TeddyRuxpin

Hi all,

Recently done a lot of work on the car:

- Gearbox service & map
- New rear ARB drop links
- All front control arms (both sets) and ball joints replaced
- Front tie rod ends
- 4 wheel hunter alignment done
- Brake fluid flush & MOT (no advisories) @ MB specialist/indie

All parts were Lemforder. I also put on my 17” winter wheels/tyres. They had no issues with balancing before the suspension change, nor did my 18” OEM wheels, both had the same issue.

My problem is that the front right wheel/disc does not spin freely when lifted off the ground - it ‘catches’ at a certain point, and then is easier to rotate for half the turn.

I know the ‘obvious’ thing is that the discs are ‘warped’ but my understanding is that this is very rare. If the calliper were completely seized I’d expect it to stick the entire way around and for the disc and wheels to get abnormally hot. I’m thinking that it would be the calliper slide pins. Would this cause this wonky kind of ‘sticking point’?

If not, what’s a common/likely cause of a wheel sticking at a certain point? I did also notice that the nipple on that side (drivers side) was completely dry after the brake bleeding?

I took both callipers off when I did the suspension arms, and even removed one of the slide pin bolts briefly, so I’m wondering if the calliper just needs a bit of grease or ‘servicing’, or cleaning?

Real world side effects are subtle - a very slight judder in the steering wheel at 65+mph and a very very quiet ‘whoosh’ of the sticky point as the wheel the wheel spins once per rotation at slow speeds. I don’t have judder when actually braking. The light vibration I have at motorway speeds is only felt through the steering wheel and is minor enough that some might not notice it. Same with the sound while driving slowly - it’s only due to my ocd level of analysis that I noticed it, plus contrast to driving the car before I did all the work.

I am away at the moment so can’t take the car to a garage or look at it myself but thought I’d ask what some likely issues could be as I’ve spent so much time and money on the car I’d like to get it perfect.

Oh and I’ve checked the plate behind the disk but will do again to be 200% sure, when I’m back. I’ve also done multiple hard stops, but I don’t think that’s the answer.

Cheers

rapidoxidation

what happens if you spread open the brake pads manually (like leave an 1/8" clearance between pad and rotor for both pads in a caliper)?

Left Coast Geek

guessing the slider pins on the brake caliber need lubing, and maybe new seals.

S-Prihadi

Try reading this : https://mbworld.org/forums/e-class-w...y-achieve.html

Use marker like I did on the rotor outer and inner surfaces and see which region actually get rubbed hard by brake pad.
Find the region with highest friction, that will be the "high spot"

If you termed it as STICKING and can be felt during a drive albeit only subtle, I guess it is quite a friction you encountered and we have to agree that it is not normal.

If your car is RWD, front bearing freeplay when adjusted properly to 0.02mm or better 0.01mm will be good to reduce negative effects.
Bearing freeplay effects to what degree your brake rotor can "wobble" and can be adding to perceived rotor "warp".
https://mbworld.org/forums/e-class-w...ent-again.html


The other possibility of rotor being 1/2 rotation sticking and 1/2 rotation OK, is the rust at the hub.
The rotor sits on the HUB and rust can jack up surfaces to easy 0.5mm higher and if the rust is uneven, your rotor is then jacked up one sided that much.
https://www.ebay.co.uk/itm/122011769149

I do not know if your rotor is a drilled version or non drilled ones, drilled ones overtime create high-low uneven surfaces from rust and if the car get little use, the rust form thick enough surface and
the high and low spots will eat into the brake pad and rotor stay the same with high and low spots while brake pad wear accommodate those high and low spots, no good.
https://mbworld.org/forums/e-class-w...e-bedding.html
This high and low spots depending on severity can reduce good braking feel and smoothness.

The dust plate behind the rotor if it touches your rotor, you wont miss the weird metallic sound.

