front coil and shock ?

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fishman
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front coil and shock ?

Post by fishman »

Hi there i have a question on the front coil and shock system on my race car....when i bought the car it had stock shocks in the front and springs with a chain bolted to the side with maybe a 1 or 2 inchs slack at the most.
i replaced the front shocks with 90/10 drag shocks and was wondering if i should remove the front chain that holds the coil and shock from extending very far.

Thanks
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Post by BillyShope »

I guess it's a safe assumption we're talking drag racing.

Is the chain on the right side only? If so, this might be a trick to load the right rear on launch. Hadn't heard of it before, but it might be better than nothing. A better setup would be simply a higher rate spring at the RF. See my blog for rate determination and use of a traction dyno to check the effectiveness:

http://home.earthlink.net/~whshope

If there are chains on both side, I'd use them to chain the dog.
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Post by fishman »

There is chains on both sides.....i know years ago i use to see this on drag cars but was not sure why..............
Cobra

Post by Cobra »

How did car respond with the original shock/chain setup? The chains may have been used to prevent shock hyperextension, keep car off of back bumper, or to tune chassis/suspension. You need to critique your whole chassis/suspension setup! There may be a lot of performance left on the table! 90/10 drag shocks may not be appropriate for your combination. A stab in the dark would be double adjustable Afco's. Need to know more about car.

http://www.afcoracing.com/
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Post by fishman »

car is a 74 pinto
4 link coil overs rear
9 inch ford 5.14
tires 32/14/15
tranny glide 1.76
motor 383 stroker 620 horse
front end is stock springs with rack and pinion
60 foot times 1.41 car weight 2210lbs....i think 60 foot times should be around 1.35-1.38 with a car setup right

right now the car will barely lift the tires off the ground and when the shocks start coming down the car spins for half a rotation.

i am new at this but i thought the old shocks where way to stiff and the chain was stopping me from picking the front end up and by going to 90/10 shocks and taking the chain off i would pick the front end up and transfer the weight probably.............correct me if i am wrong i am looking for ideas........thanks
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Post by fishman »

no comments from u guys.........looking for input please thanks
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Post by John Wallace »

In my Firebird I did that on the driver side front.
On some tracks, the driver side would raise a lot higher twisting the car.
I would limit the lift so that the front came up level. Then the traction was better.
This was in a 3650 car and ladder bars.
1.38 short times.
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Post by fishman »

i felt that the shocks that were on the car were way to stiff as they were a stock 50-50 shock and thne the chain on the front of the coil to the frame would only let the shocks extend maybe 1 inch...... the car is such a short wheelsbase that even with 32 by 14 tires on a preped track it will still spin coming out of the hole.......if i am wrong set me straight as i thought by putting on 90/10 shocks and taking the front chain off i would have about 2 1/2 extentsion on the shocks that it would load up the back tires giving me better weight distubtion and launching the car harder and then getting better 60 foot times................am i right or at least going in the right direction..........thanks
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Post by BillyShope »

John Wallace wrote:In my Firebird I did that on the driver side front.
On some tracks, the driver side would raise a lot higher twisting the car.
I would limit the lift so that the front came up level. Then the traction was better.
This was in a 3650 car and ladder bars.
1.38 short times.
I'm afraid you put the chain on the wrong side. Suppose total car weight is 3000 pounds with the sum of the LF and LR being 1500 pounds. During launch, the RR tire tends to be unloaded by the driveshaft torque. But, since the RF and RR sum must equal the LF and LR sum (1500 pounds), this means that the LF must lose more weight than the RF. This is the uneven lift at the front which you observed.

Now, what happens with a chain at the LF? While the chain is slack, the situation is as just described, but, as soon as the chain goes taut, virtually all the weight transfer comes from the LF. In fact, it's even worse than that, for the RF will continue to lift, twisting even more of the weight transfer into the LR. So, the LR...already overloaded by the driveshaft torque...becomes even more overloaded.

With the chain at the RF, however, everything works to help alleviate the unequal rear tire loading caused by the driveshaft torque.

No, I do not recommend the "chain trick," though, as I said in an earlier post, it might be better than nothing. I do recommend adjustable coilovers and the proper spring rates at the front to perfectly cancel driveshaft torque effects. See Page 7 at my blog:

http://home.earthlink.net/~whshope
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Post by fishman »

sorry for missing this but it had a chain on both sides
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Post by hotrod »

There is chains on both sides.....i know years ago i use to see this on drag cars but was not sure why..............

Sounds like if they are on both sides, they are snubbers to prevent excessive front end lift. On front wheel drive cars they do that to minimize weight transfer off the front tires by keeping the nose from raising too much and raising the CG height.

It also allows them to have a reasonable spring rate to keep the front air dam from plowing up the track when the car comes down but once the car is on the snubbers the weight of the front wheels is added to the front as it tries to lift the wheels/tires off the strip. That way they can dial in exactly how much maximum nose elevation the car will have on launch.

I suppose on a rear wheel drive it could also be used to keep it from biting too hard and or to help keep it from carrying the front wheels.


They may have been added using monkey see monkey do R&D after seeing them on some of the Front wheel drive cars. Thinking they were the hot setup without understanding what they were for. If you have a RWD car and it won't hook I'd try pulling them off (or at least adding length to them) to see how the chassis behaves with more front end lift.

One thing to check is make sure they are not there to keep the front end from over extending and dropping a coil spring out of its perch.
If they are slightly different lengths they may be there to tune how the chassis loads the rear tires as it winds up due to torque reaction. I think you might want to check out that traction dyno web page linked above.

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Post by MileHighMan »

Fishman. I have been working on this exact problem [for my car] today. Here's what I've come up with. In video, my car kind-of teedder-todders off the line. My front-end is chained downed to ride height. I've decided to put back the shockabsorber of 50/50, and let out the chain, to slow the reaction on the front-end going up, to theoretically enhance weight transfer. I have a mid-70s Camaro @ 3400 lbs. Before runs are 10.60s. After,[ though not tested ]Maybe Quicker. Good Luck With Your Project. Dan.
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Post by fishman »

thanks for the replys guys
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Post by John Wallace »

Interesting web site, Billy.

Doesn't the force of the chassis have an effect on your setup?
I don't see where their is any input for it?
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