Globalti
Legendary Member
I've read about the dreaded Mavic "howl of death" which affects ageing freehubs. Having taken mine apart a few times (it's a wonderfully simple and robust design) I've come to a couple of conclusions:
The wear happens because the freehub rotates on a simple alloy boss machined as part of the hub. After 9,500 miles mine is beginning to show signs of wear and fretting of the outer surface of the boss and there is some play. When I remove the freehub body I see that the light oil has turned black, which indicates metal wear. The freehub has a spiral machined into the inner surface to encourage oil distribution and the standard servicing advice is to reassemble with copious amounts of light oil so I've been using 3 in 1 oil.
I guess the howl of death will happen when the wear becomes so great that the freehub begins to oscillate on the boss, so it's in my interest to keep the oil fresh and clean. The freehub has a white plastic washer, which bears against a rubber seal in the hub so it may be that, which sets up the oscillation when it becomes dry.
So this time around I cleaned everything up and re-lubricated with EP90, which is a heavy grade of oil that's used in low-tech high-stress applications like Land Rover differentials. It smells horrible. I wanted to try car engine oil buy hadn't got any handy. Anyway the EP90 has done the trick; it has filled the tiny gap between freehub and boss and no play can be detected when rocking the biggest cog from side to side. The freehub rotates smoothly and almost silently and doesn't stick and pull forwards, which can be a problem in cold weather if you use grease. I'll report back when it comes to the next service in a couple of months. Servicing the freehub is quick and easy so no hardship when I've got the cassette off for cleaning.
The wear happens because the freehub rotates on a simple alloy boss machined as part of the hub. After 9,500 miles mine is beginning to show signs of wear and fretting of the outer surface of the boss and there is some play. When I remove the freehub body I see that the light oil has turned black, which indicates metal wear. The freehub has a spiral machined into the inner surface to encourage oil distribution and the standard servicing advice is to reassemble with copious amounts of light oil so I've been using 3 in 1 oil.
I guess the howl of death will happen when the wear becomes so great that the freehub begins to oscillate on the boss, so it's in my interest to keep the oil fresh and clean. The freehub has a white plastic washer, which bears against a rubber seal in the hub so it may be that, which sets up the oscillation when it becomes dry.
So this time around I cleaned everything up and re-lubricated with EP90, which is a heavy grade of oil that's used in low-tech high-stress applications like Land Rover differentials. It smells horrible. I wanted to try car engine oil buy hadn't got any handy. Anyway the EP90 has done the trick; it has filled the tiny gap between freehub and boss and no play can be detected when rocking the biggest cog from side to side. The freehub rotates smoothly and almost silently and doesn't stick and pull forwards, which can be a problem in cold weather if you use grease. I'll report back when it comes to the next service in a couple of months. Servicing the freehub is quick and easy so no hardship when I've got the cassette off for cleaning.
