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Trying to chase down a freak coming from my SLX drivetrain and noticed the chainring bolts were a little loose. Tightened them and one of bolts has now mashed the thread in the crankset spider, poo. Are Shimano cranks now made of cheese? Has anyone else done this? I wasn’t exactly torquing the bolt very hard and I guess the drive side crank is now useless?
Trevor.
If it was loose then the chain pulling on it probably stripped the threads, any aluminium threaded part is going to be soft, it's aluminium!
Should have added slightly more helpfully, you can probably helicoil the cranks to fix them.
That's poo....
I'm on older 2x 675's and the outer bolts are standard 104 BCD holes that take normal 2 piece bolts so I'm assuming these are direct into the aluminium.... yuck!!!
I guess the drive side crank is now useless?
I doubt it... I don't see why you can't drill out the thread and fit a normal chainring outer bolt from the back...e.g. the slotted part in this pic.
If you can countersink all the better or you will need a 2x inner bolt for the extra length.
I don't think you can, the 1x cranks have a blind drilled hole like the granny ring on 3x cranks so you'd need to machine a flat on the outside too.
They are only just over a month old, I have emailed Merlin to see if they will sort it under warranty.
Luckily I still have my old slx cranks with a Hope chainring on in the regular 104bcd.
I don’t think you can, the 1x cranks have a blind drilled hole like the granny ring on 3x cranks so you’d need to machine a flat on the outside too.
Well the warranty seems better but I'm presuming there is nothing the other side of the blind hole...??
Even if there is no way to drill through then you could probably drill out another blind hole the diameter of the outer then file away the lip on the outer bolt and epoxy it in... (probably best to use the aluminium epoxy you can use on engines)
It's obviously not ideal but most of the force is lateral (not pulling it out) and its better than buying a new set...
What would I need to helicoil pedal threads? I have cheese related issues with GXP SRAM cranks (and don't start on the BBs) - so have a few and nothing left to lose - they seem to go for £20 plus on EBay so fixing is quite attractive.
IF they were loose, this will have done the damage to the threads - I've never had a problem with the threads on granny rings, even though I've broken a few chainring bolts (before I recently decided to look up the torque value.)
Chainset replaced by Merlin/Shimano. Good news!