I’m in over my head; I’m working on an Old, Ross mountain bike. I was able to get the cranks off, and when I did, I did not find a bottom bracket like I had expected from my little preliminary research. Instead, the whole assembly just, kinda, fell out of the frame.
Now, there is a fitting leftover on the drive side which looks like it threads in but which I can’t get enough purchase to remove. I need to remove the fitting to get a new bottom bracket in there, right? How does this come apart, and how will it go back together?
I’ve pictured everything which came out of the frame, the fitting, and a picture of the opposite side of the frame showing off the threads. Any help is greatly appreciated. Thanks!
by DyslexisEmu
7 Comments
If things are in good condition, you can slather the bearings in grease and put it back together.
Indeed you do need to remove it & you do so with the correct tool, You need something like this.
https://www.cycleking.co.uk/tools-maintenance/tools/cyclo-bottom-bracket-fixed-cup-spanner-36mm__2798?srsltid=AfmBOoplbj-hwX2ExzH6e2o7FNKddr8Uwa8v9-cPwfUBvMVq5fmTVpK1
https://www.parktool.com/en-us/product/crank-and-bottom-bracket-wrench-hcw-4
Or a big adjustable wrench.
Or take it to the local bike shop.
Sheldon Brown describes a tool you can make here: [https://sheldonbrown.com/tooltips/bbcups.html](https://sheldonbrown.com/tooltips/bbcups.html)
Be sure you use fine thread fasteners.
i took something similar off one of my bikes a while back. i bought a big adjustable wrench but it kept slipping. i used a grinder to make a shallow cut across that part so i could use a flathead driver and a hammer to turn it and get it off.
Firstly it’s left hand thread, so turn it the right way.
If you don’t have the right bike spanner there are some other ways.
Clamp the flats in a vice and then turn the frame. You need a vice with sharp jaws as the flats are very small.
Another way is to find a large nut and bolt, approx M14. Put the bolt inside the frame sticking out. Tighten the nut onto it and keep tightening. You can get a spanner on this more easily and you can be sure you are turning it the rt way.
Ideally you do want to take this out as newer bottom brackets use a different system but thread into the shell in the same way.
M16 or 5/8″ Allen key screw, Allen head in the frame, tighten a nut onto the screw and it’ll grip the cup enough to turn it (part is reverse threaded)
But if your parts are in good condition you can happily clean, grease and reassemble without removing this part. That’s how this was usually done when these parts were current