master brake cylinder

[haygood at myway.com (Brian Haygood)]

Do you have a Bentley repair manual?  If not, I could try to send you some copies of the relevant stuff (via pdf or whatever).  



I just did this about 2 months ago on my 16v, so I'll try and recapture the moment and tell you how it went.  



Get a master cylinder from your FLAPS (Friendly Local Auto Parts Store).  O'Reilly had the best deal in town on mine - either $60 or $80 or something like that.  They had it in stock.  Don't bother with a used one.  Anything that has been sitting or a while might not work at all (this is coming from a consumate scavenger, by the way).



The first thing to do is to take the cap off of the reservoir and empty as much fluid as practical out of the reservoir.  Next, gently pry the reservoir vertically off of the master cylinder.  It is really on there well, so you will have to get a decent screwdriver under it or something.  Your new master cylinder should have new rubber grommets for the reservoir to pop into, so if you damage the old ones that is OK.  Just don't hurt the reservoir itself.  



With that off you can now see the 4 brake lines and the brake pressure switch (brake light switch).  Remove all of those and be careful to not bend the brake lines.



Next, remove the two bolts holding the master cylinder onto the brake booster (large flat round thing it bolts to).  The old master cylinder will pull straight out toward the front of the car.  Remove the brake light switch from the M.C. at some point.  Oh, you might have a big cylindrical thing on one brake line - that is the proporioning valve.  Remove the line from the valve, then later you can remove the valve from the master cylinder.  Put the valve on the new cylinder before you hook the brake line up to make it less likely that you will cross-thread it into the master cylinder.



Installation is the reverse of removal, but with some caveats.  When installing the brake lines, keep in mind that you are threading steel nuts into aluminum.  In other words, if you so much as think about cross threading them, you will.  Press each brake line fully up into the master cylinder until the brake line seats at the bottom of its hole.  Then slide the flare nut down while holding the brake line down against the M.C.  This helps keep things lined up.  Do not force the nuts into the holes at all.  Turning the nut counter-clockwise for about a turn while pressing it into the threads gently will help you feel when it is properly aligned.  Then tighten it in.  It isn't hard or anything, but if you just go wrench the nuts in there carelessly you will mess something up.



Once the old reservoir is snapped onto the master cylinder, you are ready to bleed the brake system.  If you can get hold of a pressure bleeder, it will save you some time and agony, but it all can be done without one.



Brian







 --- On Fri 04/07,  < silvius14@comcast.net > wrote:

From:  [mailto: silvius14@comcast.net]

To: scirocco-l@scirocco.org

Date: Fri, 07 Apr 2006 15:33:45 +0000

Subject: master brake cylinder



Does anyone have any advice on how to replace the master brake cylinder?  Any suggestion on the best place to buy one?<br><br>Thanks,<br>Karl<br>_______________________________________________<br>Scirocco-l mailing list<br>Scirocco-l@scirocco.org<br>http://neubayern.net/mailman/listinfo/scirocco-l<br>

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