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Discussion Starter #1
I have a drag race only Fox body Mustang. (BBF w/ iron heads, C-6. Sportsman chassis and ladder bar) weighs 2880 race ready w/ 59% front heavy (1700lb). Car runs low 10's @ 130MPH.
Question is about front spring rate. I have coil overs front and back, with 14-175 in front(w/ a lot of preload). It seems to have a hard time lifting front, would higher rated springs help, like 14-200?
Thanks
 

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Anytime you put a big block in the nose of a Fox body it will have a hard time "picking" the front or transfering the weight. The Fox Body has a relatively short wheelbase, which makes the weight distribution that much more important in this case. It would be best if you could find a way to move some weight towards the back, and try to get it down about 5%. Ideally on a car like that 50-52% is the best on the nose. That all being said, I would bet you would run better if you just added weight in the back of the car. I know that is not normally the idea, but you would be surprised on how often that works out for the best. What shocks and struts are you running? A dbl adjustable in the rear, setup for a good squat would help. I woud just have to know more.
 

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Discussion Starter #3
Weight

I have double adjustable Santuff shock and and single adjustable Santuff struts. The rear springs are 100lb w/ a little preload, front springs are 175lb with a lot of preload.
I know the rear springs seem light, Santuff advised me to use these and stiffen with shock. The back seems to be working much better with this set up, the front just pops up and back down. The 60' times went from a range of 1.42-1.48 not good for bracket racing. Now the range after 30+ runs is 1.43-1.44.
The change that I made was in the shock. Same spring (100lb) but the shock was to loose (10 top extension and 15 bottom bump). Now top is 5 and bottom is 7. the old settings were bottoming out.
So, if I add weight to the back the springs would need to be heavier? Would this help the front stay up longer?
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Are your ladder bars "off the shelf" or did you weigh the car out and find the IC? I'm thinking that you're either down on applied power or you're IC is a little high. As far as adding weight to the rear, Cale is right. Weight to the extreme rear and high in the chassis will, with you're present set up, be a usable band aid to get you more transfer. Weighing the car out and making the necessary IC location changes and then fine tuning the IC and shock/spring settings is, IMHO, a better way to go.
Rob
 

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Discussion Starter #5
IC

I did map car, center of gravity is about 6 inches be low side mirror. IC, There are 3 holes and the bars are in the middle (bottom of bar is 0 deg.). I tried the top hole and performance went down. I have not tried bottom hole, the 60' have become pretty consistant since the tighter shock setting. The bars look to be off shelf, the adjuster is on bottom and has safety loop around ends. I bought this car as roller, was a real street outlaw car and has run in the high 7's in 1/4.
Next step I thought was to keep front up longer?
Power of motor is about 550 HP.
So, if add weight will need more spring?
Thanks
 
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