4l80e transmission help

todster · December 12, 2004

i have a 1993 gmc 3/4 ton hd ( biggest piece of @!$#% i ever owned) with a 4l80e tranny in it,at 120k the tranny went while on the highway.had it rebuilt and now at 135k on it the tranny is slipping again just like the first time .when its cold from a start up it doesnt slip,but once it is warm the truck can hardly go without slipping.i can keep it from slipping if i let off the gas between shifts doesnt always work,but it has me thinking is this a eletrical problem? or did the tranamission shop give me the sausage?

whitesnake01 · December 14, 2004

i have a 1993 gmc 3/4 ton hd ( biggest piece of @!$#% i ever owned) with a 4l80e tranny in it,at 120k the tranny went while on the highway.had it rebuilt and now at 135k on it the tranny is slipping again just like the first time .when its cold from a start up it doesnt slip,but once it is warm the truck can hardly go without slipping.i can keep it from slipping if i let off the gas between shifts doesnt always work,but it has me thinking is this a eletrical problem? or did the tranamission shop give me the sausage?

<{POST_SNAPBACK}>

Is your tranny cooling working properly? I have a 93 3/4 ton Suburban with the 4L80E. I bought it new and I still have it. From the factory it does not have a trans temp gauge. Mine started running hot in recent years. What temp is the tranny running at when slipping?

The source of the problem was not enough cooling. The old stock radiator had basically clogged up. I also switched over to Amsoil in the tranny.

GSchretter · December 15, 2004

Are you one of the following:

1. Tows a lot of weight

2. Thinks his truck is a hot rod and keep it floored all the time

3. Never checks for leak or see if the fluid level is low:

4. Are you running really big tires (35 and up)?

If so you wore your tranmission out.

If not they did not fully repair the tran. They probably did not replace all the clutch bands.

One solution is:

I had this problem on a ford. I replace the tranmission fluid with a thicker fluid and it worked for about 10 more years.

Jet has one for sell for about $1500.00

If you are going to keep the truck, I would go ahead and buy a new one. Stop wasting your time with fixer upper places, believe me none of them can fix it. Now if it was the old TH350 or TH400 they could fix it.

I pull 22,000 lb all the time with my 4LE80 tranmission and not had one problem. But I replace my fluid ever 6 months and never hot rod my truck.

The computer could cause the tran to slip a little but it is more likely the clutch bands or fluid flow problems. If you have fluid flow problems then you will have burnt clutchs.

todster · December 22, 2004

nope, radiator new,dont tow,plow,speed,tires are stock plus 1.so far tranny guy doesnt know whats wrong with it ,that should tell me something.

whitesnake01 · December 25, 2004

nope, radiator new,dont tow,plow,speed,tires are stock plus 1.so far tranny guy doesnt know whats wrong with it ,that should tell me something.

<{POST_SNAPBACK}>

Do you have a temp gauge for it? If so, what does it read during normal driving? Do you have an aftermarket aux cooler?

Jacqson · December 25, 2004

i have a 1993 gmc 3/4 ton hd ( biggest piece of @!$#% i ever owned) with a 4l80e tranny in it,at 120k the tranny went while on the highway.had it rebuilt and now at 135k on it the tranny is slipping again just like the first time .when its cold from a start up it doesnt slip,but once it is warm the truck can hardly go without slipping.i can keep it from slipping if i let off the gas between shifts doesnt always work,but it has me thinking is this a eletrical problem? or did the tranamission shop give me the sausage?

<{POST_SNAPBACK}>

You might want to check with the dealer and see if there were any of the problems you described in your post. I had a 91 3/4 ton Suburban with a 4L80E that kept slipping out of gear. After several visits to a Transmission shop and nothing could be found I took it to the Dealer and they had a bulletin from the General with a description of the problem(Defective module). They fixed the problem after the warranty expired at no cost to me because it was a factory defect and the basic warranty was extended on the Tranny.

vhato · December 27, 2004

During the early 90's the 4L80-E was first released and it has been updated MANY times since then. A reputable transmission shop will have knowledge of this and would only do a rebuild including the modifications.

Typical 4L80-E rebuilds include $500-$700 in labor (includes reinstallation) and $1200-$1400 in parts. You should have paid around $1600-$2100 for the rebuild w/the upgrades GM has made. If you paid SIGNIFICANTLY less, then you didn't get a complete rebuild....just a repair.