4L80E Transmission Compatability

[forbey]

Tried posting this once and it dissappeared.

I now have a 1993 Chevy 2wd Pickup with a 6.5 and a 1995 GMC 4WD Suburban with a 6.5. Both apparrently have the 4L80E transmission. Are they compatible? Of particular concern is the 2WD vs 4WD.

Thanks,

forbey

[6.5TDTahoe]

Nope,both match the engine but not interchangeable at the rear of tranmissions. Bolt yoke 4WD VS slip yoke 2WD.Units have to be dismantled & change output shafts ,etc.Just sell me the 93 fuel & electrial systems !! Hope this posts correctly this time!!

[forbey]

Thanks for the info Tahoe, but I still haven't decided if I'm going to part out the truck or run it. I'll let you know.

forbey

[THEFERMANATOR]

The 95 can go into the 93, but the 93 cannot go into the 95. The valve bodys are slightly different between the 2, and the TCC solonoid is different between the 2 as well. As for the case, the 95 has the bosses for teh NSBU switch whereas the 93 doesn't.

[DmaxMaverick]

Nope,both match the engine but not interchangeable at the rear of tranmissions. Bolt yoke 4WD VS slip yoke 2WD.Units have to be dismantled & change output shafts ,etc.Just sell me the 93 fuel & electrial systems !! Hope this posts correctly this time!!

Huh?

2wd has a slip yoke. 4wd has a coupled spline, into the transfer case. The transfer case has a slip yoke (the front drive yoke is static/bolt). THEFERMANATOR has it right for the rest.

Switching from 2wd to 4wd, or vice versa, only requires swapping the tailshaft housing/adapter.

[6.5TDTahoe]

sigh. Between memory & old age I mispoke. Not a fan of the 4l80. A short life trans IMO.

[DmaxMaverick]

Actually, the 4L80E, despite failures, common or otherwise, has been and is one of, if not the, most reliable heavy duty light truck auto tranny ever released. Everyone can't have the same experience with every component, so personal experience weighs heavy with individuals. It is still in production, although updated/upgraded for later model higher power levels. The 4L85E and 6L90E trannies are only later variations of the original base model. I dare anyone to compare any current or previous light truck auto transmission of any brand (except Allison), showing how it is inferior.

[THEFERMANATOR]

Actually, the 4L80E, despite failures, common or otherwise, has been and is one of, if not the, most reliable heavy duty light truck auto tranny ever released. Everyone can't have the same experience with every component, so personal experience weighs heavy with individuals. It is still in production, although updated/upgraded for later model higher power levels. The 4L85E and 6L90E trannies are only later variations of the original base model. I dare anyone to compare any current or previous light truck auto transmission of any brand (except Allison), showing how it is inferior.

The 6L90E is an all clutch trans whereas the 4L80/85E is a basic clucth and band style trans. From what I have read and seen they don't seem that alike. Yes the 4L80/85E is a good trans though, and has stood the test of time and milage behind many a truck.

[6.5TDTahoe]

Thats what a 4L80/85 auto trans is. 6L90 overdrive trans is a joint venture between GM & FO MO CO.

[Robyn]

The 4L80 is a derivative of the TH 400 and even today, many parts will interchange.

The main differences are of course the electronic control of the shift points, internal oil pressures and the overdrive top gear.

The venerable old TH 400 although a 3 speed box is nearly indestructible.

Used in everything from daily driver passenger cars starting in the 60's and used in light duty trucks and even in large motor homes behind the 454 and the 6.2 diesels as well as other engines.

Jaguar and Rolls Royce use/used a version of the Th400

The trannies really had few design flaws and were a beast.
The only thing required to make these work was a vacuum source either manifold or a regulated source (early 6.2 with a pump and a valve)
The 12V connection was only for a kick down and not required

The 4L80 was a "Logical" step forward when the computer controls advanced to the point of handling the shifting duties.

