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Author Topic: UNDERSTEER
Mike888 Verified Driver Made Donation to Website
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I was at the Glen 2 weeks ago and my car has a tremendous amount of understeer. I tightened up the rear sway bar to full tight which helped but the problem still exists. I am at "0" toe front and rear. 5 on caster, and -2 camber on the front(all I can get get) and -2.5 camber on the rear. tire pressure hot 38lbs. Can anyone give me some advise how to loosen up the car. I am new to racing and any help would be appreciated. Is it my driving or are there other things I can do to the car to help. I have read about changing the toe in the front and rear, but not sure it this will help. Thanks

tony senese Verified Driver
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What turns was it worse in? Was it hopping or just hard to get to turn in? how early were you turning in. Sometimes you need to adjust front and rear tire pressures to get the rear end to loosen up a bit. (higher rear pressure)

Extra toe will help turn in a little, but at a track like the Glen you need all the straight line speed you can muster to get fast laps. Toe will slow you down.

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Tony Senese
SM#99
2008 NASA-NE SM Champion
NASA-NE SM Director
2008 PRO-IT SM 3rd place
http://www.nosenseyet.com/coppermine

Mike888 Verified Driver Made Donation to Website
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where I noticed it the most was on right hand turns, the worse and the most obvious was the heel of the boot, hard right hander going up hill, car was hopping before apex and exit

Steve D. Verified Driver Made Donation to Website
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Raise the rear ride height to shift weight forward?

Are you riding on the bump stops and needing to raise the whole car? Have you done the '99 shock hats (insert obligatory can-of-worms comment here)?

Steve D.

PS - I've noticed that when I begin to have a push and keep driving the same, the push gets worse as the tires get greasier. Does it get better if you back off for a couple laps?

d mathias Verified Driver Made Donation to Website
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Put a little wedge in the car for predominately right turn tracks. I start with .5 % cross weight difference.

Sometimes just changing your line can help - wider entry/later apex?

PM me for mailing address to send check for this valuable advice.

tony senese Verified Driver
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That turn is a pain if your carrying lots of speed, I have seen lots of cars go off left there because of the same problem your having.

I would definitely try dropping the front pressures a couple pounds or dropping the left front if it really was pronounced in the right handers only.

WGI is definitely biased towards the right handers as most of our tracks are. How was it coming out of T11 onto the front straight?

--------------------
Tony Senese
SM#99
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NASA-NE SM Director
2008 PRO-IT SM 3rd place
http://www.nosenseyet.com/coppermine

Casey Z Verified Driver Made Donation to Website
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If you are new to racing as you stated, adding some toe in the front is probably a good idea. It will help you get the car turned in and will keep you from fighting it at the apex. I wouldn't worry about scrub till you are faster. Also, make sure you aren't just overdriving the corner, that will make it push every time. You could also raise the rear as Steven suggests or add a bit to the rear tire pressures.

Assume you have the car setup properly, scales, etc?

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Z Brothers Racing / East Street Auto

Casey Z - 1.6 Kettle
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Mike888 Verified Driver Made Donation to Website
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T11 and T1 felt much better than the heel and the toe, but I was still tight in those also. 11 was just horrendous. If I try to add some front toe, any recommendations on how much to start. I guess I should start with tire pressure?

Ps ride height is at 4 3/4.

PSS Check is in the mail!

Mike888 Verified Driver Made Donation to Website
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I ment the heel was just horrendous! Not 11

Casey Z Verified Driver Made Donation to Website
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I wouldn't shoot for a toe number, I would just give it a bit of adjustment at the track and see if it help. Adjust till it feels right and then see what the number is. Small adjustments...

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Z Brothers Racing / East Street Auto

Casey Z - 1.6 Kettle
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tony senese Verified Driver
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Also, try to run as many laps as you need to KNOW the adjustment made a difference. For me that normally means I see it in my lap times. Sometimes the car feels better because you are going slower, that means the adjustment didn't work!

--------------------
Tony Senese
SM#99
2008 NASA-NE SM Champion
NASA-NE SM Director
2008 PRO-IT SM 3rd place
http://www.nosenseyet.com/coppermine

Mike888 Verified Driver Made Donation to Website
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thanks for all the help, I will have to go back over the messages and start one change at a time. Racing at the new track in Millville NJ next weekend and I am doing the test day so I will have plenty of chance to see what works.

Louis Interdonato
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maybe too much toe in on the rear?...

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WDCR SM # 90 http://www.rpperformanceracing.com/

Unsafe Verified Driver Made Donation to Website
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Mike - what are your ride heights at the pinch welds? You will need a friend to help so you can sit in the car while measuring, and you'll need a level surface. At 4.5 inches or less, you've found your problem.

