Repair-It

Here they are fresh from the FSM.

Not surprisingly for a premium RWD platform, literally everything is adjustable.

I looked again at the instructions. Rather than an eccentric bolt (which would have been easier I think), I believe the adjustment is a matter of loosening the lower control arm bolts, and then they sort of just float and can be moved around to some extent.

The rear lower is just a single bolt because it is multi-link. The front lower is two bolts.

The FSM shows a turnbuckle tool to help hold the control arms in place and make the adjustment, before tightening the bolts. This would make it a lot easier to do the alignment I would think. So now my plan is to specifically get the alignment tech out to the office so I can specifically ask if he can handle caster and camber on this vehicle and if he either has the tool, or can do it without the tool. If I need to go to the dealer, I will do that. Don't want to pay for 2 alignments though. They might be able to do it without the tool but it will take a few tries and sort of random moving of the control arm and retightening so it will definitely be more annoying - which is why there is a strong chance they will not want to do those adjustments. Furthermore, getting it dialed into any kind of specific nominal value rather than a range will be even harder.

Speaking of which, there are a couple reasons to dial in a specific value...and all may not apply:
- Tire wear. This would be a practical reason. Factory settings are NOT always the best for wear, but if there is a wear problem, and the alignment was out of spec in the direction that supports the wear, it would make good sense to get into spec. But it could also make sense to add front camber, for example, if there was excessive outside treadwear due to driving style. So it depends.
- Performance. Grip and over/under-steer is most definitely influenced by alignment. And with front or rear adjustment there is some good leeway to tweak the characteristics of the vehicle.
- Tracking. This is sort of a subset of performance but tramlining over uneven pavement can be made worse, or better, depending on alignment settings. I guess I will put feel in this category - specifically, on-center feel. Toe and caster will impact this the most, but camber can have a big impact on tramline.

Factory settings are typically a COMPROMISE between performance, tracking and wear. And driving style may change where the local optima lands. They are kind of all at odds with each other. Performance is probably going to involve more negative camber, and even caster. Tracking is going to want some toe-in and caster helps this, but camber tends to hurt, and toe-in is not great for turn-in response. And wear would theoretically be zero everything (not caster, unless you want your front wheels to do that shopping cart thing) except that is not how the real world works, due to bushing deflection, and most importantly, uh, turning.

If they can do it I will also make a point that I want the before/after printout, which I always ask for.

Had a very quick and lukewarm conversation with the tech....or one of the alignment techs apparently. It is a busy Saturday morning FWIW. I briefly described the issue and my concern, and explained that the front has adjustable caster and camber, with adjustable camber also at the rear, and it is a matter of loosening the lower control arms and simply moving them. He basically nodded and I asked for confirmation that he could do it and his response was simply "if we can move the control arm.". I mean....yeah.

I'd love to assume that as long as the movement at the control arm mount does not run out of play, they should be able to handle this. So any issue I would like to be an actual problem with the car that I need to fix, not a failure of the shop to actually....like do their job and spend a little more time working at it, if that is required. We will see how it goes.

Should also mention something a little funny. I walked in and again, they are busy. The lady at the desk is on the phone and while she is on the phone, she looks at me, turns around, grabs a piece of paper and puts it on the desk. It is a Tirerack invoice. She points at the name and, yep, it is mine. She recognized me and I said nothing to her before that. So apparently they know me. That is something.

They called me at like 4:13pm. I'm thinking they close at 5pm or 4:30. In the VM, they said, we close at 4pm but will be here until 4:30pm, and that I could pay with a credit card (presumably they'd leave the keys in it....). So we hurried the hell up and got there in 10 minutes and it was fine.

Basically the person who checked me out said nothing but handed me all kinds of things, which basically is more than I would have gotten from her verbally anyway. I have scanned it all. Here we go.

Here is the alignment before on a single page. You will notice lots of red. Here are the problems:
- Total front toe is barely in spec, as in it has quite a bit. And the left toe is wrong, which is why the steering wheel was not centered. It was off center to the left, which is consistent with toe in to the right. The rest of the front is frankly fine. And I think the tires are wearing alright except for some very inner and very outer wear. That is why I run them ~3psi above recommended.
- Right rear had 0.4° POSITIVE camber, which is way out.
- Total toe at the rear was too high. So I guess I called that. Too little camber and too much toe. That explains the bad outer tread wear.

Here is the one sheet after. Notice the sea of green. The big news is:
- Front total toe was brought way down to nominal at 0.18° which is basically ideal. It looks like they did not touch front caster or camber and frankly did not need to.
- Left rear camber is now CORRECT! Yay! Right at -0.9° which matches the right rear now.
- Rear total toe is on the high side and I would have preferred closer to the ~0.2° nominal but that is pretty much my only complaint. I am not sure why he did that.

