The Physics of upgrading brakes

[Knight Rider S4]

Been having this discussing about upgrading brakes and one of the points that were raised were the actual physics of it all

Understanding the fact that upgrades helped in a sense with the fact of Four Pot Calipers, bigger surface area for friction and decreasing speed and heat displacement ,but a few questions came up 'that could the servo/master cylinder handle the extra load from the bigger piston size and maybe cause uneven braking .........and that you would not get the full braking capicity that you should get as Porshe have upgraded Master Cylinders for Turbo Models?

Your Thoughts

[ctolladay]

Urrmmmm? I think it's all about the speed of light or summint? Physics that is.

[90quattrocoupe]

Been having this discussing about upgrading brakes and one of the points that were raised were the actual physics of it all

Understanding the fact that upgrades helped in a sense with the fact of Four Pot Calipers, bigger surface area for friction and decreasing speed and heat displacement ,but a few questions came up 'that could the servo/master cylinder handle the extra load from the bigger piston size and maybe cause uneven braking .........and that you would not get the full braking capicity that you should get as Porshe have upgraded Master Cylinders for Turbo Models?

Your Thoughts

Hi,
Forgot physics, but I upgraded both the fronts and the rears. I found the pedal travelled a little further, because I was using more fluid. Bigger piston area. But found no trouble as far as braking went. It just stops a lot better.

Greg W..

[Graham]

I would have thought it would have no effect other than a slightly increased stroke, you will still be only applying the same force to the pedal as on the 2 pots, just a tad more stroke, the pressure in the system isnt changing, only the force exerted on the pad is increasing due to increased area of the extra pistons.---
Force=Pressure / Area,
so to achieve an increased brake effort means either More pressure OR more Area, using 4 pots gives you more Area so an increased force.

[rotoryboy]

'that could the servo/master cylinder handle the extra load from the bigger piston size

If you do a search this has been asked time and time again. The RS2 uses the same master cylinder as the S2 and has the Porsche upgrade, then they also offered the 'Big Red' upgrade on the RS2 meaning the master cylinder is capable (otherwise Porsche wouldn't have offered it)
HTH

[Keeper of The Kitten]

The load on the master cylinder is baloney - if you go to bigger / more pistons, the load on the master cylinder decreases for a given applied load at the brake pads.

The stroke would increase at the m/cyl because the amount of fluid to displace will be increased - but that will only become a problem if you run out of m/cyl piston stroke!

__MDC__

[S2central.net]

Tis fair to say that nobody has ever reported master cylinder related problems after a brake upgrade. As rotoryboy correctly points out - the S2 has the same m/c as the RS2 which happily runs the official 'big red' upgrade option that was available from the factory. It has sufficient capacity for the extra fluid required...


Paul

[Greg_S]

Quick question, how much brake fluid is needed to fill the system & how much would you recommend to flush through the old stuff?

[4WheelDrifter]

IIRC it was a litre. I used another litre flushing them. HTH

[HPmuirt]

Quick question, how much brake fluid is needed to fill the system & how much would you recommend to flush through the old stuff?

Hi Greg,

When I did my brake upgrade, I bought 2L of ATE racing blue and used around 1.5L during the process. I think the actual capacity is a little over 1L and I found that the fluid was a nice blue at all 4 corners after flushing around 0.5L through.

Next time I change the fluid, I will buy the orange version of the same fluid (the ATE racing is fabulous stuff ) so that I can see when I am flushing pure new fluid as that really helps.

Cheers n

Si

[Greg_S]

Good job that, ive got 1.5 litres of Castrol SRF brake fluid to use. Brakes a feeling a bit spongy so thought its time to change the fluid

[Skull]

You are all forgetting about the tyre size.