Wheel alignment w/new tires
 

I just got new tires (BFG G-Force Sport 245/50-ZR16) and the car started drifting slightly toward the left. So I brought it back for an alignment and it drives straight again, but am not sure on the specs (I posted on other boards but need more opinions):

Before (front)
LEFT -- Camber = .01*, Caster = 4.7*, Toe = -.08"
RIGHT -- Camber = -.0*, Caster = 4.2*, Toe = .06"
FRONT -- Cross Camber = .1*, Cross Caster = .5*, Total Toe = -.02", Set Back = .35*

After (front)
LEFT -- Camber = .01*, Caster = 4.7*, Toe = .10"
RIGHT -- Camber = -.01*, Caster 3.2*, Toe = .05"
FRONT -- Cross Camber = .2*, Cross Caster = 1.5* Total Toe = .15", Set Back = .54*

If these are really off, I have a hard time believing it since the car drives great (straight at all speeds even at 75-80mph, steering wheel is perfectly straight, etc). Should I just ignore what the paper says since it rides good? I appreciate everyone's input. Thanks

Ok... what year car? Suspension mods/lowered?

Cross caster seems wacked to me. I wonder if they compensated for tire pull. Swap the front tires side to side and see if it pulls again.

Oops, it's a 97 Formula, stock wheels, stock suspension, stock ride height.

Hmmm, I can only try from front to back since they're directional tires (only one way).

Air pressure is the same on each side?

for a test it would not matter...however f2b will work too.

Yes, all 4 tires were set at 30psi.

Called the alignment place again. They asked me if it was pulling, I said no, they said not to worry.

What about NJ inspection? I hear they check alignment. Would this cause a problem passing inspection in the future?

No problem with NJ.


I still say rotate and see if it changes.

That cross caster is worse on the "After." On most cars, cross caster tolerance is usually no more than 0.6º and thats pushing it.From the looks of the "Before" spec, the car shouldn't have pulled. The car will tend to pull toward the side with the least positive caster so it looks like they took some caster away from the right to compensate for the pull to the left. Like Bonzo said, try rotating the tires.

In my experiance, when customers are complaining that their car is pulling, 90% of the time its due to the tires. In this situations I always rotate the tires first and see if it made a difference before I start the alignment.

Well, the car drives great with these settings. If it didn't ride good, then I would definitely be complaining to the shop about the alignment. I did talk to them about the cross caster. I even asked them if there is a possibility of tire pull. They said no, and that I would've experienced a stronger pull rather than the slight drift. In fact, they think I'm a bit too paranoid over the cross caster. I think they aligned the car based more on the feel of the car, rather than by the book (yes they drove it before proceeding with alignment, didn't just take my word for it).

Haven't tried rotating the tires yet. Is there any disadvantage on the 1.5* cross caster? I've driven cars with a bad alignment (and it was downright scary!) My car drives perfect in every way (steering wheel straight, car drives straight at all speeds including 70-80mph on the highway). I even tried to look for something wrong while driving, and honestly, couldn't find anything wrong.

As mentioned, excessive (you want ~.5 or less, IMO excessive is 1.0+) cross caster (difference between L&R caster) caused drift/pull to low side. It's just suspicious you had a pull to the left and now your alignment appears to push right.

Who knows, car could be bent. Rotate the tires & see if anything changes. No? You're fine. Pulls to the right? You have a tire & alignment issue.

Read up on cross caster...

One of your front wheels might be bent. How much gas was in the car? Fuel weight plays a big part in vehicle alignment. I'm assuming the wheels are aluminum. Some factory aluminum wheels have a wide lip where the alignment sensor sits, this causes some play in the sensor that gives inaccurate readings. There are so many variables when it comes to alignments. If the car drives OK, leave it.

After driving for a while, I noticed consistently that the steering was softer than before. So I took it back, and they re-adjusted the toe (took some out, but is still slightly toe-in). The toe is the only thing they adjusted (camber and caster were left alone).

