W203 lower front arm

[Tim203]

Sorry about wrong place but can't start threads in technical for some reason.
My question is are the lower arms for sport pack suspension different to standard ? I put a new arm ( non genuine but expensive pattern) on this evening and the steering wheel is so far off centre looking left the ESP has chucked its toys out the pram. Car still drives straight though! Probably the hideous amounts of toe it's trying to cope with. The tracking has not been adjusted before the ball joint wear caused this replacement to be necessary and tyre wear is not uneven, hence wanting to find our about the arm first before I put another one on.
Thanks
Tim

 

[whitenemesis]

If you fit new suspension arms one has to have the geometry checked and adjusted. Even when fitting genuine MB parts. The manufacturing tolerances are large enough to upset the angles. This from my MB service manager.

 

[Tim203]

Thanks white nemesis for your input. It does make me wonder how accurately these parts are made, I didn't have this issue doing a top arm on the near side a year ago. Think I'll take it off again and measure it against the other one once I've got it out the scrap bin!

 

[whitenemesis]

The worn rubber bushes will skew your measurements?

 

[Tim203]

The worn rubber bushes will skew your measurements?

True, but I can take the hole they go thro in the forging. Update tomorrow!

 

[Tim203]

If you fit new suspension arms one has to have the geometry checked and adjusted. Even when fitting genuine MB parts. The manufacturing tolerances are large enough to upset the angles. This from my MB service manager.

Just a thought, apart from the tracking what can I do? I assume the locating lugs for the bolts in the slotted alloy bushings are fixed and the slotted hole to prevent subframe damage in the event of heavy curbing ( sacrificial so to speak)

 

[Tim203]

Comparative measuring of suspension arms, new for old how too. This is tricky to do at the best of times especially because of ball joints.
I've kept it simple ( tool wise) as I'm fortunate enough to have a good workshop. As you will see from the photos there are 2 squares, a clamp, a suitable bolt or in my case piece of tube to locate inner bushes and a flat surface. As you can see the replacement arm is approx. 5 mm shorter than the OE.
I photographed both front wheels ( offside arm changed) and the steering is set straight ahead. I haven't had any problems before with motaquip but these parts ( I got a second to compare) obviously went under the inspection radar.



























As you can see 4-5mm caused a lot of toe out!

 

[Tim203]

After getting a first line part today it's now clear that they and motaquip should sort their databases out for these parts as the spy suspension arm is definitely different. Worth noting as with most German cars they have an appetite for ball joints.

 

[Auto-mobile]

When these arms are changed you will need the geometry checked, bolts should be tightened with suspension under load, on the bush end of the arm there is a lot of movement pre tightening, the means you can tighten it in any position.

 

[Rory]

If you fit new suspension arms one has to have the geometry checked and adjusted. Even when fitting genuine MB parts. The manufacturing tolerances are large enough to upset the angles. This from my MB service manager.

Had mine done twice at the dealer and they insisted it wasn't necessary to check the geometry and the car seemed fine.

Never done this job myself, but think I've read it's important to tighten them up with the car on ground.

 

[whitenemesis]

Had mine done twice at the dealer and they insisted it wasn't necessary to check the geometry and the car seemed fine.

Never done this job myself, but think I've read it's important to tighten them up with the car on ground.

I think we know what your dealer is like, from your previous posts?

 

[Rory]

I think we know what your dealer is like, from your previous posts?

To be fair, I'm super-sensitive to alignment issues but it was unchanged from how it was before being done.

 

[Tim203]

Thanks for your contributions guys. The plot has now thickened. My local motor factor phoned me today and said there was only one part regardless of suspension options. Sooo, off to Benz in Taunton where they echoed this and I checked my arm to their OE part (£115 ) twice the price!. Exactly the same, 5mm too short. Both arms on my car look to be of the same manufacture marked with L&R but not original. So what do I do. If the parts are correct there should be little or no toe adjustment required. If I change both it will look like Charlie Chaplin going down the road ands require probably 5-10 mm adjustment on the track rods to sort it. Can anyone throw any light on this.Both upper arms were switched for the last mot and it steers perfectly. Tyre wear is even as well. Cheers Tim Ps. I know it should be in technical but page freezes on my I phone for some reason.

 

[Auto-mobile]

You can get camber correction bolts from Mercedes.

 

[Tim203]

^^^^ what I don't understand is what model arms are fitted to my car and if they are wrong then whoever fitted them must of adjusted the tracking by 5 degrees each side to get it steering straight. Surely you'd question that wouldn't you?

 

[wu56Shoozz]

A variant that may cause this is "Sports Pack" - your car may have been fitted with a sports pack hence the change of suspension.. I'm finding this on my C320

 

[Tim203]

A variant that may cause this is "Sports Pack" - your car may have been fitted with a sports pack hence the change of suspension.. I'm finding this on my C320

I thought that but MB and 2 other pattern suppliers give the same part no.
Did you get the correct part or part number?

 

[whitenemesis]

EPC shows only the one part number, no mention of Sports Pack/Sports chassis

A2043302011 - Right
A2043301911 - Left

 

[Tim203]

EPC shows only the one part number, no mention of Sports Pack/Sports chassis A2043302011 - Right A2043301911 - Left

Thanks very much for looking for me. I'll pick up a pair tomorrow and borrow some tracking gauges. God knows where the other pair came from.

 

[Auto-mobile]

A variant that may cause this is "Sports Pack" - your car may have been fitted with a sports pack hence the change of suspension.. I'm finding this on my C320

The arms are al the same, sports pack or not.