Threaded SLX left crank

[Jameslaskey]

Hi hubbers

 

I very smartly broke the threads on my crank arm and did a pretty great job of it, Does anyone know of a place I could take the arm to get it fixed? I am in the joburg south area

 

Any advice would be greatly appreciated.

 

Regards

S.Laskey

[Cruz Addict]

i would suggest looking for an engineering firm that could re-tap the threads for a slightly larger bolt size, you could theoretically go to builders( i assume) and look for the tool to do it yourself but i suspect its not as easy as it seems watching american chopper.

[JXV]

which thread? pedal or one of the securing bolts? pics?

 

If its the pedal thread then maybe time to start looking for a new crank

 

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[Ispeed_V]

Sounds like an upgrade is on the cards

[Bomberman]

Hi hubbers

 

I very smartly broke the threads on my crank arm and did a pretty great job of it, Does anyone know of a place I could take the arm to get it fixed? I am in the joburg south area

 

Any advice would be greatly appreciated.

 

Regards

S.Laskey

 

 

Had the same happen to me on saterday, the pedal destroyed the crank thread.

I took it to a engineering shop to see what the can do so hopefully they can get it fixed. Will let you know if its works.

[Ispeed_V]

https://www.bikehub.co.za/classifieds/211321-shimano-slx-10-speed-triple-crankset-chain/

[MTBeer]

which thread? pedal or one of the securing bolts? pics?

 

If its the pedal thread then maybe time to start looking for a new crank

 

Sent from my SM-G935F using Tapatalk

If it's the securing bolts, then fit helicoils. If it's the pedal thread then not so simple. Don't think pedal threads are standard, so I doubt you'll get helicoils to suit.

[cfcjim]

Pedal threads are 9/16" by 20 tpi. Just FYI.

 

Any friendly engineering shop should be able to help with inserts or machining and retapping.

[JXV]

If it's the securing bolts, then fit helicoils. If it's the pedal thread then not so simple. Don't think pedal threads are standard, so I doubt you'll get helicoils to suit.

The difficult part with drilling and re-threading the pedal hole to take a helicoil is getting it lined up to the crank axis. On the left hand crank arm I think it is a right hand thread so the availability of the helicoil itself may not be a problem.

 

Secondary issue is that helicoils are best for axial forces. The pedal thread on a crank arm has to withstand significant leverage exerted on a fairly short thread.

 

Not sure about SLX but many alloy cranks have a hardened threaded steel insert for the pedal to ensure the threads are strong enough. When you try to insert a helicoil you have to drill the old damaged threads out and tap a larger thread to accept the helicoil. This will weaken the insert and could even damage it. I haven't seen it done but I imagine there could be difficulties and it may not be possible....depending how the crank is constructed.

 

Sent from my SM-G935F using Tapatalk

[MTBeer]

The difficult part with drilling and re-threading the pedal hole to take a helicoil is getting it lined up to the crank axis. On the left hand crank arm I think it is a right hand thread so the availability of the helicoil itself may not be a problem.

 

Secondary issue is that helicoils are best for axial forces. The pedal thread on a crank arm has to withstand significant leverage exerted on a fairly short thread.

 

Not sure about SLX but many alloy cranks have a hardened threaded steel insert for the pedal to ensure the threads are strong enough. When you try to insert a helicoil you have to drill the old damaged threads out and tap a larger thread to accept the helicoil. This will weaken the insert and could even damage it. I haven't seen it done but I imagine there could be difficulties and it may not be possible....depending how the crank is constructed.

 

Sent from my SM-G935F using Tapatalk

left hand crank is left hand thread.

[KathF]

I did exactly the same thing...whacked my SLX pedal on rocks one too many times. I knew when a bunch of silver coils fell out it was game over. I wound up buying a new one for +- R550, Greg Minnaar Cycles in PMB sorted me out pronto.

 

We investigate the whole inserts thing and tapping etc - in the end it was just easier and quicker to get a new crank arm. I was really surprised it was in the R500 mark.

[divernick]

Find a replacement crank arm on ebay if nothing locally

 

http://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=SLX+left+crank+arm&_sacat=0 

[droo]

Pedal threads are 9/16" by 20 tpi. Just FYI.

 

Any friendly engineering shop should be able to help with inserts or machining and retapping.

 

Left hand thread, which is where the fun starts.

 

OP, get your LBS to order you a new crank. You should be able to get just the left one. Rethreading is expensive and a waste of time, particularly with hollow cranks.

 

For future reference, pedal threads are handed. Left pedal is a left hand thread, right pedal is a right hand thread. My guess is you tried to screw the wrong pedal into the wrong side - I've seen it many times.

[Bomberman]

https://www.olx.co.za/ad/slx-crank-arm-only-one-arm-ID15Rkuu.html#6e5f268c83

 

Maybe he can help

[Jameslaskey]

Thanks for all the feedback guys

I have decided that I will get a new set / Arm I wouldn't feel too confident with a repaired crank anyway