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Posted by: tornik550 Oct 2 2012, 10:51 AM

My master cylinder grommets have a slight leak. They are cracked and old. I purchased some new grommets. I removed the old ones already and did not pay attention to how they were installed. Which side of the grommet goes into the master cylinder- the wide side or the narrow side? Also, when I install the lines from the reservoir, do I push them all the way through the grommet so the line is pushing against the washer in the master cylinder or does the line rest in the bore of the grommet?


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Posted by: pilothyer Oct 2 2012, 10:58 AM

The wide end goes in first, on top of the washers, then the line just pushes in. You will feel it seat. Since this is not a pressure connection that is all I have ever done and the brake fluid is just gravity fed to the master cylinder.

Posted by: pilothyer Oct 2 2012, 11:02 AM

Here is another link about this procedure:

http://www.914world.com/bbs2/index.php?showtopic=7961&hl=

Posted by: mepstein Oct 2 2012, 11:33 AM

Looks like an easy job but it's not. Patience during and beer after.

Posted by: URY914 Oct 2 2012, 12:14 PM

The picture above is unside down from the correct position.

Posted by: infraredcalvin Oct 2 2012, 11:23 PM

My method, lay under the car with drops of fluid running down your arm, push real hard for a half hr or so, stop a few times, throw tools around, kick car, try again, push real hard until fingers are too tired, get more frustrated and give a courtesy half pressure attempt before giving up, they'll slide right in. All i could figure is that putting too much pressure causes rubber to expand, blocking clean insertion, moderate pressure seemed to allow lines to slide right in without over compressing rubber. Good luck!

Posted by: cwpeden Oct 2 2012, 11:28 PM

I had to loosen of the master cylinder to get the rear one in. It is close to the 'firewall' and can be a bear. Then again I have a 19 mm cylinder, word is they are different in this aspect.

Posted by: euro911 Oct 3 2012, 12:44 AM

... and wipe off any brake fluid that gets on the grommets. I didn't properly seat the supply lines when I installed a new M/C and at some point, they leaked.

Sounds weird, but I think the leaking fluid caused the grommets to deteriorate. The grommets just disintegrated when I attempted to pull the lines back out to re-seat them


Some people remove the fuel tank, disconnect the supply lines from the M/C reservoir and press the nipples into the grommets before bolting the M/C to the floorboard, then re-route and reconnect the supply lines to the reservoir. This way they're sure the nipples seated completely.


For the sake of safety, if you haven't already done so, read up on the differences between DOT-3, DOT-4 and DOT-5 (and DOT-5.1) fluids. Know what's in your system and don't change it without knowing all the rules.

Someone at a dealership 'accidentally' added some incompatible fluid in one of my cycle's front M/Cs when a new Russell braided brake hose was installed. I noticed the front caliper had started to leak. We had to purge the system, flush with alcohol, replace the seals in the M/C and the caliper, and refill with the proper type fluid.