# Loctite 680 on carbon fibre



## doogsdouglas (Apr 24, 2008)

Has anyone had experience using loctite 680 on carbon fibre? I'm working on an '08 Trek Madone that has a knock in the BB. The BB shell is carbon fibre and bearings are press fitted into the shell. I've seen this problem with several Madones so far but Trek doesn't seem to have a solution for this. I'd like to use loctite 680, a bearing mount formula, but I'm not sure if it's going to damage the carbon.


----------



## mtnbiker4life (Sep 19, 2005)

I hope you haven't used 680 yet? This reacts and breaks down thermoplastics. I have a friend who use to use 680 on everything....use to piss me off because he would come to me to fix things. One day he used 680 on the fasteners that hold the SIDI buckles....well 680 outgases and makes plastics brittle.....mid ride his buckles break. Here is the data sheet page 2 under General Information. I would try Loctite® 513™ Dri-Seal™ We use another product on ABS/PC but I'm not sure of the number.


----------



## mtnbiker4life (Sep 19, 2005)

Here is another option LOCTITE Assure 425 Surface Curing Threadlocker


----------



## doogsdouglas (Apr 24, 2008)

I ended up calling Trek's dealer support, and while they hadn't seen this problem with any of the Shimano cranks they have had it with both SRAM and Bontrager. Apparently a shim is needed between one of the crank arms and the bb bearings. Their solution for me was that I grease the bearing receiver with a synthetic grease. Since my understanding has been that greases will break down carbon fibre I decided not to listen to them and ended up just replacing the bearings and bearing seals. Problem solved.


----------

