Wheel Cylinders

[David53]

Having pulled the hubs it seems I do actually have a sticking wheel cylinder on each side - actually two on one side. These are later cylinders and as original MM style reproductions are now available from ESM I plan to revert to the original type and refit new cylinders all round.

From reading other forums apparently it is a good idea to use some red rubber grease on the cylinders when assembling to help prevent contamination and keep them moving. Can anyone tell me exactly where to apply and how much?

[mike.perry]

I find that by clamping the working cylinder and giving a hard shove on the brake pedal is usually enough to free the sticking piston. Clean the cylinder and piston thoroughly, including between the top lip of the piston and the cap which the adjuster sits on, then smear a finger dip of Rubberlube red grease around the piston. Re-assemble and test.
I don't knoow how much Rubberlube costs now but I remember paying £7 for a 1lb tin 30 years ago

[David53]

I'm afraid these cylinders are a bit far gone, some surface rust showing on the piston. As I say they are also a later type which I switched to 10 years ago when I couldn't get the original type. Now that ESM have MM type cylinders I am going to refit the original backplates and install the original type cylinders. There is a slight difference in size which I found makes it hard to adjust the brakes properly when using later cylinders with MM drum/hubs.

So just a smear around the piston is the go?

[bmcecosse]

Yes for the smear.. If the repro cylinders have an O ring seal - I would avoid them.

[ASL642]

Try http://www.merlinmotorsports.co.uk They list Red grease

[minor_hickup]

ESM sell red rubber grease, get them with the cylinders. Don't pull the piston completely out of these new cylinders as they are a pain to refit!

[bmcecosse]

So it does indeed sound like an O ring seal.........

[David53]

Don't think they have O-rings Roy, these are the ones:



These are MM/Early Series II Cylinders, different from later units. I think the later type ones I'm taking off which I fitted ten years ago before these repro's were available are indeed "O-Ring" seals, which maybe why they've failed.

I have found a 500g tub of red rubber grease locally so all good!

[bmcecosse]

Just the comment about being hard to get the piston back in - suggests to me an O ring. The bucket seals and piston could never be described as difficult to install!

[David53]

Yes, I think he is referring to the later type

[minor_hickup]

I think they were O-ring seals, it was a little while ago now!

[David53]

Finally got the new cylinders a few days ago, and they are not the O Ring type. There is a cup type rubber seal inside the bore, with a spring underneath. Very well made for a pattern reproduction.

Got the car out this morning and stripped the hubs and brakes. When I started the restoration original MM type wheel cylinders were not available so I changed the backplate to a later type and fitted the more recent cylinders (which were indeed the dreaded O Ring type, and had all seized to some extent). So, now that I have been able to source the correct original cylinders I fitted the original backplates, installed the new original spec cylinders and then......Damnit, I realised that these older type cylinders have totally different fittings at the back with a two way brass fitting on each cylinder to take the flexible hose, bleed nipple and bridge pipe, wheras the more recnt ones have the threads cut directly into the back of the cylinder. I still had the original brass fittings but not the banjo bolts needed to fit them, and then I discovered that the threads on the flexible hose and bridge pipe were wrong (there was a change from BSF to UNF with the newer type cylinders).

So have had to order new parts, assemble the hubs again and wheel her back into the garage till they arrive. Goes to show - check what you need before you start!!!!