What Are Optimal Alignment Specs

[crazy4trains]

So I put new tires on my e39 in July of last year. The purchase included lifetime rotation/balance and a one year alignment warranty. I'm going back in Friday for my rotation and am going to have them check the alignment. Car feels a little unsettled at interstate speeds.

Rather than just shoot for the car being in specified ranges, I really would to tell the shop what alignment measurements I want. On the front I want both toe measurements to be the same, so what should I shoot for? I've read that positive toe accounts for the rolling resistance of the tires etc. so I'm thinking a little positive toe on each side, something like 0.05-0.10 degrees, but the same on both sides.

With regard to rear toe I haven't found as much info on that. Again, I think I want them both the same. Should I lean toward the lower end (0.05 degrees) or the higher end (0.22 degrees).

Ditto with the rear camber.

I know I'm probably slicing the baloney pretty thin, but I want to get it as close to optimal as I can.

Below are the alignment results from July 2018. Hopefully the alignment tech doesn't look at me sideways.

What are your thoughts/recommendations?

[crazy4trains]

Bump


Getting this done tomorrow.


I'm leaning toward zeroing in on the middle of the spec'd range.


Front toe: 0.07 to 0.1 degrees with emphasis on both sides being equal. Staying away from negative (outward) toe values
Rear toe: 0.12 to 0.15 degrees again with emphasis on both sides being equal
Ream Camber: -2.1 to -2.2 degrees again with emphasis on both sides being equal


As I said before I'm probably slicing the baloney pretty thin, and the shop may tell me as long as it's within spec that's all they can do, but I won't get what I want if I don't ask for it.


Let me know what you think.

[WBAD530i]

If they are using a proper hunter alignment rack the specs should be built into the system. Just make sure they choose the correct car (530i sport).

The only issue I have ever ran into is the tech not having any idea the rear alignment can be adjusted with the control arms. They gave me the car back and said that was the best they could do. The alignment sheet showed the rear wayyy out of line. I then showed them where the adjustment bolts were. Live and learn. Hopefully the tech at your shop has had some experience with BMWs and not just hondas with tie rod adjustments.

[crazy4trains]

If they are using a proper hunter alignment rack the specs should be built into the system. Just make sure they choose the correct car (530i sport).

The only issue I have ever ran into is the tech not having any idea the rear alignment can be adjusted with the control arms. They gave me the car back and said that was the best they could do. The alignment sheet showed the rear wayyy out of line. I then showed them where the adjustment bolts were. Live and learn. Hopefully the tech at your shop has had some experience with BMWs and not just hondas with tie rod adjustments.

I know that the specs are built into the computer. They're tied to the VIN.

I want to tie the specs down a little tighter (i.e. I want to give the alignment shop an exact number for front/rear toe and rear camber to shoot for) and am looking for recommendations on which side of the broader spec range that I should zero-in on. For example, should I try to get more toe-in or more toe-out, but still within spec?

[geargrinder]

Woo hoo! First in with the "there is no 'perfect alignment', there is only 'perfect alignment for you'" comment!

Srzly some guys like more neg toe (might not mean 'actual neg' but 'numerically less' at any rate) for better-turn-in, another guy wants toe leaning pos for better-highway-stability and reduced tire wear... same basically for camber... There was some guy around here a few years back who wanted the max tire life settings he could possibly dial in... and I'm sure I'd really have not liked his car and found it really dead feeling and poor handling compared to what I expect.

If you want to "play a little" tell the guy to dial it to the ends of those spectrums within factory (instead of centering it which is what they'll typically do) but if you have a real pro alignment guy he might even make recommendations that could fall slightly outside based on a discussion... My guy would for instance set the toe and camber a good notch outside factory spec if I told him I was tracking it. Of course we don't have a lot of adjustability on these cars from factory - front camber has basically zero adjust in it unless you find some camber plates (and there aren't a ton of those for the platform either... )

[crazy4trains]

Woo hoo! First in with the "there is no 'perfect alignment', there is only 'perfect alignment for you'" comment!

