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Body roll / would bushings help?

Old 04-24-03, 08:48 AM
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Body roll / would bushings help?

I put Eibachs on my FD, which lowered it an inch, with the stock shocks, and now I'm getting top of wheel well rubbing in the front, mostly on the left side. I also have more body roll than I would like.

I'm thinking if I could eliminate some roll I could get rid of the rubbing as well.

Bushings on the sway bar are stock and the car has 75K miles on it.

Do you think I could upgrade the bushings to something much stiffer, and would that make a big difference?

Any recommendations on bushings, swaybar issues, or whatever (and where to get em) would be greatly appreciated to help my body roll issues.

Thanks,

David
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Old 04-24-03, 09:04 AM
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Bushings would do little to eliminate body roll. Bushings help tighten/firm up the suspension so that your suspension can do it's job.

What is the condition of your shocks? If you "upgraded" your springs, but are still using "old" shocks, then your "old" shocks are taking more of a beating then they were before.

Also, a sway bar would help.
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Old 04-24-03, 09:29 AM
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It's the Eibachs. The Pro-Kits are progressive springs, and they're not that much stiffer than the stock spring rates. Better shocks and a better swaybar will help eliminate some of the body roll, but stiffer springs will ultimately be the true fix. I forget the formula, but I remember the basic premise ... you've got to at least double the spring rate to see any significant decrease in weight transfer.
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Old 04-24-03, 11:38 AM
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Originally posted by redrotorR1
you've got to at least double the spring rate to see any significant decrease in weight transfer.
I bet you $100 dollars I can weld my struts into solid steel bars and I will still get no more weight transfer than I did with the stock springs

I think you meant roll perhaps? Never heard this rule of thumb.
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Old 04-24-03, 01:54 PM
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Yes, I meant body roll. Stupid brain.
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Old 04-24-03, 01:56 PM
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No more 3 martini lunches for redrotor.
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Old 04-24-03, 04:28 PM
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shocks and springs are not going to significantly reduce body roll. this is the job of the anti roll bar or swaybar(bad name for this part, sorry). the end links will help but will not be a drastic help. look for a larger sway bar, new shocks, and a higher(not progressive) rate coil spring. one of the "sport kits" will work ok for the street. "race kits" will work great for the track but will be unusable on the street.
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Old 04-24-03, 04:56 PM
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Originally posted by DamonB
No more 3 martini lunches for redrotor.
Heeeeyyyy ... I'm not an alco-hhh .... aw, who am I kidding .... dammit.
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Old 04-24-03, 04:57 PM
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"springs are not going to significantly reduce body roll"
???????????????? Carl
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Old 04-24-03, 05:19 PM
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Originally posted by in2twins
"springs are not going to significantly reduce body roll"
???????????????? Carl
Surely he mispoke? Springs and bars are the only way to adjust roll.
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Old 04-25-03, 01:15 PM
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I think he's testing us
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Old 04-25-03, 04:13 PM
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Well, I've always have been told that they each should be used to handle their own areas. Shocks/springs are used to control fore/aft movement and swaybars are used to control side/side movement. I know in the real world this isn't as black and white is it sounds in writing but it's just a good rule of thumb to go by.

That being said, if you have a lot of body roll and want to minimize it, use swaybars to handle this issue. If you have too much dive/squat during acceleration/deceleration then get stiffer springs (and shocks to go with them) to address that issue. But just changing one thing will affect ofther areas. Argghhh, there just too many variables going on to think about.

Suspension work isn't as straight forward as engine work is. What feels good to one person might not work well for another driver even in the same car. On top of that the suspension needs to be able to be adjusted (if you want/need that much adjustability) for different conditions such as for weather and/or road surface quality. Suspension tuning is sort of a black art. Good luck finding your happy setting.
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Old 04-25-03, 04:29 PM
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Originally posted by Jerk_Racer
Well, I've always have been told that they each should be used to handle their own areas. Shocks/springs are used to control fore/aft movement and swaybars are used to control side/side movement.
I have to strongly disagree with this. Springs control all movement of the chassis, whether pitch or roll. Period. Shocks are along for the ride and damp the springs (chassis) in both dive AND squat AND roll. Anti-roll bars are used to fine tune the relative grip of the front and rear suspensions during cornering by adding additional spring rate.


Originally posted by Jerk_Racer
That being said, if you have a lot of body roll and want to minimize it, use swaybars to handle this issue. If you have too much dive/squat during acceleration/deceleration then get stiffer springs (and shocks to go with them) to address that issue
Body roll, dive and squat will be lessened by using stiffer springs. Since you now have less body roll you in fact can run a thinner anti-roll bar to control the chassis roll. This is a good thing as now the suspension remains more independent so to speak; the interconnection between the left and right sides is lessened. The suspension is always tuned with springs first, then anti-roll bar settings are developed to suit them.
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Old 04-25-03, 06:11 PM
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this is the problem with the black art of suspension tuning. Damon has a very logical and accurate idea of what he is doing, I just don't agree with the setup(for me and my driving style). his method can and does work for certain drivers. this setup tends to be very stiff and harsh, but can be effective(especially on smoth tracks). the way I go about setup of my cars is to try and run the softest springs I can. this requires alot larger swaybars and specially valved shocks(can be hard on tires). also some help on the suspension geometry side. this is some of the stuff Jerk Racer was aluding to. the number of variables and the driving styles and requirements are enormous and not one path is the "correct" setup. getting some basics from suspension setup books is what I would start with, then make some changes you feel would work for you. if they work you are on your way. if they don't try some of the other combinations until you get what works for you. but changing one part and expecting a miracle cure is not going to happen. the suspension is a system, left to right and front to back. they all influence each other.
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Old 04-25-03, 08:03 PM
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Yep, everything affects the other thing when one thing is changed. I'm right, I'm wrong. It depends on how you attack the issues you want to address. This is the reason why so many books have been written on the subject. This is why questions always come up. This is why it can be so confusing when trying to sort out an issue.