I also don't know why the printouts say 4x2. It is AWD. Though the only difference I think is a little less front caster on the AWD cars, to make up for the additional weight (GM was apparently targeting consistent steering feel and weight between the RWD and AWD models).

Here are the before/after on a single page. They do not match perfectly but are close. There is red on this one. There is just too much rear total toe. Otherwise this is good. Maybe I would have asked for like -1.2° camber in the rear, since more in the rear would make some sense. But this may also handle surprisingly neutrally, which would be quite sophisticated for an AWD car.

And he put these in the package, perhaps to show that he looked up how to do it. These are NOT GM directions but probably from the alignment machine system. The overall approach matches GM of course. You will also see he blew up the rear camber and printed that out. Again, I think left rear camber is the ONLY thing he adjusted other than front and rear toe. Haven't driven it much yet but the steering wheel seems centered, which is always a good sign. I hope the new tires wear well. Looking forward to a set of 4 next time, probably something different.

Mounting, balancing and the alignment was $147.35, bringing the total investment to like $545. That sucks.

Did a little reading. Sounds like rear toe pretty much does the same thing as front. It stabilizes the rear, which means a lean toward understeer, and perhaps a little more unwillingness to change direction (which I obviously don't like). Given a little more negative camber on the front than the rear, this may be OK from a handling perspective, especially since I do plan to switch to 255s all around. But honestly I'm more concerned about being on the hairy edge of too much rear toe per GM's spec, which I suspect is just going to lead to more wear than is otherwise necessary. For reference it is at 0.37° total rear toe and GM says the max is 0.40°. GM calls for at least a little toe due to the negative camber. If it had a toe out, with the negative camber, it would just trash the inside tread of the tires.

I suspect my best option is to do nothing, monitor tire wear, and most likely get another alignment when I do all 4 tires some years from now. In fact, I would hope at least 20k from now, which means the car will have 160k on it. And possibly consider getting an alignment annually as the PO claimed was necessary.

I really don't know how only the left rear would shift that far out of range, unless it really is just a combination of bushing wear and our lovely roads. I mean it was at 0.4° positive camber, and he adjusted it a total of 1.3°negative ending up at -0.9° which perfectly matches the right. Happy that much adjustment was possible. Wonder if that was all it had.

Took it for a test drive.

The new alignment feels great. It tracks so well and is just awesome on the highway. And that weird sideways feeling on some sharp bumps when the rear hit, seems to be gone also. Pretty happy with this. Did not try any handling. That will come eventually. But the way it tracks and steers is great.

I will put this here since this was sort of also a tire thread.

So I had been thinking that the new tires looked a little short, as in lower profile than I expected. Even though they are very similar to the front tires (really just a newer revision), I figured, maybe they run a little short. The excessive wheel well gap was a little annoying for brand new tires at full tread...

I was just outside getting Ian off the bus and I finally decided to really look closely at the size. Unbelievably, they are both 255/40-18. The size I ordered, and the correct rear size for this car is 255/45-18.

So I call Tire Pros. First he quotes me for two of them (which was like $202 or something, even more than Tirerack). I'm like....no, I am asking if you have my tires. He said we do not.

So I call Tire Rack. The lady was nice and basically said, yeah our warehouse has been crazy. I had to send two pictures of the sidewall which I did on the phone. She received those and said they will ship two out and also cover the mounting/balancing. I would have to bring the old tires to my house for them to be picked up. Fair enough right?

Well I call back Tire Pros and I basically said, OK, Tire Rack is shipping two new tires, so I guess we can do this like Saturday again. At this point, he's like "oh, well we found your tires." Definitely shame on the tech but they apparently had the EXACT same Continental ExtremeContact DWS06 in 255/45 and 255/40. That is extremely uncommon, because there are so many different tire brands, models and tire sizes these days.

I e-mailed Donna @ Tirerack that there was a mistake and to cancel the new tires.

Tire Pros will cover the re-mounting and balancing, because they should.

At first the guy at Tire Pros is like...maybe you should let them ship the new tires and get a set of 4. At first I'm like....ok that's dishonest but....yeah I could use 4 I guess. But then I told him they needed the 255/40s back and he's like...well those probably belong to a customer so, never mind all that. lol

I said please don't install my 255/45s on another car....

Annoyingly I have to go back but I will just wait for it because it should be quick. That is just crazy. Tire Pros made the mistake, but apparently the logistics situation at Tire Rack's Windsor, CT warehouse has been crazy enough for this not to be a stretch to have happened.

And fun fact: the stability control stuff apparently did not have an issue with the aspect ratio being one step too small. I mean I didn't scan so who knows, maybe there is a silent code in there, knowing this car...