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View Full Version : Calling all suspension gurus


David Schwarz
05-01-2006, 10:25 PM
After a year and a half, I finally got my car back on all four wheels today. This is my '88 hatchback that I'm building for PSCA True Street. The car will run at 3300# (with driver) and be stock suspension with 30 x 12.5 M/T ET Streets. I have the bucket set up so that more of the weight has been transfered to the rear (16g steel mini-tubs, two Optima red top batteries, 5.7 gallon (each) fuel cell and water tank, and a "firebox" that I built out of 16g steel that weighs in at a hefty 47#). Everything is resting on a Strange 9" rear end, and I'm using Maximum Motorsports weight jacker LCA.

Here's my question:

The car is currently suspended with stock springs. As it is, there's probably a little more than 1/4" between the tire and the top of the wheel well - and that's without my lard butt in the drivers seat. I have the weight jackers cranked all the way up, so it's as high as it will go. The weight in the rear is pretty much set now, with the exception of fuel and water, which I figure should weigh in at about 80# when full. Clearly with me and the fuel/water, this thing will be resting on the tires. I would like to have 1" clearance all around the tire to allow for growth on the top end. This means that the car needs to be raised 2.5" from it's current height (1" higher, plus 1.5" extra so I can bring the weight jackers back down for some wiggle room). This increase also needs to factor in the extra 80# of fuel and water, plus me.

Now for my problem:

I have no clue what the current weight of the car is. I also have no clue how to go about figuring out what length and rating spring to get, even if I knew the weight. If I need to, I will use the bathroom scale method to calculate the current weight since I don't know anybody with portable scales. But before I go that route, can any of you wizards out there give me some helpful hints on how to get started - even if it means referring me to a vendor that can get me on the right track.

Thanks for patiently reading this, and a special thanks if you have some advice to offer.
_____

jspeed
05-03-2006, 06:33 AM
I would have to guess that you'll require a 150 lb. spring in the rear of the car, (asuming your using a 12" coil over sping).

Only allowing for 1" from the top of the tire to the wheel well may be a problem. We try to have 3-4 inches, to allow for tire growth. I would advise checking with your tire manufacturer and see what they recommend.

Good luck with your project,

I hope this helps you out.

tuffguttj
05-05-2006, 06:57 PM
get a different back space on the wheel to suck the tires in trim the inside of the well and as the tire grows it narrows considerably

jspeed
05-08-2006, 06:59 AM
How are you making out with the car? any progress over the weekend?