21 replies to this topic

[slar]

Hi, I have just purchased a VK commodore double diaphram booster for my upgrade and this booster came with a master cylinder not attached to the unit.

The master is a 1 inch cylinder with the square type reservoir it has PBR 1 cast on the top of it but has no numbers that I can match to any PBR parts list.
The only numbers are 21B4 stamped on the end and a poorly stamped C3 1, as well on the under side it has cast numbers 3011 right where the front brake line attaches.

I have looked up the PBR listing and can only find this type of 1 inch cylinder being used on WB holdens P7955 (disc, drum,) P7954 (disc,drum) P7953 (disc,disc ,disc drum)
and commodore BT1 police packs, P10037 4 wheel disc I presume.

The problem is the numbers stamped on the cylinder dont match anything and there is no P- - - - number anywhere.
I know its for a holden because my old torana flare nuts screw into it.

The other clue wich might help identify it is that it has a black plastic reservoir cap with the standard rubber surround like normal and GMH moulded onto it but all other commodore ones Ive seen have had a steel cap with rubber gasket.

So Im at a lose to know what it is. I would like to use it if possible as its in real good nick but Im worried it might be for 4 wheel disc and Im going to keep the rear drums on my project..

So Datto if your there could you help and what type of master would I need to run standard disc on the front of my LX and drums on the rear with out rear wheel lockup, as i said earlier Im using a commodore booster and i would like to get rid of the original proportioning valve.
Also do VB-VL rear drum cylinders fit Lx Toranas as these are 22mm on the commodore and 19mm on the torana, Im thinking bigger diameter cylinders would remove rear wheel lock up if I did use a 4 wheel disc master due to the extra volume of fluid needed to activate them.

Any way look forward to any responses
Cheers

[slar]

Just a correction, I said earlier that my torana flare nuts screw into this master cylinder, well the small ones do but very losely and the large one doesnt so im guessing the master cylinder is metric which would make it a commodore unit and not a Wb.

[dattoman]

WB and Commodore are both metric

The C3.1 means it has a crack pressure of 3.1 ... which means its not Commodore cause they are C225

So I'd say its WB drum brake rear
Either way the disc and drum WB cyl interchange

Larger rear cyls increase pressure to the brakes ... so you would be more likely to have rear lockup than with the 3/4

[dattoman]

The digits after the C stamped on the end denote the crack pressure

So C155 would be 155kPa

Commodore is 225 though... might be a typo...lol

 

Same bolt pattern... just double check rod clearance from booster is set right

[dattoman]

Look inside the ports

Does the flare come back at you ?

Or is it a drill point seat ?

 

I'd say its a WB ute or van one 

[dattoman]

Photo of inside the fluid ports please

[dattoman]

Wrong hole she cried

The outlet ports

[dattoman]

Looks like WB ute or van (not 1 tonner)

[dattoman]

Only car to have 15/16 was Commodore

So if is that then its def Commy

 

WB was the first with metric ports... and they were drill point seat

VB-VN were inverted flares... then they went back to drillpoint

[dattoman]

They changed in 92...  mid VP

[dattoman]

yup