I'd talk to your alignment guys. Often an aggressive alignment which is good for quick steering and response and maximum grip in the turns can be bad and sometimes scary at high speed on straights. Everything is a trade off. Dragsters don't do well in the canyon twisties.

If your alignment guys are good they will realize this and can alter your alignment for high speed stability or anything you want. Your springs rates and damper settings should not affect high speed straight line performance much unless the springs are making your rake angle (caster) too steep, or possibly the roads you are attempting to go fast on are very bumpy. Stiff suspension works well on smooth roads, soft on bumpy. A bit over simplified, but you get it.

 

36/40 max w ps2's on stock twists. Unless you need to diet. Then over 40Psi on rear.. Maybe.

 

Did the alignment shop recalibrate the steering angle sensor?

 

I do not know - however the problem was evident when I got the car 1.5 years ago. Previous owner had an alignment done about 2 years ago, I had one done @6 months ago.
Will likely go down the quick and easy route first - pressure / tires / alignment before diving into new coilovers.
Thanks for the input.

 

Just read your post. Your problem is simple.
Tire pressure.

I'm not sure which pp are telling u the tire pressure your running but they either are driving to slow or speaking out of their rear end.

Run 34 front hot
34-35 hot rear - send me a paypal payment for my advise for thanking me.

 

If you are correct - I will send you beer.

 

A friend of mines car with Jic's acts a similar way, we cant stand the coilovers. they will be coming off hes going with KW v3's

 

Is there a rake set? Rake can be important in regards to aero and at triple digit speeds that would definitely be a concern. I felt the effects of an improperly set rake at just 70 MPH in another car.

 

Based on the advice of TurboTodd, MadNess, '02996TTx50, and the sure as ***** response by f1CrazyDriver - I fiddled with the tire pressure.
I always measured cold and was running:
34f/42r (cold)

Tried cold setting of:
34f/35r (cold)

Felt better at around town speeds and better at 70-90 speeds. Not 'solved' IMO - but it definitely made a big difference.

When I got home, after a 15 minute drive - I measured again as they were hot and got:
37f/42r (hot)
Brought them back down to:
34f/35r (hot)

I'll keep messing with it - but this appears to be on the right track.

Thanks all! <...and I am an idiot for not fudging with this sooner!...Got my original setting from various 'advice' on these message boards>

 

I care about you... no need to **** away money when you dont need to.

I run 32 front 33 rear hot.. and i mean HOT. so get them down to those low to middle 30's and you will like it.. Then again i might be speaking coolaid!

at 42 cold--- hot you were probably at close 60 psi at the rear...that sounds scary. p.s. sometimes a lot of the advice found here can be WAY off

 

Hehe - thank you sir! Would be glad to buy you beer. PM me contact info if you'd like to collect.

 

glad you're geting it sorted. at least we know how f1 stays on the track! with those numbers LOL

 

It's amazing how everyone has learned different things and has different opinions.

He's my point of view for whatever it's worth. This assumes you don't have a tire pyrometer, which of course would be the best way to set tire pressure and alignment.

In general you want run the air pressure as low as possible (for maximum contact patch) as long as the tire doesn't overheat or stops providing enough sidewall support (provided by the air pressure, more on street tires than race tires).

You will know when the tire doesn't have enough air pressure for support when the sidewall "rolls over" in turns. This is why you see autocross competitors mark the sidewall of their tires with shoe polish. They can easily see when the tire rolls over too far onto the sidewall.

You will know when the tire is overheating when you have too much pressure rise. Typically this is when the differential between the hot pressure and cold pressure is greater than 7psi. You may have more grip at a lower psi, but the tire may give up grip later in a session, it may wear out prematurely, or it may fail (an extreme case of course).

Given the 3 psi rise (34psi vs. 37psi) on the front tires, I would actually consider running less than 34psi cold on the front tires. I think I run 30psi. Keep in mind that our cars have about the same amount of weight on the front tires as a typical Miata.

On the rear you had a 7psi pressure rise (35psi vs. 42psi). Given that you were able to generate this differential in only 15 minutes, I would actually raise the air pressure 1-2 psi. The tire needs more air, to run cooler. For comparison, the rear of our cars carries approximately 2,200lbs. (assuming a total weight of 3,550lbs. and a 38%F/62%R weight distribution). This is similar to an 4,700lb. SUV with a 53%F/47% rear weight distribution.

Keep in mind that this information is for street tires. Race tires and "R" compound tires can have different constructions, that allow you to run much lower air pressure.

Later, Steve

 

Good info Steve! thanks
My lastest test =
31f/32r <cold>
30 minute drive
pressures went to:
35f/36r <hot>
reset to:
34f/35r <hot>

Car felt much better - I actually did not have to work to keep it in line!
Will keep tweaking a bit, but lower tire pressures certainly did help.

 

Awesome! When are you in SF California ? We can get that beer.. I don't think you can ship.