Hello my name is Luke im a first time owner of an 89 xjs v12 and loving it. I just wonted to know if any body has put bilstein shocks or any other more preformance shocks on there car to stiffen up the ride I love the cars looks and power just not the Cadilac like ride. Also I would like to swap the trans for a t700 with a kit from johns cars any body done this and what were the results. A manual swap isn’t for me I’ve got some leg issues so that not an option.

thanks for ant imput

 

There's a relationship and a difference between using stiffer springs and/or harder shocks that's a little tough for me to explain. I had sufficient damping and the ride height was good, but I thought the springs were a bits soft, so I added one of these rubber spring spacers to each coil over. The effect is to raise the spring rate and stiffen up the ride.

Coilover Spring Rubbers - Speedway Motors, America's Oldest Speed Shop

That done, the best way would be to use the proper rate coilover, but for me, this worked well.

 

89 XJS should have bilsteins from the factory. If not they may have been swapped already. A T700 is a good swap and the John's kit is very comprehensive. Then later you can swap the 2.88 for something a bit shorter like 3.54.

 

Ok I understand the difference between stiffer springs and harder shocks so no need to explain the difference. The factory shocks were replaced with some nasty car quest off brand. There super soft. I hope t700 swap works well I have one sitting in my garage from my old firebird. they say its a bolt on so im hoping thats the case.

 

Just so you know, it is NOT a bolt on exactly, you have to use an adapter plate and the flywheel has to be adapted as well. Still, it sounds like a very nice mod!

 

yeah i know all that thanks

 

Wondering ... if I remove say 500 lbs. from the XJS, what impact will that have on the effectiveness of the springs? I would expect ride height would increase. Would it be dangerous to use spacers to lower the spring perch attached to the lower wishbone? I've heard various comments about the advisability of cutting the springs. Thoughts?

 

With shocks there are a couple of options depending on what you want. I went the bilstein route bought off eBay for about 900USD for all 6 half what I would pay retail. The prescription is Spax adjustable skittles more expensive but with adjustable ride height.

Last is Monroe much cheaper but nowhere near as good but still ok.

 

There is one more option, over this side of the atlantic at least. There is a brand called Gaz. These are adjustable over about 35 clicks and very good quality indeed. Much better (in my experience) than Spax. Quite a few people use them, and the XJS racers use a racing version. Worth a look if you are considering changes. The on-car adjustability means you can get exactly the damping you like.

 

I don't have any experience with the suspension or transmission mods, but there is one thing I bet a lot of folks would find useful:

timed 0-60 and 1/4 miles runs before and after the transmission swap. Very little concrete data out there on exactly how much performance improves.