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I have a nice stretch of freeway which lets me stretch my 06 speeds legs, but once I get over 120 the steering starts to feel extremely sensitive. My tire pressures are 32 psi, and the tires are the original stock ones. (the car is an 06 with about 20,000 miles on it). I was under the assumption that the steering would be adjusted to get LESS sensitive at speed instead of MORE, so wassup? Would higher tire pressures help this problem so I could go for the big 150?????
 

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That's fast and these cars don't make a lot of down force.....how smooth was the road? Last time you had an alignment and tires balanced? If you think these are unstable try an 03 cobra at 175.....you may leave a streak in your pants.
 

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Hmmm, sounds like you have an alignment, tire, or possibly an air flow problem around/through the radiator. It could be that you're not accustomed to how any car "feels" at high speed? My Speed6 is smooth and stable @ 150+, even around curves.
 

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My Speed6 is smooth and stable @ 150+, even around curves.
Yeah we found that out last night. What do you mean by the airflow? Could I be having these issues too? I guess I'll wait until I get my hubcentric rings put on. :( Sorry, no thread jacking intended.

I would get the tires rotated by a reputable tire joint for a start. I had the same issue at 120 and had them re-rotated by another good tire joint and was able to squeeze out 20 more mph. Keep us posted. I'd like to hit 150 too without my car feeling like it's going to fall apart.
 

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Sorry to threadjack

Hmmm, sounds like you have an alignment, tire, or possibly an air flow problem around/through the radiator. It could be that you're not accustomed to how any car "feels" at high speed? My Speed6 is smooth and stable @ 150+, even around curves.
and where is this :)

Yeah we found that out last night. What do you mean by the airflow? Could I be having these issues too? I guess I'll wait until I get my hubcentric rings put on. :( Sorry, no thread jacking intended.

I would get the tires rotated by a reputable tire joint for a start. I had the same issue at 120 and had them re-rotated by another good tire joint and was able to squeeze out 20 more mph. Keep us posted. I'd like to hit 150 too without my car feeling like it's going to fall apart.

Is it really that bad. I still have the Potenza's on there and they felt fine on the ride home tonight @110 :) i had to stretch the legs. I hadn't had the chance to do it with this. I've done it with my bike but that's a no brainer and it can easily hit literally any MPH you want almost as fast as you want.
 

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How is this thread not locked? I thought we weren't supposed to talk about excessive speed/racing on this forum? That is what that derelict forum is for. Remember how much everybody flamed that perfectxtreme dude for being irresponsible when he got popped speeding?

Alright I'll take off my mom hat now. :)

But yeah, over 130 is fast, but the car should remain pretty stable.
 

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sucks, na's have the fuel cut off at 120. the speeds have no cut off?
 

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i will say this, i am opposed to going that fast. i have done it, only about 130 so far in the speed but 148 in the RX8 and it was super stable obvious advantage in aero though. if you want squirely try going 108mph in an ambulance (thats where the estimated speed limiter is on the new ones, the speedo stops at 105 but i was beyond that)

I believe the op has the right to ask these kind of questions here because he's not asking how he can beat someone in a race, or if he can out run the cops. he is taking his OWN risks and we have all done it.
 

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Yeah we found that out last night. What do you mean by the airflow? Could I be having these issues too? I guess I'll wait until I get my hubcentric rings put on. :( Sorry, no thread jacking intended.

I would get the tires rotated by a reputable tire joint for a start. I had the same issue at 120 and had them re-rotated by another good tire joint and was able to squeeze out 20 more mph. Keep us posted. I'd like to hit 150 too without my car feeling like it's going to fall apart.
I'm referring to the airflow through the engine bay that can be disrupted and cause excessive drag and lift at the front. It can make the steering feel very light.

It is usually caused by curbing the lower section (lip and air dam) and damaging it. The Speed6 has very good aero flow control up front if not altered from OEM.

Nah, you have a tire/wheel issue I'm sure. Get those hubcentric rings before sweating it too much. The fact you can remove/replace the wheels and alter the vibration speed confirms it.

With "good" tires rated for the targeted speed and balanced on a Hunter 9700 Road Force balancer machine ( Hunter GSP9700 Wheel vibration Control System solves wheel vibration and tire pull problems that balancers and aligners can?t fix )that measures the road force applied by the tire/wheel combo for true for radial and lateral runout(the Hunter will tell you), the car should be rock stable at high speed.

