100mph+ handling

[Goblin]

Not that I go 100mph very often but...

The other day coming home I took my car up to around 100mph and was crusing home on the freeway. Then a car merged out infront of me, no big deal I did a lane change but only had enough time to pass the car that just got on and then shoot the gap back over or rear-end someone.

When I did my second lane change the car was VERY squirly. It was weaving and bobing rather unpleasently (as can be expected at high speeds but my Eclipse isn't the only car I've done this with, but it is the most "unstable" car I've ever done this with).

What would be my best shot at improving the cars handling characteristics and stability at high speeds(aside from good tires)? I'm aware of the things I CAN do, but I'm not sure in which order they should be done to get the most "bang for buck" per say.

If anyone is offended that I'm going 100mph on the freeway please feel free to pretend I said track.

ps. No I don't speed with even MODERATE traffic, so you can imagine how empty the roads were (we're talking 1-2 cars every 1000 yards on a three lane, one way road).

 

[poet]

check dsm.org and look for steering probs,
if you are not gsx once you hit over 100 your steering becomes real loose to make sure you dotn jerk the wheel at like 100 plus and flip your car
1G
http://www.geocities.com/lil4x4/pspump/
2G
http://maritime.dsm.org/vfaq/pspump/index.html
this should take care of it for you
dsm.org is a great site, i spent days and weeks sifting through all of it before i found this place

 

[2-0turbo]

My car is quite stable through 110 MPH sweepers. I know this because I did it on a track. PLEASE do yourself a favor and register for a HPDE in your area. You will come out of that first event firmly believing that you knew NOTHING about driving before that.

Before I did mine, I thought I knew where the limits of my car were. I had no idea!! Loosing it at 100MPH on the track and loosing it 100MPH on the public roads with cars around are two totally different things. One you will likely live through, possibly with very little car damage--the other, your odds aren't so good and you are likely to kill someone in the process.

I am not slamming your driving fast on public roads--I do that too when I get the opportunity and Johhny Law isn't around. But it is clear from your post that you don't know how your car handles approaching or exceeding its/your limits. The road is not the safe or prudent place to find these limits. Any amount of talking on forums is not going to help you find them either--Seat time is the only way.

Check out http://www.nasaproracing.com/ or any number of SCCA events in your area.

PS - "It was weaving and bobing rather unpleasently as can be expected at high speeds " is not normal. I don't know your fix. It could be the loose nut behind the wheel.

 

[igs]

Handling at high speeds is no different than handling at low speeds, only the forces are magnified. Lower you center of gravity. Minimize polar moment of inertia. Minimize weight transfer. Minimize body roll. Minimize chassis flex. You get the idea.

 

[Goblin]

Originally posted by 2-0turbo
My car is quite stable through 110 MPH sweepers. I know this because I did it on a track. PLEASE do yourself a favor and register for a HPDE in your area. You will come out of that first event firmly believing that you knew NOTHING about driving before that.

Before I did mine, I thought I knew where the limits of my car were. I had no idea!! Loosing it at 100MPH on the track and loosing it 100MPH on the public roads with cars around are two totally different things. One you will likely live through, possibly with very little car damage--the other, your odds aren't so good and you are likely to kill someone in the process.

I am not slamming your driving fast on public roads--I do that too when I get the opportunity and Johhny Law isn't around. But it is clear from your post that you don't know how your car handles approaching or exceeding its/your limits. The road is not the safe or prudent place to find these limits. Any amount of talking on forums is not going to help you find them either--Seat time is the only way.

Check out http://www.nasaproracing.com/ or any number of SCCA events in your area.

PS - "It was weaving and bobing rather unpleasently as can be expected at high speeds " is not normal. I don't know your fix. It could be the loose nut behind the wheel.

I won't disagree with you there, I'm very far from a pro driver (and would never consider my Eclipse a race car) and never claim to have skill that surpass my car's abilities. I'd log a ton of time on a legal street course if it weren't for the sad fact that THERE ARE NO STREET COURSES IN IDAHO! There are legal drags and oval tracks (pathetic oval tracks) but no street courses, and autocross although entertaining just really isn't my thing.

