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Old 11-15-2009, 05:05 PM   #1
BERT
 
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Default Changing over to coil over in front of 71 nova

Hi everone, I'm changing out the stock A arms upper and lower to Global West TLC tube A arms. I'm going with a coil over double adjustable shock from QA1. I want to use a coil over so I can access the adjustment knobs easily (I know that Afco makes an killer double adjustable front with adjustments at the top and bottom # 3870 BNC but I was told that it will not work with the Global West TLC A arms). My question is I have Morroso front coil springs on the car now with the stock A arms that have a 213 spring rate, The springs that are being recomended with the coil over set up are 350 spring rate. The car weighs about 3270 with driver now and should weigh about ten pounds less ( off the front ) with the new set up. Should there be that much of a differece in spring rate from a standard coil spring to a coil over spring?
I dont know the weight of the front of the car but it has a small block with aluminum heads, no alternator, 5LB elec waterpump skinny hoosiers / Weld 3.5 x 15s, no fender skirts . The car is used for drag racing only. If you have experience seting up cars for drag racing please advise what spring rate on a front coil over would you use in this application?

Last edited by BERT; 11-15-2009 at 06:38 PM.
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Old 11-17-2009, 01:16 AM   #2
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How long a spring are they recomending to run with the 350# spring. How long is the moroso spring you're running?
More then likely they moroso is a 2-3 inches longer at least. Which means the coil over will need to be stouter. If you could squeeze the same length spring on those new coil overs then I'd recomend 250-300 pound springs. But you do need to remember your over 3000 pounds.

Don
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Old 11-17-2009, 11:23 AM   #3
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Thanks for the reply Don, I think the coil over spring is going to be about 3 inches shorter I'll check into that. Thanks - Al
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Old 11-17-2009, 11:22 PM   #4
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Sounds like you're going to need the 350 then.

Don

You're welcome btw.
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Old 11-18-2009, 02:49 PM   #5
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Last night I scaled the car, it weighs 3215 with driver, fuel, and helmet. The front weight is 1652. The options I have are 250 and 350 and the weight split frome Qa1 is 1700. I'm going to try the 250 rate. I'll report back and let you know what happens. I appreciate the responce Don and I'm open to comments and sugestions. Thanks - Al
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Old 11-19-2009, 10:49 PM   #6
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Then you'll need to get the longest springs you can fit on the shocks then I think. After you get them installed you can adjust on them for the correct height. When you get to there you'll more then likely have a few more questions. Good luck.... and keep us informed.

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Old 11-29-2009, 01:57 PM   #7
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the diameter causes the spring rate to be different from stock diameter to the little base of the coil over. You will need the 350 for sure. Also, the 350lb spring means it will support 350lbs per inch of compression per spring. You can do the math but the heavier spring will be needed over 3000 or 1500lbs for the front is where I make the change!

Last edited by Awesome Bill; 11-29-2009 at 02:00 PM.
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Old 12-07-2009, 11:38 PM   #8
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well I did a little testing on saturday with the 250 spring I left off idle and it picked up the front very easily so that was cool, I let off before the 330 and when I hit the brakes the nose dove down to the bump stops - not good. That was with the coils jacked up about half way, shocks where 2 from soft on extention and 7 from soft on compression.
With 2 220 LB guys on the front bumper you can push the body down to about 1/2" off the bump stop on the control arm, that seems pretty soft.
Someone sugested that I use the shock settings to help control the dive on the front end but I thinking with this situation I'm wondering if the car gets out of shape at speed will it be managable?
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Old 01-02-2010, 08:25 PM   #9
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The spring does not make the front end to most extent harder or softer to push up and down if properly sized. You can get a real heavy spring rate, clamp them down for ride height and then when you push down, it won't move. But, this is stored energy and can be used for certain chassis tuning if you know what your doing.

A chassis is a lot like engine, it has to all work as a team with power, torque, weight etc. All of it has to come together. I love that when people come over and push the front end down and watch it come up and down and the same with the back. That means little to nothng. If you have a particular problem then you can work that out with a ton of stuff at hand to correct the problem.

The shock on the rear has to extend on the hit and then the following getting out of the first 100 ft ro so, it allows the shock to come back together after it gets out. The front has to extend also and comes back after the car gets out also. If you have to quick of shock extension, it kills the sidewall, to little extension, it blows the tires off. Either way, you have to know what to look for and correct. Looks like your springs are to light
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Old 01-03-2010, 07:55 PM   #10
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Thank you for the replys Bill and Don,
I've been fighting alignment issues latley at the track ( the factoy sub frame upper control arm mount has run out of adjustment and I cant get the 1 1/2 degrees of camber out of the right wheel but Ive got 7 degrees of caster on each side and .04 deggrees of camber on the driver side wheel. I'm thinking of trying an offset shaft on the right upper control arm to band aid the problem.)
Anyways I went to the new years race with the new 350# springs and tuned the front shocks with 2 of 24 clicks from soft on the extention and 16 of 24 clicks on the compression and the car left with a 1.39 60 foot and ran 6.36 in the eighth mile and felt really controlable for once except for the slight pull to the left I think is caused by the camber thing. We ran eighth mile because the track was very wet from rain and about 55 degrees cold. I think thats an improvment
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