I took my 2001 M5 (79,800 miles on it) to a tire store to get the wheel alignment checked and I have a few questions post-results.
Now the car went down the road true and straight, but the outer-edge of both front tires are showing considerable wear. Back in August I replaced the thrust-arm bushings due to steering wheel shimmy over 40MPH, and that solved that problem. I thought the wearing on the outer-edges might have been caused by the worn thrust-arm bushings (that is one of the symptoms as I understand it), but I thought it could also be caused by a bad case of toe-in.
1st question: Is the camber and caster on our e39 M5's adjustable? The tire store service writer claims that is not. I'm pretty sure this is not true, but I thought I would ask the M5 forum knowledge base before I call BS.
2nd question: What would cause my right-front wheel's caster to be out of spec? A worn bushing?
3rd question: For those alignment wonks out there, please look over my before and actual alignment values and tell me if there is anything I need to get taken care of (see attached image).
Just had mine done. Also, make sure they weight the car per BMW spec. Typical alignment shops give you a blank look on this one, but a good indy shop or a dealer will know exactly how to do it. Procedure includes weight in the front, rear and the trunk. Specs are out here, just do a quick search.
As Easy E said, the front looks like it has be making love to curbs, but NOT too much "love."
The rear camber is OK, for most NON-spirited drivers ... Lower NEGATIVE camber will give better rear tire wear ... less rear inside wear, wear which is common for factory settings. However, I don't understand why the rear Toe-in is so great ... large amounts of rear Toe-in would increase rear wear I would think, and possibly make the rear tires "humm" more loudly. I would think it offsets the wear advantage of less negative camber.
I am NOT an expert, but I would be thinking along those lines.
Thanks for the replies everyone. I didn't watch them do the "alignment" as I dropped the car off and picked it up after the fact. I wasn't expecting a miracle from these hicks, as their lack of BMW knowledge was to be expected. I honestly just wanted to get the alignment values so I could then determine if the work of an expert was needed. Looking at the right front caster as well as the rear toe, I think I should start looking for this expert.
Can anyone recommend an alignment expert with e39 experience in the Northern Virginia / DC area?
I am of the thought that alignments are better done by a knowledgeable dealer as opposed to a tire retailer..The average tire retailer may not see too many of our cars in a year, and you may not want them "learning" on your car..Just my thoughts
... I wasn't expecting a miracle from these hicks, as their lack of BMW knowledge was to be expected ...
Don't worry TOO much about their lack of BMW knowledge. From the looks of the printout, they are using a machine where you key in the type of car (BMW M5, for example) and year, and the alighment computer compares the Actual numbers to the Appropriate numbers for your car. But, in your case, I am still puzzled at the rear toe. They maybe had a reason for that setting ... you should point it out to them and ask.
The alignment machines available today, don't take any brains, other than setting the steering straight, or resetting it and knowing how to compensate for the change (herein, could be problems for people who are dummies), and knowing what to adjust to change the settings ... You or I could do it just fine, with 5 minutes of training.
The rear toe has me concerned and just as soon as I locate the best shop I will get it aligned again.
I'm starting to think the out of spec caster on the right front might have been a bad pot-hole I hit recently. Pot-holes are sprouting up around here like mad due to the snow plows. Could a bent strut or control arm cause this negative caster?