It might be a dumb question - but you have taken the circlip out of the bore that stops the piston going into the chamber - haven't you?

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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!

There's a circlip in the main bore and yes it has been removed and all the components down there removed so yes it could be a lttle silly.

This is the smaller piston that hangs off at a 60 degree angle to the main bore. It's in it's bore, and although it will move down, it won't come up as it has been locked in there for 20 years.
It is vented below to the main bore by a very small drill hole, and this is where I am hoping to get the pressure through to remove it.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Nothing fancy when they came outa the factory, I think- ie bodies were genuine cast iron and eminently rust prone

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1967 Cooper S - new front bearings to do.
1965 Cooper S shell - Slow progress. No time or money!
1966 Deluxe- next rustoration!
Mk 2 & XJ6 Jags. Less said the better.

I don't know if it will work in this case but I have had a good deal of luck with stuck brake pistons by soaking the cylinder in vinegar for about 24 hours and then the piston will always come out.
You need to wash off the vinegar and then coat the cylinder in oil quickly otherwise it will begin to rust as soon as it hits air.

Well vinegar it might have to be, I've made a plate up to bolt onto the back of the unit to hold the pressure in. I might soak it in vinegar before I have another try.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I finally got the bugger out, I had a problem which you can see in the last photo put up, where the grease was leeching out under the gasket (there was a lot of pressure going into this thing as those nuts were done up pretty tight on the metal blanking plate). the grease was then creeping up through the bolt threads from underneath and into the air gallery through a hole made by lockheed when making the unit. Once I nipped a bolt right up to the end to block the piercing then it came out with a bit after a little more pumping with a loud pop.

At least that's one job nearly done, onto the next insanely difficult rusted in component....at least I have the sand blaster for therapy...

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Just for an update if someone else comes along with this drama.

There's a repair kit available for the Lockheed servo, with no air valve....It seems the air valve is a fairly substantial component to produce featuring a cast center and a one use only construction (the large plate washers holding the assembly together is crimped in place). It will take some fettling to create a new diaphragm and re-fit it to the center.

Bendix make copies of the unit, but don't appear to be selling parts. Why? I have no idea.

But if you aren't feeling so very adventurous, there's an option available but you have to look pretty hard for it. Someone is selling a replacement diaphragm, but it comes with a plastic cover. Looks nothing like the original even from a distance and is a little expensive (at about 49 dollars Aust.)




Me...I reckon I will just create a petrol resistant diaphragm myself and then fettle the bugger and be done with it rather than pay through the nose for a normal rubber part with a substandard plastic cover.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

I remember seeing an advert recently for a bloke making dizzy diaphragms.....

I've got a large diaphragm or two around here from a booster, I'll cut it from that to the same pattern.

Seems the kits for the rest of the lockheed booster is no longer in production either (as of the last 5 months)

EDIT: Found a parts supplier with the overhaul kit and the air valve in stock in the UK....just need to make a phone call.....

EDIT EDIT: Got it, a rebuild kit AND an air valve kit. 30 pounds but it is the complete all in everything kit. Nothing else to search for.
Whew, how ridiculously hard is that? I would rather pull teeth than deal with a lockheed servo. I should have just put in a VH44J.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Re MK1 Lockheed Booster
The cast iron cylinder body on these was unpainted. The pressed metal parts, air chamber, control valve, air filter etc were zinc plated and passivated. The passivation process gives the gold colour and increases the corrosion resistance.
According to Parnell the very early boosters were finished in what appears to be a plain zinc finish, a sort of pale silver blue colour and the later ones were finished in the gold colour caused by the passivation process.
Karkraft and other Mini specialists should have overhaul kits (cost about $80 - $100) which includes the main diaphragm, piston and control vale cups etc and most but not all metal retainers circlips etc.
I also tried ABS Brakes and they had a kit in WA at a cost of $300+ so I rapidly lost interest at that price.
I recently (12 months ago) rebuilt mine and had all the pressed metal parts, screws etc replated, (zinc and passivated and that cost $25 at a local plater and that was their minimum charge)
The only part I couldn't find was the air filter/air valve assembly (Karkraft didn't have them and said there were NLA). Fortunately I had a new one I brought 30 odd years ago so I used that but it probably wasn't necessary to replace it. You need to make sure the rubber valve the control valve presses against seals properly and that the filter is clean If the valve doesn't seal properly the booster will be partially applying the brakes as it will allow some atmospheric pressure into the back of the main diaphragm.
Hydroboost in Melbourne also do O/Hs and changeovers of Lockheed boosters.

