I pulled appart an alloy body / plastic tank master cylinder the other day.

It was siezed, so i used a pin punch through the outlet in the top, to tap the piston out the other end. It seems like there was A TON of powdery residue in there. What on earth would that be? It had been sitting dry for some time, prior to disassembly.

Before putting a kit through it, would it be wise to hone the cylinder? Can a brake shop do this? I don't have any hones that size.

A piece of dowel with some sandpaper wrapped around it makes a good poor-mans hone if you don't have one the right size. I would hone it if there are any signs of imperfections, but obviously you don't want to go to far or the seals won't work, but if it got that far and there were still imperfections it is time to have it sleeved anyway.

Just my 2c but if you take it to a brake shop to have it honed, they probably won't let you leave until you've had it resleeved.

Most of the master cylinders I've pulled apart that have been sitting for a while have required coaxing to get the piston out, but I would say they were stuck not siezed, usually tapping them further in to the master cylinder to break the bond and then they eventually decide they want to come out.

Funny how in the dual line M/c the top piston won't come out until you pull the little pin out of the side

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

White powder is aluminium oxide (going back to natures' bauxite), a bit of moisture and oxygen.....
I think you may find the bore is now pitted or slightly larger or mis-shaped.

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Over 1,000,000Km, but now my retirement restoration project

was thinking that.......

I have it soaking at the moment...... Going to clean it out and look at the bore tomorrow.

Is this the reason why people recommend you store them with fluid in them?

Don't store them with brake fluid in them. It's hygroscopic and sucks in moisture like there's no tomorrow. Best to dismantle, clean and reassemble with brake assembly fluid or rubber grease and keep it sealed in a plastic bag or similar.

For alloy master cylinders it's probably best to replace or resleeve. To keep originality resleeve with stainless or nickel bronze, otherwise get a PBR replacement. I don't know if Lockheed cylinders are available now, at least not in OZ, maybe try the UK.

RonR

There is a special "storage fluid" if being left for any length of time - probably a very light oil

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

I'd go for re-sleeving in stainless. Especially if it is a car that doesn't get a lot of use. You should never have that seizing problem again. I've had that done to all my old cars and they have never given me a problem.

Pete

What's the cost of getting that done, and would any old brake specialist be able to do it?

Bicarb and a wire pipe cleaner

I had the MC's for the Cooper resleeved in stainless and rekitted at the same time for $93 ea.

Way to go.

As for longtime storage, I do as miniron suggests, strip, clean and re-assemble with rubber grease, seal off pipe hole with a bleed nipple and store in a ziplock plastic bag.

Where did you get them done David?

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

NEVER put mineral oil in there it rots and swells the rubbers.
I'd use PBR rubber grease, you can get it from most brake shops or Repco etc.
That's what they used to rebuild my VH44 servo.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

Could use Castor Oil

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David L


My greatest fear in life is that when I die my wife will sell my Mini and tools for the price I told her I paid for them!

agreed, had my SS sleeved about 6 years ago, never had an issue since.
i might have one for sale soon, might be changing to the earlier tin type, so wont have use for the other type

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real men race downhill - keiichi tsuchiya