4l60 or 4l80

[85burb]

I have a 85 burb with a lq4 and cam. Currently I have a 700r4 in it. The problem is the truck is 4 wheel drive. I think my front pump is leaking and want to change to an electric trans anyways. Will a 60 hold up or will I need a 80. If 80 is gonna be needed how can I make my np208 work with it? My harness has a connector for the 60 already just not being used.

[mongocanfly]

The 60e is basically a 700r4...the 80e is basically a t400..so the 80e is better..not sure what transfer case you got but they do make adapters...but they ain't cheap..your 700r4 could be built and beefed up much cheaper I would think

[85burb]

My 700r4 is built......well was. It has been behind the 6.0 for almost 6 years. Only killed one converter and if I use anything past half throttle in 4th something slips. Not sure if it's the converter or 4th gear. The new circle d converter didn't seem to fix the slip in 4th so I'm thinking it's the clutches. I really want to have an ecm controlled transmission so it will lock and unlock the converter when it needs to and down shift to the correct gear.

[clinebarger]

In a heavy 4x4 Suburban with a 6.0L......4L80E!


Find a 2wd with a Fully Splined Output Shaft. You will have to cut the output Shaft to the correct length. Fully Splined units are generally found in Vans.

Locate a Cast Iron TH400 too 6-bolt T-Case Adapter, You will need to have it machined to fit a 4L80E Register, Any competent machinist can do this quickly for not much money.

You should be able too score a 32 Spline Input NP208 & TH400 Adapter for around $300, An '85 K20 truck/suburban will have the exact parts you need.

[85burb]

So a 4wd 80 would not work? I have found 32 spline input shaft for the 208.

[85burb]

Would this help. Gm part number 15654927?

[clinebarger]

Originally Posted by 85burb

So a 4wd 80 would not work? I have found 32 spline input shaft for the 208.

Originally Posted by 85burb

Would this help. Gm part number 15654927?

The issue is that (At least Late Model) 4wd 4L80E's do not have a OSS/VSS Reluctor Wheel on the Output Carrier, Because the OSS sensor was on the Transfer Case.
You can tear the trans all the way down & press a reluctor on the output carrier. Or if your having it rebuilt, This can be done at that time.

2wd "Fully Splined" Output Shafts & 4wd Output shafts are actually the SAME shaft, GM just cuts a "Fully Splined" shaft for 4wd applications. I can give you the exact length you need so you can cut the shaft the correct length for either the Factory 4L80E to NP241C Adapter or a TH400 to NP208, As they are different lengths.

Also... Buying a 2wd unit gets you a 2wd Tailhousiong that you can take to the machinist so he can machine the Register down on the TH400 Adapter to the exact dimensions needed.

That part number is for a 4L80E to NP241C Adapter, While it will work with your NP208, The Trans Mount Pad is COMPLETELY different than what a K-series square body truck has.
Using a TH400 to NP208 Adapter like I suggest would spare you the hassle of fabricating a spacer for the 4L80E to NP241C Adapter to use your existing "Horse Shoe" mounts which would be a ton of work & not near as strong, Gets the Driveline angles correct, All you have to do is slide the Crossmember back & drill some holes in the frame......And your done!

Here is a pic comparing 2wd (bottom) & 4wd (top) Ouput Carriers, Note the reluctor on the 2wd.

[clinebarger]

Picture of a 700R4 to NP208 Adapter vs a TH400 to NP208 Adapter, The arrows are pointing too the Register that needs machined to a slightly smaller O.D. to fit a 4L80E.