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Author Topic:   Front spring split?
sixwillwin
Dirt Full Roller

Total posts: 35
posted January 18, 2001 01:54 PM
Question: Metric dirt stock car. Currently have been running a front spring split with the RF being 200 # heavier than the LF. With all else the same(crossweight, ride height, etc.), what would the effect be if I lowered the split to 100#(RF still heavier)??? I am changing front spring rates at this time and would like some input. The car has a moderate amount of roll which I want to elimate, would the change help or hurt the amount of roll? The car is driven very hard/deep in the corners. Thanks sixwillwin

junkyard
Dirt Full Roller

Total posts: 32
posted January 18, 2001 05:40 PM
It will depend in how much banking you track has. On a very high banked track cars will run the same fronts. I have known guys that have tried running a heavier left front spring in hopes of transfering more weight faster to the right rear. I'm not sure that it worked. But the theory sound good.

bbracer17
Dirt Maniac

Total posts: 168
posted January 18, 2001 11:07 PM
What are you calling a moderate amount of roll? What are shock travels on the right side? I beleive increasing the left front spring while leaving the right front the same will tighten the car. Also consider measuring and changing your front roll center before just changing springs. You might be able to change it with just ball joints.

sixwillwin
Dirt Full Roller

Total posts: 35
posted January 19, 2001 08:34 AM
Thanks for the replies so far. My tracks are all medium to high bank fast 3/8 ths. Me and sway bars don't get along, something else to bind and get get ******* up. I won't even tell you guys what I run for spring rates, you wouldn't believe me anyway. Anyway, it works...last year had the most feature wins in my Sportsmans class at three tracks combined. I am just looking to stop some of the body roll, I have improved it quite a bit last year and am looking for even more improvements. I will lower the car and reduce the split to 100 pounds, I think. It seems I used to use more sidebite and utilized the body roll(we run the IMCA mod tires), last year it just was too much and was lacking in forward bite a little. I don't really know what changed, sidebite used to be the ticket, i think the tracks stayed a lot tackier last year and just simply did not require the sidebite of the previous years. More thoughts are welcome. sixwillwin

awkwardjeff
Dirt Freak

Total posts: 218
posted January 19, 2001 09:20 AM
I agree with kk17, Your front roll center is no located in the conventional position....I didn't say wrong because you are fast with the car the way it is set up now. But because you won't tell us the spring rates because we wouldn't believe you.....well that tells me you are springing the car real stiff on the right front.....and this is to keep the roll to a livable amount now....your question was about springing the left front stiffer....this will tighten the car on entry, by not letting the rear unload as much ..........there are other ways of keeping chassis roll out while running the same springs or softer springs........one way to accomplish this is to change roll center location............the reason for locating the roll center where most people do is so that the changes made to the car can be felt by the driver........if you change spring rates on the right front by 50 pounds the change is more drastic with going from a 850 to a 900 then say 1200 to 1250
percentage wise the softer springs have a much higher amount of change.......this is the reason to work with roll center location. This way the changes made to the chassis are noticeable...........Jeff

sixwillwin
Dirt Full Roller

Total posts: 35
posted January 19, 2001 03:08 PM
Thanks AJeff. What about this though, in the Sardeson racing catalog(they make mods, late models, in Neb.) they have a "chassis troubleshooting" page in the back, anyway, it lists amnong other things, that to decrease a push on entry...try increasing the LF spring rate. I believe that is opposite of what your telling me. I'll try it to start the year and change from there. I like your roll center ideas, its make sense to me. Thanks

bbracer17
Dirt Maniac

Total posts: 168
posted January 19, 2001 10:42 PM
Hey Six, got to www.proshocks.com there is an article and graph to teach you how to measure front roll centers. I promise you that if you get your roll center anywhere from 3 to 4 inches above ground your car will feel better. I drive a home made mod and I'm constantly learning and changing and this is one thing that drastically helped my car. Also learn to set bump steer.

awkwardjeff
Dirt Freak

Total posts: 218
posted January 20, 2001 08:07 AM
six, under a normal car that holds up.....How it works is because the LF is stiffer it keeps the right rear planted,(while braking) this will help the car turn under power entering the corner.......BUT because you have the roll center wrong in the front of the car you have done other things to the car that no longer let this happen properly.
See because the front is so stiff now, to stiffen up the left front would help keep the right rear down, but would make the front so stiff it wouldn't transfer weight to the right front like it does now....so you would end up washing the front end out.
It would still push, instead of the rear not coming loose like now. It would not plant the front to steer the car......UNLESS you slowed the car down more.....
If your roll center was located properly in the front you would not have a crutch up there and the rest of the car would work with the standard adjustments........I hope I explained that clear enough......Jeff

six tell us what the car is doing and what you are trying to accomplish.......this is the short cut through the woods.......

sixwillwin
Dirt Full Roller

Total posts: 35
posted January 20, 2001 02:44 PM
OK I'll check the roll center. The PRO shocks page tells me how. Thanks for that. What roll center am I looking for? It is a 2900# metric using basically stock a arms and suspension. I am assuming the roll center will be way high. If so, what is the best way to change it, ball joints? I would prefer to keep using metric front end parts since I have piles of them. Thanks sixwillwin

bbracer17
Dirt Maniac

Total posts: 168
posted January 21, 2001 02:34 PM
Actually your roll centers are probably extremely low this would cause excessive body roll. I think anywhere from 3 to 4 1/2 inches high and either centered + or - 2 inches to either side would be close enough for the average racer. Maybe Jeff or Jammin will correct me if I'm wrong. There are upper and lower ball joint that AFCO sells that help alot. I'm not sure what your rules are but you might also need to lower your upper mounts on the chassi.

awkwardjeff
Dirt Freak

Total posts: 218
posted January 23, 2001 11:30 AM
My bet, too far left. let us know where the roll center is located and we can give ideas on the proper way of adjusting.......Do you have a extended ball joint in the right front? and do you have one in the left front?
I'm not sure who put these A frames together, but this maybe the problem, someone tried to help but someone put the extended ball joint in the left upper A frame and it needs to go into the right????? Just a thought......Jeff

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