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Discussion Starter · #1 ·
Has anyone got any advice on freeing up a caliper that is seized on (front N/S) causing the steering to wobble badly all above 30mph. Is it just a simple take off caliper, then piston push back and forth with the bleed nipple open, while squirting the caliper piston with WD40 and then afterwards bleeding the brakes again, or is there a better way.
 

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Working the piston in and out with WD40 might free it off but probably only temporarily and there is the risk of more serious failure later.
I would take the caliper, off remove the piston and check it for corrosion. You may need to use the hydraulics and pressure on the brake pedal to get the caliper out so be prepared for a resulting mess of fluid. If the piston is only lightly marked you can clean it with a very fine grade wet & dry, 1200 or finer and finish off with metal polish. Check also the bore in the caliper, if it is heavily scored forget it. If the scores are light, again light work with fine wet & dry might take them out. However if the rubber outer seals are split and letting the weather in you are wasting your time unless you relace them. I don't know if a seal kit is available for 9000 front calipers but exchange calipers can be got from ECP for only £58+ Vat.
Don't forget to check that the caliper assembly is sliding freely on the retaining pins and that they are clean and greased.
 

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TheScrappy......
There is a guy in Inverness of all places selling overhaul kits for front calipers. I got one about a year ago for £6. I just consists of the seal for the piston and a bellows type dust seal. This was a bit of a pig to fit since my bleed nipple was f***ed and I was trying to do a fit and bleed job at the same time.
Unfortunately I don't have this guy's full address here at work but from memory it is L'Arch Engineering, Inverness. Directory enquiries may help or you could e-mail me direct. I'll have a look for it when I get home. My e-mail is [email protected]<br />[email protected]
 

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I would agree with Derek on most points,sounds like your disc's have bitten the dust already with to much 'run out',on brake systems tho' i would tend to replace,rather than repair parts.
As pointed out you may be better just replacing the caliper for around £60,less faffing about etc.. ,but do check your sliding pins, because most aftermarket Xchange calipers do not come with the 'carrier' just the piston housing.
Happy calipering
G.
 

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Discussion Starter · #7 ·
Might give this guy in Inverness a mail, see if I can sort this Service Kit. Usually I'd stump up the £60 for a recon caliper, but I'vegota bit of time on my hands next week so I'll have a bash at sorting it the cheaper way....if i get p****d off with the job I'll just get a recon! defeatist I know but probably wiser for my sanity!
 

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Discussion Starter · #8 ·
This Caliper problem has come back to haunt me, managed to get acouple more weeks out of it though by freeing off with WD40. Emailed the guy from Scotland but no reply. Anyone know if he's still there?
 

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I assume the piston itselfs the problem.

Take the pads out and then press the brake a few times, get the caliper to come out about an inch. Lift the main seal off the caliper dody (you need to pop the retaining ring off) and then you can have a good gander at the piston. If its scored etc then its probably a gonner. If its just a bit gmmed up (it happens) then a bit of nail polish remover on a clotch run around the piston may solve your troubles.

If you feel up to it then take the caliper off completely and give it a clean up. You shouldn't need to replace the seals unless they are damaged.

Wd-40 rots rubber you know.

If you wish I can give a run down on what to do to take the caliper apart.

Chris
 

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Discussion Starter · #10 ·
I know there is small amounts of rust on the piston on its outer circumference where it meets the caliper itself and where the rubber cover tries to keep the sh*t out. The rubber cover has come away in places (I've tried after tried to try and get it back into the caliper to hold, but it won't) and I think the elements have got in there and caused this seize because the surface isn't perfect enough to let the piston slide in and out of the caliper.
 

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Whip the caliper off and sort it.

Won't cost anything and it will be salvagable in 99.99% of cases.

Get it out and like previously said getr busy with the 1200 grit.

A small watchmakers screwdriver is ideal for cleaning otu the groove and popping out the internal seal.

Jobs easy enough.

