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Discussion Starter #1
Hi,


Long time no visit, so happy new year All!


I have just got a quote for the replacement rear rotors(discs) and pads for my AMG 55 (2013-R172) with performance pack. A whopping £595 inc labour.


I am pretty sure they are the same as other 55 R172's on the rear, but am being told the price is due to the 'Performance Pack brakes.


I have searched on here and can only find info on R171 but nothing on R172 55 rotors and pads... anyone had experience (I have done 21K miles) or advice for these 85% worn expenses?
 

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Try Amazon.com and "SLK 55 rotor".

Besides Amazon, you'll find sources at the very bottom of the page. Looking at prices, I'd bet the parts alone will come close to $500.

Are your rotors worn or warped? The rear rotors seldom need replacement. Also it is a pretty simple R&R.
 

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Discussion Starter #3
Try Amazon.com and "SLK 55 rotor".

Besides Amazon, you'll find sources at the very bottom of the page. Looking at prices, I'd bet the parts alone will come close to $500.

Are your rotors worn or warped? The rear rotors seldom need replacement. Also it is a pretty simple R&R.

Thanks for the info, but I'm in the UK :).... The rear rotors are worn @ 85% of minimum thickness and suitably lipped, the pad backing is rubbing on the lips of the outside edge of the rotors, pads are at about 75%.


Go figure.
 

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Thanks for the info, but I'm in the UK :).... The rear rotors are worn @ 85% of minimum thickness and suitably lipped, the pad backing is rubbing on the lips of the outside edge of the rotors, pads are at about 75%.


Go figure.
You wore out your rear rotors beyond minimum thickness in just 21K miles???
Wow, that must be some driving you do.....:grin:
 

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Driving it hard would cause the front rotors to be eaten, not the rears. When breaking the fronts take most of the load. Are you sure your Additional Braking System (ABE , I believe) is not acting up? That system causes the pads to shed water from the discs (when in the wet) before actual braking takes place, and it tries to predict when an emergency brake action is imminent based on a 'sudden' release of the accelerator. If the timing isn't right the brakes are constantly rubbing the rotor. But I would still assume the pads would be giving in first. Or is this your third set?
 

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Discussion Starter #7 (Edited)
Driving it hard would cause the front rotors to be eaten, not the rears. When breaking the fronts take most of the load. Are you sure your Additional Braking System (ABE , I believe) is not acting up? That system causes the pads to shed water from the discs (when in the wet) before actual braking takes place, and it tries to predict when an emergency brake action is imminent based on a 'sudden' release of the accelerator. If the timing isn't right the brakes are constantly rubbing the rotor. But I would still assume the pads would be giving in first. Or is this your third set?
Disagree. driving hard would eat front AND rears, not just the fronts. The rear pads are vastly inferior in surface area as are the rotors, so wear faster.

This is the first set of pads on the rears, the front is on it's second. both on original discs.


I'm not sure of the ABE, never heard of it and my Merc dealer is certainly not in the habit of ripping me off, so I trust all is well as it's just had the second service.


EDIT: Just in negotiations around a GLA 45 as the missus is finding it a struggle to 'get in' the SLK nowadays.. so may have had my fun in the sun already and going to be resigned to fun without the sun :(
 

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Disagree. driving hard would eat front AND rears, not just the fronts. The rear pads are vastly inferior in surface area as are the rotors, so wear faster.

This is the first set of pads on the rears, the front is on it's second. both on original discs.


I'm not sure of the ABE, never heard of it and my Merc dealer is certainly not in the habit of ripping me off, so I trust all is well as it's just had the second service.
Pads front and rear for P30 are the same: A007 420 90 20
Discs are only different in size and the fronts are ventilated

Adaptive Braking system introduction video from MB: ADAPTIVE BRAKE 1
 

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Discussion Starter #9
Pads front and rear for P30 are the same: A007 420 90 20
Discs are only different in size and the fronts are ventilated

Adaptive Braking system introduction video from MB: ADAPTIVE BRAKE 1
Thanks for the link.


Not sure what P30 means.


I have the composite brakes on the front as I have the Performance package... is the same still true?
 

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Thanks for the link.


Not sure what P30 means.


I have the composite brakes on the front as I have the Performance package... is the same still true?
P30 is the MB babble for Performance package.

My bad: there is one digit in the pads that is different. So the pads are NOT the same! (at my age I need glasses ...)

Full details:
A1724230112 Rear disc (no matter P30 or not)
A0074209020 Rear pads (no matter P30 or not)

A2214211812 Front disc not P30
A0074208420 Front pads not P30

A2194210212 Front disc P30
A0074209720 Front pads P30
 

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Discussion Starter #11
P30 is the MB babble for Performance package.

My bad: there is one digit in the pads that is different. So the pads are NOT the same! (at my age I need glasses ...)

Full details:
A1724230112 Rear disc (no matter P30 or not)
A0074209020 Rear pads (no matter P30 or not)

A2214211812 Front disc not P30
A0074208420 Front pads not P30

A2194210212 Front disc P30
A0074209720 Front pads P30
That is interesting...... my dealer tried on the "the price is due to you having the performance package.... I did protest at this as I looked at mine and a std one in the showroom when I bought it and could not see any difference between the rears at all, where as the front differences were night and day. I managed to get a further £70 off now, the bill stands at £525 inc tax for the replacement of the rear discs and pads. The service director assures me that it is normal to expect to replace the rears between 20k and 30k miles depending on how much I use the 'hold' feature and how much traffic I'm in and how hard I drive the car... as I tick the box for being at the wrong end of all 3 for economy ideals, I guess at 21K miles, it's normal.

