2manyoranges
Old School Grand Master
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This is the first instalment of a potential solution to a problem.
I picked up a very high end carbon FS frame for Not Very Much - an object which had been much neglected, was missing large amounts of hardware and needed a new rear suspension element. I have overhauled our existing frames and repaired them many times so this one seemed like A Good Idea.
Carefully does it, I review all threads, order new parts and bearings.
In pressing out main pivot bearings I can see that one of them is loose in the housing. Yep, it’s very notchy. And it’s an oxide coating MAX 6903. The oxide ones are a pain. If the bearing gets notchy, the lack of any surface corrosion on the bearing means it can really easily slip in the housing. This one has done exactly that, and there’s 1mm of slop. Drat.
So….different solutions:
1
Whack a load of peen holes in the bearing housing so that the inner surface is raised and gets a new interference fit.
Downside: whacking the housing with a pointy punch wil transfer huge amounts of energy to the carbon - which can cause micro cracking in the surrounding carbon.
2
Use 603 Loctite to hold new bearing in. Will need to use activator.
Downside: good for gaps up to 0.5mm and this is more.
3
Use 660 Loctite to hold bearings in. Will need activator.
Downside: good for larger gaps. Almost certainly will hold bearing In. Will almost certainly mean that bearing can NEVER be pressed out.
4
Ream housing and use tolerance ring.
Downside: haven’t got big enough bit and can’t find 30x7 tolerance ring anywhere amongst suppliers.
5
Use coke can or baked bean can as shim material
Downside: will almost certainly cut my fingers when I do it and it probably won’t hold
More as I begin to dive in with gloves on….
And all advice welcome….
I picked up a very high end carbon FS frame for Not Very Much - an object which had been much neglected, was missing large amounts of hardware and needed a new rear suspension element. I have overhauled our existing frames and repaired them many times so this one seemed like A Good Idea.
Carefully does it, I review all threads, order new parts and bearings.
In pressing out main pivot bearings I can see that one of them is loose in the housing. Yep, it’s very notchy. And it’s an oxide coating MAX 6903. The oxide ones are a pain. If the bearing gets notchy, the lack of any surface corrosion on the bearing means it can really easily slip in the housing. This one has done exactly that, and there’s 1mm of slop. Drat.
So….different solutions:
1
Whack a load of peen holes in the bearing housing so that the inner surface is raised and gets a new interference fit.
Downside: whacking the housing with a pointy punch wil transfer huge amounts of energy to the carbon - which can cause micro cracking in the surrounding carbon.
2
Use 603 Loctite to hold new bearing in. Will need to use activator.
Downside: good for gaps up to 0.5mm and this is more.
3
Use 660 Loctite to hold bearings in. Will need activator.
Downside: good for larger gaps. Almost certainly will hold bearing In. Will almost certainly mean that bearing can NEVER be pressed out.
4
Ream housing and use tolerance ring.
Downside: haven’t got big enough bit and can’t find 30x7 tolerance ring anywhere amongst suppliers.
5
Use coke can or baked bean can as shim material
Downside: will almost certainly cut my fingers when I do it and it probably won’t hold
More as I begin to dive in with gloves on….
And all advice welcome….
