HELP!!!! Rear brake caliper piston won't seat

[Andy Clap]

ARRRGGGGHHH!!!  I've had the rear brake caliper stripped to clean up a sticking piston (wheel side), now the bugger won't go back in.  I can't get it past about 5-7mm sticking out.


Think I'm trapping the oil seal?  Any tips?


Bank Holiday and off the road, would appreciate help!!


Ta,
Andy

[His Dudeness]

Did you replace the seals or take them out? I'm guessing not. It's most likely a chewed up dust seal or corrosion behind the dust seal forcing it out. That's probably what was causing your original sticking problem. I'd say you'll need to take out the old seals, scrape away the corrosion in the grove and put some new seals in.

[Jules-C]

Have you opened bleed nipple?

[anutz]

if you do got for seals, be aware of OEM verusus pattern - i went for OEM, little more but i know they are sound.....

[Andy Clap]

Thanks for the replies.


The caliper is off the bike, bleed nipples out and split in half.


No, I hadn't replaced the seals, but will have to now, totally FUBAR 


Thanks for the hint on corrosion behind the seals, and using OEM.  Given the price I wonder if it's worth getting a replacement caliper?  I believe others are a direct fit.


Cheers,
Andy

[anutz]

Look at my thread...

http://foc-u.co.uk/index.php/topic,16810.0.html

I got a FZS1000 rear from ebay US - 51£ total delivered but i was lucky!!!!!

Last one i saw on UK ebay went for 110£

Regards seals, i ordered pistons as well as seals from USA, and the large cost made it worth while....

If you buy just seals alone then may be similar price from UK as lower shipping...as opposed to US Air Mail and potential customs taxes...

Have you also considered getting them serviced - i don't know what there work is like but have heard good things and its going to cost me around a hundred to get all my calipers sorted when the pistons arrive, i will box the lot and send it to them to fit and service for me http://www.powerhouseautomotive.co.uk/co...rvices.php, they have been prompt and helpful in conversations so far...

Having said all that the use of a FZS1000 caliper is popular if you can get one, fitting needs a little bit filing off and a few washers, but i am yet to try - will report back when i do!

A few on here have done it...

Anutz

[Andy Clap]

Good call on Powerhouse Anutz, only 16 miles from me.  Shame I can't pop over on the bike  :'(

[His Dudeness]

You could remove the dust seal and temporarily only have the fluid seal in the caliper.  The dust seal is just there to stop dirt getting in at the fluid seal. If you're replacing them anyway you could temporarily remove the dust seal and get the caliper back together and working. The caliper will work fine without the dust seal but it's a temporary bodge to get you to a mechanic if that's what you want to do. Don't leave it out for more than a few miles though. Locked on brakes or no brakes is no joke.

[Andy Clap]

Thanks for that advice, but I seem to have knackered the fluid seal as well  :rolleyes

[Jules-C]

You could remove the dust seal and temporarily only have the fluid seal in the caliper.  The dust seal is just there to stop dirt getting in at the fluid seal. If you're replacing them anyway you could temporarily remove the dust seal and get the caliper back together and working. The caliper will work fine without the dust seal but it's a temporary bodge to get you to a mechanic if that's what you want to do. Don't leave it out for more than a few miles though. Locked on brakes or no brakes is no joke.

Took the dust seals out of mine as quick fix to get it through MOT as didn't have time to overhaul replacement caliper.  It's been about 15 months now and still haven't got around to overhauling and fitting the new(er) caliper.

[paulchucky]

start again get another set of seals completely strip caliper clean thoroughly and rebuild
then [size=78%]polish pistons with wire wool and put a smear of vasaline on them slip them back in all the way [/size]
Then install dust seals abit fiddly but can be done

[His Dudeness]

[quote author=His Dudeness link=topic=17081.msg197013#msg197013 date=1432561080]
You could remove the dust seal and temporarily only have the fluid seal in the caliper.  The dust seal is just there to stop dirt getting in at the fluid seal. If you're replacing them anyway you could temporarily remove the dust seal and get the caliper back together and working. The caliper will work fine without the dust seal but it's a temporary bodge to get you to a mechanic if that's what you want to do. Don't leave it out for more than a few miles though. Locked on brakes or no brakes is no joke.

Took the dust seals out of mine as quick fix to get it through MOT as didn't have time to overhaul replacement caliper.  It's been about 15 months now and still haven't got around to overhauling and fitting the new(er) caliper.
[/quote]

It's still not something I'd be recommending people to do. I'd only use it to get out of a jam. It is the brakes after all and they're there for a reason. The dust seal always seems to be the one to start sticking on because it's doing it's job stop all the dirt getting to the important fluid seal.

[darrsi]

start again get another set of seals completely strip caliper clean thoroughly and rebuild
then [size=78%]polish pistons with wire wool and put a smear of vasaline on them slip them back in all the way [/size]
Then install dust seals abit fiddly but can be done

Should be red rubber grease. That's what it's for. 

[Andy Clap]

[quote author=paulchucky link=topic=17081.msg197053#msg197053 date=1432583022]
start again get another set of seals completely strip caliper clean thoroughly and rebuild
then [size=78%]polish pistons with wire wool and put a smear of vasaline on them slip them back in all the way [/size]
Then install dust seals abit fiddly but can be done

Should be red rubber grease. That's what it's for. 
[/quote]


Luckily I bought a small tin of that off somebody on these forums a couple of months ago "just in case" 


Is that right, put the dust seals in AFTER the pistons???