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MG TD TF 1500 - brake cylinder opinion

See the attached. Piston was seized but came right out with little effort. Under the seal the cup and spring were fine and moved. Piston had some surface rust and wire wheel on bench made quick work. Cyl was honed with sone brake fluid, no ridges felt. There is still a little dirt in there that I need to clean out.

I have rebuild kits. Should I rebuild?

Vincent Piña

I rebuilt all my cylinders and when finished three of the six of them leaked. I ended up with the 'classic gold' repros and these worked perfectly. Unless your brakes are really in good condition I would opt for new replacements. Hard to tell from your photo, but I thought my rebuilds were good too... until I had to fix the leaks. Just my 2 cents.
Geoffrey M Baker

There are fine hone marks, should it be more like a polish?
Vincent Piña

A complete set of 6 wheel cyls is about $165 from Moss. Total agreement with Geoffrey, replace all 6. If you ruin one set of shoes with a leaker that is a hundred bucks. I think I see rust on the piston and pitting, throw that cylinder out. George
George Butz

I agree with the above ... the "Gold" replacements made in China and sold by Moss are fine. They look and seem to perform like the originals and they are very reasonably priced.

That being said, if you want brakes that will last a great many years, then send them off to one of the brake re-sleeving places (White Post, Apple hydraulics, etc.) and get them to insert brass sleeves. Then have the pistons re-blued (or do it yourself) and use silicone fluid. I did this more than 25 years ago to my Sunbeam Alpine (all the hydraulics - clutch and brakes, including the servo) and I've never had to touch them since then. I also used stainless pistons in the disc calipers, BTW.
Kevin McLemore

I rebuilt mine. Some held, some did not, especially the MC. In hindsight, new ones are the ONLY way to go. Brakes make the car stop! It's a big deal! Replace the MC as well before you put in the fluid! Moss has them on sale from time to time.
efh Haskell

Not sure why I asked as I kinda already had my mind made up. Thanks for steering me in right direction. l will be replacing all brake lines (even though seemingly solid), MC and wheel cyls. Not worth chancing it.

Shoes are dry with little wear and drums look good. Going to mic them up to make sure they are ok.

Vincent Piña

I am amazed as brass re sleeving is not allowed now in NZ. This has been the case for many years.

We get seamless stainless steel re sleeving done now and that signals the end of the corrosion problem.

New alloy ones will still pit eventually and will need replacement again, in our experience this can be after only one winter lay up sometimes.

We re sleeve the master cylinder with S/S as well.
Rod Brayshaw

Why is brass not allowed? It seems to work just fine.
Kevin McLemore

How much would SS sleeves be for 6 cyls and the master?
Vincent Piña

The brake experts here in NZ advise that a Brass sleeve as a replacement for cast iron wears out quicker as it’s softer than cast iron. Brass as a replacement sleeve for alloy cylinders has shown the wear is about the same. Stainless only wears out the rubber cups so the sleeve job is a once only in Stainless Steel.

Stainless is fit and forget. Brass will have to be done again in the future. Just economics.

Brass has not been used in NZ for nearly 20 Years now, that’s why I asked.
Rod Brayshaw

I could have bought replacement cylinders but would have ended up with AL again just like stock, and they can pit and wear. I bit the bullet and had all wheel cylinders and master sleeved in Stainless. I'll likely never have a problem in my life time.
L Rutt

Hmm. Well, I accept that NZ disallows brass by law - you'd know better than I. But I really don't see the disadvantage of using brass, and I do see several advantages. It has worked beautifully in my 1967 Sunbeam and 1949 Triumph, and I'll offer a quote from a reputable workshop that supplies brass sleeves, Sierra Automotive:

"Why do you use brass? Why not stainless steel?

The proper grades of stainless steel are fine for sleeves *if* they are installed properly. For metallurgical reasons, they must be put in with a quite tight interference fit. This fit works fine on massive disc calipers, but can break relatively thin-walled master and wheel cylinders. Much of the work we do is on cylinders that are difficult if not impossible to replace, so we can't take a chance on breaking them. We can use different assembly techniques with brass that do not risk breaking the casting.

We often re-sleeve cylinders that have had stainless sleeves installed improperly. The typical failure mode for these cylinders is that the bond between the sleeve and the casting fails, allowing the sleeve to push out of the cylinder when pressure is applied. See a set of Dunlop caliper pods with three out of four failed sleeves (ed. note: I linked the photo below). The fourth sleeve was close to failure.

It's important to note that these systems do not fail from wear but rather from pitting caused by rust or corrosion. Brake parts move so slowly and so seldom, relatively speaking, and are so well lubricated that wear just isn't a factor. Even soft, non-anodized aluminum cylinders (that haven't been honed) show very little to no wear if we can find enough uncorroded surface to get a measurement. If we can prevent the pitting, we prevent the failure. The tempered brass we use is much harder than cast aluminum and not much softer than cast iron. The additional hardness of SS is just not an advantage in brake cylinders. In addition, brass is by nature a bearing material. SS is not."


Kevin McLemore

Kevin, an interesting topic has developed, NZ did have an issue years ago with a bus and a brass sleeve failing so Stainless Steel is now all we get without specifying.

I imagine the in service heat comparison between cast iron and stainless steel is similar so no problems there, but stainless steel and alloy are different so it is possible the sleeve could fail, and move. Wheel cylinders would not get as hot as calliper pistons?

I had a sleeve move on my Dunlop Twin Cam MGA front calliper, looks like your image. The brake calliper jammed on and stopped the vehicle until I loosened the bleeder screw. Do you think that was a heat induced problem?

Rod Brayshaw

This thread was discussed between 29/06/2014 and 01/07/2014

MG TD TF 1500 index

This thread is from the archive. The Live MG TD TF 1500 BBS is active now.