Master Cylinder Sizes
Turbo Mini Forums

Chaps, ive recently been fitting a floor mounted pedal box and have been thinking about the brakes. Because the front and rear brakes now have seperate master cylinders what is the effect going to be using standard 0.75 master cylinders? Will be harder but the effort will be halved??


Im confussssted

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

erm pedal effort will be doubled i think,

I thought the yellow tags were .75 front and .70 rear, where the bean cans were .70 (Except early cooper brake discs)

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Well i also have a 0.65. Im
may give this a whirl on the back brakes. Tbh the brakes before felt shite, they didnt give me any confidence.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

i'd put the small one on the front, more pressure.

Right, can someone explain to be how a bias bar works? All i can see is a threaded bar thats got more threads on one end than the other?? I also have an inline bias controller which ill also use.

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

Brake Balance Bar
Setting Up and Adjusting Your Balance Bar
In our experience, one item that people often get "wrong" is the balance bar. As this component is central to the overall efficiency, and performance of the braking system, listed below are a few pointers that should help you to set up, and adjust the balance bar, therefore obtaining maximum benefit and optimum performance from your brake system.

The side to side end float of the balance bar within its housing should be approximately 2mm. To obtain this clearance, one of the clevises should be screwed on or off the bar as required.


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Push rod adjustment: This must be carried out with the brake system bled, and the pads fitted. The object of this exercise is to ensure that the balance bar lies square within its housing, and at 90 degrees to the master cylinders when the pedal is depressed. To obtain this setting adjust the pushrod lengths, which normally means the front rod being 6 to 10mm longer than the rear. Then with a normal load applied to the pedal, the push rods should appear the same length, and the balance bar square to the pedal, The above settings are very important, and once set should not be disturbed.
One other important point, when carrying out the above adjustments it is essential that the master cylinder pistons return fully, with the push rods back against their retaining washers. Check that there is no interference on the pedal such as stoplight switch that prevents the master cylinders coming fully off.

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Setting the brake balance: Before this can be done it will be necessary to bed in the pads and get the brakes up to a normal operating temperature Brake balance can vary from driver to driver, but for tarmac rallying or circuit use most drivers prefer to have a slight bias towards the front. This is best achieved by carrying out a series of stops (high speed is not necessary).

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Remember, adjusting the master cylinder push rods does not adjust the brake balance!!!

Thanks for that :)

1/4 Mile 14.3secs 96Mph Terminal 10psi of boost.


Fibreglass Parts? - http://www.tdkracing.co.uk/
Split Rims? - http://www.force-racing.co.uk/

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Edited by gr4h4m on 30th Mar, 2014.

I run a supercharger and I don't care the TB is on the wrong side.
VEMS + 12 PSI + Liquid Intercooler = Small Bore FUN!

Line Pressure Comparison
The table below shows the range of bore sizes available and shows the % step up from the previous size and line pressure based on 50 lb pedal load and a 5 to 1 pedal ratio.


Master Cylinder Size mm/in. 14.00/
0.551" 15.00/
0.591" 15.875/
0.625" 16.80/
0.661" 17.78/
0.70" 19.05/
0.75" 20.638/
0.8125" 22.225/
0.875" 23.813/
0.9375" 25.4/
1.00"
Area sq in. 0.2386 0.2739 0.3068 0.3436 0.3848 0.4418 0.5185 0.6013 0.6903 0.7854
% step up from previous size N/A 14.8% 12.0% 12.0% 12.0% 14.8% 17.4% 16.0% 14.8% 13.8%
Pedal Load lb. 50 50 50 50 50 50 50 50 50 50
Pedal Ratio 5:1 5:1 5:1 5:1 5:1 5:1 5:1 5:1 5:1 5:1
Line Pressure p.s.i. (single cylinder) 1047.76 912.72 814.87 727.61 649.61 565.88 482.17 415.75 362.17 318.31