Chris
 

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Discussion Starter · #12 ·
So I wont need to remobve or even dismantle the caliper to repair, and how will I get the rubber sleeve back into the caliper base, they seem like they'll only go back with piston removed.
 

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Sorry didn't see this reply!

Anyhoo,

The caliper has 2 seals in it. One is actually in the bore (this is the seal that holds the fluid in) and sits in a recessed groove in the caliper and sits proud of the bore so it seals against the piston. To get to this seal and clean the caliper bore out properly the caliper has to come off the car.

The seal that you can see is merely a dust seal to keep rubbish out of the caliper so it doesn't corrode or score, it does a good job when you think about it even if it lets some through.

The seal that you can see sits in a recess in the piston and its held to the caliper body by a wire clip.

So pop the caliper out of the carrier but leave it attached to the brake hose then get someone to press the brake pedal so the piston comes out a bit (a bit being about 20 mm from its resting position or so). This should mean the rubber gaiter is opened out. This is when you see if the gaiters split etc as well.

Pop the clip off with that magical device commonly known as a screwdriver. Don't worry the tensions pathetic so no finger loss or anything should happen. Then just pull the gaiter off the piston. Now you can see the piston. This should be spotless and nice and shiny, not chromed more matt.

If its rusty and gummed up with [expletive deleted] then thats not to good. However its its just a tiny bit of rust or preferably gummed up old grease/brake fluid etc then you should be able to wipe this off the piston. I find nail polish remover and a bit of paper towel are the best. Get it nice and clean, you don't really want to use anything abrasive as you will not get all the dust out and it may damage the inner seal.

When you look in the groove where the seal sits itmay have rubbish in it, scrape this out with a small screwdriver then clean the piston again. A quick wipe aroudn the piston with a bit of brake flid help pull out any dust etc as well.

The gaiter itself won't mind a wash either, a toothbrush and fairy liquid are best.

Pop the gaiter back on the piston then push the piston back in. Then yuo need to fit the gaiter ontot eh caliper body. You can sometimes do this with your fingers or the easuier way I find is to start it off then rotate the seal around so it slots in. Then pop the clip back on.

Magic.

Shame my scanner died (a 1.4 renault engine fell on it - don't ask! lol) or I woudl scan in a caliper as I have 2 on my desk painted blue (if you paint then you can sell them for more, people are so vain).

Also while you are there give the sliders a good clean up and a bit of grease on them won't hurt either. Use either brake grease or moly, don't use copper grease like the average garage does.

Hope this helps, any trouble just ask.

Chris
 

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Discussion Starter · #16 ·
Chris, will finally be doing the job tomorrow, all things being well. Any last minute tips for me before I start, or anything you might have missed in the first posts. If you've got the time and the inclination take me through what I've got to do step by step (I know I'm a cheeky b*****d!!).
 

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Discussion Starter · #17 ·
Right, started job today, removed rubber piston seal (although there was nothing holding it to the piston, it just fitted into a groove, although this is ATE not Girling Calipers) Cleaned the piston properly, then went to fit the rubber seal and as I warned before, IO couldn't get it to fit into the piston base to hold it there. I can fit it into the groove easy...but not to the base, if it does go in, a little mopvement of the piston outwards and it pops back out again. I decided to remove the whole caliper and get it on a vice to maybe make it easier to fit the seal but it isn't. What sort of an overhaul job can I do with it off, and where can I get the overhaul kits from...and will I need them. Or is carrying on with the cleaning the way forward. By the way the piston didn't look too scored, and it cleaned up well. And all important how the heck do I get this seal into the base of the piston, and getting it to stay there!
 

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The outer seals seem to get out of shape and loose their elasticity with age. That's why you can't get it to stay on. The only cure is a new seal kit but I can't help with a source for that I'm afraid.
 

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Discussion Starter · #20 ·
Cheers chaps, have mailed them and hopefully they will get back to me. Could just do with an exploded picture and explanation of how to dismantle and service the caliper now, can anyone help? Haynes dont say much, and Quasi and Townsend sites dont list it either.
 
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