Ran into this issue: drive side went in smooth, but non-drive is super hard to tighten when reaching the threads that have locking compound pre-applied. It’s so tight on the last 3 threads that I had to stop, because I think it’s not normal. Probably another mistake of mine. So i double checked the length is correct at 68mm….🤨
PS: I applied grease moderately on both side in bb shell.
by mc-lino
13 Comments
I’ve installed one a few weeks ago and I’ve had the same experience. I even slightly damaged the cups – since they are made of aluminium. Maybe try a wire brush to remove some of the thread locker.
I’ve had the same experience with those BBs. Also found that they don’t last very long in wet weather. It’s a shame that the Un55 is so hard to get now because I found them to be much more reliable…
Remove the thread lock and use copper grease imo. I’ve never had one seize in place when doing this.
Take it to a shop and get them to run a tapping tool through the bottom bracket shell to clear up any dirt or debris in the threads.
Make sure the frame threads are clean. Use a toothbrush and chain cleaner, then a rag.
Actually, in the last picture I don’t see any threads in the frame. Maybe it’s just the picture, but it looks like some kind of pressfit.
I also do not see threads on the frame itself, which is concerning.
Sometimes the left cup gets wedged in once the cups hit the bearing seat. Due to gravity and bearing play, the axle might be tilted just a bit and the bearing on it will block the left cup from tightening. You can try unscrewing the right cup a bit, then insert the left cup as far as you can, then retighten the right cup while wiggling the axle a bit. When you feel a pressure increase then it is wedged in. when you feel a release, the bearings have found their seats. You can then screw in both sides of cups completely then.
As a few others have said, the thread lock is the culprit. I’ve installed lots of these on a variety of frames; new, old, pristine, freshly retapped, cruddy.
The thread locker is always a pain in the ass. If you run it in and out like it’s a tap, it helps a little. You can also just clean off the stuff like someone else said. Muscling it in will also mostly strip off the excess thread lock with no negative side effects, that I’ve found. I tested with a junk frame and have had no issues thus far.
At this point I wouldn’t just clean the threads, I’d chase them out with a tap. A shop can do this if you don’t have the tool. Get the bb shell ends cut parallel to each other and square to the body of the shell (“faced”) at the same time. You can tell this hasn’t been done previously because there’s still paint on the surface of the ends.
I had the same exact issue with the same model, drive side went in fine, non drive side ridiculously tight. I triple checked it wasn’t cross threaded and then just muscled it in, which is probably not ideal, but I haven’t run into any issues…yet. As others have said, the culprit is probably the threadlocker. I wonder if you could clean it off with a pick.
Last picture, bb bearing peeking out from shell, has that thing taken some hit or does it just look like it’s bit mangled?
Yeah man, they have an unholy amount of blue loc on them. My buddy (bike mechanic) scrubs it with a wire brush to get some off before installing
Remove the bottom bracket guide. The bolt may be protruding Into the bottom bracket causing some misalignment