BB shell threads worn

graemeferguson

I recently got an alloy frame and as part of my frame prep chased the threads in the bottom bracket, fitted a shimano bb to the specified torques. ( Think it was 40 nm on Drive side and 15Nm on non drive.) After a few moderate rides with some steep uphills I felt some play in the bottom bracket. The cartridge had worked its way loose and when I striped and inspected the bike the threads in the BB shell were worn down. The BB cartridge threads were fine. Does anyone have any idea if I can save this frame?

jonnym5

Argos racing cycles can put a new threaded insert in but it's the cost involved in doing that. Had it done to two bikes in the shop recently and the repair was to a very good standard.

Did you happen to put a 68mm BB in a 73mm shell?

http://www.argoscycles.com/www/renovation-pricelist.htm

jonnym5

I've found them to be a bit censored in terms of longevity and some of them suggest the shell faces be cut out to match the angled surface of the BB.

ScareyJ

Don't know if this will help or hinder, But in my student days I kept a knackered Motorbike (Alloy frame, all threads goosed) on the road with green thread lock. It's more of a gel than a liquid, meant for thread repair, I never had any problems with threads after that, took a bit more effort to remove parts, but just cleaned the threads and reapplied the thread lock, fastened finger tight, leave it for five mins to set a little, then torque up as normal.

Might get you out of a bind

J

graemeferguson

Thanks very much guys, I'll try the threadless BB first. If it doesn't work I might just buy the Italian cutting dies.

craker

I've been happily using a threadless BB happily for a year or so now.

First time I fitted it it came loose after a few rides, so I chamfered the inside edges of the BB shell (I think you'll see there's a chamfer on the matching edges of the BB.) This can stop any vertical play in the system causing it to come loose; it's worked for me and wasn't a difficult job (hand drill with a small grinding wheel in).

The BB I bought (ebay special) doesn't appear to be as good as the Shimano ones it replaces. Little bit of play after a year, still going though.

graemeferguson

Cheers Cracker

I'll give it a go.