I've done the 100mph+ run on the freeway in my bro's supra and my friends MR2. I didn't have near the roll or bobing that the Eclipse has. That's why I was asking for a guide to attack the handleing issue.

I'll check that site I'd love to find a legal track. Thanks for the advice and the help all.

 

[Defiant]

Originally posted by 2-0turbo
My car is quite stable through 110 MPH sweepers. I know this because I did it on a track. PLEASE do yourself a favor and register for a HPDE in your area. You will come out of that first event firmly believing that you knew NOTHING about driving before that.

AAA-MEN! [long pinheaded post follows]

The fast freeway ramp grooving we all do, the pitch-the-corner-instead-of-slowing-for-it runs through the woods, the simple game of cat-and-mouse with a BMW, all the fun we have with our cars is NOTHING. Driving too fast on the road for even the most sociopathic of us just can't give you the exposure to a car's raw, beyond-the-edge behavior you'll find it has on a real course where the very last vestige of reserve is gone -no kids on bikes, no deer, no cops, no dad-with-the-gas-money watching over what you really _can_ do. For this little rant, it has nothing to do with being "naughty" (or criminal) in public places, it's just a matter of what a big, sloppy, wallowing pig of a street car will truly do with itself when -surprise!- the looky-I'm-a-sports-coupe tank runs completely dry, and that cellmate standing far too close behind you in the showers is Mr. Physics. And he's got the buttlust for YOU. Oh, and don't look now, but that was just turn 6, there's three more just like that one, and two that are worse, before you get past that goddamn line that EVENTUALLY might be the "finish".
A lot of us are the best driver in town. A few can get from the 7-Eleven to the Citgo quicker than anyone else most of the time (well, he's running more hoozbedah than me, of course he beat me). Some can take that double-hooked 30 MPH off ramp at 70. And the very best of the best you'll ever meet on the street will wind up facing the wrong way six carlengths past the apex wondering, "what the hell happened THERE?"
If you're lucky enough to have access to a road course, find when they have a club day or the like that'll let you go out there and run. If anyone runs a one-day course, all the better. Finding out what a hideous skank a car is without its makup out on a track will forever change what you think every time you sit in a car.

As for dicey surprises at a hundred, yeh, your car needs some mods to deal with that. You'd want to start with your head.

 

[2-0turbo]

Originally posted by igs
Handling at high speeds is no different than handling at low speeds, only the forces are magnified. Lower you center of gravity. Minimize polar moment of inertia. Minimize weight transfer. Minimize body roll. Minimize chassis flex. You get the idea.

This is a HUGE generalization and for some cars might be true. It will NOT be true for all cars. There are a ton of factors that play in, including aerodynamics as speeds increase. My car becomes more neutral as speeds increase, as do many cars.

My slow-speed understeer is not as bad as it was stock due to suspension mods, but it is still there with a 60/40 weight distribution. But, my car definitely trends toward more neutral as speeds increase.

I used to autocross a 1981 RX7 extensively. That thing would push like crazy below about 40 mph and then go decidely neutral/oversteer. It was tricky to drive at the limit and very intolerant of lift-throttle. You'd be spinning 360* before you could say "what the hell just happened?"

 

[Goblin]

There is nothing wrong with my head

Way to go though, it takes a very smart person to simply attack someone rather than offer advice.

 

[Antilles]

Proposed facility: Idaho Motor Speedway, Boise Idaho. 1.3 mile paved 14 turn road course.

 

[2-0turbo]

Originally posted by Goblin
There is nothing wrong with my head

Way to go though, it takes a very smart person to simply attack someone rather than offer advice.

I think you misinterpreted this as a slam when I think it was advice--I interpreted as I think the poster intended: education. Same reference I made to "tightening the loose nut behind the wheel". Chill out a bit. Honestly, after you do your first track event, your eyes will be opened at how little you (and me) know about your vehicle and its dynamics.

