anybody know the stock spring rates for the z-28 springs? esp. the rears....i need to stiffen the rears a bit for autocross. i hear that they aren't progressive....so, would eibach pros be higher rate and be progressive? also, does anybody make a 1" rear sway bar? i prefer hollow. i'm currently running 34/24mm.

 

bump

 

Depends on which suspension you got. The lowest were approx 350lbs and the IROC/WS6 springs were 548lbs in the front. Don't remember the rears.

Spohn sells a 1" rear bar.

 

103 for the rear (I think, not sure).

 

How would one get new stiffer springs at the stock ride height? How far can one advisbly go with springs before they are for track use only?

Thanks,
Jason

 

What they were, and what they are now, are 2 completely different things. Don't waste your time working off of the OE "specs" because they have little in common with how the car acts now, today, after the originals are worn out. If they were originally 103 lbs/in, and you put new 103s back in there, I guarantee the car would change.

Those springs are easy to measure. Measure the height off the ground of some convenient part of the car; put a couple hundred punds of weight on the car; re-measure; divide the weight by the distance, and divide by 2; that's your rear spring rate (on jounce anyway.... stock ones are variable rate, so it will be different if you do it by removing weight). I'd bet that if you do that, you'll find that your rear rate is something completely other than the "spec".

 

Is it worth it to replace the worn out springs with brand new OEM ones? Is there a more cost effective approach? Before delivng into all of this, how does one determine whatthey are looking for in springs?

 

No it is not worth it. They cost far more than buying them as an aftermarket part, and that's all they are... they're not the same as the original ones anyway. So there's not alot of sense in buying a Moog part in a GM box.

Kind of reminds me of buying silicone dielectric grease, if you'll allow me the diversion. At one time I worked at a TV station. They had an antenna that they bought from RCA, but that had been made by Dielectric Communications. The transmission line is basically 20' pieces of copper tube, with bolted-together flanges, with O-rings. The O-rings were supposed to be lubed with this silicone dielectrci grease. It came to pass one day that they needed more of the grease, and they filled out a PO to buy it from RCA. It was $36 a tube at the time from RCA. It came in; they opened the RCA box, and inside that was a Dielectric box. They opened that box; inside it was a Dow-Corning box, with a 4-ounce tube of 4 grease. I had just recently left working for a place that sold electric motor rewinding supplies, and we were a D-C distributor; we sold it for about $6.50 a tube. The exact same tube of 4 compound. Incidentally, you can buy that stuff from Accel or MSD, I'm sure; probably for alot more than buying it straight from D-C. Just like buying springs at the dealer.

Springs are like tires, and gasoline, and alot of other things; best bought somewhere besides the dealer. Going back to the dealer is the best option, or even the only option, for some things; but not springs.