My Ramblings

So, I've been polishing the pistons with WD40/wet and dry for a little while now and I think I've got all the crud off that I need to. Unfortunately I have found some pinholes of rust that have left pits which means that I will need to replace all of the pistons. I've tried to capture the pit on the rear caliper piston in this photo. Sorry it's a bit blurry, I really need to get a macro lens for close up shots like this. Still I am glad that I tried to clean them up first as I could have saved some money if they had been okay, and I know how to clean the pistons on my other bikes too. okay, I'm off to order the parts now, and then I can reassemble the calipers and it's on to the front forks.

I have done a bit of reading on how to clean brake caliper pistons, and found an article that said you could use fine wet and dry to clean corrosion off them [ http://www.motorcyclenews.com/new-rider/choosing-kit/2006/november/jan26-05-how-to-service-brake-calipers/ ]. as it suggested using 1500 grit wet and dry, I decided to be cautious and start with 3000 grit. I cut the wet and dry into strips about an inch in width. I put some wd40 onto a strip and started polishing the rear piston. After quite a while I started to notice the difference. it was getting cleaner. well, it was working, but it was going to take a long time. well, I was patient and I really didn't want to rush it and ruin the pistons. Over the next couple of weeks, I polished all of the pistons using the 3000 grit wet and dry. As it seemed it was going to take the rest of my life using 3000 grit wet and dry, I decided to take a risk and bought some 2000 grit. yep I was really pushing my luck here. I cut the 20

So, I now have all of the calipers dismantled and ready for cleaning and polishing. I have been doing some searching on the web about cleaning carburetors (for the CB750) and found soda blasting. This is taking an air compressor, attaching an extra hose to a nozzle and using that hose to feed bicarbonate of soda through the nose similar to sand/bead blasting. using bicarbonate of soda is supposed to be safe on delicate parts as it is a soft material. it's also water soluble so I can soak parts after blasting to get rid of any left over soda. I have a small air compressor so I thought I'd give it a go and see if I can get the calipers clean using it. I got some clear tubing and made a cut in it. then I fitted it over the end of the nozzle and used duct tape to try to seal the connection. The other end of the tube was put into a tub of baking soda, and I fired up the compressor. it took ages to pressurise the tank. I wanted to get it up to 100 psi, and it's only a lit

The piston puller has arrived. it looks like a pair of pliers, but works opposite so that when you press the handles the "nose" of the pliers expands. the idea is that you put the nose into the piston, grip very hard and turn and pull the piston so that it comes out. the theory is great, but actually using one isn't. in use you are trying to grip as hard as you can, and at the same time trying to pull the piston out of the caliper (as well as maybe turning it if it's stuck like mine). it took a herculean effort to get one of the pistons out, I was gripping as if my life depended on it, trying to twist the piston and pull it out of the caliper. when it turned (a little) it gave me renewed hope of getting both pistons out, and eventually the piston was out, so just one more left. so now on to the fifth and final brake caliper piston. I put the piston puller tool into the caliper, gripped with all my might (no laughing please) and twisted. Well something mo

So, the gas bottle has now arrived, so it's time to see if this heat business really does work for freeing up parts. of course, if I'm going to heat the caliper with a blow torch, then I dont really want to hold it in my hands, so I set up a vise on a bench, and clamp the caliper into it. now again I dont really want to pull the slide with my fingers so I need to put some pressure on it. to do that I attach a bungee to the slide and stretch it a little and attach the other end to the bench. now the slide is being pulled off by the bungee and the only thing stopping it is the corroded in rubber boot. time to apply the heat. I turn on the gas and ignite the flame. I adjust it so that it looks really hot (not really sure how to tell, so I'm guessing, but it looks and sounds hot). then I start to play the flame over the caliper where the rubber boot goes through. I try not to burn the boot itself, but if it melts at least the slider should come out, and I can clean up an

I thought that some photos would be in order rather just all that plain old boring text, so here is a front caliper and it's pistons:  This is the caliper before I managed to get the slide off. the pistons show a before polishing started and part way through. Here are the pins that hold the pads into the calipers. again you can see the before and part polished (I hope you can tell which is which) I thought I would show a picture of the rear caliper in pieces: there are more bits for a single caliper than I realised. The rear is a single piston caliper. and one of the front calipers. the front calipers are twin pistons (as I hope you noticed) I dont think that I will be able to remove all of the corrosion from the caliper pistons, so it looks like I will be getting all new caliper pistons. I'll order them once everything has been cleaned thoroughly.

Just a quick picture of what it should look like to remind me !! Between piston polishing I've been trying to get the sliders off the calipers, but they are stuck fast. I really can't see how to get these sliders out. I've been through the Haynes manual and it says the sliders should just slide off, there are no bolts or screws keeping it attached, but they won't budge. Having now looked at the "Rebuild Kit Full Seals Caliper", one of the caliper slider pins has a rubber boot that goes through the hole and comes out the other side with the slider pin inside it. Seeing as I will be replacing all of the rubber bits on the calipers, I cut the end of the boot off so that I could get to the other side of the pin to see if I could push it through, but still no luck. still it did allow me to spray WD40 on the other side of the pin (I'd already sprayed some into the boot to try and free it). so I carry on polishing the brake pistons while I think thro