Seca900 dual piston caliper rebuild

IM in the process of rebuilding my front calipers. Of course, pistons are stuck in there. I realized this morning that I could block the banjo bolt hole with one the bolts that hold both caliper halves together. This information could be helpful for someone else.

I read about a few methods to free the pistons out. I don't have a grease gun, but I'm pretty sure I could use my car mechanic's one. I have a compressor but I don't think I have the necessary attachment to put good pressure, but I'll give it a try first.

Before I do anything, I just want to make sure i do it OK. If I inderstand well, the best way to start is to put the caliper halves together tight, put a piece of soft wood or somethnig compressible between pistons to make sure that I will not end up with only one piston coming all the way out, and then apply pressure with air or grease and see if just one or both pistons move and then work it out accordingly.

Is that about right?

 

Once the pistons are removed, could it be a good idea to put calipers in boiling water for a few minutes to dislodge the crud from the little passages?

What is the general consensus on the best way to clean the area the piston slides in? the pistons themselves? If they are not pitted, is superfine steel wool acceptable to clean and polish the pistons at the same time? Should I wet sand the mating surfaces of the caliper halves with very fine paper?

 

Also, is that correct to use a Dremel equipped with a smal brass-wire brush to clean the inside of the caliper piston chambers and the MC tunnel?

 

Sooooo , nobody here has experienced cleaning the inside parts of the calipers with a brass-wire brush and could tell me if it is safe and efficient?

 

honestly. im rebuilding mine too and all i have done is used like a hook type screwdiver handled tool and just scraped the crud i could out as best as i could

 

I went to a Dentist's office and salvaged some instruments that cold no longer be used on patients.

You can "Fabricate" an angled-scraper to clean Seal Channels by doing a bit of Blacksmith work on a solid slender car radio antenna.

The Bores usually don't require more than a scrubbing with BrakeKleen soaked sections of ScotchBrite Pad (Med.- Gray).

Scrub the Bores clean.
Scrape the Seal Channels with a Fabricated Tool that you deliberately dull to prevent scratching the Channel.

 

Thanks guys. My question is specific to the small brass-wire brush because I own a Dremmel-like tool with lots of attachments, including a small brass-wire brush that looks like a 1/8 inch thick and 1 inch in diameter disc.

I think that would be perfect to clean the seal channels but I need to know if it would scratch the caliper metal. Maybe I could try it on the bottom of the bore if I can reach it, the shaft of the brush is pretty short.

 

I would not use any power tools to clean the caliper bores; there is too much risk of nicking the bore if the nose of the tool should accidentally come in contact.

 

Thank for the advice. I may try to fin an extension.

Do you think that the brass-wire wheel is safe for the caliper alloy?

 

Just rebuilt both of the front calipers on my 83 seca 900 RK. Guy that did them before used a lot of caliper grease to put them together. Fluid was pink and the whole thing was pretty messy.

Very small amounts of carb cleaner (make sure all the rubber gaskets are out the way), a toothbrush, some 1500+ grit wet/dry paper for the internal bores, some quad naught steel wool for the pistons. You might need a pick and some soft hands to clean the recesses where the rubber piston seals sit in.

Lube everything up with dot 3 and slide them back together.

Don't forget some good slide lube on the pad retainer and slides and just a little bit on the back sides of the pads between the pad and piston itself to make sure nothing gets stuck there.

 

aSECAwrencher

Thank you for your answer.

I will get back with pictures of my pistons, I damaged them a bit when I removed them, not sure if all of them are still usable.