Any issues with shimano 8000 motors throwing cranks !

[Simon]

G’day all anyone’s shimano 8000 motors having issues with cranks not staying on ! After getting my warranty replacement motor it’s throwing the crank arms of ! I’ve been through 3 lefties & one right now ... it’s becoming a serious issue as I can not commit to anything as I feel as though my crank is going to wrigle loose ! I’ve spoken with shimano Australia ?? & they are investigating the matter! All I want to do is ride & get sendy with my trail slaying machine ? any help would be greatly appreciated.
Cheers simmo.

 

[Jonnymac]

Yes. I've experienced it with both the original XT cranks and my 155mm Miranda cranks as have 3 of my mates who have E8000 equipped bikes. Even with thread lock it still happens. Checking crank bolt tightness is now part of my pre-ride check before every ride unfortunately.

 

[Gary]

change the HTII pre-load caps to alu versions (ebay) and use a little blue loctite on your pinchbolts. Use a torque wrench to make sure you have them tight enough,

 

[Jonnymac]

Cheers Gary. Certainly worth a try. Purchase made!

 

[Gary]

Should have said. I had the LH crank come loose and fall off on my first E8000 motor. the above solved the issue and I've done the same on every motor since and had no issues with cranks loosening at all.
The plastic threads on the OEM preload caps just don't hold a loose crank on the splines.
(that's not their job. They're made of plastic to avoid owners overtightening them on standard HTII cranks but unlike standard HTII cranks E8000 cranks don't need to be adjusted for correct bearing preload. So you can do up the Alu caps a little tighter.
it's a PITA most Alu caps use a 10mm allen key though.
I carry a short 10mm adapter bit rather than a big allen key in my tools on the bike (just incase).

 

[Jonnymac]

Just noticed another thread on the site regarding the same subject and they suggest using longer (35mm) crank bolts. Might give that a go too.

 

[smokey_jo]

Had the same with mine - managed to get just enough purchase on the plastic ones for them to have stayed on for a while now but they will be replaced by alu ones next time they fall off.

 

[Simon]

Yes. I've experienced it with both the original XT cranks and my 155mm Miranda cranks as have 3 of my mates who have E8000 equipped bikes. Even with thread lock it still happens. Checking crank bolt tightness is now part of my pre-ride check before every ride unfortunately.

Yes. I've experienced it with both the original XT cranks and my 155mm Miranda cranks as have 3 of my mates who have E8000 equipped bikes. Even with thread lock it still happens. Checking crank bolt tightness is now part of my pre-ride check before every ride unfortunately.

Yeah that’s what I’m doing but it’s driving me insane ! & I also got little metal end cap bolts today instead of the plastic! It held up today fingers crossed ?

 

[OlaGB]

Are the preload caps even neccesary at all on M8000 motors?

If so, why?

 

[Simon]

Had the same with mine - managed to get just enough purchase on the plastic ones for them to have stayed on for a while now but they will be replaced by alu ones next time they fall off.

Just got the alloy ones today with lock tite

 

[Simon]

Are the preload caps even neccesary at all on M8000 motors?

If so, why?

change the HTII pre-load caps to alu versions (ebay) and use a little blue loctite on your pinchbolts. Use a torque wrench to make sure you have them tight enough,

Yep did that today cheers man ?

 

[Simon]

Should have said. I had the LH crank come loose and fall off on my first E8000 motor. the above solved the issue and I've done the same on every motor since and had no issues with cranks loosening at all.
The plastic threads on the OEM preload caps just don't hold a loose crank on the splines.
(that's not their job. They're made of plastic to avoid owners overtightening them on standard HTII cranks but unlike standard HTII cranks E8000 cranks don't need to be adjusted for correct bearing preload. So you can do up the Alu caps a little tighter.
it's a PITA most Alu caps use a 10mm allen key though.
I carry a short 10mm adapter bit rather than a big allen key in my tools on the bike (just incase).

Carrying this at all times now

 

[Gary]

Ah.. you got shimano Alu caps.

Using most multitools and a little ingenuity you can also tighten/undo those. Eg. using the flat blade screwdriver/bottle opener/spoke key or even an allen key jammed into the spline at an angle

I just have super cheap 10mm allen key ones from ebay

 

[flash]

Don’t the original cranks come with a little lock clip to stop them falling off if loose? Did you remove that?

Gordon

 

[Eckythump]

Are the preload caps even neccesary at all on M8000 motors?

If so, why?

The caps needing to be installed seems daft. Having said that the only times my cranks have worked their way off is when I have previously taken the cap out to use a crank stand and forgotten to put it back in.
Cue crank dropping off yesterday ?

 

[tonyker]

I had this issue and thought it was just me. after torquing the cranks to the required amount they still kept coming off then went higher and higher still coming off.

Then got the ali caps and now all good!

 

[Gary]

Don’t the original cranks come with a little lock clip to stop them falling off if loose? Did you remove that?

Gordon

That little clip is only a thin plastic spacer with a tab. It's not secure enough stop a loaded crank falling off.
E8000 cranks that do fall off often aren't actually even particualrly loose. (pinchbolts still tight enough they need loosening to replace the crank arm on the spline)
what is actually happening is the crank arm is "walking" on the splined axle under load/flex.
The STUPID plastic shimano HTII pre-load bolt/cap with it's weak plastic threads then deforms as the crank walks and flexes, gradually walking the crank arm right off the axle. As the pre-load bolt lossens it will occasionally fail completely at the threads and the little clip also being plastic deforms/fails/pops out when the crank ejects itself from the axle.
The reason an Alu HTII pre-load bolt/cap fixes the issue is because it does not deform so easily and the threads are stronger so can be nipped up tight enough it's holding the crank arm tight(er) to the axle (less flex). Also when the crank pinchbolts nip down on the alu cap they actually hold it in place. unlike the STUPID plastic ones which deform.

