E82 alignment question - short term

[02Pilot]

So as I mentioned here previously, I'm going to be refreshing the suspension in my 128i - at 115k, it's time. The sway bar end links and upper control arms are the most worn, unsurprisingly. I already did the former, and while I was planning to wait until returning from a trip next week to tackle the rest, turning around in the driveway last night I heard a loud pop/crack from the left front at full lock. I checked this morning and, while everything was still intact, I am not about to drive a thousand miles with a suspension that makes noises like that, so the timetable got pushed forward to now.

All of which would be fine except that the parts vendor doubled up on one of the arms to the exclusion of another, so I only have three of the four arms at the moment. The fourth is on its way, but time's a-wastin'. I'm leaving Saturday morning.

This is all leading up to my question. Assuming I get and install the fourth arm, I will be very pressed for time. How crucial is it to get the front end aligned before I head out? The alignment was fine prior to this work, but these are the M3 arms that I believe add some camber over the stock pieces. Toe shouldn't have changed, as I didn't touch the tie rods. OK to wait until I get back (and have time to do the rear) or disaster waiting to happen?

[bmwdirtracer]

The M3 control arms won't add camber. Camber will happen at the top of the strut, with M3 or custom camber plates. I routinely change front control arms on BMWs without ever aligning the car afterwards.

Make very sure that the suspension is fully loaded when you tighten the bolts that go through the inboard bushings. Officially, this means 150 pounds in each front seat, and more weight in the trunk, but really, you can just jack up that corner under the ball joints until the suspension is fully compressed, and the car starts moving upwards.

[02Pilot]

Thanks Chris. It may be a moot point - though I got the correct arm yesterday, I don't know that I'll have time to get everything done by Saturday morning in any case.

I've done front arms on previous cars without realigning, but I was under the impression that the M3 arms added around .75deg of negative camber (some vendors list that info) over the stock pieces (I assumed they do this by being slightly longer - I should measure). The jack-under-the-ball-joint approach is exactly what I do.

While I've got you here, let me as you about the rears. Is it the same situation as the front in that the two upper control arms (not the swing arm or the toe link) can be replaced without disturbing the alignment?

[dworthy]

If you are talking about the 2 dog bones up top, then no. The lower swing arm is where the adjustment lies on that car thru an eccentric bolt.

[02Pilot]

OK, that's what I figured. There's an adjustment on the toe link too, right?

[dworthy]

Roger that, for you have two different adjustment available to you: Camber and Toe

If you don't mess with either one, or plan on lowering the car, then you should get it checked.

[02Pilot]

The car was lowered 10mm by the PO and aligned afterwards. I have the alignment report from exactly two years ago which shows everything in good order at that time, so I think I'll be good to go (assuming I can get the work done).

[bmwdirtracer]

IF the (front) M3 control arms really add negative camber, then you will have to have an alignment, because the tie rods will not be correctly adjusted if the bottom of the spindle/upright/wheel carrier moves outward. I haven't been aware of this before, but knowing how erudite you are, my friend, I'll certainly take your word for it.

Now, you CAN align FRONT toe, at home. It really just requires two flat ~2 foot long metal plates, and two tape measures. Have a look at Longacre Toe plates, and you'll understand the concept. It's not super-fast and easy, because you'll have to have several attempts to get the toe perfect, and then you'll drive it, and find out the steering wheel's a little off, so you'll have to adjust it again a time or two.....and then, you're going to have to reset the steering angle sensor. (What scan tool do you have?)

[02Pilot]

Well, good news and bad news. The good news is that I managed to get all the new arms installed - front and rear - this afternoon. Much less objectionable job than it was on the E39. The bad news is that the car doesn't feel right, which I suspect is due to the increased camber (and thus toe) from the M3 front lower control arms (which were bitchy to install on the subframe end, BTW - that was the only connecting point that required some persuasion to get the arms seated).

Handling feels a bit nervous, part of which may be down to the front LCAs having ball joints instead of bushings inboard. More worrying is that, when turning to sharp steering angles, the steering suddenly wants to take the car in the direction of the turn; in other words, it wants to self-steer all the way to the lock. Not ideal behavior.

I've done the home toe alignment with the string method on my 2002, so I know the basics, but with the E82 having adjustable camber up front as well, I think it's going to have to go on a rack. I've got a guy here who can do it, I just don't know if he can do it tomorrow. If he can't it will have to wait until I get back from my trip.

Chris, can you elaborate a little on the steering angle sensor reset procedure? The scan tool I have should be able to do it, but never having dealt with it I'm not sure what's involved. Should I bring it to the shop that's doing the alignment, or can I do it later?

[bmwdirtracer]

Likely, you have toe out. That equates to "nervous".

Are the tie rods in front of the upright, or behind it, on this car? If the tie rods are behind the upright, gaining more negative camber would likely cause toe out.