BRAKE CALIPERS
If your car has done enough mileage and brake caliper never overhauled , probably you can never get the seal kit and dust boot from MB anyway ,
to expect the caliper to be super smooth to create zero touch to rotor is quite difficult, more so if single floating piston caliper which I find as a very crude caliper design lacking
the 0.15 to 0.20mm piston retraction capability equally on inner and outer side. One side has no caliper seal as there is no piston , how would we get the natural piston retraction behavior from the seal ?

I have the luxury of doing my zero touch brake pad to rotor with brand new rotor and brake pad and new FRONT caliper seals + dust boot from Brembo.
If your brake caliper is a floating one with single piston, I doubt zero touch can ever be achieved to the level of 4 pistons calipers non-floating caliper,
as seen on my rear brake caliper compared to front ones.

You do not need to get rotor warped to feel its negative effect.
Merely uneven wear on the rotor to 0.25mm or so can cause subtle unwanted effect/s.


Good luck troubleshooting............

TeddyRuxpin

Hi all, thanks so much for the feedback so far. I just remembered that I had a short video showing the level of sticking, unfortunately it’s cut short as a kind older gentleman came over as I was filming it (in a wet car park) so I unfortunately it doesn’t show the problem side as much. You can see that the left is fine - the right looks like it sticks the whole way but there is a ‘sticky’ point and a ‘more free spinning’ point.

The sound to me comes from the inner side of the disk.

Apologies in advance for the breathing noises 😂


Forgot to mention: The car is RWD E350 CDI, brakes are drilled with single piston calliper. They are OEM discs and pads. There is no noticeable ‘play’ in the wheel bearing when you rock it back and forth when the wheel is in the air. The car is pretty well used.

I am eager for the new year to get back and try to find the source of the issue. I think I will try regrease the slide pins anyway as it looks like an easy job. I haven’t done much work with brakes before so have lots to learn.

Thanks!

ygmn

Check rotor runout.
Are pads equal thickness?
Is rotor thickness greater than Minimum? they look to have a pretty thick "EDGE"

If this was mine and I checked things over and nothing obvious.

I would replace pads, rotor, caliper & Caliper bracket. and perform proper brake job using brake grease on slides.
Use wire brush to clean hub where wheel center goes over.
light coat of brake grease (copper never Seize) on rotor face where wheel contacts to make future removal easy.

PS when all the brake stuff is off it is a good time to check wheel bearing.

TeddyRuxpin

Thanks all,

I'm going to investigate more and start with trying to find caliper slider and boot/seals and replace them as it seems an easy job, but trying to find something good for the OEM brakes. I'm guessing MB won't sell those parts alone, but I'll check.

When I last had the calliper off the disc spun smoothly with no play.

In the mean time if anyone has had this exact issue, I'd be curious to know what caused it for you!

Cheers,

S-Prihadi

Yes Right wheel seems very high friction and left wheel has some.
If all good and brake pad is a mere feather touch or zero touch, one 90 degree push-to-spin by hand with wheel attached, the momentum can produce 6x revolution easy with super slow stop...aka very smooth. Too bad the video of the test I did with wheel attached is in my home PC.

MB does not show caliper repair kit, seal and dust boot as parts you can buy, this upset me too for my rear caliper ATE brand.
I am fortunate Brembo has repair kit for sale, except the crossover seal. https://mbworld.org/forums/e-class-w...-overhaul.html

There are other aftermarket repair kit possibly, but do be careful when shopping them as brake piston seal quality being a dynamic one is a life and death matter.
Dynamic seal duty is tough. The aftermarket crossover seal I had no choice to use is static duty, so I do not worry so much as NO LEAK when installed means no leak for a long time.

TeddyRuxpin

Hi all,

Happy new year - I'm finally looking into this problem now. The W212 has sat for about 6 weeks on a battery charger while I use a different car as it's too cold/I've been abroad. Please don't mind the rust on the discs, I moved it a little but ultimately it needs a good drive to clear the discs and pads. I discovered that:

1) The slider pins are indeed seized. I could tap them with a hammer and move them about but they both don't move freely. I didn't check the left side of the car.

