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MG MGB Technical - Brake/Clutch Master cylinder Mods

I have heard people complain how hard it is to replace the brake and especially the clutch master and I think I came up with a great idea to make the process relatively painless after you need to replace the one curently in your car. Going forward my idea will make life easier - a lot easier.

I plan to helicoil the threads of the masters rather than screw with trying to get the nuts on the lower bolts. Getting the nuts off isn't the problem - it's getting them on. This will make replacement/service a breeze in the future. I helicoiled the rocker stud threads on an aluminum head in my Datsun Roadster and they haven't pulled out and that's with competition valve springs. Chrysler's aluminum Hemi heads also helicoil the threads and they use spring pressures of almost 400# as do almost all aftermarket manufacturers of HP Chevy aluminum heads.

So, what do you think?
Mike MaGee

Mike - Helicoiling the bolt holes inthe master cylinders works wonders for ease of reinstalling. I did that on the clutch master cylinder that last time I replaced it and will do the same on the brake master cylinder the next time it comes out. Cheers - Dave
David DuBois

Excellent idea.
David
David

Rather than have to add helicoils to every future
replacement cylinder, I fabricated a one-piece
threaded backplate from 3/8" flat steel that is
easily positioned by hand behind the mount
flange on the clutch M/C while installing the
screws. Now it takes me less than a minute to install those screws.

I've never had problems getting the screws on & off
of the brake m/c. I wrap some paper masking tape
around each mounting nut and squish it onto a
box-end wrench. That's enough to hold them on
the wrench without falling off while installing the
screws from the front. The bottom flange nut is
accessed from the large round hole that is on
the side of the m/c mounting box assembly
- instead of trying to get access from the top.
Daniel Wong

Seems I'm not so original after all :(

BTW, I helicoiled the 3/8 bolt holes in the w/s posts and the lower front bolt hole in the alt and it made alternator/generator installation and tightening much easier.
Mike MaGee

Hi Folks:

Why bother with all the work for helicoils, etc. I have been using crazy glue on the bolt heads for the last 30 + years without a problem, and the installation is original.

Good Luck : Rich Boris
Rich Boris

Mike -I wish you had posted this a few weeks ago as I've just replaced both - and aligning those nuts was the most frustrating element of the job. But next time I'll be ready.
Vic
V Todman

you guys know wayyyyy to much about this. fortunately I have forgotten most of the pain associated with that particular job and can't visualize it now as to how that will help....get the car later this week from the body shop and will have to look and come back and read this thread. Assume this allows you to pre-thread the bolts in the master cylinder, put them in place and drive them home.
J.T. Bamford

I helicoiled and installed both masters and it worked. Unfortunately the pre-driled holes are a bit larger than the recommended drill bit size but after much testing everything appears fine.

One more mod. I used 1" stainless bolts which I installed from under the dash and which serve as studs to install the bolts on the l/h side of the brake/clutch box. This made installation of the box mucho easier as I couldn't get the threads started on that side and my arm didn't like being bent in that shape!!!!!! Lots of antiseize as s/s does meld together.

I don't know why the factory didn't use studs to install the brake/clutch box as it is way easier.

I also used foam under the box to seal the area from water. I guess a bead silicone will accomplish the same.
Mike MaGee

This thread was discussed between 17/06/2004 and 24/06/2004

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