Crank fell off

[Cuppa Bru]

Was riding the Spruit with my brother on Saturday.

His non-drive side (left) crank came loose at the bottom of the new slalom single-track next to Bantam Dr.

Thanks to the guys who let me use their allen keys to tighten the crank back on. :thumbs-up:

 

Bike's done about 15 hours now.

 

Please look at pics and let me know whether the profile of the splines is still hundreds.

Not sure why the cellphone camera makes everything look .

It's a 2013 Shimaon XT crankset.

 

If the profile is hundreds, then all I'll do is clean the crank, re-lube and re-attach.

If something is amiss, I'll ask the guys who assembled (nicely) to make it right.

 

Also, what is the silver pin @ 8 o'clock inside the crank splines in pic 1?

 

http://i1249.photobucket.com/albums/hh508/rudig/Crank/IMG_20130617_095409Medium_zpse8f0eb74.jpg

 

http://i1249.photobucket.com/albums/hh508/rudig/Crank/IMG_20130618_191443Medium_zps71838464.jpg

 

http://i1249.photobucket.com/albums/hh508/rudig/Crank/IMG_20130618_191532Medium_zps12fccf4c.jpg

 

http://i1249.photobucket.com/albums/hh508/rudig/Crank/IMG_20130618_191545Medium_zpsefbab13f.jpg

[Cruz Addict]

Splines look good to me, don't think the silver pin is part of the crank, I have stripped many cranks off bikes and never seen a silver pin, perhaps some shrapnel picked up when the crank arm came off on the trail.

As for the build who did it? Would be worried that they didn't tighten the retaining star bolt thingy and the bolts to the correct torque.

I Would perhaps drop by another shop to ask if they would be so nice as to help and quickly put it right.

If not and you need some help drop me a pm ill gladly assist,I have my own way of tightening the bolts that has yet to fail me and I have built 7 bikes so far.

Would give it a good clean and use a degreaser to clean up properly before using fresh grease, also use minimal grease on the splines, just enough to ensure it doesn't bind permenantly.

 

[Cuppa Bru]

Splines look good to me, don't think the silver pin is part of the crank, I have stripped many cranks off bikes and never seen a silver pin, perhaps some shrapnel picked up when the crank arm came off on the trail.

As for the build who did it? Would be worried that they didn't tighten the retaining star bolt thingy and the bolts to the correct torque.

I Would perhaps drop by another shop to ask if they would be so nice as to help and quickly put it right.

If not and you need some help drop me a pm ill gladly assist,I have my own way of tightening the bolts that has yet to fail me and I have built 7 bikes so far.

Would give it a good clean and use a degreaser to clean up properly before using fresh grease, also use minimal grease on the splines, just enough to ensure it doesn't bind permenantly.

 

Thanks, bud! I'm glad the splines are still good

Drop me a pm with your details and I'll visit later this week.

[Johan Bornman]

The silver pin fits inside the plastic spacer that lives in the groove of the crank's pinch-bolt arrangement. The pin pushes into a hole that's in the crank axle. It looks like your broke off.

 

What's with the green stuff?

[Johan Bornman]

The silver pin fits inside the plastic spacer that lives in the groove of the crank's pinch-bolt arrangement. The pin pushes into a hole that's in the crank axle. It looks like your broke off.

 

What's with the green stuff?

 

Don't use any grease on the splines. That's not a friction surface at all. Goes in clean. Grease is for inside bearings and inside bearings alone.

[patches]

Splines look good to me, don't think the silver pin is part of the crank, I have stripped many cranks off bikes and never seen a silver pin, perhaps some shrapnel picked up when the crank arm came off on the trail.

 

From the looks of it that silver pin IS part of the crank.

 

It seems like it's the pin broken off from the little plastic plate that can be seen where the pinch bolds go (in the last pic).

 

The purpose of this plate is to prevent the cranks from falling off in the event that they are not correctly installed or work themselves loose. That pin protrudes through into the main shaft (you'll see a little hole in the splines of the shaft where this pin fits).

 

So simply, clean it up. Get a new plate. Assemble properly.

 

EDIT: JB beat me to it

Edited June 18, 2013 by patches

[divernick]

Don't use any grease on the splines. That's not a friction surface at all. Goes in clean. Grease is for inside bearings and inside bearings alone.

 

And seatposts?

 

Assembly compound....right!

