92 MTX Oversteers

[Shoaz]

What model year is your car? IIRC the 24mm front bars were only shipped on cars with 26mm rear bars (GenI, 89-90 or so), so if you took something smaller than a 26mm off the rear, it's likely that you have something smaller than 24mm in the front.

Check your front end links to make sure they're not damaged/disconnected. It won't matter how thick the front bar is if it t'aint hooked up well.

Serious oversteer will be the result of something being seriously wrong or you've got much less effective front bar than you think you do.

 

[ShelbyDoug]

I did notice two things, first, when you lift off of the throttle, it wants to go towards the inside of the turn, secondly, it feels like it did when I had a broken, and therefore disconnect from anti-sway bar. The front bar is 24mm, is not disconnected and had the bushings replaced withe STB's. It is the original front bar.
I went to 225-55-16's on slicers.
I'm set at -3/4 front camber and I'm wearing the outside edges around a 2:1 ratio with the insides.
The right front, as always is wearing faster then the left side.
It's a '92.
I'll try the tire pressure trick.
It is much better under full throttle or if I power through the turn.
I will get to the bottom of this. Thanks all.

 

[Dan H]

Is it possible your front bar is fatigued or damaged? Has the car ever been in a front end collision?

Try Swapping the stock rear bar back in a see what it does, it should definitely have some understeer with the stock bars.

 

[ShelbyDoug]

I was thinking the same thing. I didn't want to suggest it . These things are forged steel.
I suppose that stranger things have happened.
I must admit though, in all of my years, I have never heard anyone suggest that an anti-sway bar can wear out.
The only way I can tell for sure is to pull it out.

 

[38SHO]

disconnect the rear swaybar and see what happens.............

if you still have problems I think you have something installed wrong or not aligned right. When I put a rear STB and larger swaybar on I had a problem with the inside wheel picking off the ground in hard corners or on uneven surfaces..... maybe its just uneven surface of that corner and your weight balance entering it that picks up that wheel and your not used to it........
my car would exhibit oversteer while braking if I did that, but I most certainly could control it very easily........ ASFB's helped the responsiveness and directness of the steering 100x over it seemed like though....

I would get some ASFB asap, in fact they should almost be the first mod to the suspension......... it might not help your problem but you sure will love them and will notice the night and day difference right away.

 

[yamahaSHO]

'92 SHO's come with a 24/23mm sway bar combo from the factory.

My '92 would have some serious lift-throttle-oversteer and oversteer at speed.... So much it was dangerous. Chris (AutoSHO) had it come around on him during a track even and he found himself in the grass... I almost did the same thing in the same spot. I also had the car at a 45 degree angle looking at a wall on the freeway when getting on the freeway from an onramp.

Mine was due to poor suspension combinations and possible bad alignment.

 

[shobote]

Do you have SFC's welded on ? if not, would highly recommend; those really tightened up the handling on mine.

 

[ShelbyDoug]

After repeatedly searching high and low and finding nothing wrong, I pumped up the tire pressure to 40 psi.
Result?
Problem gone. Handles like a slot car now.

 

[Racer X]

After repeatedly searching high and low and finding nothing wrong, I pumped up the tire pressure to 40 psi.
Result?
Problem gone. Handles like a slot car now.

What PSI were you at before? And what tires are you running? Are they the same at all 4 corners?

 

[38SHO]

hey now that you reposted in this therad, I re read it entirely and found something very odd........ maybe a typo?

you said the front tires were wearing on the OUTSIDE........ when I think outside I think the part away from the car..... if your car is lowered it should be wearing the insides of the car........ something is bad wrong with your alignment, either that or a typo.......

 

[ShelbyDoug]

I'm runnig Nexen 2000 225-55-16's on the stock slicers. I think that is part of the problem. This tire wants a wider rim.
I was running 30-32 psi all around. Now 40-42 all around.
Front camber is set at a -1.25 degrees. Rear is -1/2 degree.
What I am seeing is that in order to get the inside tire to wear I would need to run something like -2.5 degrees camber on the front, maybe more.
It is strange and I think has to do with the nature of the tire design.

 

[bobreimer]

my car will oversteer with any throttle life in a turn .... i can control it by getting back on the gas, but its scarey at 80 mph plus

i asked for "twitchy" when i had my alignment done because i use it for autocross and i didn't want understeer ....

also, i find the car is quite sensitve to tire pressure ...... i run 42 fr and 32 rr when racing .... and +/- 2 lbs in the rear will change it from neutral to oversteer (with race rubber)

for what its worth

 

[DemonNeno]

Where are you aligning the vehicle? I would say your specs sound good. How much toe are you at? Positive toe would wear out the outer edge of the tire. Keep in mind, TOE is the primary tire wearing angle. Beyond -1.5 will give you edgewear on the inside. If your toe is a 1/4" beyond spec, you will notice wear within a few months. The SHO's toe askes for negative toe. This should cause inner tire wear.

As for the oversteer. What control arms are you using? I'd recommend reinforcing your h-brace as it's a very weak link in the rear suspension, along with the stamped control arms. The rigid suspension will take it's toll on your flimsy control arms.

Finally, whenever oversizing your tires, compensate air pressure accordingly. Keep in mind, you'll get more tire roll with a wider tire-than-wheel setup. I would recommend a bit less pressure then 40PSI, perhaps 38 at the highest. You will be likely to produce excessive center tire wear from over-inflation.

 

[ShelbyDoug]

I have an alighnment rig in my garage.
Front toe is 1/16 to 1/8 total. Toe is an approximate setting.
The rear arms are stock. I know what you mean about the rear arms. I have crinkled the rear arms on my SVT Contour.
You are correct they are vey flimsy.
I should take my own advice and put a performance set in both.
They logically may be a factor in the oversteering situation. Oversteering is a "push" and the rear is what pushes in an oversteer.
I started at 40 psi as a starting point. There may be a better setting.
With the shorter profile tire I may be increasing bump steer also.
That could be what I am feeling also in the dartiness.
I have not been able to induce center wear on these tires to any measureable degree with higher pressures.
I suspect that the best solution may in fact be that front to rear the air pressure may need to be offset.
I do realize that many race car suspensions get tuned with an air pressure gauge.
Since I am so close to a race setup, it seems logical that the final tune on my car will be done that way and that the car reacts so drastically to air pressure. I am surprized about the degree of response though.
I do know that I wear out the right front tires at almost a 2 to 1 ratio. I don't know how characteristic that is of the SHO or me.
I think that it is most likely my use of the car.
Thanks for your input.

 

[DemonNeno]

Front toe is 1/16 to 1/8 total. Toe is an approximate setting.

I'm an alignment tech, i know my way around it. You keep giving a measurement but not stating whether you mean positive toe or negative, is what I'm going at. You DEFINITELY want negative toe.

As for the wear, i'm assuming you just started running a higher pressure. Tire wear from an insignificant factor to the vehicle in regards to slight overinflation (within a 10# difference of what the vehicle specifies) would take a few thousand miles to notice.

Just for the sake of accuracy, i'd try one of those free alignment checks with an actual machine. You can then work the factors from that basis and see if it's something you're overlooking.

Good luck!

 

[ShelbyDoug]

Negative toe.
I started new tires with 40 psi and dialed them down to 32.
That obviously was a mistake.
FYI, original equipment tires were recommended at 32 psi from Ford. According to Goodyear that was over-inflated.
They were Goodyear Gatorback GT+4 unidirectional 215-60-16.
Chassis settings have been verified. I can't live on someone else's alighnment rack.