The reason shimano make those caps/bolts from plastic is to deter home mechanics from over tightening/pre-loading their HTII BB bearings.
when an E8000 crank is pushed on to the BB/Motor axle with the HTII pre-load bolt/cap the crank doesn't add pre-load to the BB/motor bearings so there's no need for it to be plastic. infact it being plastic is the entire reason multiple cranks are falling off.

Sort it out SHIMANO, eh?

@Eckythump also see above

 

[ottoshape]

My google-fu is very weak today, go figure! Anyone have a link to the ebay aluminum cap?

 

[Gary]

Just type "Hollowtech bolt" into Ebay search bar

 

[Spiff]

Thank you guys. My crank arms have not fallen off yet, but I already purchased two red Alu caps in ebay (1,44€ each), they come from China so it may take up to on month but I hope mine will hold until I receive them.

FJ- CN_ G-20 CNC CRANK ARM FIX BOLT CAPS NUT SCREW FOR SHIMANO HOLLOWTECH CRANKS | eBay

 

[Simon]

Don’t the original cranks come with a little lock clip to stop them falling off if loose? Did you remove that?

Gordon

No mate they do bugger all ! There is a little spring like thingy in there it absolutely useless !

 

[Simon]

That little clip is only a thin plastic spacer with a tab. It's not secure enough stop a loaded crank falling off.
E8000 cranks that do fall off often aren't actually even particualrly loose. (pinchbolts still tight enough they need loosening to replace the crank arm on the spline)
what is actually happening is the crank arm is "walking" on the splined axle under load/flex.
The STUPID plastic shimano HTII pre-load bolt/cap with it's weak plastic threads then deforms as the crank walks and flexes, gradually walking the crank arm right off the axle. As the pre-load bolt lossens it will occasionally fail completely at the threads and the little clip also being plastic deforms/fails/pops out when the crank ejects itself from the axle.
The reason an Alu HTII pre-load bolt/cap fixes the issue is because it does not deform so easily and the threads are stronger so can be nipped up tight enough it's holding the crank arm tight(er) to the axle (less flex). Also when the crank pinchbolts nip down on the alu cap they actually hold it in place. unlike the STUPID plastic ones which deform.

The reason shimano make those caps/bolts from plastic is to deter home mechanics from over tightening/pre-loading their HTII BB bearings.
when an E8000 crank is pushed on to the BB/Motor axle with the HTII pre-load bolt/cap the crank doesn't add pre-load to the BB/motor bearings so there's no need for it to be plastic. infact it being plastic is the entire reason multiple cranks are falling off.

Sort it out SHIMANO, eh?

@Eckythump also see above

Couldn’t agree more ?

 

[HORSPWR]

Just type "Hollowtech bolt" into Ebay search bar

Are the left and right bolts the same thread, some of the eBay descriptions state left hand. Can I just get 2 and they’ll fit the left and right cranks?

 

[Spiff]

The eBay descriptions state left hand because in analog bikes with Hollowtech2, right crank arm is attached to center axis and does not require the cap, it is only required in left side.

According Shimano doc, HT2 left and right bolt use the same standard thread so I purchased 2 "left side" caps, but I have not installed them yet ( if it ain't broke, don't fix it)

 

[Gary]

Are the left and right bolts the same thread, some of the eBay descriptions state left hand. Can I just get 2 and they’ll fit the left and right cranks?

Yes. the threads are the same
other than the pedal threads. The arms are the same.

 

[HORSPWR]

The eBay descriptions state left hand because in analog bikes with Hollowtech2, right crank arm is attached to center axis and does not require the cap, it is only required in left side.

According Shimano doc, HT2 left and right bolt use the same standard thread so I purchased 2 "left side" caps, but I have not installed them yet ( if it ain't broke, don't fix it)

Cheers, I’ve got 155 Miranda crank arms on the way so I’ll fit a pair of these at the same time.

 

[Jonnymac]

Cheers, I’ve got 155 Miranda crank arms on the way so I’ll fit a pair of these at the same time.

Fitted the Alu caps with Miranda cranks a couple of months ago and had no further problems with cranks since doing so.

 

[HORSPWR]

Fitted the Alu caps with Miranda cranks a couple of months ago and had no further problems with cranks since doing so.

Has anyone else noticed that the machined step on the ebay aluminium caps is larger than whats on the Miranda crank and doesn't actually sit in properly flush, looks like that step needs to be about a mil smaller in diameter.

 

[KenX]

Has anyone else noticed that the machined step on the ebay aluminium caps is larger than whats on the Miranda crank and doesn't actually sit in properly flush, looks like that step needs to be about a mil smaller in diameter.

Yes, same for me! Just worked the cap in by rotating back and forth until it was seated, can't get a better fit than that

 

[Miguel.975]

Hi everyone. I've just had the same problem with the left crank that you describe. It has happened a couple of times so that the internal thread of the crank has worn out. I lost the plastic bolt twice and I have bought an aluminium one from Amazon. By the way, the warranty covered new cranks but they haven't arribes yeti.
Did you manage to solve the problem completely by installing the aluminium bolt?

Thanks a lot