this is the 4L60
<img src="http://www.gm.com/automotive/gmpowertrain/transmissions/images/4l60_lg.jpg" alt=" - " />

this is the 4L80
<img src="http://www.gm.com/automotive/gmpowertrain/transmissions/images/4l80_lg.jpg" alt=" - " />

only dimension difference of any consequence is the tail shaft length...and with a 4x4 app that doesn't matter at all

the 1500HD's already have the 4L80's in them and they are a standard 1500 body and frame...this will work....like i said before...I have seen this done, is damn near a direct swap except for the crossmember and haveing to rebend the cooler lines a little...and on a 2 wheel drive it is almost too easy

 

it will have to take a different converter/flexplate too, right?

 

someone needs to try this, i like what yelo is saying but i have heard alot of conflicting info on this suject. i would swap to a 4L80E in a heartbeat if it is really that easy. seems like i remember seeing the 4L80E was a couple of inches longer than the 60

 

it definately takes a diferent converter. i don't know for sure on the flex plate but i bet it is the same one. they don't cost all that much anyways if you did need to buy one. not like a $700 converter.

 

this may be dependent on what year the transmission is. if you remember the disaster i ran into with my 6.0, the crank is about 1/2" longer in them before 2001. so is it the converter, bellhousing, what?

 

yeah...the converter IS different...the reference converter is a 300mm converter vs. the 280mm for the 4L60...the flexplate IS the same between the two transmissions.

I do know that there are two converter applications for the 4L80..one for '99-'01 and one for '02-'03...that may be for the different crankshaft lengths between the years

The 4L60 is 31.15 inches long for both 2x4 and 4x4 apps

The 4L80 is 29.5 inches long for the 4x4 app and 31.95 inches long for the 2x4 app

on all the 2 wheel drive trucks there is nothing to worry about at all except changing the trans mount out for the HD mount...the extra length is taken up by the slip-yoke on the tranny...on the 4x4 trucks you have to adjust the transfer case back using the elongated bolt holes on the t-cae mount...the slip-yoke will again make up for the the length difference

hope this helps

 

Would the conversion be worth it if you lost more HP? The 4L80E produces about 5-7% more loss.
Also, I've heard that the pcm will want to see what is was programmed for. Will the pcm have to be flashed to the 4L80E code?
I'm sure it will install meachanically just fine though.


allen

 

yeah what texas terminator said

 

On a stock truck the conversion is probably not worth it...but, on a built truck with a blower or a big N20 shot it is definitly worth it due to the strength of the tranny.....personally I would be happy with the power loss to gain the reliability of the HD tranny

as for the other question...on the conversion that I saw and helped do the PCM was not reprogrammed....all the research that was done made us determine that it was not necessary...as far as I know the PCM has never been flashed for a different tranny in that truck...and it seems to work just fine...although I haven't seen that truck in almost two years

 

i would expect to loose around 1/2 second switching to the 4l80e, it is something like 100lbs heavier, eats up more power just turning over the thing and has alot worse gear ratios. that said what choice is there when you start making BIG power?

i have serious doubts that these people making 4l60e's that will hold 600hp have ever tried their trannys in 5000lb trucks. the weight seems to hurt more than the hp level.

i have an flp tranny(4l60e level4) that i plan on throwing ~600fwhp with great traction at. you can bet that i will be leting you all know how it takes it.