Front Springs - sports pack to standard

[Jag190902]

Does anyone know if you can swap the sportpack springs on a 3.6 coupe for standard ones from a V12? Also is the same swap possible on the rear?

My wife is constantly moaning about the ride quality being too firm (not that I mind!) and a little low when she drives over the speed bumps, so any info would be greatfully appreciated if only to satisfy her whether it can be done or not!

Many Thanks ]

[poprivet]

Welcome Jag190902
(If that's your birthday, you're even older them me - or maybe very much younger!)

Springs do seem to be a black art, especially as it's impossible to measure the rate. I'm guessing here that you're 3.6 is post late '87 when the 'sportspack' was introduced? If so, I *think* that was the only variant, a choice of standard or sportspack being only available as a choice during the facelift years. If I am correct, (pjts help!), then changing to V12, DB7 or any other springs may result in ride height issues. Pre '87 3.6 springs are a possibility, although as the sportspack package also resulted in changes to dampers, roll bars and other settings so the end result may be different from what you are expecting.

I also have a sportspack 3.6 and I do agree the feel can be very firm compared to other cars, especially around town, but in touring mode on long journeys, or when cornering a bit harder then most would be comfortable with, I find the handling most enjoyable and predictable. My old V12 Sovereign covered the miles in a much different way, rather like traveling on a sofa, very comfortable but far less sporty.

Pop ] ] ]

[Hosier77]

Oddly enough i have done the opposite swap, which drops the front of the car several inches, so I guess that sticking v12 ones on a 3.6 would give a problematic skyward stance. But on the plus side it would be better for off roading!
I wrote a little bit about it at :
http://www.rhel.co.uk/jag/sprongs.htm

The issue is that the V12 weighs 120kg more than the 3.6 so the springs have a different length.

I suspect your best bet is to find the non sportspack 3.6 springs.
]

[ptjs1]

jag190902,

Welcome to the Bulletin Board!

As others have mentioned, this is a bit tricky. My limited knowledge on 3.6s is that until September 87, all 3.6s had standard suspension and after March 88, all 3.6s had sportspack suspension (I think it might be VIN 147269?). In between these dates one could specify either form of suspension.

And there's also sports and standard V12 suspension, just to confuse matters further!

There's only about 100lb weight difference between a 3.6 & a 5.3, but I suspect it's all up the front end. So putting even standard V12 springs on would probably throw the front end up a few inches as hosier77 has said. (I know one guy who did it and said that the front looked really high)

The sports springs on the 3.6 are much revised at the front but not a lot different at the back. There's also differences in shock absorbers and anti-roll bars (a sports 3.6 has a roll bar at the back, standard 3.6s don't).

I don't think you can buy standard 3.6 springs or shockers from Jaguar any longer. You might be able to buy them from after-market specialists, but I don't know what is the spring-rate.

I suspect that changing just the front springs and shockers for standard ones would give you much of the desired effect, even if you leave the rear alone. I think that you're going to have to use the after-market for new bits, but make sure they understand the difference between sports and standard 3.6s (and the difference between 3.6s and 5.3s!)

Another way might be to use non-sports springs from a facelift 4 litre, but again I couldn't guarantee this would work either.

Why not give Dave Marks a ring and see what he says?

Hope that helps a bit.

Paul ]

[ptjs1]

Pop,

Just noticed the 500 posts - Congratulations!

Paul ]

[Brakebuster]

from the information i have obtained while trying to source parts for my own car, i can say that all V12 sportpack XJS's had the same springs as the later standard 3.6's non sportspack mentioned above

these springs are very hard to get hold of, and i think are NLA from jaguar

as luck would have it, i got a brand new set of genuine Jaguar XJR-S front springs today

but they did cost me £130...........

BB ]

[Jag190902]

Thanks to all who've replied, your info has been invaluable and no doubt I'll have fun in sourcing some non-sport pack springs for the 3.6! ]