[Healeys] 100 master cylinder rebuild

S and T Miller stmiller96 at hotmail.com
Tue Dec 8 11:29:25 MST 2020

Thanks Hank. Ah, simple enough so the "rubber band" is just used in conjunction with the rubber boot. That crossed my mind, but was way overthinking it. Crocus Zcloth is basically 1500-2000 grit so kinda basically my "super fine" paper. My thought was that bores aren't typically perfectly smooth, and since the rod slides inside the rear seal, that maybe perfectly smooth isn't ideal. Again probably way overthinking it.

I have also had great results with sleeved brake and clutch parts. I went through probably 3 sets of repo rear wheel cylinders (Bugeye), before resleeving the original ones. Not one problem since.

The Millers

"Always drive them, but remember each drive in an antique car is a test drive."

From: gradea1 at charter.net <gradea1 at charter.net>
Sent: Tuesday, December 8, 2020 12:51 PM
To: 'S and T Miller' <stmiller96 at hotmail.com>
Cc: 'healeys at autox.team.net' <healeys at autox.team.net>
Subject: RE: [Healeys] 100 master cylinder rebuild

Don't sand any internal parts. OK to use crocus cloth to polish but no emery or other abrasive.  Clean all with brake fluid.  Rubber sleeve can go over the boot when installed to keep dirt out and boot from slipping...use rubber grease to lube all rubber.
Brake Pedals & Master Cylinders BN1, BN2

If you sleeve the cylinders they will be a permanent fix, but costly.  If the bore is clean-no pits or scores then you do not need to sleeve. End cap is for access and is original. See pictures attached. Hank, healeyhelper.com


From: "S and T Miller"
To: "healeys at autox.team.net"
Sent: Tuesday December 8 2020 6:07:18AM
Subject: [Healeys] 100 master cylinder rebuild

Included in the Moss seal rebuild kit is a large wide/thin "rubber band" type seal that is not pictured in the service manual.  I assume it goes over the thin round "castle top" spacer in the end cover??? Also my "castle top" spacer is removable (also not pictured seperate in service manual). Is this correct or an aftermarket MC?

Also looking for plunger surface prep advise since it is a sealing surface and slides in the rear seal. Polish it? Super fine sandpaper? Just clean it? I plan to send the body out to be re-bushed.
Thank you,  Shawn

The Millers

"Always drive them, but remember each drive in an antique car is a test drive."
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