1993 XJS V12

Do you know if the transmission has been rebuilt? The original trans should be really smooth going into gear or shifting between gears. That smoothness also wears the clutches in the trans, so if it's been rebuilt, it's common for the rebuilder to put in a type if shift kit to make the trans last longer, and improve shift response. The one thing that happened to me, is that when they rebuilt and reinstalled the transmission, they screwed up the rear mount. The transmission would make similar noises to what you said, but would make more of a grinding sound, and would clunk like mad when driving on rough roads. Oh also check to make sure the right side silencer that mounts to the trans isn't too close, because it can overheat the transmission.

 

GM400 is a three speed and is bulletproof. The vibration and noise you describe sounds like a driveshaft issue.
When can we see it?

 

Mike,

Yes the GM400 is usually a bulletproof trans. The way the original transmission was set up in these cars though made the clutches wear, and at around 100k the transmissions would go. The good thing is that they're pretty inexpensive to have rebuilt. If your car shifts pretty quick, then it's probably been rebuilt, and if it clunks into gear, it's probably been rebuilt. Usually the clunking into gear will soften up.


If it's a driveshaft issue it's probably a U Joint, and I believe there is a U-joint where it connects to the rear differential.

Jim

 

I dont know if your car has it but my 95 xj6 had a drive shaft bearing/isolator thing that would come loose and cause a bad vibration. Mine broke twice. Freaked me out the first time. I was adding up half a drivetrain in my head as i was pulling over.

 

Nice!

 

That's REALLY nice! I think they look fantastic in white.Did you get a chance to check your Trans out yet? If the gearchange isn't smooth as silk i'd check your fluid level , if it's a bit low or the oil is old it can cause clunky changes, and as others have said, check the often wobbly rear mount but also check the two cotton-reel engine mountings at the front. they are pretty close to the manifolds on the V12 and when they get a bit soggy than can sheer off. They are visible from underneath. I replaced them on my last XJS and fabbed up a couple of little alluminium heatshields that slid between the rubber mount and the motor bracket to stop it happening again.

 

Very nice car. I had the 87 version in the identical color.

 

Looks very nice.
If you want a spare, I just bought a V-12 to rebuild and sell.

 

Nice car Mike

 

That's a beauty in White & that XJS V12 badge is so tantalising I've been a fan of the long Jag since young & they are strangely quite cheap now (very little $ for a lot of car).

I missed a chance on a blue 3.6 here few months ago & I'm still kicking myself for it.

Li-ge?!

 

You got that right Mike. It's a heck of a car for little moolah. Had a drive in a mate's way back 20+ years ago in the UK. T'was a roundabout on a wet day and exiting the roundabout, I stomped on the throttle and the back end comes round..and even though I 'caught' the slide oppo-locking, it sure did turned me blue for a sec.... A magnificent long distance cruiser and even tho' the said car that I drove was a 'banger' owned by one of my Uni. friends, it got us to Dundee and back to London in comfort and nary a glitch. Only problem was the fuel consumption nearly bankrupted us students then...

 

Yes, that jag independant rear suspension does wonders for the handling if that car. You can actually set up and stick turns in that car very nicely. It's actually pretty good in the snow too, as long as it's not over 6 inches.

 

There's a lot you can do to improve the handling. Over the years they start to feel a bit "saggy". It shares most components with the DB7 V12, harder v-mount bushes, six shooter bushes etc. are a straight fit, as are the rear trailing arms, with uprated bushes, as well as shock absorbers, springs etc. The front geometery is fully adjustable too. Of course all these parts aren't cheap, but they sure do make a difference without compromising comfort too much. You can also pack the steering rack mounts either side with steel washers, there's quite a bit of movement there, and it improves steering feel quite a bit, although the "dead spot" in the middle feels the same.

 

It's funny you mentioned steel washers. I was told there was too much movement in my steering rack when I was getting an alignment one day. The mechanic was showing me how the rack would move because the bushings were worn. I saw the gaps in the mount and thought about putting spacers in there. A mechanic had told me you shouldn't do that, but I see NO reason not to. I wound having to replace the rack anyway because it leaked badly. I had the poly bushings installed which really improved the steering response, but I would still put in the spacers because even the poly bushings wear out about the same time as the originals.

 

It's exactly what Aston Martin did with the DB7 Vantage. Wobbly rack?......Wedge some washers in there...job done! British engineering eh?

 

I wonder if anyone has done a drivetrain swap and put the aston V12 and manual gearbox in an XJS?