Brake master cylinder ... front / rear tandem type non servo
Turbo Mini Forums

As my poor old turbo is miles away in storage I can't peek under the bonnet to get the part number off the master cylinder. Anybody here know which one is the front rear split tandem master cylinder????

I know there are three types;

Front rear split
Diag split
late servo type.

The girlfriends build has single line brakes and as I always change them as a mater of course I thought I'd go for the IMO safer split front / rear system.

Cheers.

P.S. if anybody knows the part number for the correct system valve to go with that it would be great .... Although I think there was only one for front / rear split......

Every day is a school day ...........

How fast and how expensive ...... the same question...

GMC227 with the yellow tag.

Cheers miniminor63 ..... will look for one of those.

Every day is a school day ...........

How fast and how expensive ...... the same question...

http://www.minispares.com/Product.aspx?pid=36659

there it is. This type is commonly mounted with one circuit (upper one IIRC) to the front circuit, and the lower one to the rear circuit. inline with the rear there as often mounted a bias valve to limit the rear brakes.

I have it like this on my car now and it works.

BUT recent thinking and reading makes me wonder why it works.... The two pistons in the master cylinder are connected, so if we limit travel in one of them, the other will also stop.

When we limit the pressure that we can give to the rear circuit(lower piston) we will limit the travel of this piston, and therefore also limit the travel of the upper (front) circuit..... hmmmm

I thought the upper on was the rear and the lower the front as the upper the larger diameter piston is the lower one IIRC. I would have thought you had to move more fluid to engage the brakes on disc calipers (especially 4 pots) than you do the rear wheel cylinders ..... I am happy to be proven wrong though.

I also thought that the two pistons where not physically connected but via a plunger and spring to give some possible relative movement between the top piston is floating. Also the rear brakes have positive return via the springs which could return the upper piston in a semi floating arrangement .... again I am happy to be proved wrong on this.

Edited by RogerM on 30th Dec, 2006.

Every day is a school day ...........

How fast and how expensive ...... the same question...

its all about pressure, not volume in a brake system as its already full of fluid. A small cylinder makes more pressure than a big one with a fixed amount of travel.

Your last point is interesting, and may be the reason why it works:)