Rebuilding calipers?

Originally Posted by Mike1234

It is possible to rebuild even some very badly corroded callipers.

First of all I would agree with the suggestion of replacing the bleed nipples. A corroded bleed nipple will only cause air to get in to the system in addition to being difficult to use.

When cleaning out the grooves where the seals sit I would use something wooden or plastic that isn't likely to damage the surface to scrape off some of the worst corrosion and plenty of brake cleaner or WD40 helps also.

When rebuilding I have found that rubber grease rather than a bit of brake fluid works best. Apply it liberally to the seal, the grooves and the sides of the pistons to help keep the air out.

Once everything is back together bleed it the best you can and then hang it upside down overnight which should help shift the air bubbles caught in all the little cornes where they can't get out easily.

Good luck.

Yup, that's what my dealer told me trying to save me money, they'd but the calipers together, squeeze the brake lever onetime and pop the pistons out....

if your calipers are all pitted & corroded adjacent to theseals from winter salt...
don't bother trying to rebuild them, a waste of time

Originally Posted by RandyO

if your calipers are all pitted & corroded adjacent to theseals from winter salt... don't bother trying to rebuild them, a waste of time

On the contrary, if you've got the time and the inclination the results can be quite impressive. I rebuilt the callipers on my race early/mid season 2003 and they are still going strong.

It may not be worth the amount of effort compared to the cost of buying new callipers or pistons but it can be a very successful operation.

Originally Posted by Mike1234

On the contrary, if you've got the time and the inclination the results can be quite impressive. I rebuilt the callipers on my race early/mid season 2003 and they are still going strong.

It may not be worth the amount of effort compared to the cost of buying new callipers or pistons but it can be a very successful operation.

Beleive me, if your rebuilding them cause they have been corroded with winter salt, it is a waste.... once you get the corrosion out, tollerances are too loose, piston pops out..... my dealer lernt the hard way, they ate the cost of thier rebuild attempt. Your race bike prolly didn't have much corrosion

Originally Posted by RandyO

Beleive me, if your rebuilding them cause they have been corroded with winter salt, it is a waste.... once you get the corrosion out, tollerances are too loose, piston pops out..... my dealer lernt the hard way, they ate the cost of thier rebuild attempt. Your race bike prolly didn't have much corrosion

Before we get in to a p**sing contest to see who has the most valid opinion it is worth reminding everyone that we have all had our own experiences on the subject and they can all be considered, or dismissed, as you see fit.

My race bike had done a couple of years road use and then sat in a breakers yard for a number of months until I bought it. The callipers were a mess but with a lot of elbow grease and determination they were brought back to be some of the best brakes in the race paddock.

For the sake of a fair argument I know a number of racers, or their mechanisms and/or their local bike shop, who opted for the brake fluid on the seals option but many of us found that rubber grease worked far more effectively and reliably. Maybe it had the benefit of evening out some of the corroded surfaces or maybe we just got lucky.

Either way I am just adding to the number of different options put forward by the people on the forum. If you can do the work yourself then new seals and a few hours work is a good investment, if not, then maybe keep an eye out for some callipers from a newer machine that have had an easier life.

Originally Posted by Mike1234

On the contrary, if you've got the time and the inclination the results can be quite impressive. I rebuilt the callipers on my race early/mid season 2003 and they are still going strong.

It may not be worth the amount of effort compared to the cost of buying new callipers or pistons but it can be a very successful operation.

+1. I've re-built calipers on bikes 20 years old and other brake parts on vehicles 50-60 years old with good results. If there is pitting then yes, they're trash but since they're always covered in brake fluid and are doube sealed, that's not too likely.
Personally, if the calipers are only ~$100USD each, I'd think about replacing them.

what happens is the corrosion ring works it's way in deeper with worn pads. when you put new pads on, the seals are then backed out over the corroded portion..... I have replaced the front calipers on my SV once and the rear caliper twice

Righto, without wishing to drag up an old argument, I wanted to get people's opinions on buying new calipers vs. rebuilding old ones. Apologies for the length of the post, but I thought the more detail now, the fewer questions later.