Srzly some guys like more neg toe (might not mean 'actual neg' but 'numerically less' at any rate) for better-turn-in, another guy wants toe leaning pos for better-highway-stability and reduced tire wear... same basically for camber... There was some guy around here a few years back who wanted the max tire life settings he could possibly dial in... and I'm sure I'd really have not liked his car and found it really dead feeling and poor handling compared to what I expect.

If you want to "play a little" tell the guy to dial it to the ends of those spectrums within factory (instead of centering it which is what they'll typically do) but if you have a real pro alignment guy he might even make recommendations that could fall slightly outside based on a discussion... My guy would for instance set the toe and camber a good notch outside factory spec if I told him I was tracking it. Of course we don't have a lot of adjustability on these cars from factory - front camber has basically zero adjust in it unless you find some camber plates (and there aren't a ton of those for the platform either... )

Thanks! That's the type of discussion I'm looking for. I really want to maintain highway stability without sacrificing all the handling characteristics of the factory sport suspension. I'm willing to live with some tire wear due to the negative camber on the rear but I don't want it excessive. I'll let the negative camber on the rear compensate for the slight loss of steering response gained from toeing the front tire in slightly. I rotate tires every 5000 miles so that helps mitigate some of the tire wear.

I realize I may not be able to get everything I want, but the more discussion we have will allow me to make and informed, but not necessarily correct, decision.

[geargrinder]

LOL. Sounds like you're a perfect candidate for "factory alignment!" then

[philly98540]

Less negative camber in the rear with stiffer sway bars is a good set up IMO. Keeps good tire contact on hard turns yet reduced tire wear on the insides of the rears. I like -1.5 to -1.75 rear camber with my 275 tires.

With softer stock sways, the car leans more in turns and needs more negative camber to compensate.

[geargrinder]

Hmm.... good tip!

[crazy4trains]

Less negative camber in the rear with stiffer sway bars is a good set up IMO. Keeps good tire contact on hard turns yet reduced tire wear on the insides of the rears. I like -1.5 to -1.75 rear camber with my 275 tires.

With softer stock sways, the car leans more in turns and needs more negative camber to compensate.

I do have an M5 sway bar on the rear so this is something I will definitely consider. The M5 sway bar is really the only modification I have made to the car. When I had the crap Conti DWS06 tires I couldn't tell any difference. They wiggled anytime I rolled into a corner. With the new Michelin Pilot Sport A/S 3+ I can tell the difference.

[crazy4trains]

I had to reschedule my alignment. Let's keep the discussion going if anybody has anything to offer.

[R Shaffner]

I have a 540 M Sport that was lowered, with HR springs. When I had it aligned a few months ago I had them use the M5 alignment as opposed to the normal "sport" setting (or as close to it as they could get without front camber plates). I've driven these cars for 200,000+ miles and on my current 540 that alignment makes a big difference. Much more balanced. Less understeer.

I haven't heard others chime in on that yet, but I wished I'd tried that alignment many years ago.

[Barrman]

Any alignment shop that has a Hunter machine and current software will have an option when doing the alignment. It is called "Tuner Alignment." It is already in the Hunter program. Once in the Tuner Alignment part of the software there is a choice for performance or tire life.

Most techs don't want to mess with the Tuner alignment because it wants ride height, tread depth and exact psi from each tire. You can't just click through without entering something for those values. The program even goes into test drives, tire temps at different parts of the tread and such.

Something to point out is the parts in your suspension and steering system. No matter what numbers you want it set at. If all of the parts, bushings, wheel bearings and ball joints are not in like new condition. The alignment will be useless due to movement caused by the worn parts. Your first post in this thread mentioned setting more toe in to make it so when the vehicle is moving the toe will be closer to spec. The factory toe setting is made with the knowledge the bushings in the system will compress or stretch a known amount. Worn parts move more than what that known amount is.

There is something called a "dry park check." Basically with the car on even concrete have someone saw the steering wheel back and forth about 45°. Or however much it takes to get tire movement in each direction. While the steering wheel is being moved. Another person is under the front of the car with their hand touching each and every bushing and connection of the steering and suspension system. You can feel slight movement before you can see it and you can see it before you can hear it normally.

Until everything that moves when it shouldn't is fixed. An alignment really won't do as good as you want it to and it will have to be done again after parts are changed to get to the exactness you seem to be hunting for.