Brake piston cleaning and installation

[kuoh]

I finally decided to take apart my brakes and clean and reinstall new seals but like always, half way through the job, I'm stuck with questions.

First, what can be used to clean the pistons and the bore? The manual I have says not to use any mineral based cleaner. My choices were generic brake cleaner, denatured alcohol, and some Castrol Superclean solvent. The Castrol label said it contains some sort of "sillicate" which I took to mean some sort of minerals and I don't know what denatured alcohol has in it, so I used the brake cleaner.

My second question is what the packets of red stuff that came with the seal kit is? Is it a lube to help the pistons back in the bore or some sort of glue to hold the dust seal?

Lastly, what's the best way to install the new seals? It looks like it's not going to be easy to get the seal seated on both the bore and the piston.

HELP!!

KuoH

[Beav]

If the pistons just need a solvent cleaning use regular old O'Reilly's brake clean. Don't use carb clean, it leaves a residue that might eventually react with the rubber parts. Actually, xoap and water would be just fine, as long as the pistons are completely dry before reassembly. If there are tougher rubber deposits on the pistons I just sashay over to the bench grinder and polish them on the wire wheel. Follow with the solvent/cleaning metod of your choice.

I was never sure of what the red stuff was for, many Japanese OEs include it and/or another packet of a different color lube. Personally I always just wet my fingers with a little brake fluid and then pull the o-ring through them. Place it in it's groove and then insert the rubber boot into its groove in the caliper (I can't recall if the SVX uses an internal or external boot. I'm figuring if you're asking it must be an internal. The externals have a steel ring to hold the boot on the outside of a lip. The internals usually just sit in place in a groove and the piston eventually keeps it in place. Some internals have a larger groove and a steel ring. Whew. ) The internals without a ring are the more difficult to install. If you have clean, dry compressed air available you can blow air into the caliper therough the brake hose hole while pushing the piston into the boot. When the piston touches the boot it balloons out and over the piston. In the absence of compressed air you will give your dexterity a workout. After placing the boot into its groove place one finger from each hand inside the boot and use your thumbs to slide the piston down those fingers while they gently stretch the boot over the piston. Once you do it you'll see how easy it is, but be prepared to spend a few minutes doing the first one.

If the boot is external just place it into position over the piston and insert the piston into the bore. Position the boot as required and finish it off by installing the steel ring.

Use a good disc brake silicone grease (a good thing to have around for many items) to lube up the sliding rubber parts and you're home-free.

[kuoh]

Thanks for the quick reply Beav. There is an O-ring inside the bore, followed by the groove for the main dust seal. There is no retaining ring, so the seal must be kept in place by the piston. From your reply, it appears that I should first install the seal on the piston, then try and seat the seal in the bore, then try and push the piston back in? I don't exactly have compressed air, but I figured out a way to adapt one of those 12V portable compressors to fit into the hole. I'm not sure how well that's going to work since the front calipers have two pistons.

KuoH

[Beav]

Uh, the o-ring goes in the bore first, then the boot followed by the piston. One other way, usually a bit more awkward but sometimes handier, is to insert the o-ring, place the boot just on the lower edge of the piston and then try to get the boot lip into its groove in the caliper followed by pushing the boot and piston home. Normally the boot doesn't seat completely when doing it this way, but if you're like me abd have large fingers trying to work in small holes it could be the only alternative.

When working with multiple bores place both o-rings in position and one piston without a boot in one bore - that will contain the air while working with the other boot and piston. You may have to use something to retain the incomplete piston and be careful with the air - blood blisters (broken fingers? doubtful) are easy if you get crazy and allow the piston to pinch you. After the first piston/boot is in retain it and use the air to pop the incomplete back out (place a rag or someting between the piston and caliper to cushion it when it pops out.)s

[kuoh]

Well I did the boot on the lower edge of the piston method because I just couldn't get it to seat correctly without the piston in the middle of the boot. I figured out that red stuff is some kind of lube and initially used it to lube up the bore and piston, but then I figured that probably wasn't what the lube was for so I took it all apart and cleaned it all again and used brake fluid this time. Hopefully everything will work ok.

KuoH

[mohrds]

For cleaning, I use a parts cleaner filled with Pine Sol Heavy Grease formula (water soluble). It works well for cleaning the parts. Then I wash them with soap and water and throughly dry. I also bake the parts prior to powdercoating for 45min at 500 degrees to bake off anything that might be on the pieces.

The manual says to coat the inside of the calipers, the outside of the pistons and the o ring lightly with brake fluid.

The red stuff is for lubricating the slide mechanisms.

In order to install the dust shields on the front calipers, I took a piece of 2" PVC from a central vacuum system (sch 80) and cut a section off about 1.5" long. I stretch the piston side of the dust seal over the PVC, the reach my fingers through the PVC to set the outer lip in place. Once that is done, I install the piston 2/3 of the way (through the PVC into the caliper) and then hold the dust seal while pulling off the PVC. The dust boot snaps onto the piston and I push the piston in until the dust boot fits in the groove.

Doug

[kuoh]

Finally got done with the front brakes around 1am last night. I put some of the pictures in my locker if anyone is interested. Those of you with the brake warning light in cold weather problem should look at the two pics of the brake reservior cap. One shows the bladder extended, which if not corrected, will cause it push down on the fluid level sensor and cause it to light as well as giving you a false indication of the fluid level because of the increased displacement.

Next week, the rears...maybe. I thought I had ordered a front and rear seal kit, but I got two front kits instead. I'm going to have to give them a call and see what the deal is.

KuoH

[Beav]

That's a good idea Doug. Unfortunately for me I work with too many different sizes so I never thought about doing it that way. Gold Hammer of the month Award to ya!