The front brakes on my K4 aren't what they used to be. The front left disc rubs ever so slightly when spinning the wheel and consequently the pad is wearing unevenly (although only a little bit). One of the 'R' clips is buggered, although the other is okay. I've not had the pistons out completely in ages (at least 20K miles), but judging by the bit I saw when I pumped them out a bit and gave them a spray with break cleaner and scrape with a steel brush, they are fairly rough surfaced. I noticed one of the outer seals (dust seal?) looked like it was twisted out of shape a bit, but it wasn't leaking fluid and I needed the bike today so I have just put it back together. Whilst the bike has 44K on the clock, I'm not interested in junking it; I will run the bike into the ground and get considerably more mileage out of it before it goes pop and even then I'll probably just put a second hand engine in, so to a certain extent I'm not worried about it "making financial sense" for an old bike.

My riding style and type of riding I tend to do means I don't use the front brakes terribly hard with any sort of regularity. Because of this, it's still on the original pads (which are in surprisingly good nick) and discs although I wonder given the rubbing if the front left disc isn't a little bit worn. Discs wear is within the tolerences (haven't checked the exact distance for about 6K miles, but it was 4.2mm then). The original rubber hoses have yet to be renewed and are due given they are now 4 years old. In terms of servicing, the brakes have been checked twice by a (comparatively) reputable dealership. In addition to this, every time I've had the front wheel out, I've had the pads out, scraped them with a steel brush, sprayed them with brake cleaner and pumped the pistons out as far as I dare without them coming out and cleaned as much of them as I can access in the same way. I've then liberally doused the backs of the pads and the pistons in coppaslip and re-assembled. I have changed the fluid completely twice and topped up & re-bled it once in addition to this.

For personal reasons, I would rather minimise the amount of time I spend in the garage tinkering so if rebuilding takes ages I'd rather new ones, but not at the expense of a hell of a lot of money. Whatever the option I go for, I'll be fitting it all myself. Not wishing to jinx myself when it comes to doing these, but I seem to have the 'knack' of bleeding brakes and have a new mityvac waiting to be used so that shouldn't be a problem, it was more the rebuild itself I was seeking opinions on, rather than the bleeding aspect.

So, given I'm reasonably comfortable working on brakes, what are people's opinions on a rebuild vs. 2 new calipers? What is a ball park for two new OE calipers from a dealership, just the parts, not labour? Anyone got any links to rebuild 'kits' containing the seals/pistons, etc. ideally ones people here have used and rate highlt, as I've had problems with the fit of some pattern seals recently and this makes me cautious about using them on something as important as front brakes!
I've just fitted new fork internals so no gixxer front end swap suggestions please. Likewise, for insurance reasons I don't want to try and fit gixxer calipers or anything like that.

I am tempted that given the need for hoses to be replaced and whatever I do resulting in it needing to be bled, to fit S/S hoses at the same time. More for the fact they'll last the rest of the bike's life and probably cost less than OE rubber hoses, than wanting the extra performance. Opinions?

As ever, TIA, Ceri.

[yorkie_chris]

I've had good results rebuilding calipers with new seals and not replacing pistons.

Obviously knackered pistons are knackered, but rebuilding them with a good dollop of rubber grease prevents the corrosion from occuring. Prevention is better than cure.

I call b0llocks on replacing the calipers. It's worth having a go at rebuilding them. You said your dealer recommended replacement? Well they probably didn't do a very good job of servicing them at previous attempts, if at all.

[admin]

Pistons can be pain to get out. I find a compressed airline quite a good way of removing them. I've even used a footpump. You just need one of those conical adapters and shove it in the hole where the hose attaches. A few PSI later and pop. Just watch your fingers as a stuck piston can suddenly shoot out, especially with loads of pressure behind it.

Originally Posted by yorkie_chris

I've had good results rebuilding calipers with new seals and not replacing pistons.

+ 1, the callipers I have on the 800 are from 1996 and have been rebuilt a few times now...





The pistons will get to a point where they will need to be replaced, mine took eight years (from 1996) to need replacing. Overall the servicing has cost me less than the price of buying new callipers each time, afterall it is the main body of the calliper which is still working 100% to spec and cost the most to replace.