Thanks Andy,
I suspected as much. Grinnall uprated my SD1 rear drums by using the "TR8" wheel cylinders as they call them in the papers I have with the car, of course with the pins swapped the other way they would fit an SD1 axle backplate with no mods.
To end the argument regarding smaller brake cylinders you only have to apply some simple engineering maths:
The forumla for fluid pressure in PSI is found by:
Fluid Pressure - P (PSI) = Force (Pounds) / Area ( Sq. In.)
So you can see the smaller the area within the bore, the higher the pressure. You can turn this into braking effort by taking that answer and using it in this formula for cylinder force:
Cylinder Force - F (Pounds) = Pressure (psi) × Area (sq. in.)
So you can see that the higher the pressure, the higher the braking force. Braking force is also increased by applying that pressure over a larger area i.e bigger brake shoes.
This explains Grinnalls modification on my car. He has used SMALLER wheel cylinders (4 speed cylinders) to increase braking pressure but larger drums and shoes (from a Rover SD1) to increase braking area.
Hope that helps [:D]
<b>2.0 Litre DHC Grinnall
Red 4.0 Litre V8 DHC Grinnall (with huuuuuge arches...!)</b>
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