MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGA - New Master Cylinder Kit

I'm close to fitting new rubbers to the master cylinder and would like to hear of experiences from others.
I will try and do the job without releasing the two outlet pipes as the screw attachments on mine are so rounded they could be wrecked.
Is it possible to raise the MC and pull it forward and up a little, place a tray beneath to catch the fluid, remove the pistons, replace the rubbers, reassemble, and reconnect to the cradle?
Can this be done without loosing the fluid seal?
Or am I dreaming?
Fingers crossed! Barry
BM Gannon

Hi Barry

Yes it can! I recently did this with my 1600. First I drained the master cyclinder of as much fluid as I could by bleeding the brake line. I then carefully folded and placed a number of rolls of absorbant paper (stolen from the kitchen) around the master cyclinder together with numerous sheets and towels (stolen from the linen cubboard) to protect the body of the car. I went a little overboard here as my car is a fresh rebuild.

I didn't bother to disconnect the master cylinder from its cradle but found in the end that this wasn't really necessary as only a small amount of fluid leaked out when I removed the front cover (all of which was easily absorbed by the first few layers of paper towels). Just be careful when removing the front cover as the pistons will be under spring pressure.

Reassembly is a little finnicky but pretty easy really.

Regards

Steven


S HILL

Baz

As Steven says, it can be done. I have done both in the last 3 days and I used his method with the MC in place. However, the exits from the MC are both upwards, so you will not get all the fluid out, although I guess you could push the brake pedal to drain as much as possible. Also, there is a divide at the bottom of the MC, so perhaps you should do the same with the clutch circuit.

If you go down the removal route, the clutch pipe is thicker and therefore less flexible. I undid that first and was then able to pull the MC forward to get better access to the brake pipe union. I use silicon fluid, so fluid loss on the paint was less of a hassle with me.

Steve
Steve Gyles

Barry,
"Can this be done without loosing the fluid seal?" If by that you mean "will I have to bleed the system?" I would say, almost certainly, yes. Are you planning to hone the bores? I think it would be wise. Be careful to ensure that the rubber seals are fully seated on the pistons. This is sometimes not as simple as it sounds and can result in an overly tight fitting piston.

Cheers, GTF
G T Foster

I replaced the seals on my MC a few years ago . I managed initially to replace them with the MC in place without making to much mess with leaking fluid - unfortunately the pistons would not move in the cylinders and I had to remove the whole unit to free them up again - spilling fluid everywhere in the process! Good luck which ever way you choose - cheers Cam .
Cam Cunningham

Thanks for your thoughts and suggestions.
All went well and a test drive down the steepest hill assures all is OK.

I did move the MC up and tilted back (see photo below) and saved the fluid seal. Did not disconnect the pipes, so did not have to bleed the system!
I was able to check the outer part of the bores to see they were still shiny, so assumed they were acceptable. Pistons are moving freely. Braking effort is not changed - clutch allows gear-changes smoothly. No leaks! Only took about an hour.

I think the term - "saved the fluid seal" is the highlight here, no bleeding saves a lot of time and restricts the margin for error. But ONLY if the fluid is clean and relatively new.

On the road again with 'confidence', Barry




BM Gannon

Barry,
One of the things I love about this BBS is the continual reminder of the concept that there is more than one way to "skin a cat".
Cheers,
GTF
G T Foster

Barry

Is that the old faithful white car or a new project car?

Looks like I am going to be doing the same this weekend. Second time in a week! Having just got my car back on the road today (MC and runaway engine) I have noticed the MC is still weeping a tadge at the front. I retained the existing seals (2 years old) except for the deformed brake cup valve (had a spare) as I needed the car today. Just ordered genuine Lockheed seals from Bob West, made in Western Europe. I hope they are better than the current Far East set.

Bob mentioned that most MGAs heve weeps at the front of the MC. That's why he always uses silicon fluid to save the paintwork. I would concur with that. The one area on my car that will never rust is the shelf!

Steve
Steve Gyles

GTF it only took an hour! I expected a full day at least!

Steve it is the "old banger", the white 1600 (below), has been my daily driver for 37 years now. On its fourth motor and second gearbox! And STILL giving faithful service. They are indestructable!
And I'm only 21!
Barry


BM Gannon

When all else fails on those rounded brake pipe swivel nuts - 6" pipe wrench.
Mike


Mike Ellsmore (1)

For rounded brake pipe fittings, see bottom of page here: http://mgaguru.com/mgtech/tools/flare_nut_wrench.htm
Barney Gaylord

Barry

I have just done the seal change with the MC in place. Had I posted a picture it would have been the same as yours. I used a medical syringe (thanks Wifey, working in a GP surgery did have its benefits!) and a length of spare tube from my Eezibleed kit to drain the main reservoir. There was a little fluid loss when I withdrew the pistons. The new seals rubber seemed slightly softer than the Far East ones I had been using. All went back in fine, but I did end up having to bleed a brake line and the clutch - this was a 10 minute job maximum. Overall, the job did take 2 hours (with coffee break) rather than your fast one hour.

Best of all I appear to have a dry MC. First time in quite a while.

Steve
Steve Gyles

Steve, glad to hear you are dry!! The trick to avoid bleeding is to release the two top bolts of the MC from the cradle, tilt it back, involves a slight bending of the pipes, but that is easily rectified. I have previously always taken the whole thing out.
The seals I used have been in my garage for a few years so I'm hoping they last the distance. They may as well sit on my shelf as on a suppliers shelf!
Cheers, Barry
BM Gannon

This thread was discussed between 15/01/2009 and 18/01/2009

MG MGA index

This thread is from the archive. The Live MG MGA BBS is active now.