coolformula

iTrader: (21)

I was eating somewhere and I heard the nascar announcer talk about having springs rates of 600 to 1000 on the rear of the car. That sounds high for the rear dont' it......

Sam Strano

iTrader: (41)

Possible. But on some tracks they mandate the rear spring, and I know it's not in the 600 range.

But, let's be clear on a few things here. First, this isn't a street car, it's a car with downforce, and downforce requires spring rate to hold the car up off the ground. They DON'T run those kind of rates on short tracks etc. where aero is not important but mechanical grip is. Just watch the cars @ say Martinsville VA sometime. Lots of movement.

Also, the springs are not in the same place on all rear axle cars. And that placement varies the motion ration and therefore the leverage. Ever notice that our rates and what Mustangs tend to run aren't the same? Mustangs springs have more leverage and need more rate to give the same rate at the wheel. Cup cars I recall are the same way, the spring is not mounted on the axle like ours is (which gives a more 1:1 ratio).

coolformula

iTrader: (21)

Thanks sam. I know the post was kinda off topic for a fbody site and I dont' really watch nascar but just found it interesting but that all made sense.

Thanks for your input.

Good night guys.

SSCamaro99_3

iTrader: (1)

I think a few years ago the mandated rate at plate tracks was 300 in front and 180 in the rear. The next year they bumped the rears way up (about 300) to keep the spoiler up in the air. I don't know what the current rates are. they are also passing out identical shocks from NASCAR at plate tracks.

promod1955

iTrader: (44)

Yea, before they started mandating springs, they would run them soft in the back on super speedway cars to get the spoiler out of the air. I use to work at a shop who i wont name... you would be surprised of the cheating that goes on...lol

chicane

1000+ springs in the right front and left rear are not uncommon.

SSCamaro99_3

iTrader: (1)

What really comes to mind for me was Joe Nemechek's Talladega pole run in the late 90's. The springs were so soft, and they had no rebound in the shocks, that you could tell the car was riding on the bumpstops. There was no give, the car moved in unison with bumps on the track. I remember him (and a lot of drivers) would wear football style mouth guards during qualifying because the ride was so rough.

leadfoot4

iTrader: (1)

That's where all the fun is!!! Smokey Yunick and junior Johnson are my heroes!

Sam Strano

iTrader: (41)

Actually they had ALL the rebound in the shocks and no spring rate to speak of. Semantics, but the more rebound damping you have, the slower the shock extends. The springs let the tail drop, and the rebound held it down. It's called overdamping, or "packing", and as you saw it was horrible for driveability. They never raced that way, because they couldn't drive the cars. It was hang on for one lap in qualifying.

SSCamaro99_3

iTrader: (1)

Doh! They definately looked like hell to drive. It was funny to note the difference between how the cars looked on Friday compared to Sunday. Joe's car looked like it had about 1/2 in of ground clearance that day. It was right on the track.