alistairolsen
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| posted on 4/3/09 at 12:43 PM |
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Brake sizing
Hi
need a bit of info in sizing brakes. Im reasonably well versed in the merits of increases and decreases in piston and master ccyl size in single pot
sliding type calipers.
In a four pit caliper, when calculating fluid displacement, you need only use two pistons area? as the run out on the disk pushing the pads back is
the same, and whether two pistons move the full distance, or 4 move half the distance makes no odds?
For calculations of brake effort however one must use the full area of all four pistons along with the line pressure to the caliper?
Any advice appreciated.
Cheers
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johnH20
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| posted on 7/3/09 at 08:57 PM |
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Hi, I am no expert but since you have received no replies I will have a go. My knowledge, such as it is, is derived from the Brake Handbook by Fred
Puhn ( now out of print I think ). The answer to Q2 is definitely yes, you need to account for all 4 pistons and line pressure. As to Q1 I have never
considered this specifically ( nor does the book ). But the question is comparative any way and assumes a sliding caliper as base ( or have I
misunderstood? ). If yes I think your logic is right, but I am not sure that helps very much. You need to get the master cylinder sizes and pedal
ratio right for the combination you are using to get acceptable pedal effort, fluid displacement ( pedal movement ) will be a fall out. I stand to be
corrected.
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