Pulling left under braking

[Fergalw204]

My car (W204 facelift) recently failed its MOT on rear brakes, handbrake efficiency and front near side control arm.
I put the car into the local merc indie for repair and since it’s came out the car pulls to the left quiet bad under braking and it is a pain to drive.
Before any work was carried out the car drove straight as an arrow, the car has been on the hunter wheel alignment machine twice and looks to be good but the pulling left under braking continues.

I have today changed the front pads and discs to rule them out, the Caliper looks good and the sliding pins etc are all fine and working well.

As the car was fine before the work was carried out could the control arm that was installed be at fault?
The rest of the suspension looks to be in good condition, I checked myself while the car was on the hunter wheel alignment machine and it’s recently passed the MOT where it was all checked.

 

[optimusprime]

You should have returned the car back to them .Giving a car back to you in an unroad worthy condition is bad on their part . You could get a second opinion on its condition .

 

[Montreal300]

Control arm bushing bolts were probably tightened when the wheels were off the ground. They must be torqued in the loaded condition to make sure the bushings are not preloaded.

 

[Fergalw204]

Control arm bushing bolts were probably tightened when the wheels were off the ground. They must be torqued in the loaded condition to make sure the bushings are not preloaded.

Do you think it would be a good idea if I Jack the car up, loosen the bolts the drop the car down and then torque them back up?

It’s a strange one because I’ve been back to the garage today and without looking at it they are adamant it’s the brakes and not suspension even though there was no problem with pulling left before the control are was replaced.

To rule out the brakes I changed the front discs and pads yesterday, Caliper seems in good condition, no leaks, the rubber boot looks good, sliding pins are working right.

I’ve been out on straight roads today experimenting and trying to get to the bottom of the problem.
If I drive at 50mph and hold the steering wheel straight, brake hard the car pulls to the left.
If I drive straight at 50mph let go of the steering wheel with both hands the car stays pretty much central but the wheel turns to the 1:30 position at the same time.

Now if it was brakes I would expect the car to go left with no hands on the wheel, anyone have any thoughts on this ?

 

[Fergalw204]

You should have returned the car back to them .Giving a car back to you in an unroad worthy condition is bad on their part . You could get a second opinion on its condition .

Problem is I left it a few weeks after picking up the car thinking it was only the tracking that was off and I use another car as a family car so it was parked up most of the time before I got around to getting the tracking done, although I don’t have much faith in the guys using the Hunter machine.

 

[Montreal300]

Do you think it would be a good idea if I Jack the car up, loosen the bolts the drop the car down and then torque them back up?

It’s a strange one because I’ve been back to the garage today and without looking at it they are adamant it’s the brakes and not suspension even though there was no problem with pulling left before the control are was replaced.

To rule out the brakes I changed the front discs and pads yesterday, Caliper seems in good condition, no leaks, the rubber boot looks good, sliding pins are working right.

I’ve been out on straight roads today experimenting and trying to get to the bottom of the problem.
If I drive at 50mph and hold the steering wheel straight, brake hard the car pulls to the left.
If I drive straight at 50mph let go of the steering wheel with both hands the car stays pretty much central but the wheel turns to the 1:30 position at the same time.

Now if it was brakes I would expect the car to go left with no hands on the wheel, anyone have any thoughts on this ?

You can try to reset the bolt torque but this comment has me confused. "If I drive straight at 50mph let go of the steering wheel with both hands the car stays pretty much central but the wheel turns to the 1:30 position at the same time." Are you saying the steering wheel moves by 90 degrees but the car stays straight??

 

[Fergalw204]

You can try to reset the bolt torque but this comment has me confused. "If I drive straight at 50mph let go of the steering wheel with both hands the car stays pretty much central but the wheel turns to the 1:30 position at the same time." Are you saying the steering wheel moves by 90 degrees but the car stays straight??

No mate, if I’m driving straight and let go of the wheel whilst braking the steering wheel will move from the 12 o’clock position to between 1 o’clock and 2 o’clock position on its own but the car stays pretty straight on the road.
If I drive in i straight line and brake whilst holding the steering wheel at 12 o’clock the car pulls left quiet a bit.

 

[Petrol Pete]

Take it to an MOT garage and ask them to put it on the brake Dyno . That will immediately tell you if the brakes are in balance .

