R129. First drive in months. Grinding noise from OSR when turning left

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R129mine

Active Member
Joined
Feb 13, 2007
Messages
676
Location
Buckinghamshire
Car
R129 SL500 from 96
Hi

went for a drive yesterday and noticed a grinding noise from OSR and after a few mins this noise only appears now when turning left

took the wheel off and the protective plate for the brake disc seems to be a tad corroded and I suspect this is the cause of the problem.
EF5E9BE1-45EE-4D3F-9CD5-9166DC5DA8E7.jpeg

there is no play in the suspension at all but

quite a few of the bushes and some of the bolts and nuts have seen better days


C5F57AD3-58AC-4F7D-9740-2362C87CC9F5.jpeg
BCE72CE2-7DE9-454E-A1C4-E377B807EA88.jpeg

will first replace the protective cover and see if that fixes the grinding issue and will investigate replacing some of those suspension parts later on
 
I am doing all of my rear suspension just now incl the subframe as it was full of surface rust..its a big job doing it on the driveway...there is a video that shows you how to do the Dust plate without taking the Hub/Flange off...that is the way I would go as it could mean having to fit a new wheel bearing when you take the Flange out..getting that out can be a nightmare... when I took my Discs off I found that the Dust plate had rusted through where the springs for the brake shoes fit and everything was loose...I would bet this is the grinding noise you hear..Good luck...
 
I have been following your rear suspension work. Very impressive. Thanks for the tip. I will give it a go

at some point I like to do drop the whole subframe and clean it up but that will be some years down the line. It is in an okay state at the moment for the age of the car but
 
I found 2 videos (both w203 cars)
  • Video 1 he cuts a part of the cover so you can slide it over
  • Video 2 he cuts it in half
Each method seems to have its advantages, with method 2 you have the full dust cover protection and with method 1 you have a bit less but no 2 halves with a possible small gap.

I also had a look at the state of the brake disc
  • 8.5-9mm thick, not sure what the min is, markings on discs are gone)
  • and pads was difficult to see but can imagine they are about half way gone if not more
my rear brake pads and discs service history tells me
  • I bought the car with 70k on the clock
  • I had FMSB up to that point and I have all of the receipts from 50k to 70k from the previous owner
  • There is no mention of brake discs/pads at the rear having been replaced by previous owners
  • I replaced the Brake pads at 120k 6 years ago and am now at 157k
  • So previous interval was min 70k miles but perhaps never been done? I am not sure what the life expectency of rear brake discs/pads are
But I may as well replace the discs and pads and hand brake components while I am in there. Seems to make sense as they are relatively cheap to purchase

I will have a fun weekend(s) ahead :)
 
It'll most likely be corrosion on the backplate rubbing on the disc, I've just had the same. It was made worse by a seized rear caliper, where the still working outer piston was pushing the disc onto the backplate under braking as well. The cleaning pattern on your discs suggests your calipers may not be too happy either.

Unless the backplate is completely haggard I'd just clean it up and give it a paint, don't see the point in bodging to replace them. Hand brake components will probably be fine, mine still look in good condition with 160k. Min thickness on the 278x9mm disc is just over 7mm, for the 290x10 it's 8.
 
I found 2 videos (both w203 cars)
  • Video 1 he cuts a part of the cover so you can slide it over
  • Video 2 he cuts it in half
Each method seems to have its advantages, with method 2 you have the full dust cover protection and with method 1 you have a bit less but no 2 halves with a possible small gap.

I also had a look at the state of the brake disc
  • 8.5-9mm thick, not sure what the min is, markings on discs are gone)
  • and pads was difficult to see but can imagine they are about half way gone if not more
my rear brake pads and discs service history tells me
  • I bought the car with 70k on the clock
  • I had FMSB up to that point and I have all of the receipts from 50k to 70k from the previous owner
  • There is no mention of brake discs/pads at the rear having been replaced by previous owners
  • I replaced the Brake pads at 120k 6 years ago and am now at 157k
  • So previous interval was min 70k miles but perhaps never been done? I am not sure what the life expectency of rear brake discs/pads are
But I may as well replace the discs and pads and hand brake components while I am in there. Seems to make sense as they are relatively cheap to purchase

I will have a fun weekend(s) ahead :)
I would have used method 2..like you say..you get full protection from the cover....one job Im not looking forward to is putting the Brake shoes back on...I hate them..those darn springs..:wallbash:
 
It'll most likely be corrosion on the backplate rubbing on the disc, I've just had the same. It was made worse by a seized rear caliper, where the still working outer piston was pushing the disc onto the backplate under braking as well. The cleaning pattern on your discs suggests your calipers may not be too happy either.

