High Mileage 4L80E Fixes (pre-failure)?

[damork]

After doing the timing gears and cooling upgrades on my 95 6.5 at 160,000 miles I'm turning the focus onto the transmission. The transmission has not seen heavy work and has been serviced regularly. Fluid changes have never revealed wear particles in the pan and a large cooler has kept temps under 180F.

There have been some symptoms of lockup shudder and 1-2 shift bump, and leaving it alone with high mileage could lead to some nasty failures - therefore the plan to install some preventative fixes.

Transgo, Superior and B&M all seem to have fixes but I'm hearing more positive news about Sonnax components from shops that use them alongside Transgo, etc. Some of the trans shops advise the Sonnax TCC sleeve update, Actuator Feed Limit Valve kit, Boost valve sleeve update and the 1-2 & 3-4 shift spring kit. It appears that these fixes address most of the weak points of high mileage 4l80E transmissions.

Has anyone had good or bad experiences with Sonnax? Has anyone done an in-chassis boost valve repair or update on a 4l80E? Trying to get over 300k on this rig without doing a major overhaul.

[jimbo6.5]

I just had the trans controller installed on my 4L80e by todd at heath diesel.
i wish i would have got it a year ago
for a little over a hundred bucks it controls the shifts and really holds on
the great thing about it ,theres no tear down to getting i on, its straight forward a guy could hook it up at home in 1/2 hour, i can see where it's going to add life to my trans ,no more slipping , just sweet possitive take hold shifts
i would recceomend this to anyone with the 4l80e, its also cab mounted and adjustable,i think 4 settings driving empty, pulling light and pullingheavey,and a high boost setting
its a great little unit

[rustypig]

I've also heard good things about sonnax products, but specifically was looking locally for a sonnax upgrade for my powerjokes 4R100. Every shop I talked to basically said to leave the tranny alone and to keep my foot out of it since the PSD will/can overtorque the 4R100.

Anyway...having rebuilts a few auto tranny's in my past, I'd have to say I agree that there is a benefit to re-springing a valve body to produce the shortest shift intervals possible. Most vehicles roll off the production line with "ride comfort" as the goal. Doing anything to your tranny that will shorten shift duration (read....clutch slippage) will improve it's longevity. There is a limit to the teeth shattering improvements though, and every auto tranny will eventually fail.
Personally I decided that the torque from a 6.5 isn't a huge issue to worry about and figure I'll do the upgrades when I rebuild the unit completely. Since mine is a 94 the computer chip also seemed to make a nice diffence in shifting as well.

I am interested to see the results from yours and others efforts though. Let's get some updates fella's!

[tom.mcinerney]

I know nothing about trannys. I bought truck with 175 K and had rebuilt as PM. The friction discs showed some wear. The large (babbit on bronze?) bushings {ca 1 3/8" ID?} were badly worn. The tranny had worn the rear diff pinion(it was sloppy), all 3 seals on front diff were leaking. The shop i took it to installed new steel pistons to replace aluminum....I think if you keep it clean, maintain connections, prevent overheat it'll go beyond the distance you call out. The rebuilder was knowledgeable. He said these trans shut down cooling circuit during some acceleration phase....

[charliepeterson]

We have alot of 4L80E's at work in the gas and diesel. We just picked up Snap-On's latest and greatest flush machine for Trans. and powerstearing units. This machine works real well. We drop the pan and filter then do a 20 quart flush. You won't believe your eyes at the change in fluid color even immidiately after a filter change.
Almost every truck is on a severe duty schedule with high mileage on the clock. Transmission swaps have been cut down dramatically. Granted everything is stock though.

[damork]

charliepeterson
I've got the GM twin to yours, a 95 Yukon and I believe in the flush procedure except I do it at home with some clear hose and a couple cases of ATF from Sams. Keeping it bright red and smelling good is key.

I've changed my ATF religiously and flushed each time, no more than 30k and usually more frequent than that. Also run a 29,000 btu cooler and temps never get above 180F.

With all of that there seem to be little glitches in the 1-2 shift and the boost valve on these trannies. If the boost valve hangs it will break the case, even if you keep fresh fluid in it. I'm trying to build in some PM before the unexpected could happen.

Currently I'm monitoring voltage to the E pin connector which feeds power to the solenoids in the tranny. It shifted fine this morning with 13.7-14.5 v, but seems sometimes when it gets hot there is a 1-2 shift delay. I'm going to add a relay to ensure that wire has no lack of battery power, if the shift delay continues I'll know it is not power.

[ 07-30-2003, 12:45 PM: Message edited by: damork ]

[ucdavis]

Twice I've had shift problems. The PCM seems to have a tranny-limp mode in addition to the diesel/IP limp mode. On those two occasions PCM set tranny to limp mode & fixes the gear (I think it goes to 2nd only, but it might be 1st only). First time I limped directly to favorite tranny shop, did a service (no codes present) & changed shift solenoids since pan was off. Second time, went to tranny shop & shut down waiting for tech; seems the shut down rebooted PCM to standard run mode & tech couldn't find anything wrong.
Sooo, if you have this problem, try a shut down; might be problem w/computer.

[Uncle Wally]

Jimbo,

Care to expound on your experience with the water injection system from Bill Heath?

Waldo

[tanker]

I have 138,000 miles on my 4L80E,(many towing) but when I replaced the engine at 112,000 miles,(another sore spot) I also replaced the torque converter. I was concerned about the clutch. I also do a complete trans-flush at home each year, and have been using "Amsoil" synthetic ATF the past three years. Like Charlie said the color will change from a dark red to a bright red when you first do it. Mine stays about the same color (each year). I also see very little sediment in the pan. Oils and fluids are cheaper than transmissions, and other components. smile.gif

[CareyWeber]

Originally posted by damork:
charliepeterson
I've got the GM twin to yours, a 95 Yukon and I believe in the flush procedure except I do it at home with some clear hose and a couple cases of ATF from Sams. Keeping it bright red and smelling good is key.

I've changed my ATF religiously and flushed each time, no more than 30k and usually more frequent than that. Also run a 29,000 btu cooler and temps never get above 180F.

With all of that there seem to be little glitches in the 1-2 shift and the boost valve on these trannies. If the boost valve hangs it will break the case, even if you keep fresh fluid in it. I'm trying to build in some PM before the unexpected could happen.

Currently I'm monitoring voltage to the E pin connector which feeds power to the solenoids in the tranny. It shifted fine this morning with 13.7-14.5 v, but seems sometimes when it gets hot there is a 1-2 shift delay. I'm going to add a relay to ensure that wire has no lack of battery power, if the shift delay continues I'll know it is not power. damork,

Do you have a picture of the "E" pin connector.

Where is located at?

Thanks
Carey

[damork]

Carey,
I don't have a photo of the connector, but it is in the main plug in to the 4L80E transmission. It is located on the driver's side of the transmission. The wire on mine that feeds the E pin power is pink colored - probably about a 16 gage wire. I pulled the plug only to make sure I had wire E and used my meter to verify it was the one supplying power. Once I had all of it confirmed I wen't ahead and spliced into the wire and soldered the wire from the relay into it.

The factor service manual shows the plug and locations of the pins, it matched what I found on my truck.

It seems Sonnax, TransGo and Superior all have hardware fixes that address some of the most common issues on the 4L80 transmissions. Sonnax seems to be most popular with shops I've talked to lately as they continue to improve their products and add new fixes quite often.

[CareyWeber]

damork,

Thanks

Carey