Repairing/Rebuilding Rear Calipers?

[Steve Crosbie]

Bernie,
    Good point about trailer grease, however the lower chamber was
completely free of brake fluid.  Neither caliper had even a  hint of
anything in there but the jelly bean and some very dried up grease. I
don't think there should be any fluid below the seal on the piston.  If
some makes it past it isn't part of the active brake fluid system so
grease contamination shouldn't be an issue.  But waterproof grease would
be a better choice to seal the shaft since water and corrosion are
important issues at the oil seal.
Steve

Bernie Benz wrote:

>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 had the same issue finding a circlip plier that was long and skinny
>>enough to remove the circlip holding the piston in 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 chamber.  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.
>>
>>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 grease and
>>re-grease the cavity with high temp. lithium grease. The seal where the
>>e brake shaft goes into the caliper is a simple oil seal.  I got mine
>>at a bearing supply company.  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 could 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 lever even before the outside spring clip is attached.
>>They have been working like brand new calipers for over 2 weeks - no lock
>>up of the ebrake cable and plenty of holding power.
>>
>>Good Luck,
>>Steve Crosbie
>>
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