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Is there a way to reduce understeer? by Stainless1911
Started on: 12-02-2012 06:48 PM
Replies: 58
Last post by: uhlanstan on 12-04-2012 09:14 PM
Stainless1911
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Report this Post12-03-2012 05:43 PM Click Here to See the Profile for Stainless1911Send a Private Message to Stainless1911Direct Link to This Post
Crap...I guess I'll have to hope for the best until I can get tires on it.
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Tha Driver
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Report this Post12-03-2012 05:51 PM Click Here to See the Profile for Tha DriverClick Here to visit Tha Driver's HomePageSend a Private Message to Tha DriverDirect Link to This Post
You should probably be running 32psi in the back & 30 or less in the front...
~ Paul
aka "Tha Driver"

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mcguiver3
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Report this Post12-03-2012 05:52 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Direct Link to This Post
OMG, That is waaaaaaaaaay too many cones.
We AX here in CT almost every weekend with an occasional track day for good measure,.
I have my 88 set up with a bit of oversteer and it is a lot easier to control.
Stiffer rear bar, adjust tire pressures as needed, run the front shocks a bit softer than the rears,
Lowered 2+ in. F/R (lower roll center is a big factor), 245-40 17 R, 215-40 17 F
2.5 deg neg camber front, 2 deg neg rear, as much caster as I can get.
zero toe F/R (seams to work the best)
Been running it for the last 10 years and is a blast to drive.
It is totally gutted and weighs 2250#, that makes it more fun to toss around.
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imabaddude
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Report this Post12-03-2012 05:55 PM Click Here to See the Profile for imabaddudeSend a Private Message to imabaddudeDirect Link to This Post
Yeah, bad tires in the winter can be pretty scary to drive on, so can unmatching tires. Good, matching tires can make a pretty big difference in how any car handles. If it still handles all squirrelly afterwards, then something must not be right in the suspension. The only reason I still have crappy tires still is because I'm waiting until I get a chance to replace the rear struts, then get new tires and an alignment in one shot. Like you, money isn't as abundant as I would like right now, and for that matter, time and cooperative weather.

[This message has been edited by imabaddude (edited 12-03-2012).]

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urbex
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Report this Post12-03-2012 05:58 PM Click Here to See the Profile for urbexClick Here to visit urbex's HomePageSend a Private Message to urbexDirect Link to This Post
 
quote
Originally posted by Stainless1911:

@ Patrick. No kidding. I've never had a car behave that way before, mist be a mid engined rear drive thing. Trouble is, tracks cost money, I have a hard enough time keeping up with parts. You can't practice in an empty parking lot, because Michigan has a ridiculous reckless driving law, so all that's left for most of us, is a public road, and a radar detector. If I could afford it, I'd LOVE to take a professional driving course, but that;s out of the question.



Yes, it IS part of a mid engine thing. What works on the typical front engine/rear drive car doesn't always work on a mid engine car. Letting off the throttle mid turn when the rear end is trying to swap ends with the front will usually let the rear end hook up and fall in line with the front...in a front engine/rear drive car. In a mid engined car, it more often than not results in an instant 180. Better to just stay in the gas and drive it out.

But in your case, best to just GET OFF THE DARN THROTTLE...PERIOD!!! Yes, Michigan has a strict reckless driving law, and you're just begging to get nailed with it. I get the impression you're closer to 18 than 35, and Michigan judges just LOVE seeing the young folk in their courtrooms...you walk in, and they see the dollar signs flashing. Go ahead..ask me how I knoiw I can't even tell you how many thousands of dollars I fed into the Michigan legal system with the "but there's no where for me to go!!!!!!!!!!!!!!" mindset. There ARE places for you to go to safely, and legally practice this driving. Michigan Sports Car Club hosts several auto cross events in the non snow months, and the SCCA has Rallycross events year-round that you can get involved in to get experience driving in the dirt and snow.

Yes, it costs money. You know what else costs money? Reckless driving tickets, lawyer fees to you out of jail, and insurance hikes after getting those tickets, along with car repairs when you lose control of your car and slam into another car or something more fixed...like a building. Again..go ahead and ask me how I know (these are also related to why I no longer live in Michigan, lol).

The "test" you did, with the snow covered grass...tells you absolutely nothing at all. About the only thing slicker would have been to take the car out on ice, and a lack of traction will certainly appear to create understeer, but it is not actual understeer. Lock up the front tires on a car that's intentionally set up to have extreme oversteer, and it too will appear to have extreme understeer. Having your alignment guy dial in as much negative camber as he could only makes your situation worse, by reducing the tire's contact patch on the ground. You need to be able to push the car hard through a turn to be able to take advantage of extreme negative camber. Oh, and no..the manufacturers are not intentionally putting any amount of positive camber in the cars, much less too much of it. Having any camber in the positive direction is more likely to induce understeer, as it will be reducing the contact patch further on the outside tires. Stock specs are typically a minimal amount of negative, to assist in cornering traction, while maximizing straight line traction, tire life, and braking ability (extreme camber in either direction will greatly reduce straight line braking performance).