Go to the link and locate the machine/shop nearest you.
 
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I hit 150 once and it felt solid. I did 140 in 97 cobra and that was squirrly. Sounds like alignment issues.
 

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sucks, na's have the fuel cut off at 120. the speeds have no cut off?
Well, I've read on the forums that it is 149 or so, but mine w/latest AP/ATR map will run up to 155 in cool weather when you can feel it nose over and hold 154 @ ~6k rpm in 6th gear. All verified w/GPS, not relying on speedo info.

FYI, it would only pull to 153 a couple days ago in the mega-heat and humidity here in Virginny.
 

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....and where is this :) .....
I'm not at liberty to say... if I want to retain the area for "testing" purposes. LOL
 

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With "good" tires rated for the targeted speed and balanced on a Hunter 9700 Road Force balancer machine ( Hunter GSP9700 Wheel vibration Control System solves wheel vibration and tire pull problems that balancers and aligners can?t fix )that measures the road force applied by the tire/wheel combo for true for radial and lateral runout(the Hunter will tell you), the car should be rock stable at high speed.

Go to the link and locate the machine/shop nearest you.
Sweet, located a shop literally down the street from me. I'll get them re-balanced when I scrape up some extra cash. Until then, the hubcentric rings are on their way will suffice and I won't be hitting close to 140 soon.
 

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there are 15 locations within 5 miles of me that have and use a GSP9700. i actually only go to places that have them. Dougie if your reading this. go to Firestone in quincy center they are super cheap, awesome proffesionals. and they can and will do anything you want in whatever specs you want.
 

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Sweet, located a shop literally down the street from me. I'll get them re-balanced when I scrape up some extra cash. Until then, the hubcentric rings are on their way will suffice and I won't be hitting close to 140 soon.
If you're running without hub centrics, no wonder, man! If you're running plastic now, that also could be probable cause. I had plastic for a while before switching to metal, and I noticed a differense at high speed.

But, I seldom go high speeds. It's just too dangerous around here. There aren't any good unpatrolled, low traffic roads around here to top her out.
So, I think the fastest i've been is prob 130, or so. I'm just a scaredie cat. But, she was smooth as butter at 130.
 

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Discussion Starter #17
Hmmm, sounds like you have an alignment, tire, or possibly an air flow problem around/through the radiator. It could be that you're not accustomed to how any car "feels" at high speed? My Speed6 is smooth and stable @ 150+, even around curves.

OK for your Speed6 at 150. What do you use for a tire pressure for normal driving? Did you do the big number on a track and if so, what was your tire pressure at the time? Thanks for answering.
 

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Discussion Starter #18
I've done a bunch of autocrossing but not with my Speed. Automobile magazine with mean Jean posted 154mph on the autobahn with no complaints on handling problems so I guess that I'm gonna have to play with tire pressures to start. My tires have low wear on them because I switch to snows in winter for 6 months. The snows have my original alloys on but the summer tires have Motegi Racing wheels. I wonder if the airflow through the different wheel design could be part of the problem??????
 

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The tire pressure for 215/45 tires on the Speed6 is 38psi. If you aren't running that, start there... if upping the pressure doesn't fix your problem, look at tire balancing, then hub centric rings (for aftermarket wheels) and so forth....
 

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OK for your Speed6 at 150. What do you use for a tire pressure for normal driving? Did you do the big number on a track and if so, what was your tire pressure at the time? Thanks for answering.
For all "normal" driving, I run cold pressure (@ ~75deg F) of 35psi in front and 33psi in the rear with the current Dunlops. Obviously at higher "cold" temps the static pressure will be more (~1psi per 10 deg F) but the ratio will remain. Top speed runs are done in "relative" safety on sparsely populated rural road, no track.

I run the slightly higher front pressure to account for tire sidewall flex from the additional front weight bias to keep the F/R tire effective rotating diameters close to the same. The front tire sags a bit more than the rear. Note that in my Miata w/50/50 weight distribution, I run equal pressures all around.

At higher cold pressures specifically for autocross, the sidewall sag will be less and I run ~40psi "cold" pressure all around at the base ambient temp for the given day. I do NOT drop pressures after a given run though, so any pressure rise from tire temp increase is "good".
 
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