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peteryates 10-25-2012 12:55 PM

Suspension for Jaguar IRS for Kit
Andy, i found this thread and seeing what a great job you did on the Jag suspension, i thought i would ask for some help on my own challenge. Building a kit (Ferrari Daytona) on a custom chassis with jag V12 running gear (i.e. same set-up as the othe rcar on this thread). The axle weights are 1450lbs front and 1680lbs rears. The front suspension is adapted with a Spax coil over shock replacing the standard Jaguar one. The problem here is that i have moved and changed the engine so the front is now hugely over sprung and need a lighter spring, but not sure what strength. The problem with the rears are that they are the original Jaguar coil overs that are also way over sprung. I am sure this is not enough information to answer the question, but be grateful for your assistance to work it out. thanks

327NUT 10-27-2012 08:18 PM

I'll take a stab at this, don't know who Andy is but if you're looking for coil springs for a Jag rear or better yet someone that would know where to get them Kugel Komponents ? Quality Parts since 1969. They make a IRS for hot rods that looks like a jag......worth a phone call.

peteryates 11-18-2012 02:40 PM

update with geometry and weights
1 Attachment(s)
Andy, Here are the updates and full stats. The axle weights are 1450lbs front and 1380lbs rears. This is dry weight but i did add about 140lbs of ballast for driver. I did not add weight for a full tank (adds 100lbs to rear). The front suspension is an over sprung Spax coil over (due to replace of Jaguar V12 with SBC 383). The rears are that they are the original Jaguar coil overs that are also way over sprung. Thanks for your help.

attached are 2 charts of each suspension geometry and weights. i hope i capuitured everything required.

LATECH 11-18-2012 04:24 PM

I would bet an earlt 90s t bird IRS setup would weigh a lot less than the jag. Seems to me the larger portion of the subframe is aluminum. Plenty of them had rear disc brakes.They were also a lot easier to change rotors on also
Made in USA and parts off the shelf even at Mc Parts
An 8.8 was used in the supercoupe and the v 8 cars and some of the standard v 6 models.

poncho62 11-18-2012 06:17 PM

The thread with Andy in it......

aosborn 01-01-2013 09:26 PM

Sorry for the delay. It looks like you have done an excellent job of laying out the required dimensions. That along with the axle weights and I should be able to come up with spring rates for you. A couple more things I will need...
Capacity of the fuel tank so I can add in the weight of a 1/2 tank.
What you would like the car to ride like, i.e. soft like a typical American sedan, firm like a BMW, or stiffer more like a race car?

I hope I am not too late to assist you.



aosborn 01-20-2013 10:22 PM

Don't give up on me just yet! I just pulled up your dimensions and will work it over for you. I am sorry for keeping you hanging, you probably have the car done and have put several thousand miles on it by now!



aosborn 01-21-2013 10:52 AM

Well, after too much time, this is what I came up with for spring recomendations...

Front=500lb/in for sport touring mode
650lb/in for track mode

Rear=300lb/in for sport touring mode*
350lb/in for track mode*

*rates are calculated assuming you are using 2 coilovers per corner or 4 springs total on the rear axle

If you are buying coilovers, allow 2/3 of the available travel for bump and 1/3 for rebound typically. For a coilover with 5" of travel for example, use about 3 1/2" for bump, and 1 1/2" for rebound.

Again, sorry for the delay. I hope these figures can still do you some good.

Keep us posted.



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