Any issues with shimano 8000 motors throwing cranks !

[RickBullotta]

Here's my technique:

1) Use the aluminum crank cap to get the crankarms snug against the splines
2) Tighten the inner crankarm bolt slightly snug
3) Remove the aluminum crank cap
4) Replace them with the OEM plastic crank cap
5) Tighten the crankarm bolts
6) Go ride

 

[HORSPWR]

Here's my technique:

1) Use the aluminum crank cap to get the crankarms snug against the splines
2) Tighten the inner crankarm bolt slightly snug
3) Remove the aluminum crank cap
4) Replace them with the OEM plastic crank cap
5) Tighten the crankarm bolts
6) Go ride

Why start with aluminium and then switch to the plastic. You can pull them up firm enough with the plastic ones from the start!

 

[RickBullotta]

Why start with aluminium and then switch to the plastic. You can pull them up firm enough with the plastic ones from the start!

not my experience. thus this approach.

cheers.

 

[HORSPWR]

I bought a TITO Titaniium Crank Cover M20. It's about 0.5mm bigger.

I have shimano cranks. I did take the pinch bolts out before tightening down.

I've attach a pic of how far out they are. Took it for a quick 12k ride yesterday and so far so good. Just looks odd.

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That's because they're made to the same specs as the ebay/china ones and the inner shoulder is too big but at least you have pulled it up in the splines of the crank. You'd strip the alloy threads on the cap before you damaged to internal threads of the crank.

 

[iXi]

That's because they're made to the same specs as the ebay/china ones and the inner shoulder is too big but at least you have pulled it up in the splines of the crank. You'd strip the alloy threads on the cap before you damaged to internal threads of the crank.

Thanks that's what I was hoping for. I've tightened it down so you can't see the inner shoulder now.

I've got a burgtec on order now, just have to wait for it to come in.

 

[HORSPWR]

The reason shimano make those caps/bolts from plastic is to deter home mechanics from over tightening/pre-loading their HTII BB bearings.

Spoken to Shimano on this have you?
I would say in my opinion (just like what you have stated is just your opinion). They're made from plastic as they only require a maximum of 1.5Nm torque, it's more likely a cost saving exercise, why make something out CNC'd of 6016 or 7075 aluminium when a plastic injection moulded cap can be made for 1/10th of the cost.

 

[HORSPWR]

Thanks that's what I was hoping for. I've tightened it down so you can't see the inner shoulder now.

I've got a burgtec on order now, just have to wait for it to come in.

The Burgtec ones look the goods, just hellishly expensive, it was about $77AUD when I last looked with currency conversion and freight for 2.

 

[iXi]

The Burgtec ones look the goods, just hellishly expensive, it was about $77AUD when I last looked with currency conversion and freight for 2.

I've ordered one from bikebug.com $19.95. If it works out I'll grab one for the left side too. They had no black so I have gone bronze.

 

[HORSPWR]

Thanks that's what I was hoping for. I've tightened it down so you can't see the inner shoulder now.

Personally if it was me for those ones with the bigger inner shoulder, I wouldn't do the cap up first and then the pinch bolts. Given that they're made out of 6061 or 7075 aluminium there's a good chance that they won't crush enough to allow the pinch bolts to toque up correctly to 12-14Nm.

 

[HORSPWR]

I've ordered one from bikebug.com $19.95. If it works out I'll grab one for the left side too. They had no black so I have gone bronze.

That's a way better price compared to Burgtec's shop.

 

[Gary]

Spoken to Shimano on this have you?
I would say in my opinion (just like what you have stated is just your opinion). They're made from plastic as they only require a maximum of 1.5Nm torque, it's more likely a cost saving exercise, why make something out CNC'd of 6016 or 7075 aluminium when a plastic injection moulded cap can be made for 1/10th of the cost.

how about both of those reasons emalgamated just to blow your mind?

 

[iXi]

Well my burgtec turned up today. It's considerably smaller which was to be expected. The cheap Chinese one had to be torqued up to about 8-10nm to get a snug fit, the burgtec fits barely tightening it.

With that said I did about 150k with the cheap Chinese cap and it didn't fall off, good luck or good measure who knows. Couple of comparison photos to compare.

I'll order one for the left crank now even though it's yet to throw that crank.

 

[Gary]

consider buying a decent allen key set too.
your new burgtec cap looks like you tightened it with a bread knife

 

[iXi]

consider buying a decent allen key set too.
your new burgtec cap looks like you tightened it with a bread knife

That's the thing hey I do. It's a wera set but the coating on the cap is so soft. Noticed that after I took the photo. Barely even tightened it.

 

[HORSPWR]

Well my burgtec turned up today. It's considerably smaller which was to be expected. The cheap Chinese one had to be torqued up to about 8-10nm to get a snug fit, the burgtec fits barely tightening it.

With that said I did about 150k with the cheap Chinese cap and it didn't fall off, good luck or good measure who knows. Couple of comparison photos to compare.

I'll order one for the left crank now even though it's yet to throw that crank.

View attachment 47390

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That Burgtec one looks way better without the shoulder step!
Did you chuck on a bit of blue Loctite too?

 

[iXi]

That Burgtec one looks way better without the shoulder step!
Did you chuck on a bit of blue Loctite too?

Yeah I did just to be sure

 

[Skel]

It's worth noting that the plastic bolt is not the primary method of retention here. It is the pinch bolts which clamp the crank down onto the spline that does all the work. If they're tightened correctly they should not come loose and the plastic(or alloy) bolt should not even come into play.

I recently swapped cranks, i have tensioned the pinch bolts to 13nm and checked/re-tensioned after a short ride and then again after each ride until i was no longer getting any any movement from the bolt before the tension wrench clicked off.

Various factors will cause the pinch bolts to lose some tension after the cranks are installed, the components will settle in after some riding and the bolts may "stretch" a little as well. I think it is important to check the bolts and tighten a several times to ensure they stay nice and snug.

I agree with this guy. The cap is meant to locate the crank, not hold it on. Appreciate that it might be a good redundancy if the pinch bolts come loose.

I have e13 cranks on a 21 Commencal Meta power SX race. Lost my left one while practicing wheelies in the carpark (thankfully not on a 49 footer). the spline mating seems a bit shite too me - only half of the female part seems to get clamped and make contact with the Shimano shaft properly.

I've refitted a new plastic cap, checked the crank is fully seated on the spline and retorqued. Will report back on longevity and retorque the bolts. I wrapped the cap thread with some PTFE tape too - should stop it rattling off again.

Be careful with retorqueing the same bolt - torque wrenches only provide a repeatable result when you start from approx finger tight. If the bolt is already near target torque when you use the torque wrench, you will likely be over torquing your bolts (not by heaps, though). So suggest you release the bolt first and then retorque as needed. Obviously this will slowly wear your threads out, though..

P.s. I also have a gold star from MacDonalds (BEng) and used to be mechanical fitter. For my sins I have been working on an automated controlled torque solution for over 2 years in a pharmaceutical application so learned a bit about the science of applying torque... Only been working on my bikes for a few years though so total rookie there!