Braking vibration

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Discussion

HumbleJim

Original Poster:

26,952 posts

182 months

Wednesday 16th July 2014
quotequote all
Hi severe judder (was minor but getting worse) medium braking from 70ish a bit through the steering but seems to come through the whole car. All the discs and pads are within tolerance but the rears look like this. Lines radiating from the centre out, is this "pad pickup"?


andyiley

9,101 posts

151 months

Wednesday 16th July 2014
quotequote all
Knackered discs & pads is what it is mate, all need replacing.

Barely 2/3rds of the surface is "in use" by the swept area of the pads, the rest is VERY badly corroded.

HumbleJim

Original Poster:

26,952 posts

182 months

Wednesday 16th July 2014
quotequote all
Thanks, I've ordered the parts.

BritishRacinGrin

24,602 posts

159 months

Wednesday 16th July 2014
quotequote all
andyiley said:
Knackered discs & pads is what it is mate, all need replacing.

Barely 2/3rds of the surface is "in use" by the swept area of the pads, the rest is VERY badly corroded.
So what would you suggest is the root cause of the corrosion on the disc? (HumbleJim I just posted in your other thread)

HumbleJim

Original Poster:

26,952 posts

182 months

Wednesday 16th July 2014
quotequote all
BritishRacinGrin said:
andyiley said:
Knackered discs & pads is what it is mate, all need replacing.

Barely 2/3rds of the surface is "in use" by the swept area of the pads, the rest is VERY badly corroded.
So what would you suggest is the root cause of the corrosion on the disc? (HumbleJim I just posted in your other thread)
Thanks I saw your post. I've had the car for 11 months and covered 4000 miles, the discs never looked too good. Prior to my ownership the car had been doing very few miles (20k in the last 10yrs) so I'm catching up on quite a few things caused by lack of use. The calipers do seem okay though, not sticking and the pads have worn evenly.

BritishRacinGrin

24,602 posts

159 months

Thursday 17th July 2014
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HumbleJim said:
Thanks I saw your post. I've had the car for 11 months and covered 4000 miles, the discs never looked too good. Prior to my ownership the car had been doing very few miles (20k in the last 10yrs) so I'm catching up on quite a few things caused by lack of use. The calipers do seem okay though, not sticking and the pads have worn evenly.
If the pads were contacting the discs properly there'd be no chance of the disc being so corroded on what should be the friction face. This is fairly typical for rear disc brakes, they simply don't work hard enough in gentle driving so lack of exercise contributes to the whole thing becoming seized up. Corrosion builds up on the pad carriers until the pads aren't free to move, and then that lack of movement allows the piston to sit still for a while.

I'd get the calipers and carriers off and then remove the pads (usually with a hammer when they're in this state!), then attack the carrier with a wire brush. If the corrosion is quite bad I dress up any surfaces where the pad touches the carrier with a small fine file. Copaslip these surfaces to give them a little lubrication. The sliding pins normally need cleaning up with a scotch pad and some light oil. I've never once replaced a caliper because I've found they often come back to life once everything else is moving freely, if they wind back okay they'll probably be fine.

I find that if you do a half-arsed job with the cleaning up and lubricating the problem will probably resurface sooner rather than later

Kawasicki

13,041 posts

234 months

Thursday 17th July 2014
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BritishRacinGrin said:
So what would you suggest is the root cause of the corrosion on the disc? (HumbleJim I just posted in your other thread)
Discs tend to corrode more under the pad, if the vehicle is left parked for a long time in wet/humid conditions. You can clean off the surface rust when you drive, but more metal is removed where the pad was, leaving you with a pad shaped shallow depression in the disc. Hello vibrations.

BritishRacinGrin

24,602 posts

159 months

Thursday 17th July 2014
quotequote all
I don't think the disc is that badly pitted, get it all working properly and the disc will probably clean up in a couple of hundred miles.

That said, if new discs and pads are 130 quid then it's not worth putting used parts back on once you've had it all apart. Personally I use OEM pads though- I've never been fully satisfied with a set of 'OEM equivalent' pads, even from reputable brands.

HumbleJim

Original Poster:

26,952 posts

182 months

Thursday 17th July 2014
quotequote all
I couldn't remove one of the rear pads when I was trying to clean it up the other day, caliper bolts seemed stuck to.

I soaked the caliper bolts with some "loosen up" and they are free now.
I've ordered premium discs/pads/fitting kits from GSF £70 (bargin) I will give it a good clean and a smear of copper slip when fitting.

£130 was for the front vented discs, they look a lot better so I'll see how it goes.

HumbleJim

Original Poster:

26,952 posts

182 months

Wednesday 23rd July 2014
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Rear discs & pads fixed it. smile
The parking brake shoes fell apart when the disc was off eek so replaced those too.