Alignment after front strut replacement?
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Junior Member
Joined: Apr 2022
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GL550
Alignment after front strut replacement?
On my 2011 GL550 with 70,000 miles, I replaced the front struts due to slow leaks in both. (It wasn't a horrible job.) It seems the slow leaks caused the front tires to excessively wear on the inside edges, or at least I thought that was the cause. After replacing the struts, I bought new tires. After 2000 miles, it may appear there is more wear again on the inside edges.
Is an alignment necessary after strut replacement? It does not appear there is any adjustment for caster or camber, and I would not expect this wear to occur from toe being out of spec.
Thanks all.
Is an alignment necessary after strut replacement? It does not appear there is any adjustment for caster or camber, and I would not expect this wear to occur from toe being out of spec.
Thanks all.
Super Member
Joined: Jan 2007
Posts: 624
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From: CA
11 ML550, 95 Supra TT, 14 Audi S4
Alignment isn't necessary on a vehicle like a GL after shock replacement, since shock position (as opposed to struts) doesn't change the suspension geometry. If the shocks were leaking badly enough to allow the front end to sag before replacement, what would increase negative camber and tire wear.
I forget the stock specs, and while camber isn't adjustable up front, I think it does have a some negative camber built in which combined with a toe setting that is off, could explain additional tire wear after replacement.
I forget the stock specs, and while camber isn't adjustable up front, I think it does have a some negative camber built in which combined with a toe setting that is off, could explain additional tire wear after replacement.
Junior Member
Joined: Apr 2025
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2012 GL 450
Not required with just struts. You should change out the bags in the rear too, they arent too expensive and are extremely easy to change out. Probably a 30 minute job. (the rear struts are much more difficult because you have to take apart some of the interior to get to the top of the shock.)
Most german cars have a very agressive stock alignment and will have more inside wear than outside. How bad is the wear?
Most german cars have a very agressive stock alignment and will have more inside wear than outside. How bad is the wear?
MBWorld Fanatic!
Joined: Sep 2005
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From: Albuquerque
'10 CL550, '12 GL550
Lots of confusion here.
The word "strut" describes a suspension component that combines shock absorber and spring into a single unit. GL have struts in front suspension.
At rear, GL have separate springs and shock absorbers. There are NO struts at GL rear.
FWIW I observed on my GL that life of the rear shock absorbers is very similar to life of rear air springs. So, replaced all four units at same time. A shock absorber leaking oil is finished. Not leaking does not mean no wear.
The original poster queries regarding replacement of struts in his front suspension. If he can get the little studs on top of strut mounted into same positions as previous struts, alignment will be unchanged.
GL has independent rear suspension so obviously there are alignment specifications. Removing/replacing rear springs or rear shock absorbers has zero affect on alignment at rear.
Some GL have ADS shock absorbers. Adjustable damping system. It's optional equipment. The front struts and rear shock absorbers have electric solenoids attached that are used to change internal shock absorber oil flow and consequently stiffness of the suspension. A dashboard switch provides positions "sport" and "comfort" with corresponding lights. Possibly little known ... your owners manual describes a third position called "normal." There are no lights illuminated in this position.
Because shock absorbers wear out, replacing both front struts and replacing both rear shock absorbers at the same times results in equal performing shock absorbing and handling across axles.
The word "strut" describes a suspension component that combines shock absorber and spring into a single unit. GL have struts in front suspension.
At rear, GL have separate springs and shock absorbers. There are NO struts at GL rear.
FWIW I observed on my GL that life of the rear shock absorbers is very similar to life of rear air springs. So, replaced all four units at same time. A shock absorber leaking oil is finished. Not leaking does not mean no wear.
The original poster queries regarding replacement of struts in his front suspension. If he can get the little studs on top of strut mounted into same positions as previous struts, alignment will be unchanged.
GL has independent rear suspension so obviously there are alignment specifications. Removing/replacing rear springs or rear shock absorbers has zero affect on alignment at rear.
