High Speed stability issues - diagnostics?

[Joe Bob]

Get it up on the rack and start shaking things...tie rods, bushings or tires are my guess. When was the last time you had it on scales and checked the balance?

[bell]

jack it up and check your rear wheels for play.....your situation sounds like mine when my left rear wheel bearing went bad.

[VZ935]

I still believe the problem you are describing has to do with toe settings. Under braking these settings are amplified greatly by the transfer in wieght. On occassion I have the same problem with the car pictured below and we go to the toe settings and it goes from scary under braking to rock solid and I can make the thing do cartwheels if I want to
Granted it is a full blow race car but the geometry involved can exist on both carsand your description of the sensation under braking is right on.

[wente]

my toe went way out of spec while the car slept in the winter. don't know why, or what caused it. my alignment guy is really good, and I have the before and after numbers.
after 1000mi this spring with really skittish steering (noticeable at 70-80mph) it wore my very new front yoko es100's bald on the inside edges. that's when I discovered the problem. sadly my tires only have 4000 miles on them, & now that I've had it aligned back into spec, they really suck in the rain. so, save your tires!!! get your alignment checked asap.

[Tyson Schmidt]

Originally posted by patkeefe
Tyson:
Where would one find this "N" rating? Is it marked on the sidewall somewhere?
Pat

Yes, it's on the sidewall. It will be followed by a number. N0, N1, N2, N3 or N4.

You want the same N number front and rear, or the higher number in the rear if they are different.

It's O.K. to run non N-rated tires, but you may end up with this problem of squirrely, tail happy handling until they break in.

[Emission]

Originally posted by wente
".... it wore my very new front yoko es100's bald on the inside edges. "

Whoa!!!!!

I just ran out to the car and crawled under with a flashlight. The inside edges of my fronts are wearing very rapidly! Two months ago, they were fine. Yikes!

I need to check the alignment ASAP.

[TerryH]

Originally posted by VZ935

Love the photo!

[cary]

I'll tenth. Have the toe checked. I have the toe on my car set at 1/16 for AX turn in. Its pretty twitchy. At high speed it doesn't take much to move the car around.
But it tracks prefectly straight down the road.

Just food for thought. Good Luck.

[stlrj]

Might be a camber issue too.

"The vehicle may feel more "nervous" and become more susceptible to tramlining. Excessive camber will also reduce the available straight-line grip required for rapid acceleration and hard stops."


http://www.tirerack.com/tires/tiret...e.jsp?techid=4.


Cheers,

Joe