Ream and sleeve?

[beanzontoast]

I have a 531 frame I want to keep, but the bb threads are knackered. (Not me, before anyone asks!). Does anyone know of (or even better, has anyone used) a place that does the ream and sleeve thing - especially locally to Derby/Nottingham?

 

[hubgearfreak]

if you have no luck, there's always this

 

[beanzontoast]

Hub - have been using one of those for a few months, but there's noise from the bb and an annoying 'tick' which I reckon is down to tiny play in the fitting - maybe not as secure as proper threads would be.

I wouldn't bother otherwise, but I'm hoping for a good 10 years out of the frame, so worth having it properly refurbed I think.

 

[spandex]

You need to go to a Frame builder they will rip out all the threads that are left and put in a Helicoil Bush. It will be good as New

 

[beanzontoast]

You need to go to a Frame builder they will rip out all the threads that are left and put in a Helicoil Bush. It will be good as New

Cheers, Spandex.

Derby/Notts forummers - anyone know a suitable frame builder I could call on?

 

[spandex]

Dave Yates, Bob Jackson..... do a web search

 

[mickle]

Argos Racing Cycles, Bristol.

 

[beanzontoast]

Argos looks possible - I've emailed them. Still open to suggestions closer to Derby if anyone has any!

 

[LLB]

You need to go to a Frame builder they will rip out all the threads that are left and put in a Helicoil Bush. It will be good as New

Helicoiling will require drilling a fair bit of metal out, then tapping to the next size and then inserting the helicoil which brings it back to the original size.

I'd say it would need to be done on a mill for a bottom bracket unless there are some custom tools to keep everything square.

I used to work for a company making ally components for the aircraft industry, and all the tapped holes were helicoiled for strength as the helicoil presents a larger surface area to bite on (more resistant to stripping out), and the inserts are made of steel, so strong in their own right.

 

[hubgearfreak]

any frame builder? here's a list

 

[hubgearfreak]

all the tapped holes were helicoiled for strength as the helicoil presents a larger surface area to bite on (more resistant to stripping out), and the inserts are made of steel, so strong in their own right.

why not just make the hole the next size up then? i understand their use in repairing things, but new?

 

[beanzontoast]

Thanks for the list, Hub. I know of Mercian cycles, but haven't had dealings with them. Will try them as well on Monday and see what their price is like.

 

[LLB]

why not just make the hole the next size up then? i understand their use in repairing things, but new?

Probably because if the capscrew (allen bolt) head size is increased when the thread diameter is upped, then the size constraints of fitting the other structures in the components around the heads counterbore become an issue.

IE capscrew head dia is 1.5 times the thread dia so an M8 has a 12mm dia counterbore, but an M10 has a 15mm dia counterbore and you need plenty of metal around it to support the load on it when it is tightened.

They can also experiment with using different thread pitches and forms to increase the surface area of a helicoils bite in the component, but retain a standard thread form with the bolts used which could be a fine thread form (IE Metric fine, or BSF)

 

[P.H]

I think most frame builders would replace the BB shell rather than do as you're hoping. Mercian charge around £90 for that, then you've got cost of a respray as well. A friend recently had one replaced, he took it to Rourkes in Stoke, I don't know how much they charged. Longstaffs in Stafford might be worth a try, they've always done more engineering than most framebuilders.

 

[beanzontoast]

Thanks for those other places, PH.

The cost of the respray is going to bump things up considerably. I wonder to what extent the paintwork is affected by the engineering operation?