I can only imagine the time it takes for a professional race team to come up with what works for them. The trial and error and all the notes documenting every little change and then the subsequent drivers notes.

MrZUMZUM - upgrading your bushings won't resolve your issue at hand, but it would be a step in the right direction. You can't go wrong with polyurethane bushings for street driving. The poly bushings wil deflect much less under load and that makes what ever they're attached to or supporting do it's job better. Go ahead and change as many of them out as you can. That way there'll be one less variable at play. The stock swaybar mounts (the front ones IIRC) on the FD are known to break with age and hard cornering so upgrade them (if you have not done so already) before they let you down.
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Old 04-25-03, 08:36 PM
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the F1 guys have a very tricky system to completely seperate the "anti-roll" rate from the individual wheel spring rate. it involves some interesting cantilevers, doodads, whatnots and a third spring/damper on each end. (actually i think they only use it on the front). regardless, for the rest of us, the spring rate and roll rate are tied together. i agree with the previous post which suggests setting spring rates first, and then fine tune the sway bar.

regards
fabian

ps.....bushings won't do much for a roll problem unless they are grossly shot. however, i wouldn't do a lot of suspension upgrades and tuning unless the bushings were servicable.
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Old 04-25-03, 08:57 PM
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Originally posted by tims
..... the way I go about setup of my cars is to try and run the softest springs I can. this requires alot larger swaybars and specially valved shocks(can be hard on tires). also some help on the suspension geometry side.
soft springs definiteley help on shitty tracks. they are also beneficial in "wet" setups. most of our tracks out here, with the exception of sears point, are pretty smooth though.

most streets in this country are terrible, however. for a street car, it makes a lot of sense to use the softest spring you can.

fabian
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Old 04-26-03, 10:54 AM
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Originally posted by foko
and a third spring/damper on each end. (actually i think they only use it on the front
The third spring has been around for sometime and is a form of ride height and pitch control; many open wheeled cars have used it both front and rear.

This shot shows the front end of a late 90's Lola, the third spring is the one in the middle. You can see that if only one side moves the third spring adds hardly any wheel rate. If both sides go into bump then they have not only their individual coils but the third spring to overcome as well. THe third spring allows the car to essentially have one spring rate for suspension movement and another for dive and squat.

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Old 05-03-03, 10:27 PM
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Just to throw in my $0.02 and possibly another variable: The stock rubber bushings in suspensions can play a significant role in the overall spring rate the wheel sees. It varies with suspension geometry, bushing durometer, and even temperature, but this effect is noteworthy because switching to urethane bushings effectively reduces the spring rate.

As far as the original post is concerned, I don't know enough about the rubbing issue to know whether it will help or not, but urethane bushings will compress less than the OEM rubber pieces under load. Since they won't compress as much, they will have an effect on your rubbing issue (the bad news is I don't know if the effect will be good or bad unless you provide more details).

Swapping to urethane bushings or bearings: This generally means that the wheels will not gain as much (positive) camber during cornering, which is a good thing. Looking at it another way, the urethane bushings (or bearings, which are even better) will allow you to run less static negative camber for better adhesion under acceleration and braking, while maintaining comparable dynamic negative camber for equal cornering performance.
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Old 05-13-03, 07:05 AM
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Hey Guys:

Thanks for all the feedback. Having read through the posts it's all starting to make some sense. Seems to me the direction I ought to take would be:

1. Leave the Eibachs in place. I say this because if they are not much stiffer than stock this would classify them as relatively soft, right? This would be OK since I run this car on a rough track, Sebring, and also drive it on the street, sometimes as a date car for me and the wife.
2. Upgrade the bushings. Btw, which and how many bushings should I replace? Are we talking the bushings in the ends of the swaybar, the control arm, etc. or are there more I need to attend to? I haven't done that much work on the suspension myself, so I'm trying to think where they all are, and which should be replaced. Also, where's a good source to buy the urethane bushings?
3. Upgrade to a stiffer/thicker anti-sway bar, to prevent the body roll. My rubbing issues only occur side to side, never under hard braking. If you guys are familiar with Sebring, the hairpin and turn 17 are where I get it. Coming off the bridge turn and turn one at Road Atlanta and would be a couple of others. None of these are braking situations so the car is pretty settled at 50/50. It's mostly the heavy cornering to the right (my 205lbs on the driver side obvioiusly not helping), where I get the body roll, and then during those corners any bump in the road will generate the rub. My thought is that if I could flatten out the car I would avoid the roll, and thus the rub. Make sense?

Anyway, if I'm close to on track here (pun intended), give me some advice for good antisway bars, and also I presume I should do them front and rear, even though I only have rub in the front?

Thanks again for all the help.

David

Last edited by MrZUMZUM; 05-13-03 at 07:07 AM.
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Old 05-13-03, 10:39 AM
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ZumZum, the Eibachs are only slightly stiffer than the stock springs but they also lower the car which contributes to the problem as you already know.

Bushings are always nice to replace to be sure they are fresh but if bushings alone are so far out of whack that tires are rubbing you have bigger problems at that point.

Running a stiffer front bar will decrease roll. It will also add push to the car (which the FD can afford. I have run some pretty obscene settings at road courses). If you are going to purchase a new front bar I always recommend going with an adjustable one as no one setting is perfect for every course. Tripoint makes an excellent adjustable front bar and will happily talk with you about your needs before making recommendations. Give them a shout.

Tripoint Engineering
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