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Old May 20th 19, 07:26 PM posted to rec.aviation.soaring
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Default Cobra Trailer Brakes

On Sunday, May 19, 2019 at 6:00:59 AM UTC-7, Nelson Howe wrote:
On Saturday, May 18, 2019 at 6:23:27 PM UTC-4, wrote:
Having just installed new brake drums, bearings, backing plates, and brakes on my 2011 year Cobra (New because I burnt up the original ones on the way to Perry, a long post on that later) I am quite sensitive to how hot the brakes should get in normal operation.

I am sure that all the new items were installed properly and the adjustments were checked and are correct.

Taking the trailer from home to SCOH is a 60 mile trip. The first half is rural but with quite a few stop signs and traffic lights. I stopped several times to check and the brake hubs were hot (and I would expect some heat due to friction, physics, and all that) but how hot is too hot? I could put my finger on the hub but didn't want to keep it on much longer than a second. By comparison the brake rotors on the tow vehicle were considerably hotter than the trailer brake drums.

At one checking stop I jacked up each side and the wheels turned freely with no sound of brakes rubbing.

The second half of the trip was open highway and upon arrival at the field the brake drums were still warm, but considerable less than the stop and go portion of the trip.

The trailer tongue compresses when stopping and expands when moving in what I assume is the normal manner. I did test how much force it takes to depress the movable portion of the tongue, unhitched from the tow vehicle, and it seemed to me about 75 pounds. When released the tongue then moved out to its full extension but did take about 10 seconds to do that.

So, having said all this, is this normal operation or is something amiss?

Next time I tow the trailer I will take actual temp readings with a thermal scanner and report actual temps.

DVM
ASG29E BV


I had to replace the pads and bearings last year because of overheating. Even after the replacement I found my hubs getting pretty warm on a short drive. We then removed the bowden cables, lubed them, got them moving freely and easily, and reinstalled them. That fixed the problem and the hubs now feel just a little warm to the touch after driving, not hot. I have a new set of bowden cables I plan to install in the future.

Nelson


My experience is the same as Nelson's. I replaced the damper and the shoes, but only after cleaning and lubricating the bowden cables really well (but without removing them), making sure friction was reduced, actuation was smooth and the whole system adjusted - only then I experienced both confident braking without too much heat build up even after downgrades. They heat up the most in city stop and go traffic.

David