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Old 29-03-2011, 01:06 PM
grayb grayb is offline
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Default 2 sets of warped AMG discs!

Just thought I would post our experience of problems with replacement AMG discs for our W209 CLK55.

We had new OE discs fitted by our local garage in April 2009, using genuine parts supplied by the nearest MB dealers, Tonbridge. By autumn 2010, it was apparent that the discs had warped - in no more than 10,000 miles, with only reasonable use (i.e. no track days! and mostly motorway miles). Our local garage referred the problem back to MB Tonbridge, who had the car in, checked the brakes, agreed they were warped and replaced the discs (with new pads) FOC under the 2 year parts warranty. Very helpful, cleaned the car etc. etc.

Come this February, we still weren't happy with the brakes. Whilst the car was with Colin & Dave at MBS we asked them to check the brakes. The rear discs were shot - ok, we had never touched them so that's fine. However, the guys said the fronts were warped again as well!!

Back to MB Tonbridge yesterday. Yep, they agreed and replaced the discs and pads again. Very helpful and apologetic, cleaned the car, can't fault their service. However, they did point out that the original warranty is up next month and that even if these new discs warp again, then it will no longer be covered.

Now, given the track record so far, I am not confident that the discs wont warp again. I think I may have to write to MB to ask what they think of the questionable quality of their discs and on why a brand new set should not be covered by a new 2 year warranty?

Incidentally, we drove our C43 for 5 years and only changed the front discs once in that time...
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Old 29-03-2011, 01:15 PM
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The main reason that can cause them to warp or go out of true is if after a hard stop the foot remains on the brake pedal.

Other than that just cheap cast iron, a very unstable metal at the best of times
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Old 29-03-2011, 05:36 PM
Bolide Bolide is offline
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Are they truly warped - and what is the runout if they are? Next question is why?

If this was a common problem I would expect there to be more mentions of it on the forum. As it doesn't seem to be common what's different about your car?

It might be instructive to put some thermometer labels on the calipers to see what temps they are getting up to

See
http://www.temperature-indicators.co.uk/

Nick Froome
www.w124.co.uk
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Old 29-03-2011, 07:03 PM
Naraic Naraic is offline
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Quote:
Originally Posted by television View Post
The main reason that can cause them to warp or go out of true is if after a hard stop the foot remains on the brake pedal.

Other than that just cheap cast iron, a very unstable metal at the best of times
I know what you mean...but, as the pads are always abutting the discs, what difference does it make keeping your foot on the brake pedals.
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Old 29-03-2011, 07:11 PM
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Originally Posted by renault12ts View Post
I know what you mean...but, as the pads are always abutting the discs, what difference does it make keeping your foot on the brake pedals.
If you do a hard stop so that the disc get very hot, if you keep the pedal depressed then uneven cooling takes place causing the disc to warp or change in shape, the brake pads and caliper can act as a heat sink, or in reverse, and the natural cooling down is interfered with. The pads can also leave a footprint on the disc.

With any cast iron object the heating and cooling is the most critical stage of any work, hence the welding of engine blocks is not easy and metal stitching is the way to go
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Old 29-03-2011, 07:59 PM
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part of the problem with these calipers ( I'm assuming they are like the famed Bremobs on my other car ) are that if the PADS aren't floating as meant to, then they will also bind = increased hot running, not to mention causing hot spots when you stop after coming off a motorway for example, the pad surface actually diffuses into the cast iron ( plus it also changes its composition ).

the only way to cure this, is oddly enough to do several HARD stops ( on a private road ) without coming to a FULL STOP & repeating a few times, IT does work.

other than that, or buy better discs... you could always push the boat & have 2 piece floating discs, again it's the cost versus what you want out of your setup
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Old 29-03-2011, 08:03 PM
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the only way to cure this, is oddly enough to do several HARD stops ( on a private road ) without coming to a FULL STOP & repeating a few times, IT does work.
Yes on my v70R i have knocking disc sometimes and a few hard braking without stopping it goes away, been gone for months now come to think of it
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Old 29-03-2011, 10:07 PM
grayb grayb is offline
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Quote:
Originally Posted by Bolide View Post
Are they truly warped - and what is the runout if they are? Next question is why?

