Tranny swap?

[Mikeandwendy74]

Hi I have a friend that has a 1988 jaguar xjs it has a th400 tranny. My truck is an 88 gmc 6.2 with a th400, anyone know if the bellhousing is the same? I know buick pontiac and olds is different but what about the jags?

[DmaxMaverick]

I don't know if the bolt pattern is the same or not. IMO, it won't matter. The tranny, although a TH400, is entirely different. The governor, VB, pressure circuits and clutches are not the same. The TH400 was used widely in many applications, including Rolls Royce and Range Rover. Each tranny application is built and tuned specifically for that vehicle mgf. Most internal parts aren't even compatible w/o a complete overhaul and R/R of gears, clutches, pistons, valves, bands, etc.

Let us know if/when you find out what it fits. I'm curious to know which bolt pattern it uses. It may be unique to Jag, or a specific pattern. I know the RR 400's only fit RR engines.

[Mikeandwendy74]

aw shucks, I think jag bellhousings are unique to jags, they mated them to v8's and v12's only certain years. I'm getting very tempted to pop my trucks tranny and try a rebuild myself.
Symptoms: all forward gears fully functional with zero slippage.
reverse gear wont engage whatsoever.
Any ideas on where to start?

[gmctd]

Start by pulling the pan, see what's in the bottom - few shavings, some brown stuff, probably not too bad, worth a rebuild.

No reverse is the rear servo or\and the accumulator - seals are leaking, which will mean all the seals are heat-hardened and will begin leaking

Unfortunately, that's at the complete rear of the case, and requires total disassembly, so may as well plan on a complete rebuild.

Rebuild kit with hard parts probably around 180bucks - band servo pistons are plastic, see if you can get the earlier aluminum versions, as the plastic pistons crack easily during disassembly.

[Robyn]

yank it out
A TH 400 is a piece of cake to rebuild.
The rear band or its servo or both have taken the big poop.
Also be sure when you tear it down that the center support where it is fit into the case has not worn the large splines in the case to the point that the support can wiggle around. There is a special hollow bolt that threads through from the channel casting side of the case through and this holds the center support in.
Get a good how to tranny book on the TH 400 from the tranny supply house and you can do it.
You will need a slide hammer that will thread into the front pump housing to get the thing out. (two of the bolt holes are threaded internally)
The rest of it can be done without much in the way of special tools. Be careful when reinstalling the servos in the clutch drums that you dont cut the seals.
Read the book and you will do fine.
Get a transgo reprograming kit for it too. The HD one is best.
If there is not too much crap in the pan your converter may be ok but if the pan is loaded with lots of crud, toss the converter and get a fresh one. A used converter will have tons of junk in it if contaminated and it will pump it back into the fresh box.
Be sure to install an inline filter in the return line from the cooler before you start it back up. This will catch any crap left in the cooler. Blow the cooler out before you reassemble things too.

[Mikeandwendy74]

Thanks for the tips I have a good book for it for complete step by step teardown and rebuild, all exploded views, looks pretty good. Now heres the question....I've been looking and there are alot of rebuild kits available...master kit, super master kit etc.....I see some for 50 bucks, some for 150...how do I know which is the best one to buy? Have you physically bought and installed any particular kit that you would recommend? Maybe theres a good website you could point me to? I hate to leave any doubt about which one I might need to get for a complete rebuild. Thanks for the advice it all sound good.:)

[gmctd]

The lower-priced kits are clutches and seals, only.

The hard-parts kits are more expensive, with everything but the drums, gears, shafts, pump, and valve body.

Then there are the aftermarket rebuild kits by TCI, B&M, etc, more expensive, but contain the re-calibrated valve-body spacer plate, stiffer springs for more pressure, etc - the shift-improver kit.

FYI - the shift kits use the stock gray Diesel pressure-regulator spring, and the vb spacer gets two holes re-sized for RV and normal street driven auto-shifting