hicost blade
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| posted on 11/3/10 at 06:24 PM |
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Brake information
First of all.....I did not write this (It was sent to me in an email) but I thought it may be of interest to people so here goes.......
It is always helpful to refresh the basic rules of brake systems.
For example if you fit larger discs you will increase the braking mechanical advantage. This will reduce pedal effort.
If you find this results in brakes that are too sensitive for track use you can increase pedal effort by changing the master cylinder or removing the
brake servo and fitting a bias controlled pedal box.
A larger master cylinder bore size will increase pedal effort but reduce pedal travel.
Master cylinders are usually available in inch sizes, pedal effort in lbs per sq inch and piston sizes in mm just to make things easy to grasp!!!
These examples will demonstrate what you might end up with:
If you increase disc size from 284mm to 300mm you would end up with a 5% decrease in the pedal force required to get the same braking force. Therefore
a 100lb force required before would become 95lb.
New pedal force = Pedal force x (Old brake disc radius/New brake disc radius)
The rolling radius of the tyre has the opposite effect - increase the diameter of the tyre/wheel combination and you increase the pedal force
required.
New pedal force = Pedal force x (Old tyre radius/New tyre radius)
In this case if you went from a 14” Wheel with 195/60 up to a 16” wheel with 205/55 you would increase the pedal effort required by 10%.
When looking at master cylinders the formula is as follows:
New pedal force = Pedal force x (new master cylinder bore diameter²/ old master cylinder bore diameter)²
Because of the square in the above formula the effect of a change is more pronounced. E.g a move from a 1” master cylinder to a 1.25” master cylinder
will change the pedal force required from 100lbs to 156lbs.
Next thing to remember is bigger pistons in the calipers mean more force and, therefore, less pedal effort. Bigger pistons in the calipers mean more
pedal movement.
For comparing one brake to another on the same car, you can simply multiply the total caliper piston area times the effective radius. If you have a
sliding caliper although it has piston(s) on one side the area should be doubled. A single piston sliding caliper with the same piston size as a twin
fixed caliper will have the same clamping force.
When planning your braking modifications it is a good idea to consider these factors.
Naturally bigger brakes often require bigger wheels so the two cancel each other out to a degree.
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grub
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| posted on 11/3/10 at 06:45 PM |
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yeh ya right
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matt_claydon
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| posted on 11/3/10 at 07:19 PM |
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quote:
Originally posted by hicost blade
New pedal force = Pedal force x (new master cylinder bore diameter²/ old master cylinder bore diameter)²
Slight, but crucial, correction:
New pedal force = Pedal force x (new master cylinder bore diameter²/ old master cylinder bore diameter²)
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boggle
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| posted on 11/3/10 at 07:24 PM |
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cheers for that..
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TigerB6 Paul
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| posted on 11/3/10 at 07:41 PM |
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Lots probably got the same message off Optimum Balance Products
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v8kid
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| posted on 11/3/10 at 08:50 PM |
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You could also add that line pressure should be less than 7 million pascals to avoid rupturing the lines!!!
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