Brake Failure! And Inadequate Runoff?

This is possibly a karter’s worst fear – brake failure.

Bruce Allan was having a run with his Leopard at Wollongong a few months back when he ran out of brakes. Pitching the kart across the inside of the corner when he realised there was a problem, he was lucky to walk away without any serious consequences (and lucky the kerb didn’t flip him into the barriers driver-first).

“The lap before this one I got the sun in my eyes and ran into the kitty litter” Allan informed KartSportNews.

“I think this is what caused the problem. I had shims in my brakes and they had come out. It was a lucky escape.”

When the link to this clip was sent to me, it reminded me about concerns I have with run off areas in certain parts of our kart tracks, particularly (but not limited to) the end of fast straights.

Total brake failure is very rare these days, but it can still happen. Therefore, we need to ensure our tracks can cope with the consequences. In my opinion, some of them can’t.

Over the years I’ve had various informal discussions with significant people at a variety of clubs.  My opinion of too little run-off to handle total brake failure has often been met with “it passed the track inspection, so it must be ok” and “what are the chances of that happening?”.

Well, I have seen it happen.

One was a total brake failure (burst brake line along with a jammed throttle; talk about an unlucky day...) while others were significant accidents as a result of contact and too little run-off:

  • A bump and hitting a kerb approaching the braking area makes the driver’s feet bounce and fall behind the pedals. Unable to brake, he goes straight off the track into the tyre barrier, knocking himself unconscious.
  • Kart in front seized approaching a flat-out corner. The kart behind ran over the rear wheel, cart wheeled and threw the driver over the spectator fence like a rag doll.
  • Kart in front got punted HARD approaching braking area, and with rear wheels effectively off the ground, went straight off the track leaving kart and driver hanging out of the fence.
  • Contact under brakes sent Troy Woolston and his KZ2 off the end of the Todd Rd straight and into the fence at the CIK round. I didn’t witness that one, but the Woolston’s inform me the data showed Troy left the track at 129km/h...

None of the above incidents resulted in serious long-term injury, so I guess one could argue the safety systems worked. But will that always be the case?

The KZ2 gearbox karts, and the 200 Super Twins before them, really push the limits of safety on many of our sprint circuits. They’re great to watch, but I feel some of our tracks need changes to accommodate them.

All it takes is a brake pedal bolt or linkage to snap (and I’ve seen that happen to!) and it’s a 120km missile headed for the nearest fence.

Above: One bolt failure could see you have no brakes. It's important to keep a check on all the parts in the braking system. For example, there is no way to check wear on this bolt unless you remove it.

It’s not just brake failure that a lack of runoff can cause problem. As previously mentioned with accidents I’ve witnessed, wheel-over-wheel contact that pitches a kart into the air will see that kart take far more distance to pull up than if it ploughed into a nice soft gravel trap.

Gravel (or woodchip) traps are pretty useless for airborne vehicles that fly clear over the top. Maybe gradually up-curved ‘berm’ gravel traps are worth looking at?

Certainly, increased run-off area is the most effective solution.

What is a safe distance? I don’t know. AKA rules currently stipulate a minimum distance of 10 metres from track edge to safety fence, and 4m catch trap for ‘high-speed run-off areas’. These measurements are probably fine for most parts of the circuit, but not for a KZ that’s run out of brakes at top speed.

Next time you’re at the track, do a ‘what-if’ analysis of the circuit. What if you had TOTAL brake failure at the end of the straight? Would you be comfortable driving your machine off the track at high speed? What if you clipped wheels in that high-speed turn? Reckon you’d hit the tyre barrier? A bundle of tyres isn’t such a soft impact for a kart, particularly one driven by a low mass Junior...

Look after your gear, drive safely, see you at the track.

Mark Wicks