Rob,
Having overhauled a good number of various types over the years, I'd say it
is not beyond the abilities of a reasonably competent amateur.
Assuming the callipers are old, and the pistons are probably sticking in the
bores, I'd advise the following steps are observed:
1. Remove the brake pads.
2. Loosen the bolts holding the two halves together a little, while the
callipers are still on the axle (2 x 5/8, 2 x 9/16). This gets more difficult,
once
they're loose.
3. With a helper on the brake pedal, gradually pump out the pistons about an
inch from the bores. You may need some slivers of wood to insert on one side,
as they may not come out evenly. This should make it possible to extract the
pistons fully, once the callipers are removed.
4. Detach the callipers from the axle, and hydraulic pipe.
5. Split the two halves, taking care to retain the 'O' ring, and note its
position. This is usually not provided with the replacement seals kit.
6. Remove the pistons completely. Treat them gently, if not replacing.
7. Inspect pistons for corrosion and pitting, and replace if necessary.
8. Clean thoroughly, and hone out any corrosion from the bores with a fine
wet-and-dry (600 grade) lubricated with a fine oil, or WD40. Take care to clear
all crud from the dust-cover grooves, with a scraper.
9. Clean again thoroughly to remove all traces of abrasive, solvents etc.
10. Renew main seals, using rubber brake grease sparingly.
11. Insert pistons into bores. This is the only really awkward bit, as you
need to ensure the dust protectors are correctly inserted into their groove at
the outer edge of the bores. I find that the best way to do this is to insert
the dust seal into the groove first, then carefully insert the piston into the
seal. Use a small hook, or bent piece of wire (blunt) to lift the lip of the
seal over the bottom of the piston, while keeping the other end of the seal in
its groove.
12. Push home the piston all the way, until the outer end of the dust seal
meets the locating groove in the piston.
13. Replace the 'O' ring between the two parts, or re-install the old one if
not available, provided it has no evidence of perishing. This is a very
important little seal!
14. Re-assemple the parts, and tighten as much as is comfortable, while
loose.
15. Re-install calliper, and torque up the 4 bolts to the specified setting.
16. Install new pads.
17. Bleed brakes. I'd advise bleeding the entire system to fully replace the
fluid if using the DOT variety, as this should be done in any case every 2
years or so.
As you can see, it's a pretty simple little job really, and should take 2
hours or so.
Good luck,
Julian - SIII (With recently overhauled callipers, stops on a dime)
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