Understeer or Oversteer?

[DSC]

I hear people saying they got a rear swaybar first so their car doesn't understeer as much. I also hear people saying they got a front swaybar so it doesn't understeer as much. It has always been my understanding that the opposite end of what you stiffened will lose traction first. So with my setup (whiteline front sway, front stb, and stock rear sway) I should be getting crazy oversteer because the front now grips really causing the back to lose traction in the new faster corners. I'm quite sure this is what I'm feeling but people say they get rear sways first to stop understeer...wouldn't it make it worse?

[HippoSleek]

Sorry, you've got it backwards.  A bigger rear bar will reduce body roll in the back - which results in flatter cornering.  Flatter cornering means more force is applied to the tires and less used by providing roll.  More force applied to tires means they will reach their slip angle faster.  Slip angle equals loss of traction.  In other words, a bigger rear bar means more loss of traction in the back, which increases the car's ability to rotate around.  That is oversteer.

If you bought both bars, you will see flatter cornering and a balance/offset in oversteer/understeer.  Usually a set of bars will slightly increase the tendancy for oversteer as it is a more desireable performance characteristic.  If you bought just the rear, you car would likely become too tailhappy - if just the front, it should plow like a mule.

[DSC]

Alright. It must be that I'm just driving harder now that I have it on causing the back to slip. I don't quite understand though...if a sway bar causes the end of the car its on to lose traction easier, whats the advantage of flatter cornering? Wouldn't increasing the tire contact patch (cornering flatter) increase traction?

[bama240]

Are you loose going into the corners (back in try to come around) or is it loose coming out of the corners?  Rule of thumb is to fix the condition going it to corners and that will fix the condition coming out of the corners 99% of the time.  Alot of times this can be worked out with air pressure.  If you car is just for racing, you might want to adjust the stagger on your tires.  The best fix would be to use "bump steering".  This is what we use on our race car.  When going straight the flat part of the tire is in full contact with the assfalt/dirt, maximum traction.  When going into a corner the tire rides on the out side edge, 1/2 the traction.  Bump stearing adjusts the camber of the front tires to keep maximum traction through out the turns.  Just remember If you make any adjustments, air pressure or what, write them down.  And only adjust a little at a time, test drive, then adjust again.  You hear them at race tracks "Chasing a loose condition...."  That is what we are doing, making little adjustments and test driving.  But you are correct.  The opp end of a stiff suspention will be loose.  But, loose is fast if you can control it.  You want it to be right on the edge.

Loose/Tight (under/oversteer) links

http://www.auto-ware.com/setup/1.htm  
http://www.seansa4page.com/resource/steering.html
http://www.bobjane.com.au/overstee.htm
http://www.rqriley.com/suspensn.html  

[DSC]

Back end loses traction I'd say right about at the apex, I may just be getting on the gas too hard too fast though.
This is my every day driver so giveing the car negative camber wouldn't be a good Idea. Thanks for the info and links...good stuff

[HippoSleek]

That was good stuff.

D - your instincts are right about the flatter contact patch being the end goal of sway bars.  The problem has more to do with force.  After you firm up an end of the car w/ a big bar, the opposite end transfers it's force to roll while the stiffer end tries to grip.  The roll force wins (thanks to physics beyond me) and forces the firmer end to loose traction.  Two bars will balance this so that both will hold more equally.  End result - flatter, more predictable cornering and better grip.

[DSC]

Cool, that makes since. I think I was just driving like a nut out of excitement when I got done. No amount of sway bars could have kept my rear stuck to the road <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'>
I'm gona go buy some new drill bits and a few other little things (unrelated to current project) and start on my rear sway bar.

[bama240]

If your back end is trying to pass the front end in the corners the ideal thing to do would be to shift weight from the front to the back, but since this is a &quot;driving&quot; car, you can't. &nbsp;I would say to add a small weight to the back passenger side of the car, but once again, the more your car weight's, the more HP is robbed to push it. &nbsp;As you are going into the corner, your areo package is making the front tires stick, but you have no downforce on the rear of the car, and it is making is lighter (not by much, but enuf to make your car loose grip). &nbsp;Might wan't a to go with a spoiler, or one that sits a little higher than stock. &nbsp;You want it in the air stream, that way it will push down on the back of the car and make it stick.

Hippo, inertia is the culprit. &nbsp;An object at rest tends to stay at rest and an object in motion tends to stay in motion. &nbsp;Your in your car, heading strait. &nbsp;All is good, car is centered on chasis. &nbsp;When you put a stiff bar on the front, it increases the Co-efficant of friction for body roll on the front end. &nbsp;So when you want to take that corner, inertia is trying to make it go strait, and the whole body wants to roll to the outside of the corner, but the suspention is harder to move than the back, and all that energy has to go somewhere, so it goes to the back, or softer suspention. &nbsp;So you are right, a bar in the front and back would balance the load of the body and the energy would be absorbed by the springs/shocks.

Sorry for the phyics lesson, but I love to figure out problems, and when I do, I like to share what I found. &nbsp;I had the same problem on our track car. &nbsp;Fixed it, but now I have another one. &nbsp;Every time I mash the gas the front driver side lifts off of the ground about a foot, and that is costing HP. &nbsp;Gotta figure it out now.

[DSC]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from bama240 on 5:42 pm on Jan. 23, 2002
If your back end is trying to pass the front end in the corners the ideal thing to do would be to shift weight from the front to the back, but since this is a &quot;driving&quot; car, you can't. I would say to add a small weight to the back passenger side of the car, but once again, the more your car weight's, the more HP is robbed to push it. As you are going into the corner, your areo package is making the front tires stick, but you have no downforce on the rear of the car, and it is making is lighter (not by much, but enuf to make your car loose grip). Might wan't a to go with a spoiler, or one that sits a little higher than stock. You want it in the air stream, that way it will push down on the back of the car and make it stick.

