Need some Spring advice... |
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Need some Spring advice... |
D1A3 |
Feb 29 2012, 04:24 PM
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#21
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Gruppe Neun Vierzehn Südosten Group: Members Posts: 362 Joined: 3-June 04 From: Atlanta, GA Member No.: 2,152 Region Association: South East States |
I have a stock '76 2.0L car and have been pretty successful in AutoX at the local PCA and SCCA level. For PCA, I run in the PA class.
I currently have red Koni's (age unknown) with 90 pound springs on the car. I also have front and rear factory sway bars. The shock/spring combo seem to work well enough for street and reasonably aggressive driving My problem is that my rear end seems to come up and dance all over the place when I'm AutoX'ing and I'm trying to get it more planted for the upcoming season. I've had folks recommend I upgrade my rear springs to everything from 140 up to 180 lbs. Any thoughts on what springs I should go with? I'm not looking to replace the shocks and springs or do any other suspension changes right now as I can drive the car very well in AutoX, but want to try and pickup some handling and hopefully a little time. Below is a pic of my car from behind to give you an idea of what I'm trying to correct. Thoughts? I appreciate any and all comments! :-) |
ChrisFoley |
Mar 8 2012, 10:27 AM
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#22
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I am Tangerine Racing Group: Members Posts: 7,935 Joined: 29-January 03 From: Bolton, CT Member No.: 209 Region Association: None |
I agree with JP for the most part.
140lb rear springs and a 19mm adjustable front a/s bar with no rear bar. Better suspension bushings would be helpful as well. |
D1A3 |
Mar 8 2012, 12:56 PM
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#23
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Gruppe Neun Vierzehn Südosten Group: Members Posts: 362 Joined: 3-June 04 From: Atlanta, GA Member No.: 2,152 Region Association: South East States |
I agree with JP for the most part. 140lb rear springs and a 19mm adjustable front a/s bar with no rear bar. Better suspension bushings would be helpful as well. Racer Chris, didn't we race at the SCCA event in Huntsville a couple years ago after the Rocket City Ramble? I think you had flown in and were driving a "borrowed" car. Anyways, what is impact will running the 140 pound springs with a factory rear roll bar? I see a few folks have said to pull that, but why is leaving it on a negative? Sorry for such questions, but I'm really not that up on all of this and appreciate the groups more seasoned advice! :-) Thanks, Jason |
jhadler |
Mar 8 2012, 02:50 PM
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#24
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Long term tinkerer... Group: Members Posts: 1,879 Joined: 7-April 03 From: Lyons, CO Member No.: 529 |
It's all how a sway bar works... A sway bar is basically a spring that couples the left and right suspension. The more the outboard side compresses, the more force will compress the inboard side. The net effect, because the "spring" is anchored to the chassis, is to use the suspension compression to keep the chassis flatter. The downside of this is that the more you couple the two sides, the more likely you are to lift the inside wheel.
In the front we see this all the time with the inside front wheel hanging just above the ground when the car is pulling hard out of a turn. This is the result of a stiff front sway bar. The outboard side compresses, and that force is coupled to the inboard suspension, resulting in wheel lift. It also has the effect of helping keep the chassis flatter in the turn. This helps minimize wheel lift in the rear. In the rear, a sway bar will do the same thing. Only now, you're lifting up on a drive wheel. This is not what we want... So... The general concept for a "slightly more than stock" configuration, is to increase spring rate in the rear, disconnect or remove the rear sway bar, and increase the rate of the sway bar in the front. Hope this helps... -Josh I agree with JP for the most part. 140lb rear springs and a 19mm adjustable front a/s bar with no rear bar. Better suspension bushings would be helpful as well. Racer Chris, didn't we race at the SCCA event in Huntsville a couple years ago after the Rocket City Ramble? I think you had flown in and were driving a "borrowed" car. Anyways, what is impact will running the 140 pound springs with a factory rear roll bar? I see a few folks have said to pull that, but why is leaving it on a negative? Sorry for such questions, but I'm really not that up on all of this and appreciate the groups more seasoned advice! :-) Thanks, Jason |
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