Alignment Results Interpretation (Camber) - PeachParts Mercedes-Benz Forum

bustedbenz · #1 10-22-2013, 11:16 PM

I would appreciate some help translating an alignment report into a parts list, please. Or at least a plausible problem description.

Car: 1982 300SD.

Tires that came off were Michelin Harmony (which have given me excellent wear in the past). Rotated faithfully every 5,000 miles. On my 240D and on my 300SDL, that same tire typically yields ~35,000-40,000 miles to a set. On THIS car, the tires were installed in 2011 and had at most 20,000 miles on when they failed. The fronts were worn down to the cord on the INSIDE (both left and right, worn to the inside) and the outside was somewhat close to the wear bars but not quite down to them. The rears were intact, but also worn down further than I expected in so short a time and so few miles.

When that set of Michelins was put on, the car was computer aligned. At that time they told me that they were unable to put the rear 100% as it needed to be because the rear springs were sagged too low. At that time, I didn't do anything to correct the situation. So, it could be that the rear springs really did kill these tires just like they predicted. I can't rule that out, but at the same time I'd like some other opinions. Merchant's Tire did the alignment previously.

I just had a new set of tires put on and got the car aligned again (different shop this time) after replacing those Michelins that wore down to the cord too soon. Here is the report. I have boldfaced the numbers that concern me, and made all negatives red.

FRONT
CAMBER specification minimum: -0.33deg. maximum: 0.17deg.
LEFT initial: -0.45deg. RIGHT initial: -0.42deg.
LEFT final: -0.47 deg. RIGHT final: -0.49deg.

TOE specification minimum: 0.14deg. maximum: 0.30deg.
LEFT initial: 0.17deg. RIGHT initial: -0.74deg.
LEFT final: 0.15deg. RIGHT final: 0.18deg.

REAR
CAMBER specification minimum: -2.25deg. maximum: -1.25deg.
LEFT initial: -0.19deg. RIGHT initial: -0.19deg.
LEFT final: -0.22deg. RIGHT final: -0.16deg.

