Does this look like heavy understeer to you?: Grassroots Motorsports forum: Grassroots Motorsports Magazine

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June 30, 2011 2:35 a.m. MrBenjamonkey HalfDork

I'm talking to a suspension guru and I'm trying to figure out if he's for real. He watched this video and said it looks to him like I have "heavy understeer." It didn't feel that way to me, and I honestly thought the car was slightly too loose.

However, I'm not that experienced racing FWD cars, so maybe my idea of loose is a lot more conservative than the fastest setups.

Here's the video.

http://www.youtube.com/watch?v=sS8Vvx3fhPs

Here's the much longer in car video if you want to watch it as well.

http://www.youtube.com/watch?v=rCtTXO8dbQk

Anyway, just judging on the videos and ignoring my impressions, does this look like an excessively understeering car?
June 30, 2011 5:59 a.m. bravenrace SuperDork

I only watched the first video, but from that it's kind of hard to tell. If I had to make a judgement, it does look a little like it's underteering, but in part because there doesn't seem to be any evidence of oversteer.
I thought I heard your tires squealing. If so, was it the fronts or the rears? I think that as long as you are confident in your understanding of over-understeer, then you are the best judge of that. Did the front tires go where you steered them? If so, then you weren't understeering. Same goes for the rear. In any case, it didn't look to me like you had "heavy" doses of either.
June 30, 2011 8:12 a.m. DILYSI Dave SuperDork

Sure sounds like understeer.
June 30, 2011 8:31 a.m. Bobzilla Dork

i loved the longer vid... I really want that first Gen Accent (Excel) early in the line up.

And yes... you are understeering. Needs more rear bar.
June 30, 2011 9:26 a.m. miatame HalfDork

It is sort of hard to mistake. Did the car go where you pointed it or did it push to the outside of the corner?
June 30, 2011 12:53 p.m. DWNSHFT Reader

Watching your in-car footage, you don't appear to have heavy understeer. Yes, there appears to be some understeer but not "heavy." And I did see one instance of oversteer. Also, how you drive might be causing your understeer. If you haven't had much recent seat time, I would suggest that the car's handling is fine for now as you get seat time and get faster. It's better to have slight understeer while learning than a twitchy car. Many pro drivers also prefer mild understeer. I'd say drive it for now, while getting prepared for an increase in rear roll stiffness later.

David
June 30, 2011 1:20 p.m. SVTF Reader

I can't tell from the vid. But here's couple thots.....

Can you very lightly trail brake into a corner and bring the rear around?

Does it come around nicely if you lift the throttle very slightly thru a sweeper?

At corner exit, a FWD car will understeer with throttle. Can you keep the steering wheel constant and drive the line (at the grip limit) with just slight movements of your right foot?

How about if you stay neutral on the throttle thru the corner, like on a skid pad - does it slide all four tires (as opposed to just the front)? (aka, can you drift?)

If the answer is "yes" to all of the above, in my opinion your setup about right, depending on driving style. If the answer is no, that is more understeer than I like, so I would stiffen the rear (sway bar, springs, shocks, tire pressure) relative to the front.
June 30, 2011 2:06 p.m. Matt_Smith New Reader

MrBenjamonkey wrote:

I'm talking to a suspension guru and I'm trying to figure out if he's for real. He watched this video and said it looks to him like I have "heavy understeer." It didn't feel that way to me, and I honestly thought the car was slightly too loose.

However, I'm not that experienced racing FWD cars, so maybe my idea of loose is a lot more conservative than the fastest setups.

If he is a suspension "guru" he would have called it "roll stiffness." You're car is obviously front roll stiffness biased, which leads to understeer. However, understeer is a dynamic condition and, in one word, cannot explain the handling characteristics of your car.

Read a book on your own to develop your car. Everyone s a suspension guru these days...it doesn't mean that they know what they're talking about.
June 30, 2011 2:57 p.m. Giant Purple Snorklewacker SuperDork

Yaarrrr. She be plowin' like a (ship or something pirates might know plows).

I suck at metaphors today.
June 30, 2011 3:19 p.m. fasted58 HalfDork

In reply to Giant Purple Snorklewacker:

or like DW would say... pooshin' like a dump truck
June 30, 2011 5:39 p.m. iceracer SuperDork

Looks normal for a FWD car. Understeer with throttle. Oversteer with no throttle. With a little suspension work you can negate both a lot. My ZX2SR was fun in a high speed corner, throttle steer all the way through.
June 30, 2011 5:52 p.m. paul Reader

Definitely not excessive/heavy understeer, but I wouldn't say too 'loose' either.

