Have completely stripped the driveside pedal thread of an M770 crankset…..am I now forced to buy new cranks or is there a repair I don’t know about and can’t find on the Google?

helicoil

Once again, and within a minute, Singlecrack has surpassed my expectations/ability to use google.

Any experience of using it?

I’ve repaired post mount forks with them well enough.

I’ve actually got a 175mm M770 chainset at home that I’m meaning to get around to listing.

May well be in the market seeing the cost of the helicoil and the potential fubar potential by myself.

Annoyingly only need the drive side as chain rings and opposite crank are in perfect condition.

Chris Bell at Highpath can fix it

Take it into a motorbike repair shop – a lot of them do helicoiling and it may well be a lot cheaper and certainly simpler than doing it yourself.

I managed to mash the pedal thread of an XT crank years ago, fortunately I was working in an aerospace engineering place with a full toolroom. Machined out the damaged thread, cut a new thread in the hole, machined an insert in stainless steel, threaded in and loktited in place, drilled new pedal thread in insert. Was probably stronger as a result as the contact patch between hard steel and soft aluminium was about double what it was originally.

Basically fitted a big custom helicoil 🙂

Might not have been quite so simple had I just been armed with normal garage tools though!

Cheers, Rich

Cheers people.

Email winging its way to Chris at Highpath as prices look pretty good. 🙂

EDIT: Rich – I think I’ve got a hammer 😆

I was just about to send a crank off to Chris at Highpath but saw on the website he is away cycling until mid-October. Any other recommendations for a mail order service?

I’ve done the exact same to my M770 cranks, I ended up just buying a new set of crank arms, I wouldn’t mind getting mines sorted at some point as they will make a good spare set.

I have re-threaded cranks before (based on my cranks being two right hand threads instead of a left and a right) but the re-thread wouldnt work due to not enough material. You would need to drill it out, make an insert, make sure the insert was tight (lots of loctite bearing sealer and potentially lots of grub screws) and then use the tap to thread it. Would not recommend. Use a helicoil or buy yourself a lathe/milling machine and a 7/16th left/right tap.

Holy thread resurrection batman!

Just thought i’d update.

Finally got round to sending the crank to highpath at the start of the week.

Crank back today re-threaded and ready for action.

£25 for the repair and £5 for postage – certainly cheaper than new cranks.