A 4L80 with only the addition of a transgo shift kit, a better cooler and a return line filter will live a good long life span.

There are really not too many failure points in the 4L80.

The electronic oil pressure controls, shift valves and such are about the only problem spots.

Now this said, keeping the oil clean is the biggest issue.

The addition of a return line filter is the cheapest and most beneficial thing you can do for one of these boxes.

The VB is aluminum and has steel valve spools. Dirt, metal flakes (they all make tons of this crap) is not well tollerated by the alloy VB.

The stuff can cause scoring of the valve bores as well as sticking and other undesirable things. :eek:


The 6L90 is/was/has been used in the 1500 series trucks and the H2 Hummer as well as several passemger cars.

The 6L90 is not the HD box.

Even the much praised Allison has its issues as well.

No matter what box your running, there is usually some goodies from the folks at Transgo that will fix whatever Ill's it has.

I praise and mention Transgo because they have been around since the late 60's and their products work and work well.

The one tranny that deserves the most hate mail is of course the 700R4/4L60 (E)
This box has gone through more updates and redesigns of any auto tranny ever produced I think.

To make one of these boxes live requires a big pile of aftermarket parts and an even bigger pile of $$$$$$

If you do all the bench work yourself (no labor) to do a 700R/4L60 right and have it live will cost you at least $1000 ++

A 4L80E done right in a 4x4 will set you back about $2000 at a shop.

(My kids had there 99 GMC 2500 done and I ended up helping with the bill)
(Shop owner likes guns, so I traded him some stuff on the Kid's bill)

The 4L80 IMHO is not a bad tranny, Light years ahead of the Ford E4OD and the Mopar boxes.

The 6L90 as mentioned is a clutch to clutch box and this eliminated the need for the roller locks/sprag clutches.

A clutch to clutch shft can be better BUTTTTTTTT
A band is tougher to control the apply and release without either having too soft of a shift or too harsh.


A 700R when set up to last is going to bring harsh Bitching from most clients.

The 1-2 shift is going to be BLOODY BRUTAL. First gear is done by applying the forward clutch which cause the planet carriers to back up against the rear sprag, then when the second gear band is applied you have second gear.

The apply IF nice and easy give a nice smooth shift, but burns the band out in short order.

SOOOOOOOOO ya engage the 2-4 band with a ZIp and a bang and the shift is nasty.

Personally I love the harsh shift as I fully understand what is happening and why.

Just dont leave your coffee mug on the dash :D It will land in the back seat, right quick.

Whenever I do a 700/4L60 I use the transgo "Dash two" kit and set all the adjustments on "KILL" they live too.

Bands are always problematic. The TH 400 did not use the band for a major range selection. The band was used for manual 2nd only. (Compression/overun)

Now the old Ford C6 used a Band for second gear as did Mopar 727 and they had similar failures with the band (for the same reason)

The 700R4/4L60 uses the band for second and fourth ( 2-4 band)

Just my take on these beasts after many years slogging through burnt up nasty smelling trannies. :)


Missy

[THEFERMANATOR]

Robyn, the 6L80E is used in the 1500's and cars, the 6L90E IS for the 2500HD and 3500 equipped with the 6.0L and the 6.2L in the DENALI. As for the 4L60E, it isn't a bad trans by any means, and isn't that hard to build up to handle a decent small block. It will NEVER handle a big block or a diesel though for any length of time. And no trans likes material in the trans fluid. Electronic controls have come a LONG ways in making a trans last now that power can be cut and brought back in on demand to help with shifting and shift strategies. Any trans will work well for it's desired application, it's when you push the limits that problems arise. Even the mighty ALLISON has a sketchy track record in the racing world.

[forbey]

Okey Dokie!

So, if I can put them all together, the 93 and the 95 are interchangeable at the engine, but the rear end needs to be modified. AND, I need to add a return line filter. Anything else that I missed?

forbey