Chevy & GMC Vans

Questions for all you 4L80E guys. I'm curious, even I'll probably just get a rebuit 4L60E when the time comes. How did you do it? Was it a direct bolt on swap? What was involved? Does having AWD make it a whole different ball game--my dream is 2 speed 4WD though...

As far as I know, Peter is the only one with a 4L80E. Everyone else just runs the 4L60E. Have you done the maintenance on your current tranny? If so, you have a LOT more miles to go.

LiftedAWDAstro wrote:Have you done the maintenance on your current tranny? If so, you have a LOT more miles to go...

I've done the fluid and filter changes/magnet cleaning. But I don't think I have a many more miles to go.
1-2 shift is good, and 3-4 shift is good. But if I floor it going up hills, it shifts to 2nd and stays there. After a little while, I'll even loose speed, while staying in 2nd. The name of the game has become keep it out of 2. If I can do that, I run good...

I don't think it's an engine issue. If it were, I think it'd affect 1-2 and 3-4 shifts. But just to be sure, I did the seafoam treatment, have new plugs and wires and a new ignition coil. It wasn't the fuel pump either.

When I put the Hypertech program in the SPB and raised the rev limiter, I got the same thing. It would tend to hold 2nd too long. I just kept the rpm's to 5k or less and it was good to go.

I also felt the trans was on it's way out around 120k but then I just kept driving it and doing the maintenance and it was still strong when I sold it to Bill at 155k+. I would think you have a LOT more miles to go.

You think flushing it will kill it? Might it help?

What about the sea foam tranny stuff?

Don't flush it. Drop the pan and change the filter and then re-fill with fluid. If the fluid that comes out is clean you can flush it out after replacing the filter. If the fluid has never been changed and it is very dirty and brown looking, I wouldn't do anything to it.

LiftedAWDAstro wrote: If the fluid has never been changed and it is very dirty and brown looking, I wouldn't do anything to it.

I've heard this said several times and was wondering why? Is it just already shot and so a waist of money to flush it or does it cause damage some how? just curious....

Trans fluid works as a pretty good cleaner. If you put all new fluid in a 100k mile tranny by way of a flush and the fluid had never been serviced before, you will wash all the built up sludge and metal and clutch particles up into the new fluid and proceed to run it through the servos which have very tiny orifices. These orifices will the plug and you won't get proper fluid flow to hold the clutches tight. The already worn clutches will then be toast in very few miles.

In general there is no reason the fluid should be brown or have excessive particles in it. If it is brown it means it over heated badly for whatever reason. In that case damage is probably already done.

Makes sense.. Thanks for the info!