Hello, recently I got a four wheel alignment on my 99 C5 Corvette. On the way home the car felt as though I had a flat tire as I also felt as though I was feeling every bump in the road. I was told it maybe a wheel hop. The car drove beautiful prior to the alignment. I put brand new tires all the way around and am still having the same issue. I am including a pic of the numbers before and after from the wheel alignment. PLEASE can anyone help me? Should I ask for the numbers to be put back to what they were prior to the new alignment?

 

Let me preface this by saying, this is a stab in the dark.

I think the term wheel hop in the vette world is commonly used to describe what happens when you loose traction and the tires hop as they gain and loose traction. This doesn't sound like that.

Did you have the tires installed with the alignment? New tires can make the car feel very different if they have a stiffer sidewall.

Either your definition of "beautiful" is different then mine, or something went awry with your alignment. Rear tire is about 26.2" so 1 degree of toe is about .3". That should have been pretty noticeable, specifically in tire wear and on only 1 side.

Is it possible you are feeling dartyness in the rear over bumps from the now wonky toe setting?

 

[QUOTE=Socko;1589731422]Let me preface this by saying, this is a stab in the dark.

I think the term wheel hop in the vette world is commonly used to describe what happens when you loose traction and the tires hop as they gain and loose traction. This doesn't sound like that.

Did you have the tires installed with the alignment? New tires can make the car feel very different if they have a stiffer sidewall.

Either your definition of "beautiful" is different then mine, or something went awry with your alignment. Rear tire is about 26.2" so 1 degree of toe is about .3". That should have been pretty noticeable, specifically in tire wear and on only 1 side.

Is it possible you are feeling dartyness in the rear over bumps from the now wonky toe setting?

The car drove smooth and you could feel control when taking corners prior to the change in the alignment. I changed to new tires thinking it may help after the alignment was done. It did not. I wish I knew how to explain better. I live far from a Corvette dealer. However I am thinking I am going to do the drive. It is just I did take the car back to the place that did the alignment. They did the alignment again and re balanced my new tires. It is even worse then it was before. They wouldn't even give me the copy of the spec changes they did this time. It is going to be dodgy drive to the Corvette dealer. I appreciate any and all comments in the mean time.

 

Before you go for the drive do this to ensure your safety. Get a friend to drive in another car so he can look at the left side and then right side when this is happening. I want to make sure something is not amiss of true significance. He needs to focus on looking at the wheels and tires for any abnormal motion.

 

Personally I wouldn't take the car to a dealer. I had a guy who did alignments at a dealer for me but it was a dealer my brother worked at so i knew the guy was OCD and knew what he was doing.

Much better off trying to find a dedicated alignment shop imo. Anyplace that works on tracked cars has worked on c5's and should be able to square you away with ease. I have a place about 45 mins away i go to now, its well worth the drive.

 

You didn't say if your vehicle had stock tires, suspension etc... If any of those components have been swapped for the z06 equivalent then the alignment specs will need to be adjusted accordingly.

It's also possible that the alignment machine isn't calibrated properly.

Looking at the alignment sheet that you were provided I'd say the most likely thing is that now that it's back to factory it doesn't feel right. The slight negative camber you had before would give that feel of grip and stability in your cornering. Now that's it's pulled out it will very much feel different.

It may be a combination of things too. The rear toe before numbers for left and right..... i would guess that would make your rear end feel unstable, and chew on the old tires.

 

Holy cow look what they did to the toe and camber. No wonder it's not comfortable to you. Those are significant enough changes to make the car feel totally different than what you were used to.

 

I don't see anything in the alignment that would cause what you're describing. It's not aggressive but it should drive just fine set how it is. In fact, that should have taken out some rear steer when you were on the gas.

 

I agree if the alignment is set to what the chart says it should be fine. My thought was that the 1 degree of left rear tow was incorrectly detected. cause a car with the toe that jacked wouldn't drive well at all, as the OP described. In turn its now jacked to 1 degree tow out on the left rear and the issue is that the alignment was done incorrectly. 1 degree rear tow out would make the car pretty darty over bumps. My car had something like 1/8" out per side when i adjusted my ride height and it was super noticeable. 1 degree is 2.5 times as much I believe.

 

So, what brand of brand new tires did you get?

What is the tire pressure? Should be 30psi cold. Try 28 too see if it goes away. If it does, ask for a little less toe in. (a little less positive toe) I doubt you will see a difference, but this would tell if the alignment is suited to the new tires.

Drive on several different road surfaces and make sure it is not the road causing this.

Jack up each wheel and make sure you don't have an out of tolerance runout (wheel wobbles when you spin it) If you do, remove the wheels and check for bad hub bearings or a piece of dirt between the hubface and the wheel.

If those alignment numbers are correct, it is optimum for low tire wear in street use, and should be safe for the street,but would be inadequate for autoX or track. You could use for the track or auto X but would would be leaving driving performance on the table.

The first temptation is to add negative camber, but for common street use, you lose a little contact patch and would therefore lose wet pavement and cold weather performance. This current set of numbers gives you the best tire contact patch for street driving. More negative camber would immediately give you a positive butt-o-meter feel that the car is riding on rails, but one wet day you might not be so happy.

That being said, the C6 GS and Z06 have factory spec alignment numbers (except for your thrust angle, of course) similar to what you started with. But if you listen to GS and Z owners, you will hear lots of complaints about that much neg camber for street driving and tire wear. I wore out a set of GY run-craps on my '11 GS in 10k miles of putt-putt street driving, and took out a lot of neg camber to solve.

 

I studied your alignment sheet a little more, and have a second possibility. You had some really off initial conditions, the left rear wheel was really toed in and gave you a.49 dg thrust angle. that would have pushed the car to the left because the rear wheels are pushing the rear to the right. This was compensated with negative toe on the left front. (was this car ever in a left-side crash?). So, before, you were giving constant right-turn steering input to stay straight on the road. You may or may not have noticed this, depending on the steering wheel position, relative to going straight ahead. So, you were herding a pig. Now fixing the alignment freed up the the system and the car is actually more nimble than before.

Have another C5 Corvette owner drive it as it is now and see what the thoughts are.

BTW if you were in a crash, or there is crash history there are some key dimensions in the factory service manual that need to be checked. For a quick check, pull a tape from hub center to hub center each side and also check to see that the distance from the tire to the front of the fender in the rear and the tire to rear of the fender in the front is close to the same from side to side. I think you can be 5mm different max side to side on these measurements and be within spec. Look for the gaps between doors and pillars too to see if they are the same side to side. again 4-5 mm is a good number. If you see one that is 10mm, then there is something going on with the frame.

 

Assuming the machine is in calibration the numbers are spot on. I use oe specs on my personal car with no problems driving.

I see you took it back with no change. I would try another shop to see if numbers match. The biggest clue here is it wasn't happening before the alignment.

Don't know if you are near me, or I'd say bring it to me.

Signed - the alignment guy

 

The pdf sheet says Dawson Creek British Columbia.

right next door

 

Has had the car for three days now. Went there today and their "tire guy," said its the tires. Yet the car was doing this right after the alignment with the older tires on. Rims balance out..tires balance out. So frustrated! Why would Corvette dealer have a "tire guy" diagnosis a Corvette. Im so lost..not a long summer up here to enjoy the vette. Thanks for comments everyone.

 

What tire size and brand did you put on the car?

 

I agree and WHAT IS YOUR TIRE PRESSURES??????????????????????????????? ???????