Now, the car is nice and tight again, still driving straight with no pulling.

he said he had new tires put on so rotating them would not have done anything unless you had a belt shift on you which can happen, but you probably would notice it somewhere else before your align.

makes me nervous after hearing **** that some dealers do and what i have seen myself and how easy it is to get the numbers someone wants to see when it is not truely there.

if your toe and camber are correct and it is gonig straight, should be ok. Since cross caster isnt going to wear tires like the other two will. Unless you wanted specific caster measurements for road racing or something

New tires can absolutely have radial pull. You don't need a belt shift to do that.

I agree though, if it drives straight and does not wear tires then it's good. Did they put it on the machine to reset the toe or did they eyeball it?

I'm pretty sure they put it back on the machine (although I did not get another printout). Reason I feel it was back on the machine is because the steering wheel is in the same exact "straight" position, and it drives as straight as before, only tighter.

I asked if anything looked bent or worn, they said no (and I'm sure they would've loved to sell me some new suspension parts). They said this was not the first car they had to adjust this way (they said even some brand new cars were pulling from the factory and had to be re-adjusted).

Actually, I did notice BEFORE the new tires that turning left was slightly easier than turning right but no pull. After the new tires and before the alignment, it drifted slightly to the left (I say "drift slightly" because it didn't really "pull", and I only noticed a slight drift when I let go of the wheel). Now, steering efforts are equal left and right, and it still tracks straight and drives tight.

I also looked underneath, did not find anything "bent". Wheels are in excellent shape as well. I'll keep driving it and continue to look for any changes as the tires "break-in".

Well, it's still driving straight today. Actually I had them re-adjust my toe again about a month ago (which was 0.09, now it's 0.03). Steering wheel was slightly to the right (not by much, but enough to notice so I had them straighten that out). It also felt like there was too much play in the steering wheel with the toe originally set at 0.15 (first alignment), which was improved at 0.09, and is non-existent at 0.03.

Tires also feel weird at warmer temps (steering felt a bit harder at lower speeds). Probably because of the softer compound on the BFG's, and being new.

Might also be worth mentioning when they mounted and balanced my new tires on my wheels, I believe they used the http://www.gsp9700.com/ machine (which is advertised on the site to correct tire pull). First time ever done on a machine like that (they told me they're using a new, more advanced tire/wheel balancing machine).

Car still has minimal shake at highway speeds sometimes (not all the time, and not as much as before). I wonder if they were not balanced properly?

EDIT -- Clamp weights on the inside of rims, stick-ons toward the front.

it can be tough sometimes to get those to balance well (stick ons)

Neat machine. Tire pull is caused by a tire issue and not balance. They basically state their machine identifies possible issue so you can be aware before you bolt it up, and maybe put the tire is a different spot to go around the issue. The machine does not 'fix' the pull. At least that is how I read it. Sometimes you can do what they say and move it around until the pull is negated, such as putting the tire in the back). IMO a tire with a pull is no good and should be covered under warrantee if it causes an issue.

Adam you are right about tape-a-weights. Older balancers expect the weight to be added to the rim lip and of course tape weights are closer to the center, causing issues since you are not doing what the machine tells you.

Well, I assume it was done on the GSP9700 since on the website it lets you locate a shop in your area that uses one, and the shop I went to was listed.

I then realized the shake could've been just "tire flatspotting" since at one moment I felt a slight shake at 65-70 mph, then about a few minutes later it was gone.

It sounds like you have a bad set of tires. If your feeling a difference in the the tire performance between cold and hot during normal driving use, I think you have a bad set of tires. How many times have they rebalanced these tires for you and you still have a vibration problem. It sounds like a belt shift issue to me.

When the tires are cool jack the front of the car up and spin the front tires. If the tires are OK and not out of round, drop the car and take it for a spin and try to get the tires good and warm. Then jack the car up again and spin the front tires and see if they are still true and round. If you see small bulges in the tread of the tire you probably have a belt issue.

They should be able to warranty these tires for you, maybe have to pro-rate them.