Hippo, inertia is the culprit. An object at rest tends to stay at rest and an object in motion tends to stay in motion. Your in your car, heading strait. All is good, car is centered on chasis. When you put a stiff bar on the front, it increases the Co-efficant of friction for body roll on the front end. So when you want to take that corner, inertia is trying to make it go strait, and the whole body wants to roll to the outside of the corner, but the suspention is harder to move than the back, and all that energy has to go somewhere, so it goes to the back, or softer suspention. So you are right, a bar in the front and back would balance the load of the body and the energy would be absorbed by the springs/shocks.

Sorry for the phyics lesson, but I love to figure out problems, and when I do, I like to share what I found. I had the same problem on our track car. Fixed it, but now I have another one. Every time I mash the gas the front driver side lifts off of the ground about a foot, and that is costing HP. Gotta figure it out now.</td></tr></table><span id='postcolor'>How would putting weight in the back help rear traction through cornering? Your adding weight but aren't you also adding to the inertia as well, negating all that was gained with the weight?

[bama240]

The rear passanger tire is loosing grip in the turns because thats the tire that wont stick. &nbsp;But that is only for left turns. &nbsp;I forgot that this is not a race car. &nbsp;You would want to add it to the middle. &nbsp;That way it would work for the right and the left. &nbsp;Also adding weight will &quot;compress&quot; the suspention on the back/front, depends on where you need it, making it stiffer or have less suspention travel. &nbsp;But if I was you, I would go with the balanced bars that Hippo was talking about. &nbsp;In a race car you don't add weight, you would move weight from the front right to the back left, to balance it. &nbsp;More weight=less power to move the car. &nbsp;Don't add weight, that was just for info purposes.

[LanceS13]

Maybe handling characteristics are different on short circle dirt tracks, but &nbsp;DSC's observation is right. &nbsp;That's why &nbsp;it's easy to spin a RR Porsche if you don't know what you're doing...all the weight's in the back. &nbsp;On the other hand, that's why FF cars plow like mules...all the weight's in the front. &nbsp;Think about a dart. &nbsp;The light feathers follow the weighted point (FF/weight forward car). &nbsp;If you through it backwards (RR/weight rearward car), it easily turns around to the point-forward position. &nbsp;Our cars have a near 50/50 distribution, so the suspension can easily be set up for neutral handling. &nbsp;

[bama240]

They might very well be. &nbsp;I all know is that when you are rapin' ass in to a corner that turns back on itself at 80+mph with 20 other cars rapin' ass in to the same corner, you better have your shit set up right or you are in for a wild ride. &nbsp;I have been there before. &nbsp;I learned from experiance and broken bones.

[LanceS13]

Hey bama, what class are you running?
Why is carrying the front inside tire so bad? &nbsp;Alot of the faster dirt cars I've seen do it...looks pretty cool.

[240racer]

The first thing to look at is the definition of of understeer and oversteer. &nbsp;This has been brought up in the past but I'll repeat quickly. &nbsp;Understeer is when the front tires have less traction then the rears. &nbsp;Oversteer is the opposite. &nbsp;Anyway, about bars... &nbsp;Use a stiff bar in the rear for oversteer which is nice for drifting, but not the fastest way around the track. &nbsp;Use a stiff bar in the front for understeer. &nbsp;Understeer is usually considered bad, however a small amount of understeer is always prefered over any oversteer. &nbsp;This is assuming you are on a high speed corner. &nbsp;When you watch racing on TV like Touring cars or Formula 1 or something you never see them having much oversteer if any. &nbsp;Of course you can't see the understeer, but I am sure they have a little of what's called &quot;stable understeer&quot; &nbsp;Of course anything on dirt or all-wheel drive cars or whatever are going to be much different. &nbsp;Anyway about DSC's car, that should have mild understeer in a steady corner (no gas or brake) This is assuming you have the same tires front and rear. &nbsp;Anti-roll bars effect traction more then springs, stb and dampers. &nbsp;However, tires make a big difference, it helps to run the same tire, same size untill you experiment a little. &nbsp;Hope that helps. &nbsp;

[DSC]

Alright, I am now running whiteline front sway on medium setting (soft/med/hard are the 3 settings) and a front stb (put on with the car jacked up makeing it a bit stiffer) and NO REAR sway or stb. <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/smile.gif" border="0" valign="absmiddle" alt=':)'> I must say, WOW it sux0rs! I did it on purpose just to see how much the stock sway effected under/oversteer. It makes a HUGE difference...I can't wait till saturday when I put my rear whiteline on(on hard). Then come next payday a rear STB hopefully.

Edit: &nbsp;and incase you were wondering, I just plowed through corners with my mushy back just floping along behind me or atleast thats the feeling I got from it. &nbsp;I can still get my back end lose (not drifting) but it really takes some effort.

(Edited by DSC at 3:40 pm on Jan. 24, 2002)

[bama240]

lances13-
We run a &quot;hobby stock&quot; kinda....... &nbsp;We have not always had the tire lift. &nbsp;We got it in the last race of the season. &nbsp;I think that the frame let loose somewhere. &nbsp;I need to get it back down, because it seems like it is stealing hp. &nbsp;I dunno, just seems slower, and I am getting killed coming off of the corners. &nbsp;But I will give you this, it does look cool from the stands. &nbsp;Try seeing it from the drivers seat, it will really make your butt hole pucker up!