C43 - skimming front discs

[cws196]

Just had to replace the rear discs as well as pads on my C43, as the discs had lipped and cut the sensor. Now thinking should I get the front discs skimmed so I don’t have the same issue and only have to replace the pads - discs run true, 1mm lip and car has done 52K. Any advice, please?

 

[DSM10000]

I am trying to work out how a lipped disc cut the sensor (wire?)

What is the actual disc diameter now on the front and what is the minimum allowable?

Personally if there is doubt with the brakes I would change them.

MB are often quite good on prices.

 

[GeeJayW]

Been thinking the same thing as the discs on mine are lipped too. Depends on the thickness specs.

Will probably just get new bits and replace the whole lot.

 

[Atavus]

The difference between new and worn is usually about 2mm. That’s on most cars I‘ve owned. You could get the Dremel out.

 

[RHDV8]

Be safe, change the discs.

 

[Teego]

New discs everytime. You could get some nice Brembos for not a lot.

 

[mioba]

If the disks are lipped its because they are worn, think of lipping as an indicator.
Skimming is only (if at best) good for warped disks and wont reverse the fact they are worn.
Either way get a new set.

 

[sgregory124]

As others have said - new discs, why put your safety into question?

 

[noogieman]

Your discs are worn at 52000 miles?
I still haven't replaced my front and rear discs at 85000 miles on my 22 year old C43

I hardly have any lip on outer edge.
I can barely touch the lip with my finger nail.

 

[Bellow]

The difference between new and worn is usually about 2mm. That’s on most cars I‘ve owned. You could get the Dremel out.

If they are still within service thickness limits I can't see any reason not to remove the lip - and without touching the rest of the disc wear surfaces.

 

[geoffus]

If they are still within service thickness limits I can't see any reason not to remove the lip - and without touching the rest of the disc wear surfaces.

I agree, if within tolerance just remove the lip, can’t see how it would cut through the sensor though? The lip would be an indicator of the wear I would have thought.

 

[Bellow]

I agree, if within tolerance just remove the lip, can’t see how it would cut through the sensor though?

Can't figure out which sensor (presumably ABS but not explicitly stated) or if it is its wire.

The lip would be an indicator of the wear I would have thought.

A rough guide. The lip makes accurate measurement with a vernier calliper awkward. If the lip is left a micrometer is required for accuracy.
Angle grinder reacquainted with electricity works wonders!

 

[Petrol Pete]

Not 100% sure what you mean by getting the discs 'skimmed' ? If you alluding to getting the job done using an on car brake disc lathe it is often more trouble than it is worth.

On modern cars (particularly on the front) getting access to both sides of the disc the calliper has to be removed, by the time you have gone that far you are one tiny bolt away from popping the disc off and chucking it the scrap bin. New discs are quite cheap these days.

We put the disc lathe on the rears of my C55 some time ago after part of the swept area showed signs of previous damage. It was more of an exercise in blowing the dust off the lathe than saving £90 on a pair of discs (which I have in a box in my workshop , but the carbon ceramic pads I have fitted are very gentle on discs) . The results are quite good , but you can't really use it on drilled discs if you have them.

My bloke normally only uses the lathe on big old 4x4's where front disc removal is a complete pain and the farmer who owns the 4x4 is a tight Ba$tard.

I too am curious as to how a sharp edge on a brake disc would cut a sensor wire. ? As Bellow says the lip will stop you from being able to use a normal Vernier to measure the thickness but 'special' brake disc Vernier's are available if you want to go that far.

 

[st13phil]

The lip makes accurate measurement with a vernier calliper awkward.

If you only have a vernier caliper then just use a packing piece on either side of the disk, measure across the whole lot, then measure the combined thickness of the two packing pieces and subtract that to get the disc thickness. If you're so close to the wear limit that any inaccuracy that gives rise to is relevant then it's time to change the discs anyway

 

[vijilants]

I changed mine out at 44000.....they looked scored and were lipped. I think the cost of the genuine disks for the C43 were about £145 for the pair last year.

You are far better off replacing them and the pads rather than skimming.

 

[Bellow]

Not 100% sure what you mean by getting the discs 'skimmed' ? If you alluding to getting the job done using an on car brake disc lathe it is often more trouble than it is worth.

What I'd do is remove the lip with everything else still in situ with the angle grinder assuming I can bend the splash shield out of the way enough and only then because it looked like the chamfer on the pad had worn the disc such that the lip was going to foul the pad and, there was still enough life in both discs and pads to make it worthwhile. And control where the swarf is going. A certain dexterity and competence with the grinder is prerequisite.
I wouldn't be touching the wear surfaces though.

On modern cars (particularly on the front) getting access to both sides of the disc the calliper has to be removed, by the time you have gone that far you are one tiny bolt away from popping the disc off and chucking it the scrap bin. New discs are quite cheap these days.

True, assuming the wheel bearing doesn't need to be disturbed.

 

[cws196]

Thanks for all the replies - having done some checking over the weekend, genuine front discs are half the price of what I expected (and cheaper than Brembo) so to prevent any issues I'll go with pads and discs when needed.