Yours is "just barely within spec". How so? On the verge of too much negative, or not enough?

If you have old tires, even with lots of tread on them, you're going to have poor traction even on dry surfaces. Tires harden with age, just like vacuum lines on the engine. The harder that rubber gets, the less traction you'll have, even on dry pavement. If pushing a car hard through a turn results in a four wheel slide, you certainly don't have understeer issues, though I suspect old tires aren't your only problem. I'll bet there are other suspension parts worn as well.

The short of all this..you wanna go fast? It's going to cost you one way or another. Either you'll put it into the car, or into Michigan's coffers
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Stainless1911
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Report this Post12-03-2012 06:42 PM Click Here to See the Profile for Stainless1911Send a Private Message to Stainless1911Direct Link to This Post
I've only had 2 sets of new tires in my life, and I'm 37. It's just a money issue. This is why Im not worried about whether a certain adjustment will cause the tires to wear out too early. It seems that geometry can be either geared for tire life, or making the car behave as it should.
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Patrick
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Report this Post12-03-2012 06:52 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
 
quote
Originally posted by mcguiver3:

OMG, That is waaaaaaaaaay too many cones.


Heh heh, I suspect you're referring to my autocross picture. Yes, there appear to be a lot more cones than you'd normally see at an autocross event. Makes for a great picture though. Let me explain...

We have a large paved area locally (within an airport) that's used for autocross on the weekend, but it's owned (and during the week used) by the Justice Institute to train police forces how to drive. Some of the car clubs make use of the layout as set up by the Justice Institute (perhaps with some minor alterations), whereas other car clubs will take all the cones down beforehand and set up their own course. But it's a big job putting all the cones back in place afterwards, so not every club wants to go through the hassle.

[This message has been edited by Patrick (edited 12-03-2012).]

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mcguiver3
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Report this Post12-03-2012 07:02 PM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Direct Link to This Post
Yes, that was my thought but I know what it takes to set up something like that and have to take it down.
How large is that lot?
We have 4 lots in CT we usually use but 3 are very small, 1 acre +
One is larger but made up of a paddock area at a local speedway and a section of a road course, (high speed 4th gear)
We usually set up about 80-100 cones depending on which lot we're at.
Just enough to delineate a course, the novices hate it though.
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Stainless1911
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Report this Post12-03-2012 07:12 PM Click Here to See the Profile for Stainless1911Send a Private Message to Stainless1911Direct Link to This Post
I didn't know CT was big enough to even reach the legal speed limit.
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Patrick
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Report this Post12-03-2012 07:27 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
 
quote
Originally posted by mcguiver3:

How large is that lot?


Took me awhile to look that up! It was just doubled in size earlier this year to 500' by 1000'. That's just under 11.5 acres. Lots of room to pick up some speed.

Here's a google image taken before the second half of the pad was paved.

[This message has been edited by Patrick (edited 12-03-2012).]

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Stainless1911
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Report this Post12-03-2012 07:38 PM Click Here to See the Profile for Stainless1911Send a Private Message to Stainless1911Direct Link to This Post
I wish I had access to that. Still though, a car does act differently on a flat lot than on a real road.
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Report this Post12-03-2012 07:51 PM Click Here to See the Profile for PatrickSend a Private Message to PatrickDirect Link to This Post
 
quote
Originally posted by Stainless1911:

I wish I had access to that. Still though, a car does act differently on a flat lot than on a real road.


Unless you normally drive through the forest, a paved pad makes for a pretty safe substitute for a "real road" when learning the limits of your car.

[This message has been edited by Patrick (edited 12-03-2012).]

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Stainless1911
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Report this Post12-03-2012 07:57 PM Click Here to See the Profile for Stainless1911Send a Private Message to Stainless1911Direct Link to This Post
Lol. I'm referring to the crown of the roads, the two track that the tires leave and how they intersect at corners, not to mention potholes, cracks, and varying surface compounds.

This has been a very productive thread.

[This message has been edited by Stainless1911 (edited 12-03-2012).]

