Hi,
I'm Kevin from upstate NY. I own two old cats. Both are 1987's. I have an XJ-6 that is just about fully restored (paint this winter) and a XJ-S that I am building into a race car. I'm just about finished with it from the mechanical side. It is a rocket ship but it needs a front cross-member before I put it on the track. I'm welding the SCCA cage in this month. Does anyone know if an XJ-6 cross-member is compatible with the XJ-S? I can change the engine mounts easily however, the geometry of the suspension is another issue to try to duplicate. My existing CM is a little rusty and pitted with small holes on the right side. Hate to lose that at 140MPH. Any information on finding one and compatibility would would be greatly appreciated.
I stripped down the V-12 to the basic motor. Without the weight and drag encumbrances the engine performance is startling. AV-gas helps too. It's almost a muscle car. I can drift it on pavement now. Nothing like the sound of a V-12 straight piped through a 2 1/2" exhaust. If anyone is knowledgeable in this type of race tuning please barge in! We can't wait to see the look on the BMW & Porsche guys faces when this old Cat shows up at the 24 Hours of Lemons next spring. Thanks, Kev
PS. not sure if I did this right so I apologize if I high-jacked somebody else's post.

 

Kev,

I've moved this one from the end of an unconnected thread in New Member Area to XJS section where the guys should be able to offer you advice on cross member interchangeability.

Graham

 

Subframes are the same as far as I know.

 

Yes they are.

 

I have a '83 and am doing the same thing as you except for track day events here in phoenix, it's amazing the amount of crap that has come out of this car, at least 1000 pounds so far lol. Im working on building a new wiring harness right now, and yes the cross members are the same.

 

You are going to have a ball with that car. Ended up with about a total of 1,600 lbs taken out of the car. It raised the suspension about 3 inches. I have to reinforce my trailing arms next. Don't trust them with all that torque now.

 

what did you do for springs? mine is sitting really high right now.

 

Might have to move to a shorter or softer spring. Sure has made it easier to work on it though. Thinking about keeping it up and using a vane suction system similar to the outlawed formula 1 technique. I can use the draft to lower the cat and vacuum my exhaust. I can also use it to cool my front brakes. I'm presently channeling my underside air to cool my fuel lines too. Those 12's will boil AV-gas as soon as it clears the firewall. A reflective foil aviation blanket wrap seems to help too.

 

if you are serious about track racing, mounting the REAR subframe solid is a good idea, i have seen the whole rear frame tear out of the car, its all mounted in rubber and the rubber rips loose from its mounts, when it gets old and rust sets into the bond.

also a guy on jaglovers, MGuar, does a lot of track stuff.

 

Sounds like good advice. I'd hate to have that come flying out of there during the race. Without the exhaust in the way I have a few good ways to spread the shear and distribute the torque throughout the rear frame section much better than stock.

 

Didn't get to it this weekend. Had to put a new differential in my land rover. I'll get some pics up too. Thanks for the advice. Kev

 

Are you swapping transmission for manual?

 

At this point I'm still running the auto. Love to swap it out and go with a standard 4 or 5 speed but it's not in the budget right now. It would make a world of difference on the track. Right now I'm just real good at doing the brakes in the pits (with help of course) I bring 5 sets of front brakes. The rears only swap out once a race. Keeping the fuel and the brake fluid from boiling have been a challenge but I think we've got it under control for now. Any suggestions?

 

has been said that the inboard rear brakes can boil the fluid , one reason Ford put them outboard ,mid 90s, along with easier service!!

inboard brakes dont cool so well as outboard., and they can overheat from the differential heat, or vice /versa, tough on diff seals also.

but inboards sure look KOOL.

 

Im making some cooling ducts where the back seat used to be on mine, but I have herd a rumor that XJ40 rear hub carriers with their outboard brakes will bolt right on. does anyone know if this is true?

 

I don't have the exhaust system to worry about anymore so I crafted ground ducts to channel the cool air up and over the rear brakes/diff. I run a 2 1/4" split system with no cats right under the door and exiting in front but outboard of the rear wheels. It really cooled things down back there plus I dropped a ton of weight doing that too. I use a set of coiled coated steel lines so I get more surface area in the cooling chamber. It's just a reverse heat exchanger. If I could find a way to hermetically seal them in an electrically circulated water vessel I would. That would dissipate heat very efficiently. Thinking about cooling my fuel supply and return the same way.

 

factory V12s had a fuel cooler , it cooled from the A/C unit.

course race cars dont have A/Cs!

once you start to add stuff, the weight starts to go back up.

you say you removed 1600lbs weight? they normally weigh in around 4100lbs stock, so you are down to 2500lbs, is that with or without roll cage? and other things you will add.

 

Pretty much so, a bit of brake piping/hose to adapt IIRC. There was a writeup in Jaguar World recently. If you mail them you can get a back issue. Or somebody with the mag handy can send you the particulars. Personally I like the original, although the XJ40 was a revelation when I first drove it in earnest. Horses for courses.

 

That is before the cage is added and fully fueled. I thought I had mentioned that before. I must be slipping...

 

This was deleted in later 6.00 litre V12 cars.