Car slightly drifts to the right at speed after alignment. - PeachParts Mercedes-Benz Forum

sjcruiser · #1 02-11-2006, 12:04 PM

Here are alignment numbers:

(Front) Left Right
=============
Camber: -0.9deg -0.4deg <== (shown out of spec - not adjustable?)
Caster: 10.1deg 9.9deg
Toe: 0.16deg 0.24deg

Cross Camber -0.5deg
Cross Caster 0.2deg
Total Toe 0.41deg

(Rear) Left Right
==============
Camber: -1.6deg -1.1deg
Toe: 0.20deg -0.17deg

Cross Camber -0.6deg
Total Toe 0.03deg
Thrust Angle 0.18deg

Could the alignment experts please chime in?

Thanks,
Frank.

stevebfl · #2 02-11-2006, 12:36 PM

That car is obviously going to drift right. In my estimation it was poorly done.

The reason for the drift is the difference in front camber left to right. The statement that it is unchangable can't be verified from this end, but it very likely could have been compensated for. The first way I would do it would be to shorten the left thrust rod which is basically a caster adjustment.

I would do it 20 flats or 3 1/3 turns (just a common counting number when doing it). This would reduce the caster on the left by about a 3/4 to 1 deg. It would also increased the camber on the seriously out of spec side about a third of a degree. This would bring the camber difference side to side to around .2deg or less, while reducing the tire eating characteristic of the poor camber situation. It also would creat a cross caster to the left of a little over half of a degree. A properly set up car with neutral tires will need at least a half degree of camber or caster bias to the left to work with the standard crown of the road average.

one can verify if this alternative was possible by viewing the turnbuckle at the left caster joint (rear strut rod mount). If threads are visable then this alternative was missed to really get it close to right with proper driveability as the real goal.

If such a real repair wasn't an alternative due to the left rod being as short as it could be, then the other alternative is to make the right side longer. This again will close up the cross camber while increasing cross caster to the left (drifts to the side of least caster or highest camber). This would not be as good of a repair although it would fix drivability. It would leave both sides closer together on camber but at the poorer setting.

t walgamuth · #3 02-11-2006, 01:22 PM

i was going to ask if you tried it on the left side of the road to see if it pulled left as much.

obviously steve knows his business.

tom w

ILUVMILS · #4 02-11-2006, 02:03 PM

If the front caster and camber numbers were swapped from right to left you'd be fine. There should be plenty of room adjustment. Unless something in the front end is bent, a decent alignment tech should be able to put a 126 right on the money.

t walgamuth · #5 02-11-2006, 04:57 PM

the tech mixed them up.

or is from the uk.

tom w

sjcruiser · #6 02-11-2006, 06:44 PM

Thanks a bunch Steve for your detailed response.

I made a mistake and have a closeby shop (non-MB) performed alignment after rebuilding the brake support brackets. I should have known better by reading a lot on this forum. Lesson learned (the hard way)!

I'm having the car re-aligned this morning (still under warranty). I'll update you guys with the new data once I pick the car up. If issue persists, guess I'd just experience with Steve's suggestions.

Cheers,
Frank.

jr6700 · #7 02-11-2006, 06:46 PM

Alignment was not corrected by the numbers. but also look at haveing the tires rotated (parrallel) it sometimes helps too.

sjcruiser · #8 02-12-2006, 11:06 AM

(Front) Left Right
=============
Camber: -0.9deg -0.4deg
Caster: 9.5deg 9.6deg
Toe: 0.22deg 0.20deg

Cross Camber -0.5deg
Cross Caster 0.1deg
Total Toe 0.41deg

(Rear) Left Right
==============
Camber: -1.3deg -0.7deg
Toe: 0.33deg -0.31deg

Cross Camber -0.6deg
Total Toe 0.02deg
Thrust Angle 0.32deg

Steve,

Would your settings still be applied with the new data? Also, if I understand correctly, my toe-ins would be unchanged afterward, right?

Regards,
Frank.

P.S: There were no threads left on both of my guide rods. I'll have to extend the PS side instead if it makes any difference.

stevebfl · #9 02-12-2006, 12:00 PM

If you are out of adjustment on the caster on the left, that is all you can do. Does it still drift? I am surprised you got .6 deg out of the caster with no change in camber. Should have made a couple tenths anyway.

If the drift is still there and bothers you, the alternative is to either fix your basic problem or finess it by increasing the length of the right side rod.

Your original problem of too little camber is likely due to worn bushings on either the lower control arm forward bushing or the upper control arm. You probably should look at solving that problem. A worn ball joint might also cause the problem.

sjcruiser · #10 02-13-2006, 01:38 PM

Steve,

Quote:

Originally Posted by stevebfl

If you are out of adjustment on the caster on the left, that is all you can do. Does it still drift? I am surprised you got .6 deg out of the caster with no change in camber. Should have made a couple tenths anyway.

If the drift is still there and bothers you, the alternative is to either fix your basic problem or finess it by increasing the length of the right side rod.

Drove the car to work today. It still does it; but less than before. Looks like I'd have to extend the right strut rod a turn or two from your earlier suggestion. Again, this would NOT change my toe settings, right?

Quote:

Originally Posted by stevebfl

Your original problem of too little camber is likely due to worn bushings on either the lower control arm forward bushing or the upper control arm. You probably should look at solving that problem. A worn ball joint might also cause the problem.

Lower balljoints, steering damper, all tierod ends, shock arbsorbers are also new. That leaves the lower control arm bushings (unlikely?), and upper control arms(UCA) left to check. I've bought the 4 outer bushings for the UCAs, so they'll be installed sometime this Spring, along with rebuilding the idler arm. How do I check the condition of the UCA balljoints? or yet, what are the typical symptoms of them going bad? I have that slack on the steering feel when going over bumps at slow speed that I have not able to identify.

Thanks,
Frank.

stevebfl · #11 02-13-2006, 02:47 PM

Making these corrections to caster does affect both camber and toe. The change in toe is fairly small but I personally wouldn't do this magnitude of change without reseting toe. If you were in the middle of the spec before you would be on the edge toe out after the left side correction. Since you gave complete new readings I figured you were checking it. You're measurements are in degrees and I'm used to millimeters (for toe readings) so I didn't pay much attention to toe settings.