Prepping a Unique for Track Day Events.

[EM-0785]

Originally Posted by NRP/MN

OK guys here goes- approached by a customer to upgrade the shock and spring package on an older Unique. He wants to do some track day events with the car. Previous discussions lead me to believe it has a 460 based engine. The plan is to put double adjustable shocks on the car. My question is what spring rates are you using with the Jag rear end? What has been recommended to me seems kinda stiff considering there are 4 shocks and springs in the rear (350#).
Thanks in advance, Mike

Hi Mike,

For my older EM replica with 460 and Jag rear, here’s what I did. I weighted my car at CAT scales and obtained the weight info of about 2,950 lbs with like 52% to the rear.

I used the QA1 tech Spring Rate Chart info, which addresses lengths, angles, axle weights, etc. I came up with 250 lb springs, based on the Jag IRS row in the chart. Then I spoke with two separate QA1 techs and ran through everything to get their recommendations, given angles, intended use, etc., and they both came up with 250 lb springs. So, I considered that verified in my specific application for my desired setup after those discussions.

That was a pretty basic approach, I found many more detailed/complex methods online, which didn’t seem to change things much from the basic approach above (at least the ones I appeared to understand).

At that time I was told that Unique still used Jag IRS in their cars, so you may want to check with them, as well as any shock/spring manufacturers you have under consideration.

Best of luck! Brent