Hi if I put a threadless bb in a threaded shell will the bb wreck the existing threads. The reason I ask is I didn't know what threadlock was and in the meantime I bought a threadless bb, I will have to wait for a week for the threadlock and I have the threadless bb in my hand and its sunny thanks in advance

By threadless, I assume you mean press fit BB? There is no way that any press fit BB can be installed in a threaded frame. A threaded BB also requires a special tool for installation. Try the Park Tool website for more info on the various types of BBs and the tools needed to install them. Thread lock, like loctite, is not required for a threaded BB.

https://www.parktool.com/search?q=bo...t+installation

Also don’t use threadlock on a threaded BB. Standard grease, taping with plumbers tape, or antiseize all work well on BB threads.

Yeah the problem is a bit difficult to explain but basically the new bb when tightened up on the drive side just keeps turning when pinched up, so I reckon the threads are a bit knackered my solution is to fit a threadless sealed unit. However the threads seem to be in good condition, some people have said use a liquid weld some people say threadlock and now plumbers tape. In the meantime the threadless sealed unit has arrived so I want to know if I temporarily fit it will it destroy the existing threads in the shell as it is sunny

I don't completely understand the use of "knackered" in this case...but your description sounds like the threads are already destroyed.

At one point you say the threads are good. And then you say they're no good.

Dan

yeah it's difficult to explain as the threads look ok it's just that I can't fully tighten the bb it gets quite tight but then keeps turning this is on the drive side other side fine and maybe threadlock would do the job

Is this possibly a Swiss or Raleigh BB?

What's the bike and what's the bottom bracket? If you took a fixed cup out of the frame and there wasn't damage to either the fitting or the bb shell, there's no obvious reason how or why the threads on anything could be buggered. Could you be trying to install an English thread BB in a Swiss threaded shell? or French into Italian?

If you do have a bb that won't accept the proper threaded cups, the threadless BB you're discussing may be one of the Velo Orange ones. They work by expanding. Their instruction video says to use blue locktight and I'm told they won't work on Italian threaded shells as the Italian shells are a little too big for a tight fit. Never used one of these, but they're said to work well when appropriate.

The bike is a Schwinn Mesa GS it's twenty years old the bb is shimano 68/116 mm threaded. When I inspected it it was loose when I tried to tighten it up anticlockwise as it is on the drive side it wouldn't pinch up just kept turning. I inspected the shell threads and there was no discernable damage so after going online I decided to use a closed threaded bb and my question was can I install this, use the bike without damaging the shell threads any further with the slight hope in fitting the old bb (which is very good) at a later stage thanks

I suspect the threads in the BB shell on the frame are damaged. You can go to a shop to see if it can be re-tapped/chased.

You should not try to press in a non-threaded BB into a threaded BB shell.

Original thread.
Bottom bracket query