2manyoranges
Old School Grand Master
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Just really working through bearing problems and solutions.
Amongst the many bearing-related issues I have been engaged with is the conundrum of black oxide bearings moving in the bearing seats. I have always used ss bearings and have only had a few instances of VERY neglected bearings moving in the seats. I recently overhauled a very neglected Transition Scout (FS 140 travel F&R), and ALL the bearing were terribly notchy and stiff. Terrible. Some very difficult to turn with fingers. But none of them had rotated in the housings. Not so the next Transition. Black oxide, expensive bearings throughout. No notchiness in the bearings, some a tiny bit stiff due to thickened grease. But all serviceable - no need to replace apart from....the fact that they had turned in the housings...rendering the frame highly problematic. Grrrr. I inspected the bearings closely ... they turned pretty freely but the oxide coating had been entirely worn off and the surface now heavily brindled with movement-related wear. Around 0.5mm smaller diameter to the bearing than should be the case, and massive wear to the housing - argh.
I now think the sequence in the problem was...
1 bearing installed in tight housing
2 black oxide partially or fully worn off during installation since softer than stainless
3 this reduced the friction co-efficient with the housing
4 with low 'hold' in the housing any minor performance in the bearing can cause the outer to move in the housing
5 movement further wears the oxide coating, increasing the amount of movement in the housing and causing nasty wear - BAD vicious circle
There's no way that these bearings were seized or notchy - the SS ones from the Scout - same housings - WERE dreadful. But no harm to the housings. These latter oxide ones were FAR better condition but ironically really bad damage to the housings.
I am NOT using black oxide again. Even with retaining compound they will be prone to this problem since it is a coating - a thin layer of molecules. SS bearings have a surface which is integral to the structure. Better - and cheaper. Installed with medium-strength retaining compound (eg Park RC-1 or Loctite 290), they will resist water incursion and prevent housing movement.
Thoughts?
Amongst the many bearing-related issues I have been engaged with is the conundrum of black oxide bearings moving in the bearing seats. I have always used ss bearings and have only had a few instances of VERY neglected bearings moving in the seats. I recently overhauled a very neglected Transition Scout (FS 140 travel F&R), and ALL the bearing were terribly notchy and stiff. Terrible. Some very difficult to turn with fingers. But none of them had rotated in the housings. Not so the next Transition. Black oxide, expensive bearings throughout. No notchiness in the bearings, some a tiny bit stiff due to thickened grease. But all serviceable - no need to replace apart from....the fact that they had turned in the housings...rendering the frame highly problematic. Grrrr. I inspected the bearings closely ... they turned pretty freely but the oxide coating had been entirely worn off and the surface now heavily brindled with movement-related wear. Around 0.5mm smaller diameter to the bearing than should be the case, and massive wear to the housing - argh.
I now think the sequence in the problem was...
1 bearing installed in tight housing
2 black oxide partially or fully worn off during installation since softer than stainless
3 this reduced the friction co-efficient with the housing
4 with low 'hold' in the housing any minor performance in the bearing can cause the outer to move in the housing
5 movement further wears the oxide coating, increasing the amount of movement in the housing and causing nasty wear - BAD vicious circle
There's no way that these bearings were seized or notchy - the SS ones from the Scout - same housings - WERE dreadful. But no harm to the housings. These latter oxide ones were FAR better condition but ironically really bad damage to the housings.
I am NOT using black oxide again. Even with retaining compound they will be prone to this problem since it is a coating - a thin layer of molecules. SS bearings have a surface which is integral to the structure. Better - and cheaper. Installed with medium-strength retaining compound (eg Park RC-1 or Loctite 290), they will resist water incursion and prevent housing movement.
Thoughts?
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