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mcguiver3
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Report this Post12-04-2012 07:12 AM Click Here to See the Profile for mcguiver3Send a Private Message to mcguiver3Direct Link to This Post
We get a running start in Massachusetts and run out in New York.
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Report this Post12-04-2012 12:29 PM Click Here to See the Profile for rourke_87_T-TopSend a Private Message to rourke_87_T-TopDirect Link to This Post
Research "rolling resistance " . I drive my Fiero in winter, short trips lots of stop and go, lefts and rights, occasional highway. I don't add weight to the front, I have Blizzak's Fronts, 205-60-15 and rears, 225-60-15. Probably average about 12 mpg's but it stops, launches and turns. I can also pass many top "heavy" SUV's on the highway, The look on their face is priceless !
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Report this Post12-04-2012 01:10 PM Click Here to See the Profile for ZaraSpOOkSend a Private Message to ZaraSpOOkDirect Link to This Post
 
quote
Originally posted by Tha Driver:

You should probably be running 32psi in the back & 30 or less in the front...
~ Paul
aka "Tha Driver"

Custom Fiberglass Parts


I agree with that, for the street, I trry to keep 28-30 in front, 30-32 in back
here is one of the places we autocross
a-track

makes for a nice safe place and it does have a couple hills, just $20

here is another, you can see the last course burnt into the pavement
another track

[This message has been edited by ZaraSpOOk (edited 12-04-2012).]

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Fiero84Freak
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Report this Post12-04-2012 05:17 PM Click Here to See the Profile for Fiero84FreakSend a Private Message to Fiero84FreakDirect Link to This Post
My apologies SCCAFiero. I guess my F1 analogy could have been applied to any form - Jeff Gordon in Nascar, Dario Franchitti in Indy, Scott Pruett in sports cars, even Rhys Millen stated in 2003 that his drift GTO was setup with a good degree of understeer in mind for corner stability (I personally know nothing of drifting or how to properly do it, other than it's an excuse to waste good tires).

I would imagine for most auto-x situations - and from my personal experience having driven a good handful - that a degree of oversteer is acceptable if the driver understands how to control the car. However for street usage I personally would not be comfortable with such a setup, and thus welcome the control and stability a degree of understeer delivers.

What was said above about tire age is very much true - and is something that is very often overlooked. For instance, there are many instances where tires will be rated the same for heat and grip, have the same amount of tread depth, but not necessarily be able to perform the same. A good factor is because one tire may have aged beyond it's optimum ability to operate. This is knowledge that is easy to figure out. As was pointed out at the end of page 1 of the thread, tires on their face have a four-digit "build date" that is imprinted onto them encircled by an oval. The first two numbers are the particular week of a year for construction, while the next two are the year. So for instance if this number reads "3507", then the tire in question was constructed in the 35th week of 2007. Now say you come across the exact same build of tire with "4311" on it. That would be a rather recent build date. Even if both had the same tread depth remaining, potential is high for the newer tire to have a much better ability to do it's job.

If the tire has gotten super old - and like any type of rubber began to harden - then it cannot properly operate when it begins to obtain an operating temperature, thus performance decreases. I also don't want to offend any one by saying this, but new 'good' quality tires are not expensive. If you're having difficulties buying new tires you might want to reconsider owning a Fiero when real 'problems' emerge. You don't have to buy the best performance tires money can buy, but there's no major excuse to not get some good quality tires. Remember, it's the only part of the car touching the ground...

I cannot personally think off the top of my head of a great deal of many production vehicles setup with heavy oversteer. I know GM kind of "cheated" with the C5 Z06 (and maybe even the performance C6 'vettes) and placed suspension settings on it that allowed it to corner quite well. However - also as mentioned above - this higher cornering ability and ease of inducing oversteer leads to most individuals whom use the factory spec alignment on these cars or a similar alignment spec on other cars to see accelerated tire wear. Not something you want to have happen when one OEM replacement Good Year Eagle run flat that fits a C5 Corvette runs in the area of $400 a tire...

I also want to echo the staggered tire pressures. Blooz I think (don't want to put him on the spot) pointed it out in a thread some time back about running less on the front. With the last two Fieros I've owned I've started running a 30 front / 32 rear psi staggered tire pressure setup and have been pleased with the minor grip changes it presents.

Finally, remember that any pre-1988 Fiero has a unique disadvantage when speaking of suspension. If you're still rolling around on the stock cradle bushings, then you cannot properly gauge any sort of quality performance cornering because your entire drivetrain and cradle assembly is moving ("cradle-slop") around under load transfer. Either upgrade to brand new bushings or use a poly or solid-mount setup, then begin to gauge what you need to do to alignment to get the car to handle how you want.
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Stainless1911
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Report this Post12-04-2012 05:28 PM Click Here to See the Profile for Stainless1911Send a Private Message to Stainless1911Direct Link to This Post
My tires are Feb, 08. Says 0808 on the oval. (thank you) They are an offbrand, RUNWAY tires, probably from China according to the tire guy.

[This message has been edited by Stainless1911 (edited 12-04-2012).]

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uhlanstan
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Report this Post12-04-2012 09:14 PM Click Here to See the Profile for uhlanstanSend a Private Message to uhlanstanDirect Link to This Post
OOOPPPs my lengthy answer ended up a new post sorry
start with the basics
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