Brake fade

Mar 14, 2005
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lutzschelisch.wix.com
Food for thought for the 'towing at 70mph+' brigade:

I was coming down a long descent on the motorway the other week, doing less than 60mph, and the warning buzzer came on indicating that the brakes of the caravan were overheating. This buzzer is one of the features of the LEAS electronic stabiliser that I've got fitted. (Because the working principle of this stabiliser is to apply the brakes, a warning buzzer is provided to indicate that if the brakes are fading, not only are you loosing brake performance but also the stabiliser can't do its job either.)

Without the buzzer I would never have known that brakes on the caravan were fading and who knows whether I would have been able to do an emergency stop from a higher speed with just the car's brakes available to slow the whole outfit down? As it was I pulled into a layby and waited for the brakes to cool down.

Just shows how borderline the braking performance of caravans is!
 
Mar 14, 2005
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Lutz, I bought two finned heat sinks and adhered them to the braking hubs and also bought some flexible ducting which i fixed to the underneath of the van so that I could direct cool air directly to the heat sinks and Hey Presto! (as we say in the entertainment trade) cooled brakes with no fade. I have tested with a porsche cayenne and found there is no brake fade from 120mph to 0 mph.

Just shows with a bit of resourcefulness what can be achieved!
 
May 4, 2005
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I think a system like they use on truck racing would be better.Water cooled brakes direct from the on board tank....Genius!
 
Mar 14, 2005
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aaah but what about the extra weight of the water? That would slow you down therefore negating the need for water cooling in the first place. You cannot beat a blow job on your hot metal
 
Mar 14, 2005
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The problem shouldn't be underestimated. Coming over the Pyrenees and in a bit of a hurry to reach the campsite before dusk, the brakes got so hot in the mountains that the plastic caps over the wheel nuts actually melted.
 
Mar 14, 2005
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When on a descent, long or short, I select an appropriate gear to control the speed. All qualified drivers should have been trained to carry out this manoeuvre!

Any vehicle, whether towing or not, will experience brake fade if the brakes alone are used on a long descent.
 
May 4, 2005
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Roger ,It really doesn't matter how you slow the car down as whichever method you use it will apply the caravan brakes, which is what Lutz is refering to.
 
Mar 14, 2005
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At cruising speeds, 60mph (and upwards!), aerodynamic drag is the main retarding force on a caravan, even on long descents, so the caravan brakes shouldn't operate so no brake fade should occur. Only when heavy braking is needed should the caravan over-run brakes start operating. By definition heavy braking can only be carried out for short periods (otherwise you'd go backwards!). Brake fade can only occur during long periods of heavy braking, which an experienced driver would avoid. I'm sceptical of electronics which indicate brake fade. Brake fade only occurs when the brake linings overheat, beyond their design temperature. Without a temperature sensor built into each brake shoe this is extremely difficult to detect.
 
Jun 27, 2005
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At cruising speeds, 60mph (and upwards!), aerodynamic drag is the main retarding force on a caravan, even on long descents, so the caravan brakes shouldn't operate so no brake fade should occur. Only when heavy braking is needed should the caravan over-run brakes start operating. By definition heavy braking can only be carried out for short periods (otherwise you'd go backwards!). Brake fade can only occur during long periods of heavy braking, which an experienced driver would avoid. I'm sceptical of electronics which indicate brake fade. Brake fade only occurs when the brake linings overheat, beyond their design temperature. Without a temperature sensor built into each brake shoe this is extremely difficult to detect.
Roger - from what I understood from the first post the electronics seemed to be detecting that the caravan was applying more force onto to tow-hitch than it should, indicating that the brakes wern't braking as effectively as they should, which seems a reasonable way to detect it.
 
Mar 14, 2005
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Brian's got it right, Roger. I was not applying the brakes on the car but relying on the engine braking. But, because the caravan was then pushing from behind, its overrun brakes were coming on and because the descent was so long, they heated up so much that they were fading. This was detected by the temperature sensor in the electronics which caused the warning buzzer to go on.
 
Mar 14, 2005
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It sounds like the 'van was unstable and the electronic stabliser was working overtime. I'd stick to the good old friction stablisers if I were you.

That way you can tell if the 'van is unstable instead of the symptoms being hidded by the LEAS.
 

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