 

[grober]

The W204 has a cornering stability system which selectively brakes each wheel independently. It does this through a variety of sensor inputs including wheel speed sensors [like ABS] cornering loading sensors and a steering angle sensor. Sounds as if the system may be getting mixed messages as to what the car is doing leading to instability under braking? The best way to solve this is to use a live version of the Mercedes diagnostic system to monitor what is going on while the car is on the move.

 

[Fergalw204]

If it was the braking system then I would think the car would pull to the left weather holding the steering wheel or not, as it is the car only pulls to the left when holding the steering wheel, if i'm travelling in a straight line, let go of the steering wheel and brake it doesn't pull to the left.

Its a strange one because the car only went in for rear brakes and front camber arm replacement and now i've got this pulling to the left issue.

 

[Fergalw204]

Take it to an MOT garage and ask them to put it on the brake Dyno . That will immediately tell you if the brakes are in balance .

Took it to a MOT garage today and the brakes a definitely in balance.

The camber arm that was replaced looks to be a cheap aftermarket part and when looking at it last night there appears to be no part number on it (picture below) so I think I should replace that with a Lemforder, Febi or Swag for better quality and see if my symptoms go away.

The issue with pulling left under braking only started after the control arm was replaced so it got to be something to do with that and a bad alignment setup up is probably adding to my issues.
It was aligned at brand chain garage so my have little hope it was carried out correctly.

 

[OneForTheRoad]

Took it to a MOT garage today and the brakes a definitely in balance.

The camber arm that was replaced looks to be a cheap aftermarket part and when looking at it last night there appears to be no part number on it (picture below) so I think I should replace that with a Lemforder, Febi or Swag for better quality and see if my symptoms go away.

The issue with pulling left under braking only started after the control arm was replaced so it got to be something to do with that and a bad alignment setup up is probably adding to my issues.
It was aligned at brand chain garage so my have little hope it was carried out correctly.

My guess Is the rubber bush in the arm is cheap crap and soft flexible rubber. It's not upto the job it's meant for.

 

[Fergalw204]

My guess Is the rubber bush in the arm is cheap crap and soft flexible rubber. It's not upto the job it's meant for.

I agree, I’ve now got a Lemforder one in my AUTODOC basket awaiting a decent discount before pulling the trigger, while I’m at it I’ll replace the drop links too then get a proper alignment done.

 

[Fergalw204]

Photo I forgot to add, couldn’t see any other markings on it other then what can be seen here.

 

[Petrol Pete]

Looks like it was cast in the 7th month of 2022. Did it have 3 positions for the camber bolt to go in ? was it put in the correct slot ?

 

[Fergalw204]

Looks like it was cast in the 7th month of 2022. Did it have 3 positions for the camber bolt to go in ? was it put in the correct slot ?

View attachment 142313

I’ve no idea, I didn’t install it.
What would be the correct position to install the camber bolt into?

I still think this arm is likely of poor quality and should be replaced with a better one.

 

[Petrol Pete]

Whatever position the old one came out . Or what the wheel alignment jig calls for . some cars (mine) do not have the slotted bolt so it can only go in one way . If the bolt is slotted it has 3 possible positions., each one adjusting the camber accordingly.

 

[Fergalw204]

Whatever position the old one came out . Or what the wheel alignment jig calls for . some cars (mine) do not have the slotted bolt so it can only go in one way . If the bolt is slotted it has 3 possible positions., each one adjusting the camber accordingly.

It’s unknown to myself as I didn’t take out the old one, might explain the pull to the left if it’s install incorrectly.

I will replace with arm with a quality one and take it to Track Torque - Car Servicing, Repair, Restoration and Racing
They know their onions, I had my car setup by them 2 years ago and it’s probably the best it had ever driven.

 

[ToeKnee]

Have you been to that place and asked them to check it over if they're that good? They might spot something else wrong and save you having to change the arm.

 

[OneForTheRoad]

It’s unknown to myself as I didn’t take out the old one, might explain the pull to the left if it’s install incorrectly.

I will replace with arm with a quality one and take it to Track Torque - Car Servicing, Repair, Restoration and Racing
They know their onions, I had my car setup by them 2 years ago and it’s probably the best it had ever driven.

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2.10 min in.

If the car is fitted with normal bolts , it will of only ever been fitted in the central position. I don't even think the w204 has the slots in the arms ,just a hole , so maybe uses cam type adjustable bolts ,if at all. ??