My civic is a good example of a fwd setup that's a little too loose, constantly having to apply light throttle to bring the rear back in-line if you're anywhere near it's limits:

http://s4.photobucket.com/albums/y143/pj350/?action=view&current=slide2.mp4

...works well for autocross, not so much for a track day.
June 30, 2011 10:40 p.m. MrBenjamonkey HalfDork

bravenrace wrote:

I only watched the first video, but from that it's kind of hard to tell. If I had to make a judgement, it does look a little like it's underteering, but in part because there doesn't seem to be any evidence of oversteer.
I thought I heard your tires squealing. If so, was it the fronts or the rears? I think that as long as you are confident in your understanding of over-understeer, then you are the best judge of that. Did the front tires go where you steered them? If so, then you weren't understeering. Same goes for the rear. In any case, it didn't look to me like you had "heavy" doses of either.

In that corner, for those two shots, all four tires were squealing. They aren't very good tires ...

Just listening to my butt dyno, I thought it was pushing a little in the hairpins and loose in the fast corners.
June 30, 2011 11:08 p.m. MrBenjamonkey HalfDork

Matt_Smith wrote:

MrBenjamonkey wrote:

I'm talking to a suspension guru and I'm trying to figure out if he's for real. He watched this video and said it looks to him like I have "heavy understeer." It didn't feel that way to me, and I honestly thought the car was slightly too loose.

However, I'm not that experienced racing FWD cars, so maybe my idea of loose is a lot more conservative than the fastest setups.

If he is a suspension "guru" he would have called it "roll stiffness." You're car is obviously front roll stiffness biased, which leads to understeer. However, understeer is a dynamic condition and, in one word, cannot explain the handling characteristics of your car.

Read a book on your own to develop your car. Everyone s a suspension guru these days...it doesn't mean that they know what they're talking about.

Haha, I've read several and they all say different things!

The car right now has 195/55/15 tires at all four corners, 9kg/mm coilovers (488 lb) with non adjustable Bilsteins at all for corners and no swaybars. I'm running it about an inch lower than stock in the front and about .5 inches lower in the back. My front roll center is about 6 inches off the ground and my back roll center is about 16 inches high.

My setup is based on Steve Hoelscher's ideas (won DSP nationals a bunch of times in a row) and he is pretty much always anti-sway bar. This other guy I'm talking to runs a very successful drift car, this one

and some relatively successful high level road race cars as well.

He is horrified at the idea I wouldn't run swaybars.
June 30, 2011 11:14 p.m. MrBenjamonkey HalfDork
SVTF wrote:

I can't tell from the vid. But here's couple thots.....
1. Can you very lightly trail brake into a corner and bring the rear around?
2. Does it come around nicely if you lift the throttle very slightly thru a sweeper?
3. At corner exit, a FWD car will understeer with throttle. Can you keep the steering wheel constant and drive the line (at the grip limit) with just slight movements of your right foot?
4. How about if you stay neutral on the throttle thru the corner, like on a skid pad - does it slide all four tires (as opposed to just the front)? (aka, can you drift?)
If the answer is "yes" to all of the above, in my opinion your setup about right, depending on driving style. If the answer is no, that is more understeer than I like, so I would stiffen the rear (sway bar, springs, shocks, tire pressure) relative to the front.
1. Yep, especially at speeds over about 40 mph. Below that the car isn't that adjustable unless I give it a flick.
2. Yes. The car feels really good in sweepers. It'll drift decreasing radius corners.
3. Yes, although I suspect my firebreathing 107 HP has something to do with that.
4. Depends on the vehicle speed. Below about 50 mph it will push. Between about 50 and 75 it will be neutral. Above that I'm either full throttle or counter steering.
June 30, 2011 11:23 p.m. MrBenjamonkey HalfDork

Bobzilla wrote:

i loved the longer vid... I really want that first Gen Accent (Excel) early in the line up.

And yes... you are understeering. Needs more rear bar.

I actually caught and passed that Accent. He was way too stiff and bouncing through the sweepers. Setup aside though, it was a very nice little car. It's actually part of this series.

http://www.youtube.com/watch?v=U_TxP9xCjBE

It's called time trial superstreet.

The Elantra at the beginning of the video though, that guy kicked everybody's ass.
July 1, 2011 12:49 a.m. Vigo Dork

This is a little subjective but i would call that understeer mild. Definitely not heavy.