Unless the backplate is completely haggard I'd just clean it up and give it a paint, don't see the point in bodging to replace them. Hand brake components will probably be fine, mine still look in good condition with 160k. Min thickness on the 278x9mm disc is just over 7mm, for the 290x10 it's 8.

Just checked the part number used back in 2014 and they were Pagid and 290x10. currently at 8.5mm so may as well replace them now

Priced it all up on Autodoc and £155 for 2x discs (ATE), set of pads (ATE) and the covers (metzger, never heard of them but middle of the range in pricing).

Agreed on the parking brake pads, makes sense given their usage

Is there an easy way to test rear Calipers? never noticed any problems.
 
Check the brake part prices with Mercedes Benz for OEM parts, you might be pleasantly surprised. Europarts are having (yet) another promotion right now (code MID60) . Sometimes their prices are unbeatable.

About a year an a half ago I bought 345mm Brembo cross drilled ventilated front discs for my C55 AMG (Stock fitment) from them for £55+ VAT !! (each)
 
ECP (with discount) and Automox have very similar prices but ECP only do Pagid (which is what I currently have) but I like to move to ATE and ECP don't do the protective covers.

on eBay I cannot find the same size (290mm) brake discs by ATE, they are all 300mm

Automox sometimes apply additional discount if you leave items in your basket overnight.

but always worthwhile checking a few different sites
 
ECP don't recognise the existence of anything except the early solid (278x9) and later vented (300x22) brakes, which is why I had to return a set of recon calipers to them this morning. My existing calipers are now in the hands of Bigg Red - those of a weak constitution should look away now.

FbYSn9Kl.jpg


The wear pattern on the disc will give some idea - in my case it was obvious the inner piston was doing nothing. The clean radius on the disc was caused by the contact with the backplate.

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Additionally, you can look at the wear on the pads to see they are balanced, and best of all unbolt the caliper and see if the pistons move evenly when the brake pedal is pressed.
 
Additionally, you can look at the wear on the pads to see they are balanced, and best of all unbolt the caliper and see if the pistons move evenly when the brake pedal is pressed.

Thanks for that and will do will have a look this weekend

New parts are on their way from autodoc (additional 1% discount overnight :)

Did you send of your Caliper to have it refurbished by Big Red or are they swapping it out like for like?
 
Hi

went for a drive yesterday and noticed a grinding noise from OSR and after a few mins this noise only appears now when turning left

took the wheel off and the protective plate for the brake disc seems to be a tad corroded and I suspect this is the cause of the problem.


there is no play in the suspension at all but

quite a few of the bushes and some of the bolts and nuts have seen better days
will first replace the protective cover and see if that fixes the grinding issue and will investigate replacing some of those suspension parts later on

Wheel bearing?
It will have been missed if the park brake was on.

There's a reason the noise is only present when turning left.
 
They didn't have any for exchange, but this is not particularly surprising given the rarity. You can see where MB have simply stretched the older caliper design to accomodate the wider disc.
 
Wheel bearing?
It will have been missed if the park brake was on.

There's a reason the noise is only present when turning left.

at first the noise was constant. After a short drive it stopped and could only be heard when turning left.

after I removed the wheel yesterday I bent the protective cover back a bit and I drove the car again today and no noise so pretty certain it is the protective cover.
 
at first the noise was constant. After a short drive it stopped and could only be heard when turning left.

after I removed the wheel yesterday I bent the protective cover back a bit and I drove the car again today and no noise so pretty certain it is the protective cover.

So a steel plate bends under the centrifugal force of cornering left?
Have you checked the wheel bearing?
 
So a steel plate bends under the centrifugal force of cornering left?
Have you checked the wheel bearing?
if you put it like that.

I put the car on a jack stand and tested for play and all seemed okay. I know it is not a definite answer. Both sides were very similar.

who knows but if seems odd that it has stopped now since I have bend the protective plate.
 
Mine was doing this. Worse when turning. It was the dust plate. Quick bend of the plate and it stopped.
 

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