Hi guys, searched the forum and can’t find anything on this.

My Mk2 is prior to changeover to VH44 booster. I managed to source a Lockheed booster recently and spoke to Terry from Hydroboost about having it refurbed. Terry advised that the way to identify a correct genuine Lockheed booster from a Chinese knockoff is the presence of a single groove ring at the end of the slave cylinder. Mine does not have a groove but based purely on appearance looks aged enough not to be the Chinese variety.

I found an excellent resource on Lockeed boosters on the forum posted by indigoBlueCooperS in Jan.

http://mk1-performance-conversions.co.u ... _servo.pdf

It shows that the rings at the end of the slave cylinder identify the bore size. No ring is 5/8, two rings in 3/4 and I can’t quite make out 1 ring - maybe 1 3/16th ? (2nd image below)

Trawling through images on Ausmini, all the Lockheed boosters as fitted to members cars appear to have no rings. Minisport do have what they describe as “original Cooper S brake booster overhauled” on their website, with the image showing single ring. (1st image below)

Question for the experts are a) what is the correct bore size, and b) does a different bore size have any significant impact on the braking setup ?

Thanks in advance

Atay

I have collected a few of these over the years, obviously used on local minis and long before China got involved. They are all plain/no identifying rings.
The main bore is 5/8inch. There is a 3/4inch bore where the pushrod guide sits at the open end of the cylinder.

Don't know about braking effects/setup. The usual law: larger bore moves more fluid. These would have been used in many applications with different capacity wheel cylinders etc.

Thanks Bill B.

The smaller the bore the greater the output psi.
I only have the specs for the PBR VH44 but the regular VH44 has a 3/4" bore and the VH44J fitted to the Cooper S has a 5/8" bore.

VH44D has a 7/8" bore and a output pressure of 780psi.
VH44 has a 3/4" bore and a output pressure of 820psi.
VH44J has a 5/8" bore and a output pressure of 1270psi.

No rings on mine at all either

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SooperDooperMiniCooperExpertEngineering

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

I agree with what all the other have said. The Aussie Cooper S had the 5/8" Bore Lockheed 5 1/2" Servo with no identifying rings.

This is a late 1967 MK1 S and it shows there are no rings on the front of the booster.

It's 11/16" (I have an original clean copy of that manual).

Edit: A copy of that manual has been added to the How To folder here - viewtopic.php?f=25&t=98726

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ex-NSW Police 1970 MK II Cooper S
VMCI #43

Nice work Doug, Thanks

Thanks all for your replies, the collective knowledge on this forum makes it such a unique reference guide.

Good thinking, Doug. A very useful reference.

The original Automotive Products (Girlock, Borg & Beck etc) have been taken over by "Caparo" who at one stage appeared to be remaking many items for classic cars, including mini 5 1/2 vacuum boosters, disc callipers, wheel cylinders etc. Have seen a catalogue somewhere, but can't find it now.
Does any one have any knowledge of their current activities and products?