The rear discs/rotors are not composite like the front ones, so there is another difference too.


In response to an earlier criticism/reply, he also ensured me that rear rotors and pads are ALWAYS replaced together on the 55 R172.
 

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That is interesting...... my dealer tried on the "the price is due to you having the performance package.... I did protest at this as I looked at mine and a std one in the showroom when I bought it and could not see any difference between the rears at all, where as the front differences were night and day. I managed to get a further £70 off now, the bill stands at £525 inc tax for the replacement of the rear discs and pads. The service director assures me that it is normal to expect to replace the rears between 20k and 30k miles depending on how much I use the 'hold' feature and how much traffic I'm in and how hard I drive the car... as I tick the box for being at the wrong end of all 3 for economy ideals, I guess at 21K miles, it's normal.

The rear discs/rotors are not composite like the front ones, so there is another difference too.


In response to an earlier criticism/reply, he also ensured me that rear rotors and pads are ALWAYS replaced together on the 55 R172.
Interesting indeed. I'm at 50K (km's) and never had to replace anything on the brakes yet. Maybe I'm a wuzz driver, but I will inspect pads and discs next time I'm taking things apart. That will be in a couple weeks when I will install the rear radars for the blind spot assistant. Rear bumper has to come off for that so no biggie to take the wheels of for inspection.

Can't you push the bill to the next owner since you're considering a GLA45?

Additional:
This IS becoming an interesting subject. WIS (workshop manual) doesn't list the values for the 55 (type designation: 172475) when to replace the disks. For all other R172 models they list them in the same sheet as the R171 models.
Tracking the disk part number A1724230112, it seems that both the 176052 A AMG and 117352 CLA AMG also use these rear disks. Back to WIS shows that on these cars the values are also NOT listed! All other models from the A and CLA series do have wear limits but not the AMG one.
What is going on? Are AMG rear disks exempted from wear limits? Than how could your dealer state that 85% is already gone?
From the internet prices for these disks vary between 110-160 EUR a piece.

If you can, I'm very interested in the thickness new of these disks and what they consider the wear limit.

For the fronts I found that the thickness new is 36mm and the wear limit is at 33mm with the wear limit upon inspection at 33.5mm. These disks are used at a host of AMG models. (like the 230472 SL55 AMG)
 

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Discussion Starter #13
Interesting indeed. I'm at 50K (km's) and never had to replace anything on the brakes yet. Maybe I'm a wuzz driver, but I will inspect pads and discs next time I'm taking things apart. That will be in a couple weeks when I will install the rear radars for the blind spot assistant. Rear bumper has to come off for that so no biggie to take the wheels of for inspection.

Can't you push the bill to the next owner since you're considering a GLA45?

Additional:
This IS becoming an interesting subject. WIS (workshop manual) doesn't list the values for the 55 (type designation: 172475) when to replace the disks. For all other R172 models they list them in the same sheet as the R171 models.
Tracking the disk part number A1724230112, it seems that both the 176052 A AMG and 117352 CLA AMG also use these rear disks. Back to WIS shows that on these cars the values are also NOT listed! All other models from the A and CLA series do have wear limits but not the AMG one.
What is going on? Are AMG rear disks exempted from wear limits? Than how could your dealer state that 85% is already gone?
From the internet prices for these disks vary between 110-160 EUR a piece.

If you can, I'm very interested in the thickness new of these disks and what they consider the wear limit.

For the fronts I found that the thickness new is 36mm and the wear limit is at 33mm with the wear limit upon inspection at 33.5mm. These disks are used at a host of AMG models. (like the 230472 SL55 AMG)
I will measure the discs when I get her back in a week's time from the workshop, (went in yesterday), I think I can get in there without removing the winter rims.


I need stopping power now, hence the requirements for them to be replaced. the pad backing is rubbing on the rotor lip so this is dangerous.... so no I can't pass this on and also I'm on a finance package that I may not be able to transfer easily, so the GLA may not happen for another 12 months if that's the case.


I do know that 3mm from stock is the wear limit as the Technician has already indicated that on the report from the service and only the driver side rotor is worn to 85%, the passenger side to 75% and when I measured the lip on the driver side it was just over 1.27mm, so if the same is on the back then that would be about 2,55mm which is 85% of the permitted 3mm. the pads have approx. the same left on them, hence the rubbing of the pad backing... I had to get them changed!
 

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Rears
Brembo P50099 (pads)
Brembo 09B78811 (disc)

Fronts
Brembo P50097 (sports pack, pads)
Brembo P50098 (regular, pads)
Brembo 09.9764.23 (sports pack, disc)
Brembo 09A81911 (regular, disc)

The partnr listed in the link is different, so no luck or partnrs have changed.
 

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According to my research, it should fit! I don’t know what part number the vendor is actually providing – that is not a Brembo number. When I search for what vehicles that part number goes for, it shows a C63 AMG, and Brembo website shows that the P30 for the SLK 2012 is the same rotor as the C63 AMG. Sooooooooo, possibility of it fitting, at 1/3 the price!
 
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