TOE specification minimum: -0.08deg. maximum: 0.75 deg.
LEFT initial: 0.31deg. RIGHT initial: 0.35deg.
LEFT final: 0.28deg. RIGHT final: 0.32deg.

~~~

So basically, the problems are as follows:
Right front toe was dramatically wrong; however, I want to note that the cord wear showed up on both front tires during the same long road trip. So I don't tend to think it caused this specific issue BECAUSE A) it affected the left side too, which was not out of spec, and B) the alignment shop was able to correct it, which tells me nothing is "too bad" wrong up there or else they wouldn't have been able to get it back where it belonged.

Front camber is too negative, by .1-.2 degrees. This was true both before and after this latest alignment.

Rear camber is slightly negative where it needs to be MORE negative. It isn't positive, but it isn't negative enough. The problem there is more on the order of 1-1.5 full degrees.

In reading forum posts, I've seen three things mentioned most frequently: sagging springs (which is what the first alignment shop told me two years ago), upper control arm bushings, and lower control arm bushings. Can anybody point me, based on these results and my experience with those tires, towards the most likely suspect and how to test for it?

The car has 180,000 miles (approximately) on the clock. Rebuilding the "whole thing" is really, really not an option financially. It was over $1700 to have a shop do that on the first 300SDL I had and the car just probably won't even be around long enough to justify doing that again. Springs are affordable and do-able; some of that front end stuff is more difficult and more expensive to say the least. If I can isolate and replace a bad component, that's one thing, but I'd really like something more specific to check than just "it's all shot". How do I prove which parts are shot and which aren't?

Thanks for any advice.

vstech · #2 10-22-2013, 11:30 PM

bring it down, and I'll look over the parts and recommend what needs to be changed.

sokoloff · #3 10-23-2013, 02:10 PM

I would think that a good alignment shop would tell you what parts need to be replaced. I've been to shops that said they wouldn't do an alignment unless such and such a part was replaced. I've also only been able to get proper alignments done at the dealer where they have and use the proper special tools. Just got a flyer from the Myrtle Beach dealer for an alignment special for $109. Not sure if that's a dealer wide ting or not.

I'd sure take vstech up on his offer.

bustedbenz · #4 10-23-2013, 03:30 PM

I'll definitely accept that offer after I do one more thing that I think I can handle on my own. After posting this, I ran across a thread that referenced a service manual procedure for measuring ride height. I think I will take the time to actually do this and see what I get. Since one shop has already told me that low rear springs are my problem, and since measuring is free, I think I'll check both ends / all four corners and see if I really can prove I need spring risers or new springs. If I can, then I can do that first.

If I don't reveal an issue there, I'll head on down towards Charlotte some weekend and we'll see what we find.

SD Blue · #5 10-23-2013, 05:22 PM

Before you point directly at the springs being the problem, there are several other areas to check for a sagging aft end. Rear subframe mounts and differential mount can contribute but the main thing that changed ride height on mine was replacing the rear trailing arm bushings. They were severely worn and it was hard to determine this until I lowered the trailing arm. I was surprised as well to find that this improved the front end as well (weight transfer I guess). Before, I had to be cautious, on uneven roads, about bottoming out. Now, she has a tight rear and everything is wearing evenly.

nelbur · #6 10-23-2013, 05:48 PM

Just a comment on the toe. When they do an alignment they fix the steering wheel straight ahead and then check the toe. They found right side way off. This would wear both front tires the same, as you would steer slightly left so the car would go straight down the road. So when driving, the tires on both sides will scrub equally. I think the front toe is why your tires wore out, and why the inside edge was the worst. In the good old days toe was measured as fractions of an inch in or out, when the measurements are compared between the front and back of the front tires. The rear was usually not a factor with a solid axle.

bustedbenz · #7 10-23-2013, 05:55 PM

Quote:

Originally Posted by nelbur

Just a comment on the toe. When they do an alignment they fix the steering wheel straight ahead and then check the toe. They found right side way off. This would wear both front tires the same, as you would steer slightly left so the car would go straight down the road. So when driving, the tires on both sides will scrub equally. I think the front toe is why your tires wore out, and why the inside edge was the worst. In the good old days toe was measured as fractions of an inch in or out, when the measurements are compared between the front and back of the front tires. The rear was usually not a factor with a solid axle.

Ahhhh!

I didn't even think about correcting for it. Makes perfect sense.

sokoloff · #8 10-24-2013, 01:08 PM

Locking the steering box (not necessarily the wheel) in the absolute center point is one of the places where a special tool, i.e. a pointed bolt, is used. There is a bolt on the steering box that is removed and the pointed bolt is screwed in a detent in the steering shaft. This is what locks the box in the exact center position and everything is adjusted off of that. Hopefully when this is done, the steering wheel is also centered, but it is possible that a shop didn't do the alignment right the last time and even though the steering box is centered, the steering wheel may not be.

Skippy · #9 10-24-2013, 05:46 PM

Quote:

Originally Posted by sokoloff

Locking the steering box (not necessarily the wheel) in the absolute center point is one of the places where a special tool, i.e. a pointed bolt, is used. There is a bolt on the steering box that is removed and the pointed bolt is screwed in a detent in the steering shaft. This is what locks the box in the exact center position and everything is adjusted off of that. Hopefully when this is done, the steering wheel is also centered, but it is possible that a shop didn't do the alignment right the last time and even though the steering box is centered, the steering wheel may not be.

I've done a lot of alignments, and I've never heard of doing it this way. I, along with every other tech I've ever seen, center the steering wheel and use a spring loaded holder to keep it that way.

KarTek · #10 10-24-2013, 06:34 PM

I'll just throw this out there: If you for whatever reason decide that you need to replace the front lower control arms, I want to have dibs on purchasing your old ones for experimenting...

sokoloff · #11 10-25-2013, 11:28 AM

Quote:

Originally Posted by Skippy

I've done a lot of alignments, and I've never heard of doing it this way. I, along with every other tech I've ever seen, center the steering wheel and use a spring loaded holder to keep it that way.

Skippy - I just went through the manuals I have on my 240D and none of them show the procedure for doing an alignment. If you have that, I'd like to see if what I said about the centering bolt is in print from Mercedes. The special tool for locking the steering box in the center is mentioned in the manuals for various other steering jobs - a part number is also given. On my ponton the centering bolt screws in from the top. On the 240D it screws in from the bottom. In both cases it replaces a standard bolt on the steering box. I have understood that this centering bolt and the spreader bar are two factory required tools for doing a Mercedes alignment properly. Any light you can shed on the subject would be appreciated.

Is it possible that if an alignment was done incorrectly previously that centering via the steering wheel will not actually center the steering box?