Problem with rear discs

Lazydonkey · Post by **Lazydonkey** » Fri Sep 16, 2011 8:20 am

Hello,

Changed the discs and pads a few weeks ago and after the intial bedding in process has been completed i'm having a problem.

Specifically the passenger rear looks like this

Now i've just been out and given the brakes an absolute pasting and still it's only gripping a fraction of the disc...........but the other three discs are perfect. I've also got my ABS light on but that may or may not be related.

So - thoughts? Lazy piston? Stop being a girl and brake harder? Take pads out? kick the car hard ?

cheers in advance,

Donkey

Rosssco · Post by **Rosssco** » Fri Sep 16, 2011 8:55 am

Check the other side of the disc for pad contact area, and if thats good, could be sticking sliders, and / or sticking piston. It would be worth taking if all apart and checking pads are properly seated too.

tut · Post by **tut** » Fri Sep 16, 2011 9:00 am

I had the same problem Martin, but not as bad as that. First action is take the pads out, inspect the wear on the dodgy one, looking at that I would expect it to have a ridge with the inside part barely worn.

The piston must be working, but it looks as if it is pushing on one side only. Check that the upper and lower bolts are still tightened and not cross threaded. Does not look like a warped disk as the wear is even and you will feel the pedal pumping.

Probably more suggestions to come.

tut

Lazydonkey · Post by **Lazydonkey** » Fri Sep 16, 2011 9:02 am

thanks tut - should point out that the discs and pads are 200 miles old so hopefully no warping involved.....

tut · Post by **tut** » Fri Sep 16, 2011 9:07 am

As Ross says, it could also be the slider. You can check the operation with two of you, take out the pads, put a thin piece of wood in, slowly depress the brake peddle, and check the action of the piston.

tut

Dominic · Post by **Dominic** » Fri Sep 16, 2011 9:42 am

Do I anticipate a spanners sesh coming on over the weekend?

Post by **Shug** » Fri Sep 16, 2011 9:50 am

Yup - betcha it's the slider. If you take a look at the caliper mechanism, odds on that the rubber gaiter for it is ripped and gone. Not a major issue - mine has run like this for at least 5 years - you just need to keep on top of greasing and freeing it. Oh, and stop using the brakes like a lady

paulW · Post by **paulW** » Fri Sep 16, 2011 9:51 am

Dominic wrote:Do I anticipate a spanners sesh coming on over the weekend?

I could be up for that, heading across on the Ferry tomorrow, lunchtime.

Lazydonkey · Post by **Lazydonkey** » Fri Sep 16, 2011 10:14 am

Shug wrote:Yup - betcha it's the slider. If you take a look at the caliper mechanism, odds on that the rubber gaiter for it is ripped and gone. Not a major issue - mine has run like this for at least 5 years - you just need to keep on top of greasing and freeing it. Oh, and stop using the brakes like a lady

hmmmm it's just come back from a certain lotus mechanic so i would have hoped this would have been done.......

I shall make some enquiries.

Thanks all

Post by **campbell** » Fri Sep 16, 2011 10:52 am

Money is on a tired caliper. Depending on age and mileage of car, time for a fresh one (even just from a breaker's...that's what i did last summer and it's been fine since)

cla5h · Post by **cla5h** » Fri Sep 16, 2011 11:39 am

Am I seeing correctly that the pad is sweeping the outer part of the disc, but not touching nearer the centre?

If the slider pin mechanism has seized, wouldn't this affect the whole surface? Unless the pad is wedged at a slight inward angle toward the rear of the caliper.

If the pin has seized, it would normally make it difficult (impossible when it happened on mine) to get the new pads in due to the extra thickness so this should have been noticeable when they were changed.

Post by **Shug** » Fri Sep 16, 2011 11:42 am

RAMTOP_ERROR wrote:Am I seeing correctly that the pad is sweeping the outer part of the disc, but not touching nearer the centre?

If the slider pin mechanism has seized, wouldn't this affect the whole surface? Unless the pad is wedged at a slight inward angle toward the rear of the caliper.

If the pin has seized, it would normally make it difficult (impossible when it happened on mine) to get the new pads in due to the extra thickness so this should have been noticeable when they were changed.

Id suggest that it's seized on being pulled out to accommodate the new pads and it's only flex in the body (which would be greater at the outside of the disc IYSWIM) that's letting the pad contact at all.

Lazydonkey · Post by **Lazydonkey** » Fri Sep 16, 2011 2:29 pm

Just spoke to ali and he was saying it was the other rear caliper that was a bit tried but i'll get it into him to have a looksie. Thanks all.

vet111s · Post by **vet111s** » Fri Sep 16, 2011 7:28 pm

Interestingly, Ali just changed my discs and pads and mine look the same. Been trying a but of rough love!
May give Ali a call but a trip to the burgh is out of the question just now.

Ali

Scottish Elises

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