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Discussion Starter · #1 ·
Hey guys, seeing if you can help me understand instant center more. Ive read a bunch of threads about it, but i dont know whats good and bad as far as anti squat percentage and measurements for IC.

Here is my rear suspension setup:
UPR Extreme series double adjustable uppers
Team Z spherical bushings
UPR Extreme series single adjustable lowers
Strange adjustable shocks
Stock gt springs cut 1 coil
Team Z ARB

Front suspension setup:
UPR tubular K and A arms
Strange 10 way struts(brand new havent made a pass with these yet)
14" 175lb springs
I have about 5" of strut travel up front

I usually run 10.5 psi in the slicks, rear shock setting on 1. Car 60's 1.37-1.39 usually but i think it has more in it. Wondering if anyone could give me pointers. Wish i had vids to see what the car is doing

Id did mine and tell me what is wrong or what to change/look for.

Center of gravity height-18 (not really sure how to get this measurement)
Wheel base-107

Upper link location and length:
Horizontal distance to rear pivot-0
Vertical distance to rear pivot-17
Vertical distance to front pivot-15.5
Top bar length pivot to pivot-10

Bottom link location and length:
Horizontal distance to rear pivot-0
Vertical distance to rear pivot-9.5
Vertical distance to front pivot-9
Top bar length pivot to pivot-18

Instant Center location:
Horizontal distance from rear axle centerline:60.5
Vertical distance from track surface:7.8
Percent anti-squat:77
Can you explain these numbers?
 

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I'm no expert but it appears your IC is 60.5 inches forward from the center of your axles (looking sideways) and its 7.8 inches off the ground. This gives you an AS of 77%. I would try and lower the car some more to bring the IC farther back. This should also increase your AS. But being you have a mod motor like me I don't think your CG height is 18" (pushrod cam height). I think its a little higher. By changing the CG height it will changes your IC and AS values.

-Mark
 

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man, i saw this car at gateway tuesday, didnt look like you were having issues. granted, i only saw one of your passes.


gilsbach is right. your car is 101, unless something has been changed, but you couldnt change it that much anyway.
 

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Discussion Starter · #5 ·
man, i saw this car at gateway tuesday, didnt look like you were having issues. granted, i only saw one of your passes.


gilsbach is right. your car is 101, unless something has been changed, but you couldnt change it that much anyway.
im not really having any issues, just think it has more in it and i wanna squeeze every bit out i can. ill plug 101 in the calculator and see what it gives me. I tried measuring it myself before i went to work and i rushed it.

Yeah Steve on mod fords said that it hooked and did a decent wheelie but i wanna calm it down so it doesnt lift em.
 

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yeah ive read it before, seems its mostly coil over setups and 4 links


it all applies. and yeah, steve was there with us. your car looked really good.

anti squat values lower than 100% tend to make a car squat, over makes it seperate.

ive got some used suspension pieces sittin around the shop, your welcome to try them out.... pm me if youd like.
 

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Discussion Starter · #10 ·
it all applies. and yeah, steve was there with us. your car looked really good.

anti squat values lower than 100% tend to make a car squat, over makes it seperate.

ive got some used suspension pieces sittin around the shop, your welcome to try them out.... pm me if youd like.
ok i didnt know that! lol, I havent been racing that long and i like to think im a quick learner and i pretty much do my own work, but suspension confuses me sometimes. Thanks for the offer, if your at the track tuesday ill come say hi or something. Id like to see constant 1.35-36 out of this car.
 

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Discussion Starter · #11 ·
id get the lower level, and try a relocated upper. i plug those numbers in, it looks alot better....
i dont know how much lower i can go in there rear without my ARB coming in contact with the floor pan though. Measuring up the center of the wheel to the fender is 28 3/8", front is 27 1/2"
 

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I have had good luck with leaving the stock points on the car and housing.Several cars in the high 1-teens without any relocation brackets.You need to get some coilovers on the back.It would make life much easier on you.That is if they are allowed in your class.
 

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Same type of car here as well and here are my numbers with a relocation upper:

Upper:
1.5" horizontal ... is this correct?
16.875" for rear pivot
16.00" for front pivot
5.00" length

Lower:
0" horizontal
9.5" rear pivot
9.125" front pivot
17.563" length.

Wheel base is between 101.25 and 101.5

I am curious about the CG height as well ... because this changes the AS drastically.
 

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Discussion Starter · #14 ·
here are some vids of the launches. also like to thank the guys from LoPro for helping me out at the track




 
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