Also, your hot pressures are a little high for Toyo...drop a couple pounds all around.

You really need to scale the corners to figure out your cross weight (wedge/de-wedge), but a problem there will make it tight (understeer) one way and loose (oversteer) the other.

Good luck...

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Mike Asselta
http://www.saferacer.com

Mike888 Verified Driver Made Donation to Website
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ride height is 4 5/8 with me in the car. Are you saying that the hot pressures should be below 38?

Casey Z Verified Driver Made Donation to Website
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quote:
Originally posted by Mike888:
ride height is 4 5/8 with me in the car. Are you saying that the hot pressures should be below 38?

Too low. Go up to 4.75", and aim for a hot pressure of 36. Most of the info out here on Toyo pressures is crap. I think Mike is on to something here.

You may still need other adjustments, but start with going up on ride height and down on pressures. Adjust from there, I would still add some toe for a new guy.

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Z Brothers Racing / East Street Auto

Casey Z - 1.6 Kettle
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Mike,
Casey's got it. If you don't have the new shock hats, then the 4 5/8 height is causing your push. Not much margin there, even if you have the hats...could still be your problem. Raise it just as Casey says.

PS...loosen that rear bar a notch or two.

Once you have the platform right, you can play with staggered pressures front to back, or some rake...but you shouldn't need to.

--------------------
Mike Asselta
http://www.saferacer.com

soupy
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you may have some set-up issues but trust me, I was there. You need to change your line.

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Charlie Campbell
Race Engineering
carbotech brakes

Mike888 Verified Driver Made Donation to Website
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Hey Charlie,
Were you running behind me at some time, or thru 7? (If so, I am sure it was a very short time)I am open to any suggestions you have.
Mike

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Just to throw you a bone, your line might have been off if you were compensating for the bad handling...but you could induce push if you're charging the corner, braking late, then tossing it in while mashing the gas.

Typical stuff from less experienced drivers (ask me how I know). The opposite is fast....brake light and long (maybe a little trail in), carry more speed in, but no throttle, let the car turn in to the apex, then back to throttle. All of this has to happen at a higher speed than you're probably comfortable with if you want your lap times to fall....but then, this was a setup/handling thread [scratchchin]

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Mike Asselta
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Ken SM-94 Verified Driver
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quote:
The opposite is fast....brake light and long (maybe a little trail in), carry more speed in, but no throttle, let the car turn in to the apex, then back to throttle. All of this has to happen at a higher speed than you're probably comfortable with if you want your lap times to fall....
I agree. I wasn't there to see what you were doing, but when my car starts pushing I have always fixed it by applying what Mike is saying.

Learn to recognize when it's pushing and make an adjustment before your tires go away.

Make sure you don't have any obvious alignment problems and then work on your technique.

Good luck,

Ken

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I would try and learn to compensate for that push with driving.(trailing, gentle steering inputs) Even a bad Miata is easy to drive. I think fast guys start with some push, gets neutral mid race and still ends up loose at the end.

Apex to Apex
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I'm late to this thread. But the first question I would need to ask would be where are you getting the understeer. Turn in? Apex? Or exit?

If at turn-in would adding some rear brake bias help loosen you up? If a few tweaks to brake bias does not help, then back off and look at the chassis. Or what about adding some rear ride hight like someone else mentioned?

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"Driving is a serious business" - John Milner, 'American Graffiti'

EBudman Verified Driver
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Brake Bias!? [Confused]

Are we still talking Spec Miata? I don't think I've ever seen that knob! [Big Grin]

Apex to Apex
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Can't you adjust brake bias with experimenting with pads/rotors?

And please bear with me. I am new to this forum. I am considering getting a SM as a dedicated track car and may jump into competitive racing. I am here to learn.

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"Driving is a serious business" - John Milner, 'American Graffiti'

Zauskycop Verified Driver
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I also am new here, and starting to absorb information as to setting up a SM. Is it normal to have more negative camber in the rear than the front? I know, in my book, that generally causes understeer.

Or is that a normal setup for SM?

Tracy Ramsey

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Tracy Ramsey
Team Blenderblaster

Mike888 Verified Driver Made Donation to Website
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Yes it is normal. Many guys use all they can get in the front which unless you work the spindles or have an unusual car is around -2 front, and -2.5 to 3 in the rear. For regional class SSM, the max you are permitted is -2 front, and -2.5 rear, and my guess is that everyone is right there.

JRandall
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would adjusting the front sway bar make any difference? I know the adjustments are limited compared to the rear but could it make some difference?

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James Randall
SM 89

   

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