Jag IRS rear spring rates

[leroy17]

Anyone care to share their spring rates for their jag IRS. And wheel size (15, 17 or 18).

I am reading plenty and the variety of info, some of which I find perplexing.

I know that there are many variables such as corner weights, spring angle, wheel size,engine weight and output, driver/passenger weight, however just seeking some rates that others may be running.

Reading through past posts, it seems that between 300 -350 was suggested. However i have come across recomendations from 200 up to 400, then other readings in that a 350 spring rate, with two shocks on each side means that this is an effective rate of 700. Is this right? It does not seem to be a good balance when there may be a say 350 on the front.

Feel free to school me on this as the Jag IRS is used in many varied builds, cobra and non cobra and I have over read in distiguishing fact and fiction.

Cheers.

[CHANMADD]

Jag made two different springs....one softer than the other. I have one of each on each side with adjustable shocks, one set soft and one set medium on each side ......an anti roll bar from a Mazda 3 front .......

[bill37341]

Leroy- I went thru the same issue a year ago. I am using the complete rear- cage and all from a 1965 3.8S Jag.(US version). It is the same width as the Jag series 3 E type. I used the cage to keep all the location points that were used on the original car. My car is a scratch build, but the frame and suspension is very similar to the old US Arntz. I first used a 200#, 10 inch spring and 12 3/8 shock. Sent it all back and finally settled on an 11 inch Carrera shock and 250 # spring. Part #s are Speedway Motors: Carrera shock # 255-3235 and Afco 8" coilover spring # 282501cr.I am using 295-50-15 tires and ride height is correct. part #s can be found on the internet. Good luck, Bill.

[CHANMADD]

The front by the way....has one of the stiffer springs set at medium......

[1985 CCX]

I used to use 10" 250lb springs on Koni dampers
15" Vintage wheels
Goodyear billboards

Awesome combo

[mickmate]

I use 250's Shocks Coil Over Jaguar Contemporary [CCX Contemporary Unique Jaguar] - $167.00 : Acton Custom Enterprises, Custom Metal for Cobras