A new understeer theory...

[240 2NR]

Ok, so I was looking at the pictures I got back from the track (actions pics!!! though I fell asleep before I could upload them to a host, I'll do it tonight) and an idea struck me.  Do you think I may have hit my bump stops?  I really hope this isn't the case but it would explain why it was so sudden rather than being a progressive loss of traction.  What does that feel like and what are the sypmtoms mid corner of hitting the bumpstops?  

Otherwise the pics look much better that last time.  The car is so flat rather than looking like it wants to roll over.  Too bad there was only one that wasn't blurry.

Also, as it was my first time getting heavy understeer, is it better to try adding more gas to bring the rear around or is it better to breathe off the throttle and give the front tires a chance to hook up.  I know in cases of mild understeer more throttle is ideal and you never want to coast through a corner, but what is the correct way to control heavy understeer?  I was feeding more throttle in a hopes of getting the rear around a bit, but it just continued to push.

[uiuc240]

i don't think it's the bumpstops, but i suppose it's possible.  i just can't imagine that, as i haven't hit the bumpstops driving around illinois' roads...and they suck.  and that's with occasional high-speed antics on back country roads.

as for the heavy understeer, there's really no "good" way to correct for that once you're pushing hard. &nbsp;let off the gas and steer. &nbsp;<img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/sad.gif" border="0" valign="absmiddle" alt=':('>

Eric

[bbp]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Do you think I may have hit my bump stops? &nbsp;I really hope this isn't the case but it would explain why it was so sudden rather than being a progressive loss of traction. &nbsp;What does that feel like and what are the sypmtoms mid corner of hitting the bumpstops? &nbsp;</td></tr></table><span id='postcolor'>

If you bottom out the rear you will know right away. &nbsp;The car will go into a snap oversteer situation. &nbsp;Very noticable. &nbsp;The front is a little more difficult to diagnose. &nbsp;It will go into a understeer situation, but normally if the case the car is not handling properly to begin with so you are probably understeering up to that point. &nbsp;

An easy way to determine how far you are compressing the front is to wrap a ty-wrap or wire tye to the shaft of the damper. &nbsp;Make it snug enough that it will stay in one place, but will slide as the shaft is compressed. &nbsp;Before the session, slide the zip tie towars the bottom of the shaft, at the end of the session, take a look and see how far up it has moved. &nbsp;If it is mashed up against the bump rubber then you are most likely bottoming out the damper.


To correct an understeer situation there are a few remedies:

1. &nbsp;OPEN the steering up a little bit
2. &nbsp;Slow down your entry
3. &nbsp;try trail braking into the corner to get the car to rotate at entry, then add throttle when the car is pointed toward the apex.

In most cases, adding allot of throttle will simply make the understeer worse. &nbsp;Where is the weight when your on the throttle? &nbsp;Where do you want it to be?

What you realy need to determine is WHEN is the car understeering. &nbsp;Is it doing it at turn in, mid corner, or after the apex (on throttle). &nbsp;The answers to these questions will help you determine what to change as far as your set-up goes.

[uuninja]

One way to tell if you are bottoming your front suspension is to mark your side walls. If you are rolling them, chances are you are out of front suspension.

As far as correcting understeer, opening the wheel and a lower entry speed are the safest for a new driver.

Also check you line, hitting you apex way early will give you a good bit of understeer.

[240 2NR]

Well the problem for me is I have taken these corners before and never experienced under steer this heavy before (on the track or ever). &nbsp;If I was going faster than usual it couldn't have been by more than 5mph from the previous lap and I was no where close to out of control. &nbsp;Both of my previous laps left me with plenty of room to the track out point (like 5 ft or more) and I'd be surprised to find that in both cases I was apexing THAT early. &nbsp;I didn't have an instructor with me for immediate feedback so it's hard to say for sure what happened.

More likely I think it has to do with my camber and toe in settings (which i don't know because of a screwed up alignment appointment) but looking at it, it appears my driver's side is running 0 to almost no camber and the front end appears toed in. &nbsp;This means that both specs are out far enough to be visable without any sophisticated equipment. &nbsp;I was just curious if anyone had ridden their bumpstops and could describe the feeling. &nbsp;Ironically I was running less tire pressure on a hotter day and my tires showed less signs of rolling than it did at the school.

