RWC - What is "service brake %"?

[adamc11]

Hi,

I was wondering, on a RWC, what does service brake mean? It's a % value.

If it was 70%, does this mean there is 70% left or 70% used, or does it mean something entirely different?

Thanks,
Adam

[Blown V6 Hatch]

It's measured with a brake tester. Basically, it's a machine that measures how fast the vehicle stops from a certain speed (the one we have is tested at 60K/M/H) and converts it to a percentage. It also has a pad that goes on the brake pedal to gauge how much pressure is applied to the pedal to get the vehicle to stop. Has nothing to do with how much brake pad/s is left, it simply tests the brake performance.

[adamc11]

Thanks for that. So the higher the percentage the better? Is 100% the maximum?

[Blown V6 Hatch]

Yes, the higher the reading, the better the performance. Believe it or not, we've actually had a couple of cars go over 100% (the highest being 110%, late model BMW) buggered if i know how that works.... The worst we've had is 40odd%, that was a 4 wheel drum 65 Mustang.

[028]

does every testing station have to actually test it?
I've seen some just write it on the rwc paper

[Tree cutter]

Your brakes must not have to be very good to pass. An RTA inspector did the brake test on loose gravel with one of my cars and it passed. he said it had to register so many Gs on the meter which it did. I would have thought you should test brakes on a grippy surface so you can put a decent load on them to see if they will fail.

[Zeussy]

If you tilt the machine on the seat when you apply the brakes, it will increase the reading - pass an underachiever.

Or If you slam it in a drawer, even seen it just sitting on the bench, tilted harshly...