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EMINENT 1 07-13-2017 10:08 AM

Alignment question
 
1 Attachment(s)
What do you think, looking at my alignment specs.
This is after I slammed it with new aftermarket bolts.
I have a slight push when accelerating to the right that's causing me concern. Steering wheel about 1 degree to the right. Also, if i'm going 30-40mph and I brake to a stop, the steering wheel also pulls to the right about 2-3 degrees when I stop.
The shop couldn't diagnose it without charging, but I made them check again and they adjusted the toe to get the steering wheel a bit more center. Granted, they did not have the rear caster tool.
They said maybe a tire, but they're new or maybe a stuck caliper.

Could this be rear caster cause?
Also, with such negative camber, am I going to eat up the insides of my tires again or is the toe ok to compensate?

BEZ06 07-13-2017 10:26 AM

What's your rear caster???:confused2:

The rear caster is critical on the C7, and if it's not set properly (especially if it's not the same both sides) then that could well be your problem!

.

TEXHAWK0 07-13-2017 10:28 AM

Even though front camber is within specs., unless you are driving the car hard all the time, -1.38 deg, seems excessive. You might want to reduce closer to zero. For good tire wear, camber and toe-in need to be near zero.

Also, looks like left rear is toed out. Might want to correct that. If right side is toed-in and left is toed-out, could push the car off.

If car is pulling and you suspect a tire, try swapping tires from one side of the car to the other just to see if it changes.

As mentioned above, front and rear caster need to be close to the same, or it can cause the car to steer in one direction.

I usually get it backwards, but I think on the front, the car will drift towards the side with the most positive caster.
Too much cross-caster can make a vehicle pull or lead towards the side that has the least (negative) caster.
Positive is toward the rear of the car.

EMINENT 1 07-13-2017 11:46 AM


Originally Posted by TEXHAWK0 (Post 1595137135)
Even though front camber is within specs., unless you are driving the car hard all the time, -1.38 deg, seems excessive. You might want to reduce closer to zero. For good tire wear, camber and toe-in need to be near zero.

Also, looks like left rear is toed out. Might want to correct that. If right side is toed-in and left is toed-out, could push the car off.

If car is pulling and you suspect a tire, try swapping tires from one side of the car to the other just to see if it changes.

As mentioned above, front and rear caster need to be close to the same, or it can cause the car to steer in one direction.

I usually get it backwards, but I think on the front, the car will drift towards the side with the most positive caster.
Too much cross-caster can make a vehicle pull or lead towards the side that has the least (negative) caster.
Positive is toward the rear of the car.

I suspect this is going on with the rear caster. Such a pain finding someone that can do it, but I found a dealership that does after going to this last place.

As far as negative camber, I think they tried to get the specs as close to what I provided that DSC recommended for street and light track. I'm probably never going to track and will get this back in check the next time. Most important thing I want to fix is tire wear. The stock specs ended up chewing up the insides of my first set of tires at 10k miles. Probably due to lowering on stock bolts without proper alignment. But, dealer checked and it was "green and go" I guess.

Poor-sha 07-13-2017 11:57 AM

Make sure both front shocks are properly plugged in to their electric connector under hood and the security latch is on. If one side is unplugged it would go full soft and that could cause a pull under braking or acceleration. Happened to me

EMINENT 1 07-13-2017 12:52 PM


Originally Posted by Poor-sha (Post 1595137800)
Make sure both front shocks are properly plugged in to their electric connector under hood and the security latch is on. If one side is unplugged it would go full soft and that could cause a pull under braking or acceleration. Happened to me

Could you advise on what this looks like and where to find it?

TEXHAWK0 07-13-2017 01:41 PM

If your main concern is tire wear, you need to get camber and toe in back close to zero.

Edwardz 07-13-2017 02:58 PM


Originally Posted by EMINENT 1 (Post 1595136967)
What do you think, looking at my alignment specs.
This is after I slammed it with new aftermarket bolts.
I have a slight push when accelerating to the right that's causing me concern. Steering wheel about 1 degree to the right. Also, if i'm going 30-40mph and I brake to a stop, the steering wheel also pulls to the right about 2-3 degrees when I stop.
The shop couldn't diagnose it without charging, but I made them check again and they adjusted the toe to get the steering wheel a bit more center. Granted, they did not have the rear caster tool.
They said maybe a tire, but they're new or maybe a stuck caliper.

Could this be rear caster cause?
Also, with such negative camber, am I going to eat up the insides of my tires again or is the toe ok to compensate?

first thing I would do a double check the pressure in the tires. You can rule out tire problems by swapping tires side to side and if the symptoms change to the other side you know a tire is bad.

thebishman 07-13-2017 03:07 PM

if the car is pulling to the side when the brakes are applied; the rear is stepping out on acceleration, and the steering wheel isn't centered, your alignment sucks. Sorry to say it, but it's true.

