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Master Brake Cylinder Fixing Bolt Size

Posted: Sun Jan 12, 2020 9:08 pm
by madbrendon
Hey all,

I have just purchased myself my very first Morris Minor (1952, two door), and this is also my first attempt at restoring a car. It is in reasonable condition, but very rough around the edges.

It was missing a master brake cylinder, and I have acquired a replacement brake master cylinder, but I do not have the bolts to fix it in place. Does anyone know the size of these bolts? I am hoping to find something locally that will fit. I live in New Zealand so purchasing replacement parts from U.K etc take a long time to get here, and I am really wanting to get it up and driving as soon as possible.

I have read about the mission it is to get the bolts off with the torsion bar, I am planning to put the bolt through the other way, but want to be careful not to hit the torsion bar. Will the bolt fit the other way?

I believe this is what I need:
https://www.morrisminor.org.uk/parts/11 ... r-cylinder

Does anyone know the size of this bolt?

Thanks for your help!

Re: Master Brake Cylinder Fixing Bolt Size

Posted: Mon Jan 13, 2020 8:12 am
by philthehill
The bolt shown in your link is the correct bolt.

The size of the factory original bolt required is 3/8" with a BSF thread.

The factory original bolt has a reduced thickness head to provide adequate clearance for the torsion bar.

This clearance is required as the torsion bar does not only twist it also bows as it flexes.

Re: Master Brake Cylinder Fixing Bolt Size

Posted: Mon Jan 13, 2020 12:20 pm
by King Kenny
Hi. Buy your bolts and grind down the heads to give clearance to the torsion bar and fit them the right way around. It is easy to bend the bars for future removal. I just use a crowbar resting on a piece of wood to spread the load and force the bar down to give me clearance. To make it easier I have taken one of the flats off.
474-gtp_hex_steel.jpg
474-gtp_hex_steel.jpg (56.97 KiB) Viewed 1533 times
All the braking force is front to back so there is no need to overtighten the bolts against the cassis leg.