2) I couldn't remove the actual pins/sliders inside the rubber boots as I'm unsure how to get them out so I can lube them. I can't notice any obvious cracks in the rubber. Does anyone know where I can find a tutorial on how to disassemble the W212 style slider pins (i.e. not the ones where you just lube the bolt) - I can't just 'pull' them out.

3) Spinning the brake disk with the caliper and pads removed, there is a bit of wobble on rotation of the disk. I've recorded a video showing this below. Is this an acceptable level or should it be completely 'true'? Hopefully the video isn't too shaky. There is no play in the hub/bearings when I try to shake it from side to side.

My questions are:

1) How do I remove/lube the seized slider pins?
2) Is the 'wobble' acceptable/normal and could the issue be caused solely by the seized slider pins? I assume not, I am thinking that there are two issues. What do you think?
3) What do you think would be the most likely cause of this 'wobble'?

When swapping out the control arms, I removed the brake disk and hub from the strut - you can see this in the very short second video (second vid). Could I perhaps have incorrectly torqued the two main bolts that hold the hub to the strut? I will double check this of course, just wondering if this would cause this issue.

Any other thoughts would be welcome, thank you!

Ed

TeddyRuxpin

This video shows W212 slide pin removal but it looks so easy on this car. Mine is seized. Perhaps I'd have to clamp the caliper down and hit it with a metal punch? The only punch I have is too thin for this job, but I'm worried something that aggressive will tear the rubber. Any thoughts or suggestions welcome, please!

The video below should take you to the exact spot in the video

S-Prihadi

The way your rotor disc wobble, I think the bearing is gone already. There is a bearing inside .
https://mbworld.org/forums/e-class-w...ent-again.html

TeddyRuxpin

There is no play in the bearing at all, though, unlike in your video?

I'm thinking that this is due to incorrect re-assembly of the car when working on the control arms replacement - putting things back together was a bit rushed. It could even be a rust issue as surfaces weren't cleaned nicely.

S-Prihadi

I do not know exactly how your caliper design is, but for my rear brake which is a single piston like your front caliper, the metal slider pin is sliding inside a rubber bushing and not into metal.
Therefore it should not be "very stuck".

The rubber bushing is replaceable for mine and I am sure for yours too.

S-Prihadi

01. Remove the disc rotor and place it on a glass ( flat), see if it warped.



02. Rust is possible but it would be A LOT OF RUST between bearing hub to the disc rotor to generate that kind of wobble.


I once measure by hub tolerance. ABOVE



BELOW : With the anti-seize applied very thin, rust no more now.




Approx 8 months later when I re-check rust surface.

S-Prihadi

One more thing Teddy.
When you want to spin a disc rotor to see its actual wobble, make sure the small retainer bolt is installed and add 1 wheel bolt , and add 1 more wheel bolt on its opposite side. So total 2 wheel bolts.
This way the disc rotor is secured to the bearing hub in a proper way.

See below

TeddyRuxpin

Thanks so much for your detailed posts. With regards to the caliper slide pin, my single piston caliper design is exactly as in the video I posted:

TeddyRuxpin

Thank you - the retainer Torx sure was a little loose so I tightened it but I didn't add the bolts, I'll try that next time. In any case I couldn't sense any play, you can see in the video that I try to 'shake' the hub and there's no play detectable.

I'm worried that I perhaps bent the hub carrier or bottom strut mount ever so slightly or something like that. I didn't actually take the disc off the hub when I was working on it, I took the hub off the strut completely. Please see this video:

S-Prihadi

You can't shake a hub with such little force and fingernail grip , I tried such method.
Hence I uses the 2 extra long wrenches for leverage for best result.

Well, hub flange being bent when and if the wheel knuckle assy hit the ground too much is a possibility, albeit it will take a big force to bend the hub.