Repairing/Rebuilding Rear Calipers?

[Bernie Benz]

Good write-up Steve,

One comment.
As I recall, maybe wrongly, lithium base grease is water soluable.  Inasmuch
as brake fluid is miscible with water, it then follows that lithium grease
may also be miscable in brake fluid.  Therefore I use a "waterproof" boat
trailer wheel bearing grease.

Bernie

> From: Steve Crosbie <scrosbie at integraonline.com>
> Date: Wed, 27 Feb 2002 00:56:41 -0600
> To: Peter Schulz <peschulz at cisco.com>, 200q20v at audifans.com
> Subject: Re: Repairing/Rebuilding Rear  Calipers?
>
> 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
>
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