The braking test for the inter-collegiate competition we’re entering requires the karts to go from a minimum speed of 40 kmph to a stop inside the braking zone of 5 metres. This would result in a deceleration of over 1 g, and many places I’ve seen calculate braking force without reverse calculations tend to consider 1 g as a theoretical maximum deceleration. I have considered a 50 kmph vehicle coming to a standstill in 4 metres for additional safety, which ends up with an even larger deceleration. Are there any limitations which will not let the vehicle achieve this sort of deceleration if the rest of the parameters like piston and mc bores and rotor radius are reverse-calculated considering these conditions?
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The limitation in almost all cases for vehicle’s is tire adhesion to the road.
How do you get round that, softer tires, bigger tires, downforce, lighter weight.
I wonder if it was purely a braking test if performance would be improved by decreasing the tire pressure.
Are the brakes rear only, or front and rear. That will make a huge difference.
Your limitation is generally going to be traction, karts are very over braked. At least racing kart chassis are. Brake pistons, bores etc should not require much if any examination. Find traction, then if you approach thermal or mechanical brake system limits resolve them if you have to.
I’ve used the friction coefficient between the tyres and the road in the calculations to end up with my force and torque values. Just wanted to see if there was any constraint which would not let it decelerate so quickly. I could attach a few pictures of my calculations if that would be helpful.
Highest G force I have seen karting was a whiteland 4.1G going into the braking zone a few years back. It was exhausting to drive very physical, with rear brakes only I bet 1G is pretty hard to achive.
It’s an inboard braking system with a single disc rotor on the rear axle only.
That’s what I was wondering, what would the system limits be? Theoretically I could get ungodly amounts of force and deceleration, but what limits do I need to look out for while calculation for these values? Currently I have only considered practical constraints like chassis interference, pedal sensitivity and component sizes.
Yeah it sounds pretty unbelievable, but that’s what they’re spitting at us 
. Also the calculations would give even higher values, and I’m not sure if they’re limited by any other factors.
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There’s a multitude of systems in karting, so there is no clear answer. Just like cars, pads vary, some systems have dual calipers on a single disk. There’s vented and non vented. Ceramic coated and straight steel. The only limit I think I’d be concerned with is thermals, and (Generally) it takes a lot to overheat kart brakes. Like a LOT. You’re not going to overload a typical system on a racing kart in a few stops from 50KPH.
If you have a rear brake only kart, and there is a specific deceleration test that tests only braking, move the seat as close to the rear as you can. You could even work to keep F/R load transfer to minimum by putting seat as low as possible (even below rails if it’s not hitting the ground) and raising the front ride height to provide rake. Depends how extreme you want to go.
The short answer is: (Assuming typical racing karts chassis) The limitation lies in the tires and F/R load transfer, not braking system.
Questions:
I’m curious how you concluded the friction coefficient with how many tires compounds are available. What did you use as a reference?
What kind of a frame are we looking at here? Something self fabricated, or a racing specific chassis?