Does anyone know how to break apart things which are loctited together? I have read that chlorinated solvents dissolve loctite and that heat is another solution. My problem is that I have a cromoly tube sleeve loctited onto my Coker hub’s axle. Why, you might ask? Well my bike builder who rebuilt my wheel wasn’t aware of 6203-10 bearings (40mm OD, 5/8" ID) so he used the more common 6203 bearings sitting on a sleeve on the axle. The sleeve was loctited in place. This was fine for a while when I was riding with 125mm cranks but now I want to change to long cranks for the Moonride.
One of the sleeves (plus bearing) came off by hand, as seen here
On the other side I pulled the bearing off but the sleeve remains stubbornly in place. See this pic I’ve tried dripping dichloromethane on the sleeve and trying to whack the sleeve off with a screw and hammer, to little effect. The sleeve is hard up against the ‘step’ in the axle, so there’s precious little to get any purchase on with the screwdriver. I guess the next step is to use heat on the sleeve. I’m not sure whether this is a good idea - will this reduce the strength of the hub (I think the UDC Coker cromoly hub is heat-treated?)? Anyone got any other suggestions before I take to my hub with a bunsen burner?
I think solvents will be your best bet, because any sort of heat could weaken the axle shaft (or hub shell if you got too close). Although i don’t know what type of solvent will disolve locktight. Sorry.
Locktite is a little lide epoxy in that it generally takes vry little heat to soften. Don’t remember exactly but in the neighborhood of 300 degrees or a little more. Changing heat treating of heat treated steel parts takes 3-4 times that amount. A propayne torch directed to the sleeve should supply plenty of heat without causing any appreciable transfer to other parts.
Good thing you are a chemist and have access to a range of solvents. I am surprised methylene chloride didn’t work, but you can try the methanol, I might try acetone also. The suggestion I would add is to try sonicating the part also, that seems to help with parts that have hard to get to places.
After more tinkering I’ve concluded that even if solvents did completely dissolve the locktite I’m still left with the problem of the sleeve being tightly fitted to the axle, and no easy way to whack/pull it off. I think the solution may be to take it to an engineer with a CNC machine to accurately cut through just the sleeve, leaving the axle below unscathed.
Loctite and Permatex have technical data sheets for their products that give the breakdown temperature for the various flavors of thread lockers and sleeve retainers. It depends on the particular product used. Some are designed for higher temperature applications (like in or near engines) and those will breakdown at higher temperatures. The regular thread lockers and stuff will breakdown at comparatively lower temperatures.
For example for the blue medium strength Loctite (243) they suggest localized heating to 250 deg C and disassemble the parts while hot.
I imagine that heat will work very quickly to both soften the Locktite and expand the sleeve to make it slip off easily. As soon as the sleeve expands a tiny bit, there will be very little heat transfered to the the axle.
If you have access to a vise with serrated steel jaws and good clamping force, you could put the axle in the center of the vise jaws (with the wheel horizontal) and crank down on it a little. Then loosen it and rotate 45 degrees and tighten again. Doing this a few times will probably expand the sleeve due to the deformation of the metal. You could then twist and lift the wheel to remove the axle from the sleeve which is clamped in the vise. …I hope that made sense. It wouldn’t work if the sleeve is hardened but I doubt that is the case.
You can get the same effect using a hammer on one side and a “dolly” on the other, but I am squeamish about telling you to hammer on your hub.
Thanks for all your advice, everyone. Heat was the answer. Not my wussy attempts with a Bunsen burner but my friendly local engineer with a white 6" hot flame. A few quick bursts with this puppy and the loctite loosened up readily. [I think anybody would loosen up when threatened with such a flame!] He pulled the sleeve off with vice-grips. Yay I love engineers!
My Coker is now fitted with the correct bearings and is reassembled in offroader mode (170mm cranks), ready for the Moonride.