Edited June 18, 2013 by divernick

[Cuppa Bru]

Happy 6000th post

 

I don't know what the green lube is as I didn't assemble the bike. I've heard people arguing for and against grease on the splines, so it can't be all bad

 

Guess it was hopeful at best to think that the silver pin wasn't necessary. Fark.

[patches]

The silver pin fits inside the plastic spacer that lives in the groove of the crank's pinch-bolt arrangement. The pin pushes into a hole that's in the crank axle. It looks like your broke off.

 

What's with the green stuff?

 

The lumo green gooey stuff?

 

That's Shimano's OEM grease. They like putting it everywhere. Even dollops of it all over my brand new Saint RD

[wilvegza]

Splines look good to me, don't think the silver pin is part of the crank, I have stripped many cranks off bikes and never seen a silver pin, perhaps some shrapnel picked up when the crank arm came off on the trail.

As for the build who did it? Would be worried that they didn't tighten the retaining star bolt thingy and the bolts to the correct torque.

I Would perhaps drop by another shop to ask if they would be so nice as to help and quickly put it right.

If not and you need some help drop me a pm ill gladly assist,I have my own way of tightening the bolts that has yet to fail me and I have built 7 bikes so far.

Would give it a good clean and use a degreaser to clean up properly before using fresh grease, also use minimal grease on the splines, just enough to ensure it doesn't bind permenantly.

The pin is the crank arm retention pin, which is part of the black plastic spacer/washer that fits in the split on the crank arm. The washer has 2 holes through which the crank arm pinch bolts are mounted. The pin is moulded into the washer and is supposed to protrude into the hole in the shaft to ensure the crank arm is mounted correctly and does not slide off the shaft even when the 2 crank bolts are loose. Either the pin was not in the hole and broke off (which happens very easliy) or it came off when the crank came off (which is not supposed to happen). By the way you canot buy a new washer/spacer, not sure why not.

Hope this helps

[Cuppa Bru]

So the silver pin is just a gimmicky failsafe. Thanks for the info, Patches!

Looking at other pictures I think I see where it belongs.

 

http://i1249.photobucket.com/albums/hh508/rudig/Crank/IMG_20130618_191452Medium_zpsa1c379bd.jpg

 

OK, I will clean everything up and use loctite (purple) on the bolts and torque them on tight as possible with an allen key. That way I don't have to worry about the crank coming loose before upgrade time

[Eldron]

Most people just tighten one bolt then the other and call the job done. Nope. Tighten each one until its starts getting tight then tighten, turn crank, tighten other bolt and keep going until they're both tight. Sometimes tightening one makes the other loose... Also - don't use any tools or tighten the plastic retaining ring too tight - it ruins bearings. Just a wee nip by hand is enough - it doesn't need to be real tight.

[Stretch]

Don't use any grease on the splines. That's not a friction surface at all. Goes in clean. Grease is for inside bearings and inside bearings alone.

 

does it hurt? i tend to grease everything when i take apart and re-assemble

[Johan Bornman]

does it hurt? i tend to grease everything when i take apart and re-assemble

Ja, it hurts me when I have to work on someone's bike and it is full of grease. My least favourite is to grease the entire steerer tube. Thereafter, lathering the waterproof sleeve in the BB and then grease on the crank. Why do it? Stop wasting grease, Save the planet, whatever, but don't put grease where there are no bearings.

[Cuppa Bru]

Most people just tighten one bolt then the other and call the job done. Nope. Tighten each one until its starts getting tight then tighten, turn crank, tighten other bolt and keep going until they're both tight. Sometimes tightening one makes the other loose... Also - don't use any tools or tighten the plastic retaining ring too tight - it ruins bearings. Just a wee nip by hand is enough - it doesn't need to be real tight.

 

Don't use any tools for extra leverage otherwise I'll tighten the plastic retaining ring too tight and ruin the bearings?

Will use an Allen Key and do multiple takes to make sure it's tight. Will try not to overdo it.

[Cruz Addict]

Most people just tighten one bolt then the other and call the job done. Nope. Tighten each one until its starts getting tight then tighten, turn crank, tighten other bolt and keep going until they're both tight. Sometimes tightening one makes the other loose... Also - don't use any tools or tighten the plastic retaining ring too tight - it ruins bearings. Just a wee nip by hand is enough - it doesn't need to be real tight.

 

Hehehehe that's exactly the way I do it, never knew about that pin till tonight, looks like I have learnt something new.