If this was a common problem I would expect there to be more mentions of it on the forum. As it doesn't seem to be common what's different about your car?

It might be instructive to put some thermometer labels on the calipers to see what temps they are getting up to

See
http://www.temperature-indicators.co.uk/

Nick Froome
www.w124.co.uk
I don't know what the run out was. I could ask the MBS guys if they measured it - but it was mostly felt through the pedal when you braked. If they weren't warped then why would MB Tonbridge have replaced them FOC twice?

Perhaps the pads are binding as Taz says - but they have been in and out several times in this process and neither MBS nor Tonbridge spotted any other signs.

And as for whether we have we done any hard stops and kept the foot on the pedal, we certainly do not drive the car in any way that an AMG is not intended to be driven. We are not boy racers nor has the car been tracked. The discs should be up to the use we put them too. We have owned plenty of fast cars that haven't suffered like this - from the C43, through an XJR, 944 Turbos x 2, Fiat Coupe Turbo etc. So perhaps there is something else going on?

It would be interesting to know what Colin and Dave think...
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Old 29-03-2011, 11:41 PM
grober grober is offline
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Quote:
Originally Posted by grayb View Post
Just thought I would post our experience of problems with replacement AMG discs for our W209 CLK55.

We had new OE discs fitted by our local garage in April 2009, using genuine parts supplied by the nearest MB dealers, Tonbridge. By autumn 2010, it was apparent that the discs had warped - in no more than 10,000 miles, with only reasonable use (i.e. no track days! and mostly motorway miles). Our local garage referred the problem back to MB Tonbridge, who had the car in, checked the brakes, agreed they were warped and replaced the discs (with new pads) FOC under the 2 year parts warranty. Very helpful, cleaned the car etc. etc.

Come this February, we still weren't happy with the brakes. Whilst the car was with Colin & Dave at MBS we asked them to check the brakes. The rear discs were shot - ok, we had never touched them so that's fine. However, the guys said the fronts were warped again as well!!

Back to MB Tonbridge yesterday. Yep, they agreed and replaced the discs and pads again. Very helpful and apologetic, cleaned the car, can't fault their service. However, they did point out that the original warranty is up next month and that even if these new discs warp again, then it will no longer be covered.

Now, given the track record so far, I am not confident that the discs wont warp again. I think I may have to write to MB to ask what they think of the questionable quality of their discs and on why a brand new set should not be covered by a new 2 year warranty?

Incidentally, we drove our C43 for 5 years and only changed the front discs once in that time...
Its sometimes difficult to get your head round this but I will try to explain.

You initially purchased a set of front discs from MB. These had a 2 year warranty and when they warped they were replaced FOC [ that's the important bit] as part of the 2 year warranty you originally purchased with the discs. They are still covered by the remainder of the original warranty. However you did not pay for the new discs or their implicit warranty so they remain unwarranted after the original warranty expires . If you think about it Mercedes could be replacing discs ad infinitum by your your reckoning which is just plain suicide from a business point of view. Buy another pair and you will get another 2 year warranty. Not many disc suppliers would even give you 2 years! That doesn't detract from the fact they should have lasted a bit longer but modern disc and pad material seem to have increasingly shorter lifetimes nowadays. I don't know who makes the MB AMG discs---Zimmerman-Brembo ?? but I have always found ATE to be a good product if they make discs in that size.
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Last edited by grober; 29-03-2011 at 11:46 PM.
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Old 30-03-2011, 10:52 AM
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jberks jberks is offline
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A warranty is part of your sales contract and is not connected to that actual phyiscal component you bought. Think of a warranty not as a guarantee that the part will last that long, but rather a guarantee that for the period of the warranty, they will acccept responsibility for any further expense as a result of the warrantied part.
In theory, it should be in their best interests to ensure the part outlasts the warranty, or they're paying for each subsequent replacement.
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