Morris Minor Owners Club

In the next few weeks I will be doing a brake disc conversion.

I know this necessitates removing the top hat seal, but can anyone tell me where it is in the MC and how to get at it?

You need to dismantle the cylinder to reach it. Get a picture of the cylinder internals, the top hat is inside a small metal cage.

Hi Matt,

Here is the drawing showing where the top hat seal is located in the master cylinder - right at the bottom!
[frame][/frame]
Good luck with the conversion.

Ahh pants.

Not an in situ job then

The MC is good, so maybe will put some new seal in it at the same time?

Matt
A bit of a fiddle but the internals can be removed from the master cylinder without removing the master cylinder.
Get the push rod out of the way and then remove the circlip. Draw the internals out of the master cylinder and remove the top hat seal.
Re-assemble with the new seals and bleed.

Knowing my luck the curclip won't play and when indo eventually get it out, bits will shoot down the chassis leg out of reach! I think I will pull it out, its not that hard to do

Its always good to have a proper look at it and clean . Mine looked like new from the outside , but was full of mud .

Why does one have to do something to this top hat seal with disc brakes?

It's there to keep a little pressure in the system when drum brakes are fitted. The return springs on the shoes hold them off the inside of the drum but when discs are fitted (no return springs) the pressure builds up with each application of the brakes and they start binding. I think I got that right.

To enlarge the above - the pressure (8 lb/sq in) is in the drum braked system to ensure that the sealing lips of the cylinder cups are kept expanded against the walls of the brake wheel cylinders. It also assists in conjunction with the top hat seal in the process of bleeding the brakes.
See Wksp Man Section M for full description.

So can anyone advise please?

I have bought a brand new MC (reportedly a Lockheed one, it does has the AP logo) and the "valve washer" appears to be missing... ? I can't immediately see it being a problem but I though I had better ask.

The "valve cup" appears to be a rubber bit glued in to the valve body. I assume its the rubber that wants removing?

Thanks

If the valve washer is missing it is no great problem but better if it is present - all the valve washer does is seal the valve body for the recuperation. As you are now going to remove the valve cup the recuperation sealing requirements of the valve washer are no longer required.
If it is of any concern that it is not there use the valve washer out of the old master cylinder.
I have never come across a glued in valve cup they are usually just pressed in.

This one is coming out in bits...

Yes it had glue on it...

Thinners disolved the glue, and made the rubber brittle...

Now out in about 3000 pieces!