Should brake pads contact the whole disc
Discussion
Hi all,
I had the pads, discs and callipers changed on the rear of my 156 about a week ago. Since then I have noticed an area of corrosion on the disc about 2cm wide in the inside of the disc (near the hub). When I look it's clear the pad doesn't cover the whole disc. Is this normal. The parts were bought from a factors and fitted by a mechanic friend.
Tia
I had the pads, discs and callipers changed on the rear of my 156 about a week ago. Since then I have noticed an area of corrosion on the disc about 2cm wide in the inside of the disc (near the hub). When I look it's clear the pad doesn't cover the whole disc. Is this normal. The parts were bought from a factors and fitted by a mechanic friend.
Tia
Woo-hoo a useful thread!
There are areas of the disc that are unswept by the pad, but I know what you mean; that inner bit looks slightly too large.
There are areas of the disc that are unswept by the pad, but I know what you mean; that inner bit looks slightly too large.
jimmy156 said:
Hi all,
I had the pads, discs and calipers changed on the rear of my 156 about a week ago. Since then I have noticed an area of corrosion on the disc about 2cm wide in the inside of the disc (near the hub). When I look it's clear the pad doesn't cover the whole disc. Is this normal. The parts were bought from a factors and fitted by a mechanic friend.
Tia
So is the inner unswept area larger than it was before?I had the pads, discs and calipers changed on the rear of my 156 about a week ago. Since then I have noticed an area of corrosion on the disc about 2cm wide in the inside of the disc (near the hub). When I look it's clear the pad doesn't cover the whole disc. Is this normal. The parts were bought from a factors and fitted by a mechanic friend.
Tia
Edited by Orangecurry on Thursday 13th February 19:49
Herman Toothrot said:
Reason for this if often cheap s
t aftermarket pads. Just replaced rear disc and pads on my A6, pads fitted by last owner 1cm inner and outer gap, new pads hit full swept surface. If the manufacturer didn't need the swept area the disc provides they would fit smaller discs.
Pads are MIntex from a factors.t aftermarket pads. Just replaced rear disc and pads on my A6, pads fitted by last owner 1cm inner and outer gap, new pads hit full swept surface. If the manufacturer didn't need the swept area the disc provides they would fit smaller discs.Hmm, i guess its about the same but i had assumed that it was because the pads that i replaced were fooked lol.
Herman Toothrot said:
Reason for this if often cheap st aftermarket pads. Just replaced rear disc and pads on my A6, pads fitted by last owner 1cm inner and outer gap, new pads hit full swept surface. If the manufacturer didn't need the swept area the disc provides they would fit smaller discs.
Whilst some pads are larger than others.t aftermarket pads. Just replaced rear disc and pads on my A6, pads fitted by last owner 1cm inner and outer gap, new pads hit full swept surface. If the manufacturer didn't need the swept area the disc provides they would fit smaller discs.I have NEVER come across any that sweep the entire disc area.
Particularly on newer / more powerful cars.
The larger discs give better leverage AND a larger area to dissipate heat.
Many uprated brake conversions consist of a spacer to move the std caliper and pad out further, enabling the use of a larger disc.
Upgraded brakes full disc swept, is about 1mm to the bell to allow pad clearance.
My 2000 A6 2.7T both front and rears sweep the full disc again with only enough gap for clearance, only reason they didn't for a while was cheap non OEM pads.
Sure some others may have some inner clearance being cheap and not using alloy bells (most non performance stuff), but outer edge more than a mm is just wrong no good reason at all and would interfere with pad changes as you would have to clear a lip to lift the caliper off.
One of the problems with an unswept are on the outside is that it gives MOT places space for an advisory ,in the hope of work not needed. I've got OEM parts on mine and there's an unswept area on the outside. I discovered my MOT was too close for comfort and all the garages with appointment system were too late, so I use one I'd not normally use. The tester had a look at my front discs and shot in for a second opinion .Advisory -discs worn. Bit bothered ,at home I got out the micrometer and consulted Haynes. New 22mm, replace 19mm. The ridge was 22mm, using nuts to overcome the ridge, the swept area was 21mm. I got an RAC bloke to have a look, his advice was to get rid of the ridge as monkey MOT man had an excuse for advisory.
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