Corrections for Understeer - Ford Mustang Forums : Corral.net Mustang Forum
 
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post #1 of 13 Old 12-29-2005, 03:22 AM Thread Starter
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Corrections for Understeer

The car tends to push real bad on entry into the corners. What are ways to correct understeer. This is on a '93 LX hatch, suspension is
-Bilstein shocks/struts
-MM Coilover kit, all corners
-HyperCoil coils 325front, 225rear
-MM CC plates
-MM full length subframes
-MM LCA's
-MM panhard bar
-MM torque arm.


-'90 Mustang LX Coupe 5.0 SSP. 83 DSO US Gov't Issue. H/C/I Track toy
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post #2 of 13 Old 12-29-2005, 03:59 AM
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What size/type tire running?


92 5.8L coupe- manual steering/spooled autocrossing is fun!
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post #3 of 13 Old 12-29-2005, 04:41 AM Thread Starter
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245/45/17 Kumho 712 out front, not the best. Would picking up a softer front sway bar reduce the understeer? 275/40/17 BFG KDW out back if it matters. Cars weight is 3160 w/o driver.

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post #4 of 13 Old 12-29-2005, 08:23 AM
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Ok, another trivial question.........
Mustangs Push, especially with torque arms.................
Larger tires out back will make your push worse. Making matters worse is the fact that your rear tires are good and those front tires suck. Get some tires that are the same size or at least the same brand/model. I see you have a blower, do you suppose lowering your corner entry speed would help? I have seen drivers pick up 2-3 seconds on a 60 second course just by slowing down to let the car rotate and then accelerate out of the corner. Maybe I am wrong and you have been driving autoX and open track for years.


My suggestions, get your tire situation fixed, try that out. Read Speed Secrets by Ross Bently, try that out. If you are still having troubles get MM's adjustable rear sway bar. Have a peachy day.


Oh yeah, I forgot to ask..... What are your alignment settings?

Last edited by 92MNstanger; 12-29-2005 at 08:27 AM.
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post #5 of 13 Old 12-29-2005, 02:27 PM
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tell us your corner entry technique
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post #6 of 13 Old 12-29-2005, 03:12 PM
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Quote:
Originally Posted by MFE
tell us your corner entry technique

to whom are you directing that question to?

I'll answer just in case. When I started autoXing I thought my car pushed extremely bad. I asked a fellow racer and he explained that most severe pushing problems can be fixed with driving style. You need to slow down to let the car rotate, not try to work the front tires as hard, use them at their most effective slip angle ( I may never perfect this). In addition I found my car worked very well with a little trail braking. Once the car starts to rotate the way I want, I ease all the way off the brake and begin to feed in throttle. Once I realized that corner exit speed is more important than corner entrance speed things went much better for me. I didn't feel like I was fighting my car anymore.

Last edited by 92MNstanger; 12-29-2005 at 03:29 PM.
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post #7 of 13 Old 12-29-2005, 03:44 PM
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I was asking 93krwy, for exactly that reason
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post #8 of 13 Old 12-29-2005, 09:51 PM
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Chassis Tuning Guide

I have a "Chassis Tuning Guide" for over and understeer conditions that I put together in excel and keep a print out in my glove box. I'd be happy to share if I could figure out how to attach or copy/past it. MFE, this might be a good thing to add to your Forum FAQ's post if you're interested.

But before you go turning chassis knobs, do like the others suggested and take a close look at your driving style. In slow out fast and controlling weight transfer at turn-in may be all you need.

Toys - gota have'm.....


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Last edited by Toys; 12-29-2005 at 09:54 PM.
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post #9 of 13 Old 12-30-2005, 01:00 AM
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As 92MN said, first things first, fix your tire mismatch. I couldn't agree more with his assessment - the larger rear tires + the fact that your front tires are horrible = more tendency to understeer.

You can go to a softer front sway bar. The stock 4cyl swaybar is a good upgrade, and it's significantly lighter than the stock GT bar to boot. I got one free off a soon-to-be-junked 4cyl Fox convertible, and I'm sure you can find one at a junkyard somewhere.

Looking longer term, do you have any plans to do the front suspension (K-member and A-arms)? The TA/PHB rear adds enough rear grip that if you don't significantly change the front suspension too, you're pretty much always going to be battling understeer.

'89 GT convertible, N/A 357W, MM front susp w/425# coil-overs and Koni D/As, MM TA/PB rear setup (Koni Yellows, 390-430# springs), Stoptech 332mm / 12" Baers, MM 6 point rollbar, Maier 1.5" flared fenders & quarters, 18x9.5" front/18x10.5" rear Enkei RPF-1s (street), 18x10" CCW C-10s (track), etc...
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post #10 of 13 Old 12-30-2005, 04:39 AM Thread Starter
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I'm also going to be swapping Kmembers and Control arms. I'm putting together a 331, so when the old motor comes out, the new kmember is going to go in along with the new motor.

I got alot more practice in with turn entry speed, I slowed it down alot, and transfered the weight with a small feint into the turn, helped out alot. The exiting speed is higher because I'm not fighting the wheel throught the turn. The front tires are definently crap. I stil drive the car regularly on the street, so I can't put the stickiest tire on the car yet. But it is coming along. I also got ahold of a 1 1/8" front sway bar from the wrecking yard today. Thanks for all the input.


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post #11 of 13 Old 12-30-2005, 04:53 AM
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I believe MFE is correct in regards to questioning your driving style, as this can and will affect one's vehicle behavior greatly. Also the vehicle's staggered wheel sizes will also greatly affect the vehicle dynamics (in your case, more toward understeer). You can correct this understeer condition by adding more aggressive camber in the front, wider front foot print and/or wider front track, or by increasing the COF of the front tires and lessening the frontal weight. Basically reduce the frontal roll stiffness coefficient and you will see results that will yield less understeer.
Good luck!

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post #12 of 13 Old 12-30-2005, 10:13 AM
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I used the steeda adj rear bar in my '02 and it solved most of my driving problems

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post #13 of 13 Old 12-31-2005, 02:46 PM
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An easy helper (not a fix) would be adjusting your tire pressures. I run about 8psi more in the front than the rear to help reduce the understeer a bit. It helps when I experiment on the same course and I can see and feel a difference on my times. There is no substitute for good driving (which I still need to work on).
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