Disc brakes (and an old fart...)

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plumbfisher

plumbfisher

Active Member
Posts
523
Location
Berwickshire
Smelt a bit hot yesterday after a run out, right rear wheel a bit warm. Squealing a bit in (slow) reverse, seems like the pads are binding a bit. Stripped it down just now, cleaned it all up, copper grease on the sliding bits and the piston seems to be moving in and out ok, so here's hoping that sorts it out. I had a Series 2A landy for years and all that was needed was to put new brake shoes on every three or four years and new drums every five or six. No worries. :) So, my (old fart's) question is : what is it about disc brakes? :confused: How are they ever supposed to fully disengage? There's nothing to pull the piston back in. (Tho' I must admit they do stop you a lot better than drums!) I have previously had the same problem on an Audi and a Discovery, both manual, but didn't think it would be a problem on the auto Rover. :eek:
 
Disc brakes release completely when you take your foot off the pedal and move and the centrifugal force from the disc helps push the pads away the piston does also retract a tiny amount when you take your foot off. Because of these very small tolerances of movement it is imperative that everything is kept clean and greased. rear brakes tend to give the most problems as they do not do as much work.
 
What Marmite said ^^

With disk brakes, over time the rubber around the piston seal can degrade or get split with ham fisted piston reset on brake changes, once the piston seal is damaged dirt and moisture can get in and corrode the piston resulting in the caliper binding (the piston remaining pressured pushing the pad against the disk), resulting in heat fade, glazed pads, over heated disk and the heat cooking the wheel bearing lubrication.

caliper overhual kits can be bought very cheaply though. its always a good idea on brake changes to look at the piston seals
 
ukadamwest said:
What Marmite said ^^

With disk brakes, over time the rubber around the piston seal can degrade or get split with ham fisted piston reset on brake changes, once the piston seal is damaged dirt and moisture can get in and corrode the piston resulting in the caliper binding (the piston remaining pressured pushing the pad against the disk), resulting in heat fade, glazed pads, over heated disk and the heat cooking the wheel bearing lubrication.

caliper overhual kits can be bought very cheaply though. its always a good idea on brake changes to look at the piston seals
Click to expand...
New calipers for the P38 are also cheap, so cheap I wouldn't bother with overhauling them.
 
Ok thanks chaps:).
Should I replace both rear, or just the sticky one?
OEM calipers about 85.00 from Paddocks, cheapo ones 35.00 (Britpart?)
 
I would advise changing a pair together, but then i don't follow my own advice, one of my rears started to bind on the P38 and i replaced only that one !
 
plumbfisher said:
Ok thanks chaps:).
Should I replace both rear, or just the sticky one?
OEM calipers about 85.00 from Paddocks, cheapo ones 35.00 (Britpart?)
Click to expand...
I don't usually use ****part, but they don't make calipers and others have used them without problems. Have a look at Island 4 x 4. I would also always replace in pairs especially fronts.
 
An update ...
Got a pair of OE calipers (Lucas TRV) from Island for 60 each and a pair of carriers at 18 each (ex vat). Great service as usual, got them in a couple of days. Fitted them this morning, not difficult to do and what an improvement! Didn't just fix the binding but the braking is even better than it was too.
A minor detail tho' - the book says replace copper washers on the banjo bolt, and these don't come with the caliper. Neither do the bolts for the pad carrier come with them, so if you want to do a really proper job order these too.
 
plumbfisher said:
An update ...
Got a pair of OE calipers (Lucas TRV) from Island for 60 each and a pair of carriers at 18 each (ex vat). Great service as usual, got them in a couple of days. Fitted them this morning, not difficult to do and what an improvement! Didn't just fix the binding but the braking is even better than it was too.
A minor detail tho' - the book says replace copper washers on the banjo bolt, and these don't come with the caliper. Neither do the bolts for the pad carrier come with them, so if you want to do a really proper job order these too.
Click to expand...

Or anneal them ie. heat the copper washers to cherry red and plunge them in water, job's a good un.:D:D
 
plumbfisher said:
:eek: You are too kind, I am not worthy of your fartiness...

:confused: but incidentally,how did I become a 'senior member' all of a sudden? I'm just finding my way on here!
Click to expand...
We convened the Most High Council and a quorum passed the resolution that you have been deemed worthy of the most esteemed title. Your certificate will arrive by post.
 
We convened the Most High Council and a quorum passed the resolution that you have been deemed worthy of the most esteemed title. Your certificate will arrive by post.
Click to expand...

Technically speaking, it was a postal vote :D
 
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