 

[Defiant]

Originally posted by Goblin
There is nothing wrong with my head

Way to go though, it takes a very smart person to simply attack someone rather than offer advice.

Hmph, I meant cylinder head. Feeling guilty?

 

[AWDadvantage]

Regardless of driver skill (which is still the most vital part of any car), i would suggest adding downforce to improve stability (eg front splitter, wing, etc). I am not sure, however, if you need these mods, of if your steering is messed up, or if youre not driving the right way, etc. But anyways, you might want to look into some downforce-producing mods.

 

[focusedrage]

wings... this is what they were made for, with a good wing upwards of 200 lbs will be generated downforce on the rear, esspecily when swirving like that, your unloading the tires alot and there is not much wight over the back... jes i have got 110 in a strait line... wouldnt want to swirve at that speed,

 

[Goblin]

Originally posted by Defiant


Hmph, I meant cylinder head. Feeling guilty?

It was a tongue in cheeck comment

 

[Goblin]

Back on topic...


Look I'm not up for a debate on my "skills" I know I will always have room for improvement, but that isn't the topic here.

Let me clarify this mess. As I said earlier. I've done this before in other cars, my Eclipse is just the most squirly out of all of them. It's not like I almost rolled my car at 110mph or broke my tires loose, the car was just a little more wiley than others leading me to ask, what is the best pathway for suspension mods to attack this.

 

[2-0turbo]

Originally posted by Goblin
Back on topic...


Look I'm not up for a debate on my "skills" I know I will always have room for improvement, but that isn't the topic here.

Let me clarify this mess. As I said earlier. I've done this before in other cars, my Eclipse is just the most squirly out of all of them. It's not like I almost rolled my car at 110mph or broke my tires loose, the car was just a little more wiley than others leading me to ask, what is the best pathway for suspension mods to attack this.

Slightly lowered ride height (don't go overboard), higher roll stiffness (sway bars), stiffer springs (less weight transfer) and 17" wheels if you don't already have them. You should also check over your car to make sure your bushing are good, nothing is loose, balljoints are good (you know they are under recall, right?), etc. Repair anything that is bad first before modding anything. Have fun.

 

[igs]

Originally posted by 2-0turbo

stiffer springs (less weight transfer)

Spring rate does not affect the amount of weight transfer. The only things you can do to reduce weight transfer are:

1) Reduce weight
2) Lower your car
3) Increase wheelbase and track

 

[2-0turbo]

Originally posted by igs


Spring rate does not affect the amount of weight transfer. The only things you can do to reduce weight transfer are:

1) Reduce weight
2) Lower your car
3) Increase wheelbase and track

You are right--don't know what I was thinking.

 

[gp01fb]

Threads like these make me miss my MR2 MKI but then boost kicks in and I forget rather quickly. Plus, Red (MR2 MKI) vs White (90 GSX) gets less tickets. ^_^

Just curious Goblin but is your car bone stock?

 

[Rallsport]

You say your car is bobbing and loose? How old are your shocks? Have you ever done any checking on ball joints, bushings, tie rod ends, etc...all of this can make the car feel uncomfortable at speed. Also, are your tires wearing normally, if not, check your alignment. Make sure your car is in tip top shape before you complain about its lack of performance. Your car is 8 years old, stuff wears out, gets broke, bent, or otherwise damaged.

 

[Goblin]

Originally posted by Rallsport
You say your car is bobbing and loose? How old are your shocks? Have you ever done any checking on ball joints, bushings, tie rod ends, etc...all of this can make the car feel uncomfortable at speed. Also, are your tires wearing normally, if not, check your alignment. Make sure your car is in tip top shape before you complain about its lack of performance. Your car is 8 years old, stuff wears out, gets broke, bent, or otherwise damaged.

Nothing is broken I've checked the front and rear end. Recalls have been done. Again the "bobbing and loose" behavior is based on a comparison of other cars I've driven. Notice I'm not listing all the cars that it's BETTER than that I've done it in (like my old Talon, what a death trap).