Find a shop that knows what they're doing and follow the DSC street alignment specs exactly:

https://cimg4.ibsrv.net/gimg/www.cor...d9b1d8b276.jpg

Personally I run the DSC 'Track' specs and I'm not experiencing any problems with uneven wear. YMMV.

Bish

Bill Dearborn 07-13-2017 04:54 PM

My 2 cents:
Your pull could be the combination of small differences in each of the settings. Front toe doesn't cause pull but it will cause the steering wheel to look off center as the two front wheels balance the forces between them.

If camber is the cause of your pull, it will always pull to the side with more camber (from negative to positive). If your car has .5 degrees negative camber on one side and 1 degree negative camber on the other side it will pull to the .5 degree side (since -.5 is more than -1).

If caster is the cause of your pull, it will always pull to the side with less caster (from negative to positive).

Looking at your front camber and caster readings it looks like the right side has more camber (it is less negative) and it has slightly less caster as well. That should cause some slight pull to the right.

Take a look at your thrust angle. It is slightly toward the left side of the car due to the left rear wheel being toed out a little far or the right side rear wheel not being toed out enough. Basically, the rear wheel thrust direction is pointed slightly to the left which will cause the car to turn right under acceleration and to turn left when decelerating by lifting off the throttle.

Just driving down the road at neutral throttle the car will have a small tendency to want to rotate clockwise around a vertical line drawn through its center. However, is that tendency really large enough for you to notice? I doubt rear caster has anything to do with what is happening since you aren't turning the car. I drove my car on track with a track alignment for a year without knowing what the rear caster was. When I finally was able to measure it the caster was ~+0.4 on the driver's side and ~-0.5 on the passenger side. On the highway the car drove straight as an arrow with that setup.

Under acceleration the thrust angle may have enough influence to cause the car to turn more right and under hard braking the front tire alignment may do the same thing. However, these things are very small since the alignment looks like it is as close to dead nuts from a cross camber, cross caster and thrust angle stand point as a good technician can get it.

Major influences on your car's behavior could be to other things at the right front corner. Tire Inflation pressure, rolling resistance, etc. Brake caliper issue or a wheel bearing issue.

Bill

EMINENT 1 07-13-2017 05:20 PM


Originally Posted by Bill Dearborn (Post 1595139842)
My 2 cents:
Your pull could be the combination of small differences in each of the settings. Front toe doesn't cause pull but it will cause the steering wheel to look off center as the two front wheels balance the forces between them.

If camber is the cause of your pull, it will always pull to the side with more camber (from negative to positive). If your car has .5 degrees negative camber on one side and 1 degree negative camber on the other side it will pull to the .5 degree side (since -.5 is more than -1).

If caster is the cause of your pull, it will always pull to the side with less caster (from negative to positive).

Looking at your front camber and caster readings it looks like the right side has more camber (it is less negative) and it has slightly less caster as well. That should cause some slight pull to the right.

Take a look at your thrust angle. It is slightly toward the left side of the car due to the left rear wheel being toed out a little far or the right side rear wheel not being toed out enough. Basically, the rear wheel thrust direction is pointed slightly to the left which will cause the car to turn right under acceleration and to turn left when decelerating by lifting off the throttle.

Just driving down the road at neutral throttle the car will have a small tendency to want to rotate clockwise around a vertical line drawn through its center. However, is that tendency really large enough for you to notice? I doubt rear caster has anything to do with what is happening since you aren't turning the car. I drove my car on track with a track alignment for a year without knowing what the rear caster was. When I finally was able to measure it the caster was ~+0.4 on the driver's side and ~-0.5 on the passenger side. On the highway the car drove straight as an arrow with that setup.

Under acceleration the thrust angle may have enough influence to cause the car to turn more right and under hard braking the front tire alignment may do the same thing. However, these things are very small since the alignment looks like it is as close to dead nuts from a cross camber, cross caster and thrust angle stand point as a good technician can get it.

Major influences on your car's behavior could be to other things at the right front corner. Tire Inflation pressure, rolling resistance, etc. Brake caliper issue or a wheel bearing issue.

Bill

This is exactly what it feels like. Like i'm going clockwise slightly. Tire pressure is good. I guess I can try swapping tires as i'm going to have them dismounted when I get my new wheels.
Do you think I should just take it to the place that can do rear caster and tell them to fix it. I hate having to spend more money, but I might have to.

Poor-sha 07-13-2017 06:14 PM


Originally Posted by EMINENT 1 (Post 1595138127)
Could you advise on what this looks like and where to find it?

