Cooling fan failure after track runs

Terry Oxandale

Skinny Man
I'm guessing that the high speed straights are causing my radiator fans to freewheel to the point of bearing failure (any alternative failure ideas will be entertained as well). Has then been experienced by others, and if so, any remedies? This is a street/track car, so taking the fans out/in just for track time is not what I want to do (but would save weight). So one idea I have is to just insert a piece of material into the fan's grill that would block movement of the blade. The fans are never used except during longer stops at long traffic lights. The radiator intake ducting is sealed, so every bit of air entering the duct, is pushed through the radiator.
 

Mike Pass

Supporter
You don't say what the issue is or if you have dismantled the fan motor. I had failure of fan motors which was caused by a build up of carbon dust from the motor brushes shorting out the inside of the motor. The unit was taking lots of current but due to the carbon dust short circuit none of the current was going through the windings. I did a post with pics of the motor insides a few years ago.
Cheers
Mike
 

Terry Oxandale

Skinny Man
It appears the bearings are gone. One has the blade flapping off axis, the other very rough, and barely turns. both were perfectly fine before the track run. Electrically, they turn under electrical power, but appear to have suffered mechanical damage. Pull through arrangement, so nothing resulting from impact. I was running at speeds (peak and average) that were a good bit faster than previous sessions.
 
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Hi Terry,
I’d be looking at the quality of the fans you’re using. With the blades rotating under a non-loaded condition isn’t going to do any damage, other than acting as a generator.<?xml:namespace prefix = o ns = "urn:schemas-microsoft-com<img src=" /><o:p></o:p>
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I'd agree with Andy. Suggest you look at Kenlowe fans. They did the original GT40 production work in the 60s and are still going strong in Maidenhead UK with quality fans and staff who were there in the day.
Cheers
Roger
 

Terry Oxandale

Skinny Man
Update: Took the assembly off the car, and found that the fan blades appear to have suffered a centrifugal failure in that the ring and blades basically shattered. This resulted in some damage (not fatal) to the radiator fins, but it appears that there are no punctured tubes. So I'm even more inclined to believe the rotating speed must have been pretty excessive to break both fans within a single last high-speed run. Now to look for a different design that has less mass at the outer circumference of the blade tips.
 
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