Talk Morgan Forums Morgan Sports Cars Maintenance & Servicing Leaking master cylinder

The photo shows the dual circuit brake master cylinder retro fitted to a 1956 Plus 4 owned by a friend of mine. It was supplied by Melvyn Rutter and installed by the local Morgan dealer some years ago. It's leaking and the fluid appears to be coming from where the plastic reservoir meets the metal base. A new one costs 250 pounds plus all the posting and other expenses and this is the start of the season and nobody wants to be grounded. So we were wondering - does anyone have any experience at repairing such a unit? It's not easy to access but we will tackle it if we can get some assurance that it is repairable.

Thanks in advance of any advice. Kerry

Kerry

I send mine away for reconditioning- much cheaper than buying a new one and less hassle than overhauling it yourself. I used either Classicar Automotive in Cheshire or Contract Auto Engineering in the Midlands.

The master cylinder comes back looking like new and is pressure tested too.

Arwyn

Arwyn great to hear from you and thanks for that encouragement. We'll look for someone who can do the job. All the best.

Are these easy to service ie replace the internal seals?

Kerry, I would ever bow to Arwyn`s mechanical knowledge and experience compared to my own somewhat limited knowledge. And when it comes to brakes it is ever safest to employ expertise.

I am a child of the make do and mend generation thus my personal approach differs slightly.

I tend to think along the lines of...If the brakes have been worked on, and the cylinders forced back to replace shoes/pads, then it is possible that the m/cylinder has overflowed to some degree causing brake fluid to appear the be leaking from the reservoir by leaving traces on the casting..?

From a very dull memory I think those reservoirs can be separated from the casting once their fixing point(s) have been established and removed, either screws or perhaps a roll pin in the case of the cylinder in the image..?

With the fixing system removed the reservoir can be pulled free from the m/cylinder, at which point I might expect to find a sealing ring around each of the reservoir connections of which there will be two, one section of the reservoir for each of the two brake systems.

If you get to that stage I would hope that you found the cause of the leak, either a problem with the reservoir it`s self or the system of sealing..?

As it seems the issue is suspected to be on brake fluid storage and not from the pressurised side of brake operation, then with any reasonable mechanical aptitude available I might consider it worth investigating even if just to determine the cause. Ultimately you can parcel it up and send it to a repairer..

Rob, easy to replace seals...? I seem to remember some years back on eMog there was an issue with someone trying to remove the piston from a +8 dual circuit m/cylinder in order to replace the seal in the section loosing pressure, it was not straight forward. Memory fails me but I think it was perhaps the webmaster at Morganville who had the issue. The link does not provide info on brakes more a link to the webmasters Morgan history.

https://morganville.org/saga.html

As ever I expect Lorne at GoMoG will have covered all sorts of Morgan brake issues in detail, so worth rooting around on the site a bit...?

Thanks L. That's helpful. We do think it is the seal between the reservoir and cylinder housing so will have a look at that once the unit is removed. Repair kits are available from Melvyn Rutter.

The master cylinder has a separate feed to front and rear brakes, I wonder if it is a proportional pressure ie putting more braking pressure on the fronts than the rears (as the car weight moves to the front when braking) I notice on my car the rears lookup before the fronts...

Yesterday i replaced my drivers side rear brake piston it was siezed (same as I found on the passenger side) brakes did operate but only on one half of the brake shoes...well worth doing..

DSC_0566 by Robert & Ali Davies, on Flickr

173656093_133373512084211_3912586583294371763_n by Robert & Ali Davies, on Flickr

DSC_0362 by Robert & Ali Davies, on Flickr