Just wondering if anyone knows if and why the XJS upper control arms are different angles and/or lengths when comparing the front ones to the rearward ones. Also if anyone has a part number for placement reference it would be help full.

The XJ6 arms are almost identical and I suspect the XJS arms may be different for lengths and angles to support the more sporting nature of the XJS as I've read they were on the early series 1.

This may be a trerofit I'd consider for my XJ coupe. Can some one know knows shed some light on this subject. TIA.

 

icsamerica,

I don't know why the design is the way it is but all part numbers are quoted on Jaguar's Parts website. See here:

Wishbone-Front-Upper - Parts For XJS from (V)179737 to (V)226645 | Jaguar Heritage Parts UK

Paul

 

Thanks that suggest they are all the same.

 

For higher castor angle

 

All Jaguar XJ saloons and all XJSs ever made, from the time the XJS was debuted until the end of the Series III XJ and all XJSs up to the end of the XJS production (regardless of engine type, not including the XJ40, the series III successor) have identical front suspension components apart from the spring and the front stub axle which was beefed up for the HE and later saloon models. This includes the front subframe. This is one of the reasons that Jaguar could make the XJS faster, bigger and MILES cheaper than any contemporary supercar of the day. So you can pull an upper wishbone or an upright (vertical link in the US?) off a 1984 saloon and use it on your XJS.

The suspension includes anti-dive (under braking) and anti-squat (under acceleration) geometry and lots of other things such as castor and camber, all working as a system, to aid cornering, straight line stability, braking stability etc etc. All of which the three wishbone fulcrum angles (in effect pitch, yaw and roll) help to control. Huge amounts of time are spent developing cars and tyres to get this right, and Jaguar were considered at the time the masters of the ride/handling/comfort/refinement compromise. Anyone who has ever driven an HE on the original Pirelli 15" tyres and starfish rims will know that, although high speed stability is better on the facelift 16" setup, the ride does lose some of that Jaguar magic glide on less than perfect surfaces.

The only things that are different between the XJS and the saloons are the actual things that can be adjusted on the otherwise identical suspension setup. For example, the more sporting nature of the XJS led Jaguar (I am told) to use more substantial anti-squat and anti-dive settings on the suspension - which are achieved using different adjustments to the actual top wishbone angles and shims, not different components.

Greg