Repairing/Rebuilding Rear Calipers?

[Steve Crosbie]

Peter,
    I just finished rebuilding the 200 rear brake calipers, including
the e brake mechanism - with a couple of message that Bernie sent me
plus some discoveries I made in the process:

Peter Schulz wrote:

>Bernie/Folks:
>
>Wide distribution due to the fact that those of us not in warm, dry climates suffer the malady of emergency brake cable/caliper issues.
>
>I tried to disassemble one of the 200's rear calipers yesterday.  I removed it from the caliper carrier, removed the emergency brake return spring,  and brake hose.  Took it to the bench.  Using the Lisle "Cube" tool to turn the piston out of the caliper body - removed the piston and its boot.  Removed the inner dust shield from the piston cavity.  Looked into the piston cavity and saw the threaded rod to which the caliper piston is attached, and further inside, about three inches or 7.5 cm was a circlip that appeared to separate the piston compartment from the emergency brake cam and rod.
>
>I tried to remove this circlip using two different circlip pliers, then a pair of long needle nose pliers, to no avail - either the piston rod was in the way, or parts of the caliper body got in the way of the pliers.  I even tried a pair of small philips screw drivers inserted in the circlip holes.
>
I had the same issue finding a circlip plier that was long and skinny
enough to remove the circlip holding the pistonin the bottom of the
caliper body.  I bought a cheap pair of needle nose pliers with long and
skinny ends and simply filed the ends round to fit the circlip holes
(got a pair that had a spring and about 4" long ends).
That circlip holds a sort of cage that holds a spring under pressure.
 In the center of this is the threaded rod that the piston rides on.
 There is not a lot of room, but enough to get the skinny pliers in.  Be
very careful since when the circlip is released the spring will shoot
the spring holding cage (spring keeper) and itself into orbit.  The
second one I did I put the caliper in a vice to steady it and held a
small 2x2 piece of wood on the top of the spring keeper as the circlip
was removed - much less fun, but safer.  Once the spring, spring keeper
and threaded rod attached to the lower plate are removed, you can get at
the inside of this camber.  Inside this chamber you see the e brake
shaft and a small jelly bean shaped thing (piece of metal rod rounded of
at each end) that is held between an indent in the e brake shaft  and an
indent in the threaded rod shaft.

>
>I finally surrendered, pried the cam and rod out of the caliper body as far as possible, sanded it, sprayed it with Wurth Rost-off, worked it back and forth until it would easily move, covered the exposed area with synthetic brake grease, and pushed the cam and rod back into the caliper body.  I then cleaned the piston cavity, lubed the piston with brake fluid and reassembled the caliper.
>
At this point you can take out the e brake shaft and clean it up with
some sand paper, coarse to fine grain (the corroded shaft is the reason
the e brake lever does not return).  Also clean up the old gease and
re-grease the cavity with high temp. lithium grease. The seal where the
e braake shaft goes into the caliper is a simple oil seal.  I got mine
at a bearing supplNow cier.  I found a TCM oil seal part # 16x24x7TC
 (16mm {shaft opening }X 24mm {outside diameter) X 7mm {thick}).  Refit
the jelly bean and the brake lever shaft and threaded rod w/ bottom
plate.  Now comes the fun - the spring and spring keeper must be
compressed in order for the circlip to seat.  I used an appropriate
socket on the spring keeper that covered the keeper, and allowed the
threaded rod to pass through.  Then took a large C clamp and clamped the
socket down to compress the spring so the circlip can fasten.  It takes
a little trial and error and you have to center the spring keeper a bit
(first thing under the circlip before the threaded rod plate.  Sounds
worse than it is.  Once it is together there now enough spring tension
to reset the e brake even before the outside spring clip is attached.
 It has been working like brand new calipers for over 2 weeks - no lock
up of the ebrake cable and plenty of holding power.

>
>Now the ebrake cam mechanism is moving easily enough that I probably did not have to completely dis-assemble the caliper, but I still _want_ to see what's going on back there...any tips advice, etc?
>
>BTW - I did notice that completely removing the piston from the caliper appeared to allow more of the ebrake caliper rod to be exposed to cleaning, than just prying it out and moving it back and forth with screw drivers and pliers.
>
>There are some good existing instructions and guidance at http://www.urs4.com/technical/repair/ebrake/ebrake.html and also at:
>http://20v.org/brakprob.htm#handbrake - I wanted to take it to the next level, however.
>
>
>TIA!
>
>-Peter
>
Good Luck,
Steve Crosbie