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coil over spring rates


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A few weeks ago I ordered some ground control

coil overs with 225 pound spring rate all the way

around. The car has a v8 with alloy heads. Are

these springs going to be to stiff for hard

launches at the drag strip? Also. how will the

ride be around town? Thanks z ya icon_confused.gif

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Do a search for Scottie's website and find out what he's using. Duplicate that! Actually, the 225 lb setup would sweet for fast running on the road. Maybe it's not the ticket for drag racing though. JTR says the stock springs are pretty good for drag racing.

 

Davy

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Ya' know I'm a little confused. I've got 225lbs up front and 200lbs in the back. When I stomp on th egas the back feels like it's going to bump it's butt on the pavement and I kringe waiting for the wheels to bump up inside the wheelwells. To me it feels pretty soft but it also bounces around like a truck on stiff roads.

 

I've been considering upping the rear spring rates. While I've never bottomed the rear wheels in the wells I'm worried I will! Am I just not used to the squat? I'll admit breaking Ujoints has made me paranoid, should I leave it alone and see how it works out with CVs? I was actually considering going to 250lb springs!

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I recall a thread or two saying 225-250 was a good range for rear springs to minimize squate, Andrew's running 225's AIR and quite happy with his 1320 launches.

 

I can't see how we can enjoy our high speeds with great stability/control and roll around town soaking up all the bumps. My 250 rears squat somewhat but at least 1/3 or less than the stiffer than stock TRW's I was running (280ZX, ~same weight as a 280Z), I'm pleased with their rate and 225 rears in my dad's Lt1240z have him quite happy. Depending on your goal it's not so much the weight of your car as how much squat you want to reduce when you place a priority on 1320 launches. Just as key is setting up rear geometry such that on full squat (launch/corner exit/whatever....) you have as close to zero camber as your setup will tolerate to maximize your tire footprint for maximum traction. Details like this help a lot in street class road racers etc (and other arenas as well). It's been delved into a few times the degree of squat (if any) that's desirable for launches and I'm sure searches would turn it up, part of it was the more squat the more time spent moving fwd during your trap time but not at optimal traction yet (at least that's how I recall it, Rick did a nice job AIR).

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i think Jims issue is a few things.

1) he "forgot" and installed the springs backwards and the stiffer spring up front may help more weight transfer to the rear.

that in combination with that Z's do squat its probably just takes some getting used to.

 

he doesnt want to swap them around too much work icon_rolleyes.gif so i think he's thinking of just changing rears to 250 to save time.

altough with the HP he will have going 250 on the rears wont be overkill anyway.......

 

i wouldnt be surprised if his car has EFI and a supercharger by next summer icon_eek.gif

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Forgot? Nah, I just didn't recall seeing it posted anywhere icon_smile.gif It also seemed contrary to what I'd seen done with every other vehicle I've ever owned. I guess the Zs are just funky like that. I could swap them around I guess, the car will be down for the Winter just as soon as it gets ugly but right now it's been 70+ all day (and rainy) so... There's also a big race supposed to happen from the Supra forum out my way between a nasty RX7 and a C5 'vette (turbo'd) so I may take the Z out to watch or possibly the RX7. Can't decide (lol).

 

As for EFI and a blower... I've gotten the Supra bug, that will slow me some I'm afraid. Finally a driver I can wrench on and not worry as much about breaking icon_smile.gif It'll also cost more than th eRX7 so that will hurt some. I AM pursuing EFI but it will be mid-January or so before I decide on an ECU. The guy who owes me a fuel pump may actually come through and I need to send off my intake still - perhaps this weekend. I hope to have EFI done this Winter but I think a blower will have to wait. I guess if the suspension were more comfortable I'd be more eager to lay in the power too. I will be the first to admit that I'm not used to the squat from the IRS - it freaks me some. Having snapped two Us hasn't helped my confidence much either! I'm working the CVs slowly but the Supra hunt has slowed me some I'll admit. Still haven't gotten that last stub out.

 

Anyway, do you really think that 225 up front and 200 in back would feel that much better? Won't squat too much? Having never seen what it looks liek doing that I don't know exactly how bad it's squating (sigh). Nose really picks up too - especially when it hooks up in second! It's NEVER rubbed in the wheelwell yet so that's good. For struts I've got brand new Tokicos, less than 600miles on them! I guess it wouldn't take THAT long to swap them and see, shouldn't have to do anything but pull the wheels and the tops of the struts right - don't have to pull the lower pins and balljoints do I? icon_confused.gif

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theyll come out easy but i would try the 250 rate in the rear first.....

 

chuck put 225 in his car initally and changed to 250 and liked it much more. sometimes a small change makes a big difference.

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