Hope this helps
RonR

Hydroboost you say? I'll give them a look in now that you mention it but now I've sourced most(all) of the parts it's just a case of reassembly.

I was speaking to a UK fellow who rebuilds lockheed and girling brake parts for a living, he reckons that the lockheed boosters are notorious for not working once they are reassembled. I think it is the air valve you speak of above the diaphragm that are the main culprits.

That must be why they replace the diaphragm AND the cover in the repair kits I have found. (See picture above).

Like I said before, the kits as an organised off the shelf part are no longer available as of five months ago. There are some mini spares companies trying to source a replacement manufacturer (probably in india I reckon).

I'll have all those pressed parts zinc plated in the gold finish. The inside of the pressed parts are gold on my one, so I must presume it was the same on the outside.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Mick,
For what its worth now, these are the original Lockheed part Nos for the repair kits. A Google search may give some results.
SSB 1036 Major Overhaul Kit
SSB 1002 Air Control Valve Kit
I had the same trouble getting the small control valve piston out. It seems to develop corrosion at the top of the bore and is hard to remove.
For future reference leave the hydraulic lines connected and remove the control valve assembly and then give the brake pedal a slow push and the piston should come out. Do this before you remove the booster from the car. I had to reassemble and reconnect the booster to do this.
I used a NOS air valve kit I had but it wasn't really necessary so you may find the control valve diaphragm and cover are still OK. Mine was still OK after nearly 40 years.
Plus don't throw out anything you replace, keep for later.
I had no problems with mine after the rebuild but make sure you clean up the cylinder bores with 400 grade wet and dry paper and only use methylated spirits to clean parts. If there is any pitting get the cylinder sleeved usually done with a nickel bronze or stainless steel insert.

RonR

Yeah i tore my air valve as I was taking it apart.....could have been avoided had the man with the fat thumbs not taken it apart...

How do you go about scuffing up the bores? do you attach it to a piece of dowel or similar, or have you a proper small bore hone?

Mick

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Mick,
Just did a bit more checking and the control valve pictured is for the later Lockheed type 6 Booster used for the UK MK3 S and 1275 GT. There's a picture of it in the blue or black MINI Workshop Manual, section Mb, page M-10. Definitely won't fit the MK1 booster. Totally different.
As far as I know these were never used on OZ built cars. When the MK1 Booster was superseded by the type 6 in the UK, in OZ they changed to the PBR VH44 type used on the later OZ MK2 S and Clubman GT.

RonR

Mick,
I have a small brake cylinder hone but you can use a piece of dowelling.
Cut a slot in the end of the dowel about 2-3 inches deep and cut a strip of wet and dry the same width and pit one end in the slot and wrap the rest around the dowel. Put the dowel in the bench drill and your in business. Use plenty of metho, and put the dowel into the cylinder and start the drill on a slow speed then keep moving the cylinder up and down on the dowel. Its best to have a large container that will hold the metho and the cylinder so its allways got some metho inside the cylinder. Alternative you can use a paint brush to keep the metho up to the cylinder. Check frequently as its very easy to widen the end of the cylinder bore if you dont keep it aligned properly. Professional laps are actually barrel shaped so that this doesn't happen.

Good luck
RonR