4L60E to 4L80E?

[mr.tech]

Is the 4L80E a direct swap for the 4L60E? cause if I remember right the flex plate different. are the harnesses different between the two? will my computer talk to a 4L80E or do I need a different computer. and what years are the same (can I use, lets say a 97 4L80E in place of my 91 4l60E?) and which can I use?

the reason I ask is the reverse gear in my 4L60E is slipping pretty bad. this is in a 91 TBI suburban, 4WD 4" lift and 33's. this is my tow rig/DD and I cant have it down for too long (going to have to be less than a weekend).

oh If I decide to rebuild my existing trany can I just put new clutch packs in and go or do I have to replace all the sprags, bands, valve body, ext.?

[Bo185]

No and yes it will bolt in but the newer 4l80E uses the computer to shift it so it'll need a controller to shift it.. Your truck should be a 4l60 (no E) The 4L60E wasn't till 93 and up and the computer shifts those.

I would look for a 4l80 for the 93 back. I think they made some that were not computer contolled.

You will need to mod. the rear trans crosmember and the driveshafts not to mention change the transfercase input to 32 spline.

The 4l80 is a nice upgrade and if you had the parts ypu could do the swap in a weekend may be two. I would have the 60 rebuilt at a good local trans place.

[trannyboy]

x2 on needing all the parts drivelines etc. if your sre going to do this swap get the early 4l80e. if you decide to rebuild your 4l60 do it right and replace all the seals, gaskets, sprags, band, sun shell, torque converter, 2+4 servo(corvette) and shift kit the valvebody with a transgo jr. don't half ass it you will end up watsing more time and money if you don't do it right the first time. just my .02

[Snoops454]

there was no 4L80 it went from the 3L80 (TH400) to the 4L80E. I know the ones that came behind the diesels had their own ecm. you could get it reprogrammed to shift correctly behind a gas engine.

[mdill]

Or use a 93->95 ECU setup that had TBI and a 4l60e or a 4l80e

Mike D.

[rebound]

OK, here goes...
I replaced a T400 with a 4L80e in a 4x4 Suburban almost 15 years ago. All of the 4L80's are electronic. They are a few inches longer than a 400 so the driveshafts will both need to be modified, rear x-member and shifter moved back. The one I got was out of a dually so the O/P shaft was the same spline as a 400. The 2 transmissions have the same bolt pattern in the rear but the registers, or counter bores, are not the same. When I did this, no one was making 205/4L80e adapters so I made my own. It was basically a 6061 T-6 aluminum ring about 1.25" "long" that snugly fit the 205 and 400 cases, complete with bolt holes and longer high-strength studs. Since the 4L80 has forced lube for the slip yoke, I added a small passage and tube for T/case coupler lube.

With this adapter the 4L80 O/P shaft was .5" too long so that much was removed and chamfer restored. The dimension of the adapter worked out perfect as the 205 needed to be moved back anyway because the bigger case and pan would have hit the front drive shaft's Double Cardon joint.

With the 205 shift lever back a few inches two 90 degree bends were added so it could come through the original hole in the floor. If you use the original shift lever you must do this or it will end up under the seat. After lots of cutting, heating and banging, it turned out to be much easier to simply cut the entire area above the transmission and T/case out and replace it with a simple formed piece. This actually made it easier to re-carpet as well.

The bell housing is the same as a 400. The one I had used a 6 converter bolt flex plate and the same 4x4 aluminum bottom converter cover as a T400. I did'nt believe it till I got one, but the 4L80e really is about 100 pounds heaver than a 400.

That all worked out perfect. The operation and subsequent problems were another chapter. But it is still being driven today and is a real work horse.

[472Scout]

It will be a lot easier to have your 4L60e professionally rebuilt.

Rebound,

GM did produce an adapter for the 4L80e to long spline NP205.

btw: are you using the diesel computer and did you put a VSS sensor in your 205?

[rebound]

I used an early "e-Place" unit. Mechanical speedo, no VSS needed.

BTW, the 4L80e is fairly easy to rebuild, although the O/D unit can be a little trickey to assemble. That and the valve body are almost the only things that aren't T400.