[rbpeirce]

I noticed my last two alignments everything stayed pretty close but passenger side rear toe slipped from about -0.2° to -0.14°. Is this anything to have checked?

[BillC]

Originally Posted by rbpeirce

I noticed my last two alignments everything stayed pretty close but passenger side rear toe slipped from about -0.2° to -0.14°. Is this anything to have checked?

Did it slip on both alignments, or just on the last time?

Sounds like maybe one of the adjuster bolts may have slipped a little. Make sure they crank down on the bolts very tight.

And, when you get it back from being aligned, look underneath and see if they drew lines from the adjusters to the subframe -- this lets you see quickly if anything has moved. If they didn't, reach under there with a sharpie and mark all 4 rear adjusters (2 each for camber and toe).

[smdubovsky]

Measurement noise. 0.06deg is ~0.5mm across the surface of a 19" wheel. Inconsequential.

Its a good idea to put paint marks on adjuster bolts like Bill mentions but I doubt this is a problem in your case.

[rbpeirce]

Originally Posted by smdubovsky

Measurement noise. 0.06deg is ~0.5mm across the surface of a 19" wheel. Inconsequential.

OK. That's amazing! I never looked at it that way. That's about 0.02". If this is so small why do people make so much of a thing about rear toe in for stability under braking? I'm running about -0.2deg on 20" wheels. What's that, less than 0.1"?

[Vicegrip]

Rear toe is important. Measuring many points to the left of the decimal not.

[TomChan]

0.06 Deg of toe is almost a full millimeter for 20" wheels(see conversion chart in attachment). I prefer to do alignments using millimeter as the unit of measurement since its not wheel diameter dependent and I can grasp the value in my mind better.
When using Degree as the unit of measurement for toe, any value that is less than a whole number is expressed in "minutes". Its unnecessarily complicated, IMO, and for not good reason, also IMO, race car teams only use millimeter or inches.

[turkis_tii]

I guess most alignment machines use lasers. I was wondering what the width of the laser bam is, 1-2 mm? Would want to add that to intrinsic error.

[rbpeirce]

Originally Posted by TomChan

0.06 Deg of toe is almost a full millimeter for 20" wheels(see conversion chart in attachment). I prefer to do alignments using millimeter as the unit of measurement since its not wheel diameter dependent and I can grasp the value in my mind better.
When using Degree as the unit of measurement for toe, any value that is less than a whole number is expressed in "minutes". Its unnecessarily complicated, IMO, and for not good reason, also IMO, race car teams only use millimeter or inches.

My shops alignment machine does it in decimal degrees. It turns out my dealer's machine does it in minutes. That caused a bit of confusion when I first took it to my shop. 0.22deg is 13', so the first time they set it to 0.13deg. We now shoot for about 0.22deg.

[rbpeirce]

Originally Posted by turkis_tii

I guess most alignment machines use lasers. I was wondering what the width of the laser bam is, 1-2 mm? Would want to add that to intrinsic error.

I'm beginning to think for rear toe in a pretty broad range is close enough.

[Vicegrip]

Originally Posted by turkis_tii

I guess most alignment machines use lasers. I was wondering what the width of the laser bam is, 1-2 mm? Would want to add that to intrinsic error.

They don’t quite work like that. There is a grid that works with targets on the wheels. Accurate results are linked to equipment that is in tune and technicians that use the equipment properly. When done right with equipment that is right results better than factory are often seen. I know of a dealer that checks all new cars and has to adjust to listed factory setting more than a small number.

A set of strings in the right hands works wonders. The latest blinking lights and color screens can produce junk when not calibrated and used by a tech that does not recognize the issues. A while back a shop sent a number of cars out all cocked up. “but the machine said it was spot on”

Good tools in good hands.

Besides, toe in modern cars is a bit more than one setting. The other settings have to be right too.