny. Need to know what the unit is on the right hand side, behind the dipstick. It is a round cap held in with a large C-clip. inside it has a few round plates with O-rings on a pin/shaft and a couple springs. Need to know what it is, what it does, because mine is leaking.

budhayes3 · October 31, 2004

I believe that is the 2-4 servo. It is used to apply and hold the band for 2nd and 4th gear. You should be able to service it in the vehicle. You must compress the servo and remove the c-clip, then you can slide the assy out. There are a couple of o-rings in there. I also think that there are more performance oriented servos that you can get to replace the one that's in there...such as one from a Corvette...they can be purchased as a kit for under $20. Check ebay or do a search for "Corvette Servo".

Oh yea, welcome aboard!

sperry · October 31, 2004

It sounds like the 2-4 servo. They have been known to leak and need the snap ring replaced. Cases have been known to crack there also... But that was an early 2004 production run.

There were changes to that 04 model, some were a round one some were a round one with two flat faces. That caused problems seating and hurt the case.

I don't have specific info for the older units at this time. It should be quite similar.

A tool is made that allows you to compress the servo in, while you change the retainer ring: J-29714A

It bolts on using two of the pan bolts. You use a wrench to thread in a bolt, that via a lever, compresses/holds in the spring while you change the part.

I have the # for an 04 only (Round wire servo cover ring, P/N 24232065.)

Hopefully, at least this gives a clue, all I have is a graphic and brief document to go by and your description.

Rodeo · November 1, 2004

Thanks for the info, it is greatly appreciated. I don't have to worry about removing it, as the reason I found the problem was due to a whole lot of smoke as the transmission fluid was pouring/spraying onto the exhaust. I then found the snap ring part way out, and the outter cover was sitting at an angle. Once I took out the snap ring (which pretty much fell out on contact) the innerds came out easy. I then noticed the seal ring on the first plate was folded over, so I'm obviously going to have to replace the seals and o-rings.

You had mentioned a specialty tool for compressing it, thanks for the description as it sounds like it would be fairly easy to make one up.

I do have a follow up question though. Can anyone tell me roughly how much pressure it will to require to get it back together? I'm not asking for foot pounds or anything, just easy, not to bad, a little grunting, or a lot of reefing on it required.

This way if it's supposed to be easy and if I have to reef on it I'll know something ain't right.

Thanks again

budhayes3 · November 1, 2004

I'm thinking at least a little grunting.

Rodeo · November 1, 2004

Thanks for the info, it is greatly appreciated. I don't have to worry about taking it apart as when it started smoking (transmission fluid on exhaust). I found the snap ring part way out and the outter cover sitting at an angle. When I removed the snap ring (which pretty much fell out on contact) the innerds came out pretty easy, they were'nt under load or go flying or anything like that. I also noticed the seal ring on the first plate was folded over, so I guess I'll have to replace the seals and o'rings.

You mentioned a specialty tool, thanks for the description as it sounds like it will be pretty easy to make one up.

I do have a follow up question though... How much pressure is required to put it back together? I'm not asking for foot pounds, just an easy, not to hard, a little reefing required, or a lot of grunting. This way if it is supposed to be easy, and I have to reef on it, I'll know that something aint right.

Thanks again

sperry · November 1, 2004

I had an image of the tool, but I couldn't hot link to the site or post it here.

This is another part, but info anyway.

1-2 Accumulator Piston and Outer Spring Replacement #87-74-74 - (Feb 19, 1999)

1982-96 Buick Roadmaster

1982-96 Cadillac Brougham, Fleetwood, DeVille

1982-86 Chevrolet Caprice

1982-99 Chevrolet Camaro, Corvette

1982-99 Pontiac Firebird

with HYDRA-MATIC 4L60, 4L60-E Transmission (RPOs MD8, M30)

1982-99 Chevrolet and GMC C/K, M/L, S/T, G Models

1991-99 Oldsmobile Bravada

with HYDRA-MATIC 4L60, 4L60-E Transmission (RPOs MD8, M30)

Condition

Transmission built from 1982 through 1999 were built with one of two styles of 1-2 accumulator pistons and outer springs.

Correction

Notice: Failure to follow these instructions may result in transmission distress.

Important: The 1-2 accumulator pistons and outer springs are not interchangeable.

In order to replace the 1-2 accumulator piston and outer spring, remove the 1-2 accumulator assembly. Inspect the interior of the assembly for the presence of either and aluminum or composite (plastic) 1-2 accumulator piston.

Design 1

1-2 accumulator assemblies with an aluminum piston and a round wire outer spring, use service package P/N 24204495 (1982-1993) or P/N 24204496 (1994-1997).

Design 2

1-2 accumulator assemblies with a composite (plastic) piston and an ovate wire outer spring, started May 11, 1998 (Julian Date 131), use service package P/N 24214343 (1998-1999)

MoJo · November 2, 2004

Those sealing rings are cut on an angle and can easily be held in place with wheel bearing grease. Just be careful and DONOT TWIST the assembly as you install it! Lube the o-rings with tranny fluid. It is a good idea to have a drawing/picture of how it goes back in so you align everything correctly.

If you want to improve the shifting, get a "corvette" or aftermarket servo.

The hardest part of the job for me was getting the snap ring back in and correctly seated!

FWIW, the servo in question is the 3-4 assembly but it affects the 1-2, the2-3 and the 3-4 shifts in the 4l60E!

It is NOT the 1-2 accumulator piston. That is located inside the pan to the rear of the valve body on the pass. side of the tranny.

Changing that piston/spring assy can improve the 1-2 shift. If you DO descide to do it, make sure you put it back together in the same way it came apart. There was a design change in '95/96 and most illistrations are for the early design.

Good luck!

mcreyaufmiller · November 5, 2004

I have a 4L60E on my 1998 that had the shift problem. I did an internet search and found a company that has the upgrade kit for $50 or so. I was able to rebuild the valve body with the instructions provided. As part of the kit, they remove this servo and replace springs as well as springs in the valve body itself. the only addition I would make is the purchase of the alunium piston to replace the plastic ones from the factory. I highly suggest the addition of this shift kit as it solves problems that if you have not had, you will soon. If you want the information, let me know and I will email it to you from my home computer.

Mike