Help on Wheel Aligments, Rack out of Calibration?

[Tim]

Can anyone help?

4 wheel alignment 3500 miles ago on new Pilots.
Car handled and drove great even with the wear pattern. Very solid and stable with no darting tendencies.
I noticed that the rear tires were wearing on the inside more than the outside. 7/32 tread remaining on the out side and 5/32+ remaining on the inside. The right rear was not quite as bad. In my mind they both appeared to be toe out.
The wear on the front was normal.
Tire pressures run at 29 PSI
I couldn't get the car in for an alignment for 2 to 3 weeks so we rotated and balanced all 4 tires and keeping in mind that they are directional tires and rims. So they were just swapped from the rims side to side.
Car still drove and handled okay for the next 2 weeks with only a couple of hundred miles put on.

I then went in for the alignment.

I have attached the before and after alignment specs.

Before After
Front Left Right Left Right
Camber -.5 -.5 -.5 -.5
Caster 5.6 6.5 5.6 6.4
Toe .56 .46 .10 .11
Rear Left Right Left Right
Camber -.6 -.2 -.5 -.3
Caster 6+ 6+
Toe -.5 .15 .09 .07

Now the car is darting around from the mild ruts in the road when changing lanes both in town and on the hiways that I have traveled on many times in the past when the car was a pleasure to drive. I'm concerned because the car is not nearly as stable as before. In my mind to the point where it could be dangerous depending on the situation. In a nutshell no comparison to before the alignment that was just done.

A couple of questions:

„« Can anyone see where we may have gone wrong on the alignment at Fountain Tire? I was there the entire time and agreed on the settings that were displayed and printed.

„« What are the chances are that his rack is out of calibration or at least enough that it affects the Viper? Of course what they say is that we don't have any problems with any other vehicle. My Chrysler dealer won't put it on their rack as he has been having problems and does not trust his readings and referred me to the Fountain Tire Dealer. They (Leduc Chrysler) have new rack coming in next month and this is their 3rd one in a year. As well it was their rack that aligned the car in the 1st place 3500 miles ago. The XGTZ's that came off at that time showed no unusual wear except I had worn them down to the last 1/32 of tread. The other dealers in the area are reluctant or won't touch the Viper.

„« Any suggestions on ensuring that I'm getting for what I¡¦m paying for with a calibrated machine and not keeping every one in the alignment business at my expense as I'm going back in for the 3rd time in a year. As well as the unneeded wear on the rear tires.

„« Are there a couple of different racks that stand out on the market as being superior over another type for reliability and accuracy?

Thanks in advance

Tim]

 

[joe117]

My 94 seems to be a little "darty". The car was 4 wheel aligned in March, when a new rack and tie rod ends were put in, shortly after I bought the car. The work was done at a Dodge dealer. I thought it was normal for the car to dart a little on roads with irregularities such as minor crowns and ruts. I hardly drove the car before the work was done so I don't know what it was like before. It's not a big problem but it definitely does it more than my 96 Vette. I always thought it was because of the big tires. It drives fine on regular roads with no darting at all. Perhaps I better get it checked. The alignment is still under warranty.
Anyone know if this is normal or not?

 

[GTS Dean]

Tim,

I think I can help, but the formatting of your suspension settings is all screwed up and I can't follow it. Please give it to me
LF, RF
LR, RR

Gen1? Year please?

 

[Tim]

Dean,

94RT10

Sorry about the format. When I have the time to figure out on how to send an attachment it'll be easy.

Front
Camber before and after -.5 each wheel
Caster before LF 5.6 RF 6.5 after LF 5.6 RF 6.4
Toe before LF .56 RF .46 after LF .10 RF .11

Rear
Camber before LF -.60 RF -.20 after LF -.50 RF -.30
Caster after LF 6+ RF 6+
Toe before LF -.50 RF .15 after LF .09 RF .07

Thanks

Tim

 

[GTS Dean]

Camber is good all around, but definitely set for max tire life and minimum cornering grip. Lots of folks run in the neighborhood of -1.0 to increase cornering force - but with attendant wear increase (inner shoulder).

Front caster is waaaay off from side to side. Should be right around +6.0 and within 0.3-0.4 degrees from side-side. To fight crowned roadways, some shops will add more caster to the left side and make it pull uphill.

I'm not sure how they are able to measure rear caster - Dodge has special little gauges that affix to the knuckles for setting it. Perhaps the machine is a new Hunter or FMC that can calculate it - but having the rear caster out of spec on your car can be scary!

I don't measure toe in degrees, so the conversion isn't natural for me. Plus is in, minus is out. In is good. A little up front (1/16"), quite a bit in the rear (3/16") suits Vipers well.

BTW - good call on moving the tires across the car to even camber wear.

 

[Tim]

Dean,

Toe on the front is just over 3/32” each tire.
Front Caster is on the top end but there is no pull, just the darting. It is also very similar to what it was prior to the wheel alignment when there was no problem.
We used Mopars plastic protractors for the rear caster.
The rear toe is just over 3/32” to 1/16” each wheel.

Looks like I could use a little more rear toe?

Are some of these racks more suceptable to going out of calibration and is their accuracy questionable?

 

[dansauto]

I set my toe at dead zero and still had darting problems. Then I put new tires (mine were only 1/2 worn) but what a differance!! The car still steers quick, but NO MORE DARTING. If your tires have a bad wear patteren from prior bad alignement I'll bet new tires will fix your darting.

 

[GTS Dean]

The car is probably still darting a bit because the tire has taper wear. Now you have the deep tread inboard and are experiencing some tread squirm. Give it a few hundred miles and it should minimize.

3/32" toe per tire (front) is probably too much. I would recommend taking about 1/3 to 1/2 turn out of each side by going counter clockwise - viewed from the inside looking out.

Rear toe could use some more in. This is accomplished by turning them CCW. Give the rears about another 1/2 turn. The front and rear react opposite each other becase of the toe links being in front of or behind the axle centerlines at each end of the car.