No, never seen that before. Maybe over tightened at some point in its life. Were you riding it when it failed?
No, wasn't riding mate. I'd noticed a bit of uneven tyre wear so lifted the front. Found the wheel bearings absolutely shagged. During wheel removal I thought it looked like a crack, but it was much worse. There's alloy corrosion between, so I reckon it's been like it for a while. I'm wondering if the vibration from the bad wheel bearing has caused a stress fracture. It's a bit of a worry, looking back at some of my journeys. I always torque everything to spec with a Snap-on wrench.
It’s known to happen with Ohlins forks fitted as standard equipment on various bikes, the pinch bolts get over tightened and crack exactly where yours have, you can change the fork bottom but maybe cheaper to buy a second hand leg.
Hi mate. When you say 'fork bottom', do you mean the anodised bracket bit alone, or the whole section including the chrome tube?
Paul at Racelab showed me a set of Ohlins like this in his workshop a couple of years ago... they are called "pinch" bolts for a reason he said.. get on ebay, there's sure to be forks available for a decent price
The earlier Ohlins on my rsv were 12nm, the Ohlins fgrt I now have on are 20nm, both are practically nothing and as you said they’re called pinch bolts for a reason.
If you go down the route of getting a leg and removing the alloy part, The bottom alloy bit has a small grub screw holding it to the stantion, this screws against the stantion thread , after you have removed the grub screw lightly spot drill the threads that the grub screw has damaged, It was only after removing one of mine I found half the threads stripped out of the alloy then finding the reason why.
Someone with a better memory than me will have to fill in the blanks, cannot remember which model it was, but there was a need to replace the lower axel/pinch bolt assembly when issues of corrosion appeared, again cannot remember if it was a recall or service advisory, but do remember my bike needing repair, just can’t remember which one it was.
Since posting earlier, I found some docs, it was on my 929, which now brings back the memory of it, corrosion where the inner tube met the fork leg axle bracket. They replaced both brackets, and the one thing I remember clearly was Honda blaming it on owners using the bikes in adverse conditions....ie wet and salt , same old, same old Honda UK
There was a recall on the 929 where the axle bracket could crack where the tube slotted in. I don't recall the corrosion one. I ignored the recall and then it cracked and opened up on track to about 3mm which made me redefine my response to recall notices
It can be caused either by over-tightening, or else from not tightening, or even not loosening, the 2 pinch bolts equally.
Quite often if the bearings are "shagged", they seize and cause the axle to rotate in the fork. This basically pulls the fork apart in the rotating direction and cracks the aluminium. happens a lot with MX bikes suspension linkages when the bearings are not serviced or changed in time.
Reading this thread feels very concerning to me. Like Black and White says, I too always use the torque values recommended, but I'm still very wary with cast aluminium clamp parts. They usually are very small torque settings and while perfectly adequate leave a lot of opportunity for people to overtighten. Stressing cast aluminium clamps is asking for trouble. I assume the Honda torque setting are dry, but I always apply a lubricant to ensure it'll not seize. This complicates things even more. Another clamped part that caught my attention are the clip-ons. When I first removed them (07 model) I saw Honda fit a thin, wire, circlip-type ring into a groove in the fork leg. This works in conjunction with the pegs on the clip-on clamps and the triple bridge. If the clamp was to fail, the ring would stop the clip-on dropping down the fork leg, and so the peg would allow a controlled (but scary), stop. Seeing this wire ring made me wonder how confident Honda are in the cast aluminium clamps? Also, if I run the forks dropped a bit, as I do sometimes, there is no spare grooves provided on the fork leg, and so the wire ring has to be removed. Then, I fit a Herbie clamp to the fork leg under the clip-on.
