Jaguar 4L80e - how different is it from the GM version?

[DS420]

I have a 1995 Jaguar XJR engine (supercharged 6 cylinder) and transmission that I am in the process of transplanting to another vehicle. When I bought the car, the PO had broken the boots to the traction control cable so the throttle cable was binding randomly, causing idle speeds in park anywhere from 750 to 1800 rpm. Needless to say, it went into gear with quite a thump with the engine running so fast. After seeing some of the videos from Precision Tarnsmission, I'm wondering what the conditions of my clutches are. It shifts and drives as it should, but I have a nagging suspicion that it will need a rebuild sooner than later.

If I do rebuild it, what are the differences between the Jaguar version of the 4L80 and the Chevy version? So far I know the case, extension housing, output shaft, pan gasket, torque converter and wiring connector are different, are any of the internal parts different/beefed up to handle the power and torque of the V12 and Supercharged 6?

If a standard centre lube GM rebuild kit will do the trick that would make life easy, or suggestions of any other things that should be changed to offer longevity would appreciated. It's going in a limousine, so I'm not towing or doing 1/4 mile runs, but it is a heavy car (6000 lbs) and I will be driving it through long, steep mountain grades, so it will be working hard. I've done a few mods to the engine, so it's making a bit more power than factory about 350hp and 450 ft-lbs (factory was 322hp, 378 ft-lbs).

 

[nascarnation]

Don't have any valuable knowledge, so unless one of our Hydramatic experts chimes in, I'd suggest trying to find a parts list on the Jag trans and compare to the GM. Good luck!

 

[2EHA]

Should be all standard rebuild parts, the supercharged six doesn’t put down anywhere near the max limit of any 4L80E. XJR and 6.0 V12s use the same complete unit so you can find one to play around with pretty easy instead of taking apart your known good unit. if they needed a rebuilt unit they just sent the core straight back to GM, there’s a TSB on it somewhere.

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what mods did you install to make it put down 450lb/ft? you’re not doing that with the little heaton it came with

 

[clinebarger]

All the Hard Parts besides the Output Shaft are the same as GM versions, Hydramatic didn't need to upgrade anything for some puny Jaguar engine, They're designed for vehicles with @ 18,000 pounds GCWR.

I regularly put 700HP/700FT-LBS through units with bone stock Hard Parts up to 5,000 pounds, More Torque, Nitrous, Trans brake, or Weight requires a Billet Input Shaft.

A bone stock unit is rated at 450 Ft-LBS. Dual Feeding the Directs, Larger Boost Valve & Stouter Pressure Regulator Spring is all it takes for 700 FT-LBS.

Not a bad idea to refresh the unit with new Frictions, Bushings, Sealing Rings, Gaskets & Seals.

 

[DS420]

what mods did you install to make it put down 450lb/ft? you’re not doing that with the little heaton it came with

The mods were the "Andy bracket" which advances the timing about 5 degrees, plus a Powerhouse pully that drives that supercharger 10% faster. I lose top end RPM with that, but gain low end torque. I know I can max out the MAF now between 4000-4500 RPM at full throttle now with the supercharger being driven faster.
I saw an XJR owner in Denmark who did before and after dyno runs with the modifications and those were the numbers he achieved.

 

[DS420]

All the Hard Parts besides the Output Shaft are the same as GM versions,

Thanks, that makes it easier to get parts. I had understood that Jaguar upgraded various components within the TH400 to make it heavier duty than the GM version, I didn't know if they did that again with the 4L80e.

 

[clinebarger]

I was a "Authorized" installer for John's Cars of Dallas Texas for several years & built mostly Jaguar XJ-S cars with GM LT1/4L60E drivetrains to replace the 5.3L V12/TH400. I would in turn tear the Jaguar TH400's down for hard parts & scrap the trans case & V12.

There's nothing special about Jaguar TH400's besides the bellhousing & Torque Converter that made them specific to the chassis. The cars didn't usually have many miles on them & the trans hard parts were in perfect shape....Unlike a GM truck core with a half million miles on it.

I would use the Jaguar hard parts to build otherwise junk Chevy Case cores.

I realize GM is seen as a joke on this forum, But Jaguar didn't have the sway to tell GM/Hydramatic how to do anything or otherwise allowed to modify the units they purchased. Every Jaguar unit I've ever tore down was manufactured at GM's Willow Run Plant which was originally built by Ford.

 

[DS420]

I had it in my mind that the Jaguar version of the TH400 used a 34 element sprag and the standard GM was 16, or something like that? While it was all GM parts, didn't Jaguar specify different components from the parts bin than you'd see in a GM passenger car application? Or have I got that all wrong?

 

[clinebarger]

The TH400 never had a 34 element Intermediate Sprag, That's late 4L80E (center lube) only. Now....Early TH400's had 16 element sprags & then 8 element Roller Clutches later on.

With some machining.....You can convert the early Sprag TH400 Direct drums to use 34 element 4L80E sprags.

 

[DS420]

I'm taking out the 4.2 XK engine/TH400 combo and putting in the XJR 4L80, so I fortunately don't need to rebuild the TH400.

 

[2EHA]

I'm taking out the 4.2 XK engine/TH400 combo and putting in the XJR 4L80, so I fortunately don't need to rebuild the TH400.

the 4.2 limo car came from the factory with a 400 instead of the borg warner? Makes sense for such a heavy car, never knew that.

 

[DS420]

Yes, the only version of the 4.2 that did. Uses the V12 version of the 400 with an adapter plate. It had a very restrictive governor too, shifted at 2800 rpm, just as the engine was starting to make power. I changed it from one from a Cadillac and the shifting improved greatly.

 

[Trav]

IIRC RR was also a big user of GM TH400 and Harrison A6 A/C compressors back in the day.

 

[DS420]

Yes, Rolls Royce used the TH400 from about 1977 to 92. Jaguar also used the A6 until about then.

 

[MI-Roger]

Spring ratings in the valve body might be different to provide the car with a different "feel" during shifts and maybe different shift points.

Back in the day when Chevy, Pontiac, and Buick used the THM350 (also called the CBC transmission at one point), Oldsmobile used a THM 375 in their mid-sized cars. The 375 was a THM400 with one less clutch plate in each clutch pack since the Cutlass's mass and engine output didn't require all the capabilities of a THM400.

I worked for GM's Hydra-matic/Powertrain for 25 years as an Engineer, but NOT for transmission design.