front brake pistons won't budge!
 

hey. the problems with me brakes are just mounting up. :confused:

1st my brake pistons would get stuck on so i gave the calipers a good overhaul. new seals the lot. putting the pistons back in was a bit of a pain as they needed a good push to get past the dust seals but they got all the way in the end.

so i re-attached them and bled the hoses, they seemed to bleed fine until i got a constant flow of brake fluid coming out so all good so far. but now no matter how much a pump the brake the pistons wont budge. also the lever wont stiffen up.
i did notice some brake fluid on the rubber seal at the master cylinder so there may be a possible leak (i'll hav a better look in the morn) but i dont think it would make that much difference to stop the pistons altogether.

any ideas?

mark

Re: front brake pistons wont budge!
 

did you give the pistons a smear in red rubber grease prior to pushing them in?

Re: front brake pistons wont budge!
 

no i didn't, i used brake fluid. i just read the same thing in a similar post from 2008. too late now.

big problem you reckon?

Re: front brake pistons wont budge!
 

I wouldn't worry too much about red rubber grease under the pistons it will only get contaminated by the brake fluid anyway. Sounds like you have an air lock, try bleeding from the m/c and the banjos on the calipers. Always tap the part your bleeding too to free any air locks.

Re: front brake pistons won't budge!
 

Is it an 'S'?

I've found if you're not careful you can get an airlock in the res to m/c hose, prevents any fresh fluid actually making it's way down. Way to cure it is every time you release the lever give the hose a couple of squeezes until it stops bubbling in the res.

Druid

Re: front brake pistons wont budge!
 

well i bled from the caliper this afternoon with little knocks and shakes successfully so i'm thinking that if there is any air in there then its only going to be a tiny amount. but i will try bleeding from the banjo's as well just in case.

below i've added a pic that i just took in the dark. its the point the lever meets the m/c piston. it looks like it could be leaking. do we think this might be the big problem or would it not make this much difference? (it will be something i'll be fixing soon just not too sure if its the cause of the bigger problem)

http://forums.sv650.org/picture.php?...pictureid=3450

cheers

Re: front brake pistons won't budge!
 

Is it actually leaking fluid? It doesn't look wet,keep on bleeding sometimes it just takes alot of patience! I find that injecting fluid in from the caliper up cuts down on bleeding time.

Re: front brake pistons won't budge!
 

no Druid mate, its a sv650 '00 naked so there's no hose between the res and m / c. good point tho for anyone having the same problems with an 650s.

yeah i've also heard about this. never tried it tho. i'll have a go at bleeding again 2moz. and as for the leak, there was some fluid there, but not sure how much and wether it got there by any other means.

Re: front brake pistons won't budge!
 

Just how difficult was it to push the pistons in when you re-fitted them? With no fluid in the claiper they should push back in with very little pressure at all. If you really had to force them in, then there is something wrong. When you took the seals out did you clean all the gunk out of the grooves where the seals sit? Use a scrapey device, tooth pick, pointy metal thing (Not to had though) just to scrape all the white contamination off, then plenty of brake cleaner to get rid of the bits. Apprently you can use margarine as a lubricant (As recomended by spidey) on the pistons!

There is no difference in bleeding the brakes on an 'S' or naked. They all have the same components, just that the nakeds resiviour is rectangle.

Re: front brake pistons won't budge!
 

yeah they were pretty hard to put in like. had to get a tube that fitted inside the piston and pretty much used my weight to push it in. but once it was past the dust seals then it wasn't so bad.

and i cleaned out where the dust seals were, its was nice and messy in there so i scraped it all out with a rounded off little metal rod. :(