[bbp]

The tires will roll over (especially street tires) regardless of whether your shock is bottoming out. &nbsp;I knida doubt that it is personally. &nbsp;The alignment spec you just mentioned could very well cause the understeer. &nbsp;For track use try 1/16 to 1/8 out in the front and 1/16 in or 0 in in the rear. &nbsp;Camber is not really adjustable with out some modification. &nbsp;Something that should have been asked before.... &nbsp;what is done to your suspension?

[HippoSleek]

I've hit my bumpstops too many times. &nbsp;I'm still running a stock susp. on the car and it just can't handle certain corners at high speed. &nbsp;Matt/uuninja was w/ me at VIR when I was destroying my tires' shoulders (hence the old shoe polish trick). &nbsp;

Basically, I know of two reactions to bumpstops: 1) high speed gradual compression = good initial turn, but progressively stronger (almost sudden) understeer combined w/ the tire rolling onto the sidewall (as it becomes the last bit of suspension). &nbsp;The understeer was noticeable when I would run out of suspension - even after I put my tires up to ungodly psi to stop the rolling. &nbsp;Solution - slow down or increase your spring rates! &nbsp;2) transition bottoming = Dodge Spirit-like plow all at once. &nbsp;I've only felt this in autox (due to tight transitions). &nbsp;It is BLATANT. &nbsp;The car starts to turn a little bit and then the front washes out like you are in gravel, covered in ice, covered in grease.

When I was having the problem on the track, I could tell that I was just "out" of turn. &nbsp;The two places it was happening to me at VIR were in a sweeper that closed right at the end (suspension gradually loaded in the sweeper and had nothing left to allow turn in for the last bit) and in a downhill, mildly off camber turn w/ a suspension loading bump (had plenty of turn until the bump loaded the suspension - then I just pushed to track out through the end). &nbsp;In both cases, the car just felt like it reached a limit as to how much it would turn. &nbsp;Unlike going in too hot where there is almost instant push, it would start off fine and then push at a certain point.

As for correction, bbp is showing his expereince. &nbsp;Understeer is little different than oversteer in rwd - steer into it and use the throttle to shift the weight/traction to where you need it.

[adey]

Just a thought, but instead of your car, could you have hit a small patch of sand/water/oil with your fronts (or perhaps even one of the fronts)? What I mean to say is that maybe it's not your car; there're a lot of external factors- such as track conditions.

Other than that, I'm learning a LOT from this post; keep up the good info.

[240 2NR]

The reasons I think it wasn't the track is that it happened twice in one lap on different corners that I had already driven. &nbsp;I did have steering going into 7 and basically missed the apex by a little and felt like I was driving of in a tangent from there out. &nbsp;I'm pretty sure my front end has a lot to do with my problems but I was still able to make it around the track within 1 second of my previous best time. &nbsp;The bumpstop idea just came to me last night and I thought I'd ask if anyone had that experience. &nbsp;It feels balanced in transition and in sweepers, but understeers like mad in tight right hand turns.

My car:
195/60/15 Dunlop D60 A2's on stock 7 spoke wheels
F/R stbs
Whiteline springs
Koni sport shocks 3/4 stiff all around
Whiteline sway bars: Front med, Rear soft (something else I may change)
Front whiteline bushings (TC and LCA)
K&N drop in filter
5Zigen catback
Some funky front end alignment
All new ball joints up front (LCA and tie rod ends)
Harness bar and 6pt harness

[uiuc240]

195/60/15 Dunlop D60 A2's on stock 7 spoke wheels
Whiteline sway bars: Front med, Rear soft (something else I may change)
Some funky front end alignment


I think those are your biggest problems. &nbsp;Fix the alignment, put on your good tires, and put the rear bar on firm. &nbsp;Should change things a lot. &nbsp;

Eric

[bbp]

Well, since you have adjustable shocks you may want to try adjusting those (get an alignment first) to correct the issue.

Since it is a street car I assume you have single adjustable shocks. &nbsp;Single adjustable Koni's adjust the rebound of the damper. &nbsp;Now, when did the car understeer, at turn in or more towards the exit of the corner?