Let's discuss skimming brake discs

M

mr wilks

Lifer
 Lancashire
As i'm sure it will divide opinion :wink:
Anyhow the V6 TT i purchased needed new discs & pads on the rear & new pads on the front .
Rears all in around £80 no problem :) front pads are about the size of a butter tub lid :o £45 no problem but the front discs were only lightly lipped & glazed & are 2 piece Zimmerman "floating" style as with the Z4 "M"s , £185 each :o
Now i wouldn't fit new pads to old discs but didn't fancy shelling £370 out when the discs were nowhere near their end so on my BM indy's advice today he removed them & had them skimmed over
Just collected the car & had a look at them with torch once home & they honestly look like brand new discs for £20 apiece :) ( usually only £10 if not a 2 piece disc)
So , anyone else had theirs done ? Or anyone with tired looking discs that you would prefer to look like new :wink:
 
As long as they are not on or close to minimum thickness there is no real problem,unless they are cross drilled .

Discs usually have between 1.4mm-2mm wear before they are junk..
 
Yea my indy is also MOT registered so explained they would have to be measured otherwise a MOT failure
They came well within the zone
Its not like they had to remove 3 or 4mm in reality they only had a fraction shaved off
I was seriously considering the new discs but thought it was worth a go this way . Had to wait a while though as the guys machine was goosed in Dec when i wanted them doing
 
As above, no problem, just taken a few thousand miles of life off them. But as they were goosed otherwise, it's a win win situation.
 
There's more to that than 'just the minimum thickness'

Thickness can vary from side to side (so the inner side can wear more than the outer side). Or rust. So you have to take that into consideration, especially if the inner side is badly corroded. It is almost impossible to measure that variation in thickness, so it takes somewhat an experts opinion.

But other than that go for it.
Putting new pads on a skimmed disc is certainly better than on a grooved disk.
 
To be fair if they are skimmed by someone who knows what they are doing. With all the correct tools. The discs should not have any run out and should be flat and true.

I have a micrometer witch is designed so you can measure the disc. And if its mounted correctly in the lathe and run out is checked. Then what it measures in one place it should measure (will measure) The same all over the machined faces. If you get someone who dose not know then yes a world of problems can happen!!
 
.... for the 300 miles you will have the car for, it is a no brainer :evil:
 
Showing my ignorance here, but why would you not fit new pads to old discs ? I get putting new pads with new discs.
 
Bing said:
Showing my ignorance here, but why would you not fit new pads to old discs ? I get putting new pads with new discs.
Click to expand...

Tend to work on a 2:1 ratio, replace 2 sets of pads against a single disk. Then replace the disk.

If the disk has gone, you will wreck a set of pads and if you then replace the disk soon after, you have to replace the pads again.
 
pvr said:
.... for the 300 miles you will have the car for, it is a no brainer :evil:
Click to expand...

:D 1300 :P i'm off to Normandy in it tomorrow so that will add 1000 round trip :wink:

Anyhow for those curious here's a pic as of this morning before some fresh alloys went on & before the perfectionists get twitched up yes i have cleaned the calipers & also given them a fresh coat of paint :thumbsup:

TT%20Y%20spoke%20black%20005_zpszxgu6ovq.jpg
 
pvr said:
Bing said:
Showing my ignorance here, but why would you not fit new pads to old discs ? I get putting new pads with new discs.
Click to expand...

Tend to work on a 2:1 ratio, replace 2 sets of pads against a single disk. Then replace the disk.

If the disk has gone, you will wreck a set of pads and if you then replace the disk soon after, you have to replace the pads again.
Click to expand...

That makes sense if the discs are almost gone. I replaced the pads on my old car without changing the discs and had no problems, the discs were in reasonably good nick though, and I bedded the pads in properly. However every time I have had discs replaced on any car then I've had new pads too, irrespective of how worn they are.
 
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