Brake line pressure

[rj]

As I'm about teaching my nephew to brake hard immediately rather than increasingly, ending in a wheel lockup, I need to fit a pressure sensor in the brake line.

Does anyone know what pressure to expect?

 

TIA

[Jonathan Kay]

I don't think that I've ever seen figures for a 7, but the sixth edition of Hillier's has:

(At least they got one unit of measure right.)

Are you going to measure pedal force and acceleration at the same time?

Jonathan

[rj]

Thanks,

I have just found that most flexible brake lines have a maximum of 3770PSI (260bar-ish) - I have a 400 bar 0-10v sensor that then will do.g

Not pedal force, just pressure and acceleration in all four directions. (E-W / N-S relative to the car).

The exercise is mainly to show that he does not initially hit the brake as hard as he should.

[Jonathan Kay]

The exercise is mainly to show that he does not initially hit the brake as hard as he should.

How is that taught nowadays in ordinary and in advanced driving? Is it still recommended to set the car before applying full force?

I remember Mercedes discussing this when they introduced smart braking, IIRC they had some figures on the distance wasted by carbon-based decision systems.

Jonathan

PS: Something against pascals? :-)

[rj]

Yes, I can't relate to Pascals :-p

You are right about setting the car, but it shouldn't be a curve that raises for the whole braking time - until it locks and you loose control of the car. Mind you it's the first car he drives without ABS etc.

Hit it hard, wait until the car is set, then hit it harder would probably be more correct, though.

[rj]

PS:

1 megapascal = 10 bar, I know. Just not used to using it.

[Richard Price]

RJ,

I've been running a brake pressure transducer wired into my DL1 datalogger on sprints and hillclimbs for several seasons.

I'd suggest that, on a Seven, you're unlikely to see pressures greater that 50 bar.

I've just spent the weekend at Loton Park hillclimb, where maximum brake pressure was typically more like 32 bar (running AP brakes, with 1144 pads, and ZZS tyres)

[rj]

Thanks Richard.

My car has uprated brakes but runs with standard pads.

At least I'm confident tht I won't blow the head off the sensor. If it's max range is to high, then all that happens is that I get poorer resolution.