mvvette97

2007 vette z51 that just turned over 20k today. Tires are brand new eagle f1s. Had an alignment done 200 miles ago at the corvette dealer when they did the oil pan leak under warranty. it runs and drives like a brand new car but at high speeds it just feels unstable like I have to really hold the steering wheel because it feels like it wants to dart back and forth. I noticed this today while out doing some tuning and logging. Pretty much any speed over 120 it feels this way. Under that speed is fine and feels safe. I thought it was the road but I don't think it is because I ran my bmw 5 series on that same flat stretch a couple weeks ago up to 145 and it felt good and planted. This is a road in the middle of nowhere that has little to no traffic. that is why I tried the cars out there. i don't usually drive that way. But any ideas what could be making the vette feel this way? it almost feels like the steering is too easy at high speed. What do ya all think?

08z51m6Ls3

Subscribed..

I feel you OP, my 08 Z51 car does the same thing under heavy acceleration around the 70MPH range and above.. Car does dart back and forth as well, makes me skittish to drive it hard at speed.

TerryL

Tire pressure too high and or bad shocks. I had a set of tires mounted on an old Caddy I used to have and it felt that way on the way home. I checked the pressure and all four were at 50psi, apparently the psi level that was used to seat the tires that the tech forgot to reduce. Bad shocks will do it too. Their main function is to keep the tires planted on the pavement.

OlyC6

The C6 Vert I recently bought had the OEM GY RFTs and I was really unimpressed with how squirrelly the tracking was on the 5 Freeway here in WA. We have lots of asphalt snakes, grooves from winter tires, etc. and on less than great asphalt or concrete stretches, I almost feared what the tread pattern on the GYs would do when changing lanes - or just trying to stay straight in a lane; especially at higher speeds.

I replaced the GY with Bridgestone RFTs and it's a night and day difference. The Bridgestones track much better and don't seem to be affected as much by the road imperfections I've encountered.

Welker1

I also have the Z51 package & just recently had mine up over 140 on a deserted stretch of road ... drove like a dream; stable, steering was good & felt very safe - added: Michelin Pilots, 30psi, traction control on, paved (non-grooved) road

mvvette97

I checked the tires and they are all at 35psi. I guess it could be shocks but with 20k on them are would think they would be fine. I know there are no leaks from them. I'm pretty sure the car has not been beat on or anything for that 20k miles because It was a one owner car. The guy bought it while he was in his 70s and never seen rain a day in it's life. So wouldn't think he would of tracked it or anything

08z51m6Ls3

This thread has some solid opinions on what it might be.

https://www.corvetteforum.com/forums...ed-wobble.html

As some of the previous posts here have mentioned, shocks and tires could be the issue. Traction control is also thought to be a possible culprit along with bad motor/trans mounts.

HBsurfer

Tires should be 30 psi cold. An extra 5psi may be your problem.
Check the sticker on the drivers side door jamb of your car and you will see 30psi.

mvvette97

Mine is fine even at 100 but up new 120 to 130 it just doesn't feel good, haha. Ya know one thing i noticed was that to me I feel like the steering it too light at those high speeds. I know my bmw will get very stiff steering at high speed. I think that helps keep the car "or the driver" from moving the steering wheel at those speeds. I thought the corvette was supposed to do the same thing with the steering but I don't know for sure

mvvette97

Thanks man. Maybe that is the problem. I will have to let them down and see how it feels.

HBsurfer

Let us know if that solves it. Good luck and be safe.cheers:

mvvette97

yea I'm going to try it. I was reading on the link above about sometimes the traction control can cause this as well. i had everything on so I may have to turn it off and try it as well.

LowRyter

I wouldn't reduce tire air pressure going high speeds. The books says to max out pressure.

HOXXOH

I have no problems at 30-34 psi up to 140-150, but will pump up to 38-40 psi if I'm planning on 160 or more.

My first thought was the dealer alignment was done for the lower speeds of autocross that is the Z51 specialty. That plus the brand new tires that always have excess squirm for the first several thousand miles will add to the problem.

mvvette97

I see some people are saying to run 30 pounds but maybe I should try to put them up to the max. I think the tires say 40 or 45 can't remember for sure.

gsflyer2011

Most of the time it is alignment settings that will cause that. Just because the dealer did the alignment does not mean that they did it right or how. What was your settings after an alignment?

My GS is set up like that, out of choice, bit handful over 120 but handles like on rails below that speed which i drive at most of the time. Don't forget loose cars are fast cars on the track. I can get a street alignment which will fix the high speed issue but than i loose the handling. I suggest you find a good alignment shop, get them to check your suspension and give you a second opinion on your settings.

NiteriderFRC

the tires - TIRES - then again usually GY tires tend to 'wander' at any speed . so maybe your dealing with something different.

F1 tires for our cars are terrible.

Seadawg

It may be listed in other posts, but to keep all known conditions in the same thread, worn or loose sway bar links will cause this feeling, as well as the type of alignment you have. Finally, the road that you are driving on can cause it, so try opening it up on a different highway section, if all of these things above check out OK.

When I had my 2008 with the Z51 package, it felt very stable even in the 180's

Easy Rhino

With low miles, the odds are its not the suspension.

Occam's Razor says the simplest problem is usually the solution, and is easiest to check and fix.

Start with the tires set at 30 cold. They will heat up to almost 35 when hot. Do not set them at the max sidewall pressure - that's not what that rating is for.

Second, what were the alignment settings? Most days you will get a computer readout. Check the front toe-in first, but check all settings. Many alignment shops do a random job.

Eliminate the simple stuff first.

And be safe.

extrapilot

Totally
Pressure is important, and I would bet that increasing it would lead to less footprint at higher speeds, think of centrifugal forces.
Alignment is also key, not enough toe-in, IMO.
Have it re-checked.