Hoppy

Brakes appear to be this week's hot topic. How can we cool them down?

If you've seen Stef's red-hot AP discs from Donington recently, it'll be no surprise to find that the standard road going stoppers aren't up to the job.

Before spending £1,500+ on a full upgrade, has anyone tried ducting to cool things down? Stef says he's going to try some experiments. Anyone got any advice or experience?

I also heard that people have used the windscreen washers to cool calipers by redirecting the pipe work under the wheel arch. Has anyone tried it? Does it work?

Hoppy

Danny Fisher

Hoppy, What you might find is that if you're getting glowing discs on normal roads you're pushing a little bit TOO HARD!!!

Ducting may help if it is placed in the correct location. But this all changes as soon as you turn the steering wheel.

If you place cold water on to HOT discs you will find that they will tend to crack a lot easier than if just left to cool on there own.

simple solution is to drive at least one cool down lap, best to try for two laps, without using the brakes.

Dan

Squizz

I'm having to replace my discs after only 15K miles. They've got tiny stress fractures in them.

Seems like it's due to most of those miles being motorway stuff - Lotsa fresh cool air, then sudden high temperatures. All those heat cycles causing stress.

As for water cooling...Surely the calipers need to have water jackets - Otherwise plain old water on the discs/calipers is downright dangerous!!

Bugholes

The best way to keep your brakes from fading/overheating is to use the biggest/thickest disc that will fit under your wheel along with the largest area/volume pad, this will ensure that your equipment will carry on working even at high temperatures.
Spraying water directly onto your discs is not a good idea! A watercooled system means that the calipers have water pumped through extra channels drilled in the caliper and then away to a heat exchanger mechanism to get rid of the excess heat.
Good advice from Danny Fisher, the worst thing you can do on a track day is come straight in and let the car sit <I>cooking</I> do a couple of cooling off laps first.
Squizz big temperature cycles are a big problem for discs however a couple of good stops after a motorway journey shouldn't hurt your discs to much unless of course you are trying to brake from 120+ to catch your exit

Hoppy

Another thought - turbo cooling wheels!

The spoke design of wheels must have some effect on the cooling air passing through to the brakes. It would be simple enough to design a wheel which worked like a fan, sucking air through the spokes at speed.

Does anyone know if this has been tried? How about some kind of accessory wheel trim which could be clipped on for track days?! It would certainly look different!

Hoppy

gregh

Biggest problem I've seen/heard of at track days is when you get red flagged, right by the pits and dive straight in, this robbing the brakes of a cool down lap.

Any suggestions on what to do in that instance?

Greg

Don Palmer

Cool the brakes down over as long a period as possible, if they pull you in the pits you might get an option to run off round a road or carpark for a bit.
It is really important to leave the handbrake off when the brakes are hot.
If there are no options and you have to come into the pits then I would suggest that you move the car around so the pads don't stay in the same location on the disk rotor.

Ducting works well on lots of cars - Dan suggested it doesn't work when the wheels are turned - I have to say that if you are cornering on the limit and need the brakes that much then the car will go straight on anyway - don't brake in corners it promotes understeer, brake in a straight line before the corner if at all possible.
The way you come off the brakes makes a marked effect on cornering ability.

DaveW

Hoppy,

I remember seeing Group A Intergrales had something on the front wheels to push air onto the discs (or pull air off the discs, can't remember which). Looked like a plastic disc with fins. I think it was fixed on using the wheel nuts.

DaveW

Bugholes

Hoppy - Andy Rouse did some testing on a similar idea for the BTCC Toyotas he was running and found that adding cooling "fins" made a minimal difference, basically wheels do not rotate fast enough to have a <I>Fan</I> effect