Coupe

I was going to order some GT re-pop springs for my car to ride on my new OTR roller spring perches but I see over on Streetortrack that they are rated at 260? I am wondering if that may be a bit to supple for aggressive driving? I am pondering the Heidts 4 bar rear end, if the budget allows, but I may just go with mid-eyes...anyway I am looking for a decent spring that is lighter than the 620's but not squishy. Whats a good mid range spring that I can either get 1" lower or cut down?

Starfury

I'm very happy with the 1" lowering 620 springs I bought from OpenTracker. 620 actually refers to the wire diameter of the springs, not the spring rate, which is 560lbs. They sit a hair higher than I'd like, but they're easy enough to cut if need be.

I'm sure with stock perches they'd be stiffer, but they're great with my roller perches.

Shocks are the other factor. If you're running KYB Gas-A-Justs, expect a very stiff, jarring ride. If you drive hard, consider a set of Bilsteins from Shaun @ Street or Track Racing. I like my Edelbrocks, but I got them cheap, and the Bilsteins are a better bang for the back for not much more money.

2+2GT

Here's a list of spring numbers and rates from one well-known catalog:

8088 258
8090 291
8232 286
8234 288
8304 269
8306 269
8318 289
8330 289
8356 418
8534 428

I have the 8090 on my 66, and it's pretty firm for a driver. The 8534 is the sort of spring you'd put on a big-block if you wanted a stiff ride.

Coupe

So would you say your 8090 is close to a factory GT spring, or is it stiffer? Is the 8090 the same as the TRW stock spring part number, it is also 8090 from what I can tell?

2+2GT

Sadly, there is some variance from company to company, but the 8090 should be the GT spring for the 64-66.

The 64-66, and 67-70 springs are physically interchangeable, but since the upper arm changed dimensions in 67, they are not comparable. An 8090 spring would be a poor choice for any 67-73.

Coupe

Thank you for the info, I think I am going to order GT springs and then trim to fit after they settle in a bit. $80 shipped is cheap enough.

I am going to run the thin poly insulators, are there any known issues with those?

urban_cowboy

I am sorry for the hi-jack, but I am curious as this fits into my winter project as well. Star, do you suggest the Bilstein street package or sport package from streetortrack.com?

Norm Peterson

I'd think 'street' unless your driving includes moderately serious autocross and possibly entry level open tracking. Or if your NORMAL street driving just up and walks away from most everything else in the turns nearly all the time. Then I'd think 'sport', up to the point where the street driving is almost nonexistent or that you're serious enough about the autocross/open tracking to accept life with whatever 'race' compromises on the street.


Norm

Norm Peterson

For a street driven car, that's what it all eventually boils down to. At one extreme, there are people who feel that springs that are only 20% stiffer than base OE are too stiff, while at the other there are people who are actually happier with springs that are 60% or more stiffer than the OE springs that they took out.

I'd be able to comment further if I knew what the spring motion ratio was for these cars. The 'wheel rate' will be considerably lower than the springs' own rate (I'm guessing maybe half that, maybe a little less), and there are some ride comparisons that can be made from there.


Norm

OCHOHILL

Don't forget the effect tire size can have on street ride quality and handling.