Alignment Caster Problem? - PeachParts Mercedes-Benz Forum

ksing44 · #1 11-15-2004, 07:12 AM

I just had new tires installed and I had the alignment adjusted. The car drives straight down the road, but my problem is that I think the wheels are set back in the wheel wells. The wheels are not centered in the arch of the fender and I am pretty sure that they were more centered before the alignment. The printout indicates that the caster was adjusted to 10.7 on both wheels, which is within the published range of 9.92 to 10.92. Is there some other adjustment that centers the wheel in the fender, or is it the caster?

I am concerned because the new tires look very close to the back of the front wheel arch and I think I actually heard the tires rub somewhere when I was testing the handling of my new tires. I stayed with the already tested 205/55/16 tires to avoid any problems with rubbing and now I think I may have a problem anyway. I just wonder if my super duper Porsche mechanic may have messed something up.

I also noticed that my steering response seems very quick. At first I thought it was the new Bridgestone Turanza LSH tires, but now I wonder if it is something about the way the car is aligned.

I almost always have some little kind of issue after I visit the mechanic and it doesn’t seem to make any difference if I go to the Dealer, the Porsche racing guy, or the independent mechanic place with two guys from Germany. They aren’t usually big problems, but there is always something. Right now it is getting the alignment perfected. A week or two ago I had service at the dealer and they damaged the stereo volume knob when replacing the flasher switch. I also discovered a dent in the stainless steel doorsill in the rear passenger side door. I think they must have stood on the doorsill when they loaded the snow tires into the back seat. I have had really big greasy footprints on the carpets and scratches on the paint after a complimentary wash. They lost my keys and special key fob. After installing new brakes, the heat shields were bent so they were making all kinds of noise rubbing against the wheels. They scratched the dash when they removed and reinstalled the instrument cluster. They installed one of my snow tires backward on the rim. These are all minor things, but over time it gradually degrades the vehicle and I just wish I could find someone to take care of my car as well as I do. I am a victim, because I can’t do it myself. It just seems like I almost always end up with something a little worse than it was before I took it to be fixed. Sorry for complaining, but I am frustrated about the alignment and I really don’t have enough time and energy to chase down the mechanic and negotiate with him about what might have been done improperly.

JoeR · #2 11-16-2004, 08:36 AM

Your car has been lowered. Caster is determined by the relationship between the upper shock mount and the ball joint. When you lowered it that angle increased and caster went out of spec on the high side.

To correct, the lower arm had to be adjusted by moving the ball joint rearward the bring the angle back.

Try visualizing this on a piece of paper if the above doesn't make sense.

You have choices... live with the wheel moved rearward, live with more than spec caster (not that bad, really), or raise the car back to spec height (right !!)

JoeR · #3 11-16-2004, 08:38 AM

BTW, did you get a figure on pre-alignment caster? Likely 11+.

ksing44 · #4 11-17-2004, 08:12 AM

Hello JoeR,

Your explanation sounds very plausible. Thank you for the insight into my problem. You are probably right about going back to the original ride height. This whole lowering thing has been quite a nuisance. It all started when I wanted new wheels and the mechanic told me that my car would look silly with a big gap between the tire and the fenders. I think there is absolutely no question that the OEM wheels and tires are a bit too small for these cars, so I began researching the idea of lowering the car. The Tirerack website and the Eibach website seemed to reinforce the same idea that was first proposed by my mechanic. In addition, descriptions of the famous Sportline suspension option also seemed to reinforce the idea that the hot set-up for the W124 was to get it just a little lower with stiffer springs, shocks, and swaybars. I went for it, and I DO LOVE THE LOOK AND FEEL OF THE CAR. The problem is dealing with the subtleties of the alignment. The camber is a real pain, even with the KMAC bushings. I am always worried that the eccentric bushing will strip or slip or something. Call me paranoid, but the camber is about 0.5 more negative than when the bushings were installed 3 years ago. The car may have just settled on the springs and new spring pads, but the ride height hasn’t changed, based on my measurements. I do worry about those "adjustable" bushings. For now, I am just going to live with the little concerns and enjoy the look and feel of the car.

Back to my issues. My printout indicates that the caster is 10.8 and 10.7 on the left and right side of the car, respectively. The specified range is 9.92 to 10.92. I wonder how much movement of the wheel can be achieved by making small changes in the caster. I could have adjusted to the maximum range or even slightly above the range, which is what I think you are indicating. I also wondered if there is any other way to adjust the orientation of the wheels, like the "set back" that I also see listed on my alignment printout?

Thank you for your help so far.

Ken