Chch Weds Maintenance Evenings 2010

**schrodingers cat** · 18th May 2010, 13:14

Usually a jammed calliper piston is caused by the build up of brake dust solidifying on the exposed piston and jamming as the piston is pushed back into the calliper body.

If I read correctly, the problem is the piston jammed OUT? In this instance the best thing to do is remove the calliper and remove all the pistons, give it a good clean and reassemble.
If you don't want to fit new seals etc (which isn't always necessary)careful about what you spray at the calliper. Sometimes it is possible to twist the piston slightly clockwise/anticlockwise using various gubbins but be super careful not to damage the piston surface. The piston may be jammed as it has cocked over. C clamp vise grips are useful to pull the piston back in SLIGHTLY before using compressed air to get them out.

When everything is clean and new the whole process is easy. When it comes to things which are stuck sometimes the cheaper option is to pay someone who has a few clues to fix it. You may be able to do it yourself. You may be able to root it yourself.

If you can afford to learn the hard way are prepared to risk it have a go. Either way you'll learn something.

**cruza** · 18th May 2010, 13:31

Originally Posted by schrodingers cat

Usually a jammed calliper piston is caused by the build up of brake dust solidifying on the exposed piston and jamming as the piston is pushed back into the calliper body.

If I read correctly, the problem is the piston jammed OUT? In this instance the best thing to do is remove the calliper and remove all the pistons, give it a good clean and reassemble.
If you don't want to fit new seals etc (which isn't always necessary)careful about what you spray at the calliper. Sometimes it is possible to twist the piston slightly clockwise/anticlockwise using various gubbins but be super careful not to damage the piston surface. The piston may be jammed as it has cocked over. C clamp vise grips are useful to pull the piston back in SLIGHTLY before using compressed air to get them out.

When everything is clean and new the whole process is easy. When it comes to things which are stuck sometimes the cheaper option is to pay someone who has a few clues to fix it. You may be able to do it yourself. You may be able to root it yourself.

If you can afford to learn the hard way are prepared to risk it have a go. Either way you'll learn something.

Was a reasonable amount of gunk in lines and line spliter, used a fair bit of force to try and move piston, its not jammed all the way out, but theres no way a fresh set of pads would fit. Considering state of pads and caliper, reckon do it once/right policy would be safest.
strip, clean ,check bore and new seals

**schrodingers cat** · 18th May 2010, 13:39

Definately need to get those pistons out and give it a good clean with kero and scotchbrite.
Try heating the calliper with a hot air gun and trying the compressed air route.

I'm sure if you bought the callipers in to the Maint evening some kind souls might help. However bearing in mind the risk of f****ing something perhaps swopping money for the chance to watch a professional do it might be wise...

Cooks and broth you know.

**Subike** · 18th May 2010, 14:32

Are you sure it is the pistons that are siezied, making the calipers lop sided/ or the caliper slides siezed?
There are two little pins the calipers slide on to keep them central with the disc, these often are forgotten when pads are changed, not being serviced, this cancause lop sided wear on the pads, and also the effect of a piston being siezed.
If a Piston has siezed to the point that you cannot remove it by force of opperating the prake lever alone, then you are possibly up for some serious work, I would recomend a professional brake service center if this was the case.
Otherwise, if it is the slides then a wire brish, some KY gell ( white petrolium jelly) and time can do wonders to sticky calipers.
I have found from experiance that sticking calipers slides are the most common cause of uneven disc pad and disc wear on bikes.

**Peeteey** · 19th May 2010, 02:11

Originally Posted by cruza

reckon do it once/right policy would be safest.
strip, clean ,check bore and new seals

Yep, I'm going to subscribe to this policy. They're going into the shop tomorrow. Would have gone in today but I totally forgot about them rattling around in the boot!

Originally Posted by schrodingers cat

I'm sure if you bought the callipers in to the Maint evening some kind souls might help.

We are lucky to have such a great collective of knowledge, aren't we?

But after seeing the look on Cruza's face whilst trying to get things unstuck, the amount of crap throughout the brakes, the fact that they probably haven't been serviced in 26 years and the fact that for some bizarre reason I can afford it at the moment, they're going to the shop.

Originally Posted by schrodingers cat

Usually a jammed calliper piston is caused by the build up of brake dust solidifying on the exposed piston and jamming as the piston is pushed back into the calliper body.
...
Either way you'll learn something.

I reckon this is exactly it, upon reexamination in sunlight, they're bloody filthy! Even moreso than I first thought! How they worked over the last number of years I'll never know ...
And yea, the thing I've learned is often the shortcut turns out to be the longest way between two points (Murphy's Law)

Originally Posted by Subike

I have found from experiance that sticking calipers slides are the most common cause of uneven disc pad and disc wear on bikes.

There is definitely some unevenness on one side but it's not chronic. The slides seemed ok, not rusty or sticky at all. I'll bring the bike in once the brakes have been fixed. Should be able to get there under it's own steam then! Woop!

Thanks everyone for thoughts and ideas

**KiwiPhoenix** · 19th May 2010, 08:51

We do come in handy sometimes!!

well, maybe the ones that know what they are talking about!! I'll stick to holding the light and watching and learning.

**been_there** · 19th May 2010, 15:47

Much happening tonight....Maintenance wise?

**gloplg** · 19th May 2010, 19:50

Smallish turnout tonight, must be something to do with the

night.

**KiwiPhoenix** · 19th May 2010, 21:20

Great pics Gloplg!! It wasn't that cold, granted I was wearing about 4 layers under my jacket

**kerryhare** · 19th May 2010, 21:58

We we else where tonight, I didn't think it was that cold, except for my fingers they were cold.

**McWild** · 20th May 2010, 15:01

Any more photos there Gary me old mate?

**imdying** · 20th May 2010, 15:31

If the pistons are seized, don't butcher it, bring it to me on a Saturday morning and I'll strip it and clean it. PM me if you want details.

**gloplg** · 20th May 2010, 17:09

Originally Posted by McWild

Any more photos there Gary me old mate?

Andrew............ So sorry I was in a hurry and didn't check if all the photos had been posted.

**KiwiPhoenix** · 22nd May 2010, 15:27

Righty ho people, have a wee problem. When I was adjusting my headlight (a couple of weeks ago) I had to take out the speedo cable, no big thing there but I have now got a problem where the speedo is vibrating in it's casing, I have checked the connection everything seems to be ok, any ideas?? I'm going to have a look at the workshop manual to see if I can figure it but may need your help if I can't!