If the shop aligns it, and you don't have a warning light for ABS/DSC, don't worry about the steering angle sensor. If you DO get a warning light, it's a very simple procedure. You set the wheel straight, then tell the computer to learn the new straight ahead. 5 minutes, if you have an appropriate device. (What ya got, I forget?)

[02Pilot]

I've got the ECS Schwaben scan tool, which I'm almost positive does the steering angle sensor.

The rack is forward of the axle line, so that means toe in. Nervous may not be exactly the right word, in that it implies a sort of dartiness, which is not what I have. Rather, the steering seems a bit lighter and with less resistance, which amounts to more steering wheel movement (and thus correction) on rough roads, of which we have plenty. I'm not going to draw any firm conclusions until I get the alignment done, but the change is not what I expected.

What's the thinking on preferred front camber setting? If the M3 arms do indeed add ~0.75deg negative, that would put it out around -1.00deg total. Too much for street use?

[02Pilot]

Well, it's going to be a while before he can take the car, so while I wait, anybody willing and able to pull the alignment specs for the M-Sport 128i and the E9x M3 so I can compare and figure out what to request?

[dworthy]

Most BMWs come with about 1-2 degrees of negative camber. This is suppose to give the car better handling qualities, and when you go into the positive, it can get squirrely. At this point you may need a good alignment shop to ensure you are properly setup.

[02Pilot]

According to the alignment printout from two years ago, camber spec is -0.12deg front, -1.30deg rear. With the M3 front lower arms, I'm guessing I'll be around -0.9deg. I've got a good alignment guy with a new Hunter laser rack - I spoke to him this morning and explained the situation. He knows how to handle it. I'm just curious if I should ask him to dial out a little of the front camber (in the interests of tire life, mostly) to split the difference and put me around -0.5deg or so.

[dworthy]

I think that -1 degree or less doesn't do much to a tire as you are not going to wear too much on the inside. Now if you go more than -1 degree, then you start to get into the excessive wear area. I think the important thing is to keep the tire properly inflated, as the wagon loves to eat the inside of the tire if I let it get below 38 PSI on the rears.

[02Pilot]

Interesting. Keeping the tires at spec on the 128i, the fronts seem to be wearing evenly, but the rears show more wear in the centers, suggesting overinflation. Maybe it's a weight thing.

[shadowpuck]

i've always felt that toe impacts wear more quickly than camber. that said, obviously camber plays a role....
my 330 zhp runs around -1 stock camber in the front - even when i was driving that car 30k a year i didn't notice any abnormal wear up front.
to be fair, a 2003 330 is a much different car than a 128.....

[02Pilot]

So it sounds like taking the extra negative camber from the front arms won't likely be a big issue for tire wear; agreed that toe is the primary concern in that regard.

[bmwdirtracer]

I had a good forum friend (from M5 Board, in Finland) tell me that modern tires don't do overinflation wear patterns, and he's a tire guy. I disagree, completely.

Like with tire temperature, tire wear patterns really tell you the story of what's actually going on. If you're wearing the center, well, the tire's overinflated, for the use you're giving it....assuming there are no other wear patterns which contradict this.

Only time will tell, on the negative camber. Do you drive it hard enough around corners that this camber works in your favor?

[02Pilot]

Do you drive it hard enough around corners that this camber works in your favor?

Yes. Yes I do.

Eight seasons of autox, several rallies, and a few track schools may be in my past, but their legacy remains in my right foot.

[bmwdirtracer]

I had to ask.

My stepmom was bitching about her set of Hankooks on her MB E500 lasting only 2 years, so I had to tell her about the set of PS4S's that I had mounted on a Thursday, and destroyed by Sunday. $1200.....I'd been wishing for rain, but it didn't happen

[dworthy]

Yeah, over inflation is just as bad as under inflation. Got a car in that all 4 tires were around 55 psi, and the tires were dry rotting, and the tread had chunks missing. Owner didn't know anything about the over inflations, said he was just following what was on the tire. Once I pointed out the door jam had the right inflation and he needed new tires, he said thanks, and would think about the new tires.

So the moral of the story is to watch your tires, and inflate them to what gives you the best all around. I like to start with what BMW recommends, and add a couple, then remove a couple of PSI to see how it handles the best.

[02Pilot]

Just so we can have some closure here, I finally got the car in to be aligned. The M3 arms do indeed add front camber. I had it set up with -0.80 camber in the front and -1.60 in the rear. Haven't had a chance to really test it, but I'm hoping this will be a decent compromise between street performance and daily (i.e., non-tire shredding) driver.

[bmwdirtracer]

Those numbers seem quite reasonable. Interesting that BMW moved some camber alterations to the bottom. I live and learn; thank you, my friend.

[02Pilot]

I guess it was easier to just lengthen the LCAs a bit than to modify anything else. Fairly elegant solution, actually. The tech still had to pop the pins on the strut tops to tweak things, but it wasn't too far off the final numbers.