Disc skimming

[Jimmy2404]

Any one heard of disc skimming for C63 PP front brake discs? A friend of friend needs them doing

Any info on it would be great

 

[Tegs200]

Not recommended from what I've heard...

 

[automaniaman]

There are a few companies offering this service on the net.... Your friend would need to discuss the details with them.
Personally I'd replace rather than repair.

 

[optimusprime]

wast

Get a new set of discs ,thats if you can.Your discs have 3 -4 mm before they need changing.So to grind them will make them under the limit.

 

[John]

I'm all for saving some money but some savings are a false economy.

 

[Abb]

Driving a C63 PP and wanting to skim the discs???????

 

[KennyN]

I am guessing they need skimmed as they have warped due to excessive heat buildup , if so reducing their thickness to make them "true" again will only allow them to heat up quicker and therefore warp quicker next time.

Not to mention they may be under their servicable limit once they have been skimmed , which is not advisable.

Are the PP discs and pads not around the £2k mark , maybe that is the reason the OP enquired about getting them skimmed ?

Kenny

 

[cj440]

Any one heard of disc skimming for C63 PP front brake discs? A friend of friend needs them doing

Any info on it would be great

Hi, disc skimming is brilliant if done correctly with the proper equipment. Firstly if your discs are under min thickness then as above its a waste of time. If however they are still above min thickness, you have brake judder present or have done a track day & roasted them then a Procut machine makes an incredible job. We do all types all the time inc Ferrari, porsche etc. Alot of manufacturers insist their dealers have a procut machine.
Get more info here
Skim My Discs : Information on brake disc skimming and service centres

CJ.

 

[Dieselman]

The wear limit is 1.5mm per side, so not a lot of meat to play with.

More importantly, disks virtually never warp, so why do they need skimming.

It's the old " Your suspension bushes are cracking" game...99% rubbish, just a lever to get some money out of you.

The disks are probably suffering from friction material deposition and need a good scrub with a whetstone, or similar.

 

[Jimmy2404]

Would it get rid of small hairline cracks cj?

 

[Jimmy2404]

Hi, disc skimming is brilliant if done correctly with the proper equipment. Firstly if your discs are under min thickness then as above its a waste of time. If however they are still above min thickness, you have brake judder present or have done a track day & roasted them then a Procut machine makes an incredible job. We do all types all the time inc Ferrari, porsche etc. Alot of manufacturers insist their dealers have a procut machine. Get more info here Skim My Discs : Information on brake disc skimming and service centres CJ.

would it get rid of small hairline cracks cj

 

[cj440]

The hairline cracks are usually heat related, it wont get rid of them but will ensure your braking surface is flat & max surface size. It cuts 0.003" at a time so contrary to some belief its not mm's lol.
For the price of PP discs it's certainly worth trying

CJ.

 

[Dieselman]

Would it get rid of small hairline cracks cj?

I'd advise a Gillette for that...

 

[John Jones Jr]

Nothing wrong with skimming discs if they are still going to be within spec (some franchised dealerships do with the blessing of the manufacturer), but I'm doubtful they will be on a high performance car like the C63.

 

[BenzedUP]

I would replace them, especially on that type of car.

Or tell your friend to sell it and buy a car he can afford to run properly...

 

[Felstmiester]

Get em done it will be fine

 

[hotrodder]

As Dieselman said brake discs don't 'warp'. The things that people attribute to warped discs are virtually always the result of disc thickness variation (DTV)* i.e. what is felt through the pedal is the result of pads trying to grip a disc that varies in thickness not one that's physically bent or buckled. DTV can be the result of uneven wear due to runout (whoever fitted the discs didn't clean the hub properly or measure runout after fitting) or uneven pad deposits. Skimming a disc 'in situ' with a brake lathe accounts for hub runout so it can potentially save a pair of discs from being prematurely replaced if they were origionally fitted by a monkey and have "warped" as well as removing scoring etc

I'm all for saving some money but some savings are a false economy.

I agree disc skimming is a false economy on a typical car when new discs cost peanuts but on something that has (and has the potential to need) huge and very expensive brakes it makes perfect sense to me provided they aren't near to their min thickness

* google 'brake disc DTV', virtually every single brake manufacturer has published multiple articles about it and included numbers for the min acceptable runout including how to measure it with a dial gauge

 

[markjay]

From the technical point of if view, there is nothing wrong in skimming discs, as other said, as long as they have sufficient thickness left in them. In fact this was very common practice in the olden days

In terms of economy... I suspect that the labour costs will be roughly the same of that of replacing the discs, and new pads will be needed anyway. Then keep in mind that the skimmed discs will not last as long as new discs and you'll need to replace them anyway - sooner than you would have done if replacing them now.

So nothing wrong in going that, but it's provably not worth it.

 

[cj440]

From the technical point of if view, there is nothing wrong in skimming discs, as other said, as long as they have sufficient thickness left in them. In fact this was very common practice in the olden days

In terms of economy... I suspect that the labour costs will be roughly the same of that of replacing the discs, and new pads will be needed anyway. Then keep in mind that the skimmed discs will not last as long as new discs and you'll need to replace them anyway - sooner than you would have done if replacing them now.

So nothing wrong in going that, but it's provably not worth it.

Your missing the point, the discs are not removed from the vehicle. The Procut machine measures disc AND hub run out, compensates, then cuts the braking surface. What you end up with is a braking surface far beyond a manufacturers tolerance.

CJ.

 

[DuncS3]

On my old m3, after a track day at brands I had terrible brake vibrations - put new pads in, tried to clean them, hoping it was just pad deposits but no good. Got this guy out and he did it all with the discs still on the car and they were perfect after, well within tolerances. About 100 quid. Even did more track days on them without issues. There was another m3 with me who had the same issue and he replaced his discs and pads, a lot more expense vs my fix.

Under the right circumstances I would consider it definitely.