I am with Ronbros on this one. providing there is some negative camber on the rear wheels, and that the ride height is correct, I believe the XJS handles and corners better with no rear ARB.

 

I've heard this before, I spoke to one racer name Charles... he disconnected the bar at a Lime Rock track day and on the next lap out picked up a second or two. Hard to tell if that was driver variation or if it helped. Who knows? Lime rock is one of those tracks you slide around and the fastest laps can sometimes be slippy and sloppy. Every track is different.

The XJS understeers, Having the rear end flop over can help the car rotate in experience hands. On the street, under-steer is generally considered safer.

The better setup is to keep or install the somewhat thin stock rear bar and upgrade to a stiffer 1 inch front bar. This will make the back end soft relative to the front and offer up a more controlled rotation effect. I have driven a friends 1990 XJS with this setup and it's a great drive. He managed a 1:16 on a Limerock track day which is a good time for a novice in any car. The brakes over heated after 2 laps and Limerock isn't even a brake intensive track.

The Aston DB7 GT had a slightly larger rear sway bar and 1 inch front. That's the setup I use and the DB7 GT put down a good time for GT car at the Nurburgring Nordschleife. About 8 min. That's Amazing becasue that time was in line with other high end GT offerings of the day from Porsche and Ferrari. Many people dont know the DB7 was based on the XJS but the Front suspension geometry is more inline with the XK8 than a XJS.

 

i did install a 1" front bar ,when i took the rear off, way back 1994!!

truth is i dont drive really fast anymore , i'm turnin 85 this year, so gotta think about sellin the XJS HOT ROD!
i know ,but ever think what the hell would my wife do with it?
perish the thought!
ron

 

 

my understanding about the XJS , with a stiff rear bar, is breakaway happens suddenly , and collecting it up is difficult!

altho who drives like that anyway?

 

'Tis true.

On my XJS I had the 1" front bar and experimented with 3 different rear bars.

Jaguar used two different sizes in the rear, 13mm and 15mm....or something like that. I found and tried both. I also tried an Addco rear bar, which is something like 19mm.

The Addco bar was too much. The car became borderline treacherous.

Both of the smaller sizes were fine; the difference between them, subjectively, was not significant.

Cheers
DD

 

 

My XJS has a 1" (25mm) front bar and 7/8" (22mm) rear bar and it corners very flatly. The only time I have had oversteer is applying power in the wet on a corner, never a problem in the dry. The factory bar is 16mm rear I believe, paired with 22mm front.

I think you will have trouble fitting a 27mm front bar actually, as the 25mm leaves very little wall thickness of the bushing that goes into the brackets. I'm not sure you could fit bushing and a 27mm bar into the factory brackets.