General alignment question (caster - sorry it's on a Silverado!)

[Mikepol2]

I know it's not a Mustang but there are some really smart suspension guys on here so thought I'd throw this out there and see if anyone has an opinion...

I have a 2015 Silverado with 72K miles on it and replaced pretty much the whole front suspension in May (upper and lower control arms, tie rod ends, struts). Took it to the Chevy dealer that I've been going to for 20+ years for an alignment. Didn't quite feel right after the alignment, felt like there was a little resistance. Took it back today for their 2nd attempt at it and now the steering wheel turns to the right and it pulls to the right.

Question 1: The printout shows that there are different caster specs for each side; left is 2.4* to 4.4*, right is 1.4* to 3.4*. Could that really be correct??

Question 2: The before caster measurement was 1.7* on both sides, which was out of spec on the left but it tracked nice and straight. The after is 3.8* left and 1.6* right! Both readings in spec but now it's pulling right.

Only other remarkable number is that the toe spec is -.05 to +.15 on both sides, but the before left was .35, which might explain why it felt like I was driving in mud.

Can't really go back and complain because now every number is in spec but it drives like shit. Thoughts? Thanks.

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[Norm Peterson]

I have a 2015 Silverado with 72K miles on it and replaced pretty much the whole front suspension in May (upper and lower control arms, tie rod ends, struts). Took it to the Chevy dealer that I've been going to for 20+ years for an alignment. Didn't quite feel right after the alignment, felt like there was a little resistance. Took it back today for their 2nd attempt at it and now the steering wheel turns to the right and it pulls to the right.

Question 1: The printout shows that there are different caster specs for each side; left is 2.4* to 4.4*, right is 1.4* to 3.4*. Could that really be correct??

Apparently so. And different configurations/trims may take slightly different preferred specs. GM may have been considering the effect of max trailer tongue weight.

Question 2: The before caster measurement was 1.7* on both sides, which was out of spec on the left but it tracked nice and straight. The after is 3.8* left and 1.6* right! Both readings in spec but now it's pulling right.

With over 2° of cross caster I'm not surprised, and with the right side having the lesser positive caster value it would drift right.

A brief internet search turns up cross-caster values of 0.4° and 0.8° for Silverados of about the same year as yours. More right side caster and less left side caster is probably what you want, at least for your usage. A good alignment tech - think old-school here - will understand.


Norm

 

[TeeLew]

With over 2° of cross caster I'm not surprised, and with the right side having the lesser positive caster value it would drift right.


Norm

Agreed. In fact, it's a little strange to have the caster heavy on the left, because that will tend to turn the car same as the road crown. Generally, you want those two things to counter each other for straight street tracking.

Honestly, I'd go back and tell them they messed up your car, regardless of whether it's in spec or not. If the don't believe you, then have them go for a ride and see what they think. There's _a ton_ of wiggle room on those specs. They can get both sides into spec and still have it slightly (~0.2*) heavy on the right side so it drives straight down the road.

 

[Mikepol2]

Honestly, I'd go back and tell them they messed up your car, regardless of whether it's in spec or not. If the don't believe you, then have them go for a ride and see what they think. There's _a ton_ of wiggle room on those specs. They can get both sides into spec and still have it slightly (~0.2*) heavy on the right side so it drives straight down the road.

I called them back and they said it's in spec on both sides, and the tech felt it pulling right on the test drive but said it was due to road crown... soooooooo annoying. At least they didn't charge me for the 2nd attempt. Will be going somewhere else when I get time and tell them up front what I'm looking for.

 

[TeeLew]

I called them back and they said it's in spec on both sides, and the tech felt it pulling right on the test drive but said it was due to road crown... soooooooo annoying. At least they didn't charge me for the 2nd attempt. Will be going somewhere else when I get time and tell them up front what I'm looking for.

OF COURSE PULLING IS DUE TO ROAD CROWN. That's what the alignment is meant to counteract. As it is, they have the alignment making it worse, not better.

I freakin' hate dealerships. They're always the most self-righteous, condescending pricks in the automotive world.

 

[o-man]

Thats the damnedest thing I've heard. When I was in the business, my techs wouldn't let it leave with a pull even if it was "in spec". they would either swap tires to see if tire pull or change alignment so it didn't pull. And you can bet the steering wheel would be straight

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