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Ok, so for starters...If you don't already have a piston tool that works well for you...go get a RED PARK BICYCLE SPANNER from your local bike shop. I have found this item to work very well even after the tiny nipples break off. It's just a piece of spring steel w/a red vinyl "grip" bent into what happens to be the ideal configuration for F. c900 brake jobs. I've been using the same one since 1989, but I think they're still available & should cost about $7.
The devil is in the details. How bad were the old pads worn? If the friction material was nearly transparent, the pisons (in your case just the indirect one that pulls the yolk) may have gotten pressed out a bit too far...(especially likely if the rotors are worn down too) or at least have become "comfortable" in the bore & reluctant to go back.
Perhaps you can envison this; Have you ever left your hatch open for a long time loading/unloading/vacuuming out your car? The support strut "O" rings protest & squeal when you finally lower the hatch & force the dry strut piston shafts past them (I keep an oily rag in a peanut butter jar for this situation). I guess this falls into the "not so useful" advice catagory...but bear with me. Saab86 mentioned that a judicious (too much will make a mess & attract dirt) bit of PB Blaster sprayed under the piston dust seals can help pursuade the pistons to budge...well maybe, but those seals aren't all that easy to manipulate even if they're brand new (how likely is that ;) - another thought here, are these seals intact? The one that on the direct acting (the one you have to turn w/the special tool) piston is subjected to a lot of abuse every time a new pads are installed...esp if you're fumbling with a ratty old Park bicycle spanner ;) w/a flashlight in your mouth trying not to get hit by passing cars in front of your house...or are just a clumsy idiot. If the seals are comprimised, you can spray in a piff of Blaster & seal it up w/RTV silicone, but you might be best served replacing the calipers (L&R). Some rebuilds come pre loaded w/pads & all you've got to do is bolt them on & bleed em'. Figure $75 - $125 per caliper depending on where you get them & loaded w/pads or not.
Now for some useful advice. You indicated that you were able to turn the direct acting piston in & had gained enough room to put a new pad in. OK, now from there, take that pad out & using a really big (or you'll bend it) screwdriver or small to med pry bar between the yolk & outer surface of the brake disc (protect the disc w/something like piece of roof flashing or a lid from a can of Goya garbanzo beans out of the recycling bin) Mmmm, natchos...oh, sorry the wife's away & I'm f'n starving - PULL the yolk towards you, while that direct piston comes back out, don't be a pansy...really heave on it. Now try to fit a new outboard pad in. If it goes in, leave it in & go back to that direct piston. Turn it in as before...use as much pressing force as possible while turning...CLOCKWISE, until you can get another pad in. If you were not able to make any room for the outboard pad & the direct piston didn't move...that indirect piston is frozen. Yeah, I know "Duh". Here's some more useful advice...after pounding the sh!t out of the indirect piston, go get a length of hose (preferably clear) suitable for brake bleeding, put it on the bleeder nipple & stick the other end in that can of garbanzo beans. Spray a little Blaster on the threads of the bleeder & open it. Now try prying the yolk out again...use a lot of force. If this works, you're all set...if not repeat all the afforementioned steps until you give up & replace the calipers. Alternatively, throw in a set of still useable pads from an earlier brake job as a temporary measure.
You're supposed to lube the channel the yolk slides in w/special "Gletimo 540" grease. I use CV joint grease...sometimes. The a$$ backwards design of this caliper makes this a real chore because the channels (don't forget the one underneath!) gets full of sand & grit. So unless you're going to to a proper job & clean it out w/enough solvent to burn a sizeable hole in the ozone, then experience much frustration trying to get grease between the yolk & caliper body while it's tightly assembled...consider leaving it be. I refer you to the diagrams in Bently & Haynes...the caliper looks like something "Caractacus Potts" invented to make breakfast.
If this is a car that sits without being driven a lot, it's especially important not to let the brake pads (F&R) get very worn. Cars don't like to sit around...esp outside exposed to the elements. BTW, brake problems are just the beginning of a long list of issues dormant vehicles will experience.
Have fun!
posted by 68.109.25...
, Thu, 28 Aug 2008 06:20:15, Thu, 28 Aug 2008 06:37:31
, Thu, 28 Aug 2008 08:09:45
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