I don't have any pictures handy but open the hood and look for the wires coming in at the top of the shock towers. On the passenger side they go to a black connector just below the alternator. On the drivers side it's on the side of the engine compartment (follow the wires). Make sure the connectors are all the way together and the little thing that pulls out the back of the connector to lock it is pushed in.

Mad Dog 24 07-13-2017 10:26 PM

Agree with most of above comments on rear caster not effecting your issue. Disagree with to much camber. If toe is close to 0 or under .07 degrees even with a lot of negative camber you shouldn't get extreme tire wear. I got 20k miles out of a set of Contis with front camber in the 2.0 range and rears in the high 1's.

Have the steering angle recalibrated and check it is all tight. Your alignment numbers should not cause a pull issue. Its happens to not tighten up one of eccentrics in the suspension enough and one bump could shift it out of spec. I've seen it happen many times. We mark them to easily spot movement or better yet install a AMT plate kit, problem solved!

Bill Dearborn 07-15-2017 10:18 AM


Originally Posted by Mad Dog 24 (Post 1595141743)
Agree with most of above comments on rear caster not effecting your issue. Disagree with to much camber. If toe is close to 0 or under .07 degrees even with a lot of negative camber you shouldn't get extreme tire wear. I got 20k miles out of a set of Contis with front camber in the 2.0 range and rears in the high 1's.

Have the steering angle recalibrated and check it is all tight. Your alignment numbers should not cause a pull issue. Its happens to not tighten up one of eccentrics in the suspension enough and one bump could shift it out of spec. I've seen it happen many times. We mark them to easily spot movement or better yet install a AMT plate kit, problem solved!

I did forget about the cams slipping. If they weren't marked it is almost impossible to tell if they have slipped (unless they slipped a lot) unless you check the alignment again.

If you have a fairly level garage floor (from side to side) you can use some cheap vinyl floor tiles from a home supply store to level the car from side to side and then use a 2 ft long digital level to check camber at each wheel. If the camber you read is close to what your printout reads that would indicate the cams haven't slipped.

Bill

EMINENT 1 07-15-2017 01:01 PM


Originally Posted by Mad Dog 24 (Post 1595141743)
Agree with most of above comments on rear caster not effecting your issue. Disagree with to much camber. If toe is close to 0 or under .07 degrees even with a lot of negative camber you shouldn't get extreme tire wear. I got 20k miles out of a set of Contis with front camber in the 2.0 range and rears in the high 1's.

Have the steering angle recalibrated and check it is all tight. Your alignment numbers should not cause a pull issue. Its happens to not tighten up one of eccentrics in the suspension enough and one bump could shift it out of spec. I've seen it happen many times. We mark them to easily spot movement or better yet install a AMT plate kit, problem solved!


Originally Posted by Bill Dearborn (Post 1595150201)
I did forget about the cams slipping. If they weren't marked it is almost impossible to tell if they have slipped (unless they slipped a lot) unless you check the alignment again.

If you have a fairly level garage floor (from side to side) you can use some cheap vinyl floor tiles from a home supply store to level the car from side to side and then use a 2 ft long digital level to check camber at each wheel. If the camber you read is close to what your printout reads that would indicate the cams haven't slipped.

Bill

What you guys are talking about in slipping, is it possible to slip if i'm not doing any tracking? This is a basic street car. The most my suspension moves aside from dips in the street are up my curbed driveway and work at some extreme angles. Could those be enough to cause any slipping?

SUB VETTE 07-15-2017 03:42 PM


Originally Posted by EMINENT 1 (Post 1595151173)
What you guys are talking about in slipping, is it possible to slip if i'm not doing any tracking? This is a basic street car. The most my suspension moves aside from dips in the street are up my curbed driveway and work at some extreme angles. Could those be enough to cause any slipping?

One bad pot hole hit can cause a slip. Camber plates remove that problem.

TEXHAWK0 07-15-2017 06:39 PM

The cams need to be torqued to make sure they seat. A lot of places just try to use an impact and guess how tight they are.

The first thing I do is take a paint pen and mark the cam and bolt position on the frame to make sure nothing has changed over time.

KnotZ06 07-15-2017 07:26 PM

What bolts did you use? And how much did you lower? I'm about to do the same thing, do you have pics?

EMINENT 1 07-15-2017 11:49 PM


Originally Posted by KnotZ06 (Post 1595152929)
What bolts did you use? And how much did you lower? I'm about to do the same thing, do you have pics?

https://www.corvetteforum.com/forums...ance-mods.html

EMINENT 1 08-12-2017 03:29 PM

Update after getting the new wheels. They rotated tires from each side and it didn't eliminate the problem.

I notice now when I accelerate the car wants to push to the left and when braking pull to the right still.

Will probably take it in within the next two weeks.


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