Some GL have ADS shock absorbers. Adjustable damping system. It's optional equipment. The front struts and rear shock absorbers have electric solenoids attached that are used to change internal shock absorber oil flow and consequently stiffness of the suspension. A dashboard switch provides positions "sport" and "comfort" with corresponding lights. Possibly little known ... your owners manual describes a third position called "normal." There are no lights illuminated in this position.
Because shock absorbers wear out, replacing both front struts and replacing both rear shock absorbers at the same times results in equal performing shock absorbing and handling across axles.
Last edited by lkchris; Jun 18, 2025 at 05:23 PM.
Super Member
Joined: Jan 2007
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From: CA
11 ML550, 95 Supra TT, 14 Audi S4
Nope. Struts have concentric shocks/springs, but having a concentric shock/spring doesn't make it a strut. The difference between a strut and a shock is that a strut functions as a shock absorber and it also locates the upper part of the suspension, so the location of the top of the strut relative to the shock tower affects caster (front to back position) and camber (side to side position). The GL has upper control arms in front that locate the suspension so the airmatic units are shocks not struts. The location of the top of the shock has no impact on alignment since the position of the spindle is determined by the upper and lower control arms.
Super Member
Joined: Jul 2016
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From: NE OHIO
1998 SL500,2011 GL550,2009 ML350,past 1995 E320 Cabrio ,2005 ML500,2006 ML500,1996 SL500,1972 280SEL
struts vs shocks
Nope. Struts have concentric shocks/springs, but having a concentric shock/spring doesn't make it a strut. The difference between a strut and a shock is that a strut functions as a shock absorber and it also locates the upper part of the suspension, so the location of the top of the strut relative to the shock tower affects caster (front to back position) and camber (side to side position). The GL has upper control arms in front that locate the suspension so the airmatic units are shocks not struts. The location of the top of the shock has no impact on alignment since the position of the spindle is determined by the upper and lower control arms.
Notice the part where struts support the weight …
Springs on the struts are replaced with air bags in the original design. THEY ARE STRUTS..
To help the OP with the original question… tires are expensive.. alignments are relatively cheap… get a 4 wheel alignment at a shop that knows how to work on MB’s… you might want to spray all on the bolts with lubricant like Kroil especially the back bolts.
Last edited by vesiadog; Jun 22, 2025 at 01:27 PM.
Super Member
Joined: Jan 2007
Posts: 624
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From: CA
11 ML550, 95 Supra TT, 14 Audi S4
Upper control arms = not a strut. A strut does dual dual as a damper and a upper control arm. See: https://www.moogparts.com/parts-matt...0control%20arm.
People use the terms fairly interchangeably now, but strut is short for McPherson Strut, which is a suspension with a lower control arm to locate the bottom of the spindle and a strut, which locates the upper part of the spindle. Upper control arms are not part of the picture. The lower end of a strut has to mount to the spindle since it along with the lower control arm is what locates the spindle. The shocks on a GL/ML attach to the lower control arm.
Strut suspension are often used in small cheaper cars because they're compact and cheaper to produce. MB went with a unequal length control arm setup in the W/X164, which is a superior setup to due better camber characteristics while cornering and less friction in the shock since it doesn't have to deal with lateral loads.
A good picture illustrating the difference. Our upper control arms are much shorter, but the principle remains the same:
People use the terms fairly interchangeably now, but strut is short for McPherson Strut, which is a suspension with a lower control arm to locate the bottom of the spindle and a strut, which locates the upper part of the spindle. Upper control arms are not part of the picture. The lower end of a strut has to mount to the spindle since it along with the lower control arm is what locates the spindle. The shocks on a GL/ML attach to the lower control arm.
Strut suspension are often used in small cheaper cars because they're compact and cheaper to produce. MB went with a unequal length control arm setup in the W/X164, which is a superior setup to due better camber characteristics while cornering and less friction in the shock since it doesn't have to deal with lateral loads.
A good picture illustrating the difference. Our upper control arms are much shorter, but the principle remains the same:
Last edited by EWT; Jun 22, 2025 at 03:58 PM. Reason: added more info
