lift at high speed

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Gruuvin8

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At what speed do you start to feel like the force of air is "lifting" your MarkVIII?

I just got my U-joints replaced which totally fixed my high speed vibration problem, and now I find myself pushing it to or past 100 mph a lot more often than before. It's very smooth now at high speed, but I find that around 100 mph the car feel less "stuck" to the highway. This bothers me a bit, because of course I feel like I have less control. It's not a BIG difference but it is noticable. I imagine if I were to push it to 120, or chip it and push it faster, I would not have enough control to enjoy it.

I should add that I have a '95 with 1.5" lowered coil conversion suspension (new uppers & lowers as well), and I am noticing this down here in Florida during the humid winter (denser air provides more lift).

So, at what speed do you all feel that your car it lifting a bit and how much worse does it get as you go faster beyond that speed? What, if anything, have you done to help air drag push the car back down to stabilize this?

Rob
 
Also had mine up in the 130's and it feels steady to me. Maybe you just haven't gotten used to the smoothness from the new U-joints being put in. Vibration can make it feel like you're slow and stuck to the pavement but if everything is smooth, 100+ will feel like you're floating. You also have the 1 1/2 " drop so I really doubt you have any worries of lifting off the ground.
 
I'm sure all you guys are doing this on a closed test track and you have roll bars, helmet and fire extinguisher systems.:rolleyes: And you rechecked your w speed rated tires for inflation pressure?

Ever see what happens to a car at 130 mph that blows a tire?
 
Might as well throw in a few suggestions:

Is your air suspension switch in the trunk turned on?

Do you have good tires that are at the correct pressures?

You did some front end work. Did you replace the tie rods also?

Hows your rear shocks?

Wheel balance good? (i assume it is, as you said no vibes)

If all above good, then could be the EVO steering acting up, worn IRS bushes, weak or broken rear sway bar. etc.

Mine is abit 'nervous' at high speeds too. If i 'gun' it, it feels solid, but as soon as i let off, it kinda wonders abit. Im sure mine is because of worn bushes and possibly a weak sway bar giving me a rear stability issue. Doesn't bother me too much, as i rarely drive fast, but one day i will upgrade it all.
 
MonsterMark said:
I'm sure all you guys are doing this on a closed test track and you have roll bars, helmet and fire extinguisher systems.:rolleyes: And you rechecked your w speed rated tires for inflation pressure?

Ever see what happens to a car at 130 mph that blows a tire?
Click to expand...

I-565 4 lanes, 2:00 am, no helmet, no roll bar and no fire extinguisher and new tires, which was the reason for the speed test. Yes, it can be disastrous if a tire blows at that speed. I did however pick a time when no one else was out and did wear my seatbelt. :) 80 is usually my peak speed. It's hard enough to look for unmarked cars where I live and with the rush of 130 mph and wondering if you're going to get caught, I have only done it twice. No need for it anymore. I can only safely say that at 130, the car didn't fly up into the air and the tires done a good job. I just knocked on wood too! ;)
 
its the coil kit doing that, the front shocks are not all that great, same thing with mine, misteryously it has slightly gone away over time.........but its still there, plus the little excess up and down motion here and there on the highway. My Koni's are on their way, and theyre going on all 4 corners, so that should get rid of it completly.

Front Sensatracs = CRAPPIEST SHOCK EVER!!!!!! :mad:
Rear Sensatracs = VERY GOOD CHEAP SHOCK :)
 
The Lear Jets I fly get real light around 125 knots, but thats another subject.

David
 
I had a blow out a 120 and it was not that bad I held control just fine.
Ther was also a little luck
 
new tires - right pressures - good balance
replaced tie rods
never replaced the rear shocks, sway bars or bushings

interesting comment on front shocks

dunno if this would make the difference, but I have had an extra 200 lbs. of cargo in the back

thanks for the replies so far.... anybody else have this issue? just wondering how normal it is
 
Gruuvin8

Where did you get your U-joints? I get a vibration at higher speeds and think it might be time to change mine. It gets worse when I let off the accelerator. It's kind of annoying.
 
96hotrodlincoln said:
Gruuvin8

Where did you get your U-joints? I get a vibration at higher speeds and think it might be time to change mine. It gets worse when I let off the accelerator. It's kind of annoying.
Click to expand...

I had a good family mechanic do this one while replacing a tranny seal. Would've been a nasty job for me. The vibration would stop (mostly) when I let off the accelerator.
 
My 97 mark viii rides very hard, so it felt fine on 9A(I know its filled with cops now) when I did 130 MPH. I did 130 mph on the 93 but that car doesn't ride as hard as my 97 but none of them feel like they are lifting up at high speeds.
 
me and 98 cobra neck and neck 75mph roll to 135 on i-95 (stupid) BUT AWSOME!! She stuck down nice
 
mark0101 said:
My 97 mark viii rides very hard, so it felt fine on 9A(I know its filled with cops now) when I did 130 MPH. I did 130 mph on the 93 but that car doesn't ride as hard as my 97 but none of them feel like they are lifting up at high speeds.
Click to expand...

Well.... I can't say with 100% certainty that it is "lifting." I just suspect it may be because it feels as if it wants to drift a bit more than it would at 50 mph. its not much -- just enough to notice and wonder. I may have to try it without the extra weight in the back. maybe that extra weight was enough to pitch the car upward. This is my first vehicle that i've pushed to these kind of speeds.
 
From what I remember mine was pretty good at 120, my car would not let me go any faster that that, I dont have the chip yet.. kept shutting down at 120, but I was ahead of my friends Honda s2000 till it shut down then he passed me... damn I had him to.. lol I was so pissed, only thing that sucks is when you hit the bumps in a bridge or something and the car shifts back and forth but other than that it felt pretty smooth and the steering was tight..
 
ok well no one asked about the alignment, so i will, all new ft susp needs a alignment, your caster could be off making the car wander at higher speeds, plus the extra weight in the rear wont help either
 
chickenviii said:
ok well no one asked about the alignment, so i will, all new ft susp needs a alignment, your caster could be off making the car wander at higher speeds, plus the extra weight in the rear wont help either
Click to expand...

Well.... it's not that new. I've had it aligned twice since then. I think these cars are difficult to get aligned properly. I think the alignment is pretty good, but I never think it is perfect, no matter who does it. Still, that may be it!

Thanks again everybody for your replies!

Rob
 
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