[smashysmashy]

Mate i did turn it, not just with hands, it has allen key holes that you can tighten it better, did that also

The collar should be hand tightened only. Then the allen key tightened to lock it in place. I don't think this this is the issue though now. I think the crank arm interface is damaged.

 

[ualar]

The crank to spindle interface on these is similar to the old octolink. You could very easily permanently destroy them but not tightening them correctly first time, and they would often come loose, although loosening the bolt is NOT going to necessarily take the same force as tightening it did. You can also try a little non permanent loctite on the bolt. Unfortunately it may be too late and they are destroyed.

i can try to describe it now

Tightening is slowly getting harder and require some force since it up to 45-55 NM as usual tightening procedure. When it comes to loosen it, it comes loose really fast with small amount of force at start. Then you contiune loosening it to remove left crankarm, guess what happens, the easy loosening feel gets harder to spin allen key. It feels like you tightening it for a short amount of spin and then again it start to come loose and you remove it completely.

 

[smashysmashy]

i can try to describe it now

Tightening is slowly getting harder and require some force since it up to 45-55 NM as usual tightening procedure. When it comes to loosen it, it comes loose really fast with small amount of force at start. Then you contiune loosening it to remove left crankarm, guess what happens, the easy loosening feel gets harder to spin allen key. It feels like you tightening it for a short amount of spin and then again it start to come loose and you remove it completely.

Ok, that is exactly how it should be. That means the crank is on tight. The "tightening" you feel when removing the arm is the self extracting washer puling the arm off. If it has NO resistance, you would know the arm was loose.

The arm might still be ruined though at this point and therefore keep creaking, even though it was technically tight. It would get destroyed in the first few km of riding the very first time if it was installed incorrectly.

 

[ualar]

Ok, that is exactly how it should be. That means the crank is on tight. The "tightening" you feel when removing the arm is the self extracting washer puling the arm off. If it has NO resistance, you would know the arm was loose.

The arm might still be ruined though at this point and therefore keep creaking, even though it was technically tight. It would get destroyed in the first few km of riding the very first time if it was installed incorrectly.

So i should remove my XT and try to install this XTR again ? (i will add spacer too this time)

When i tighten it, ill attempt to remove it till it's getting harder to remove and leave it like that ? That's the ''tightened'' sweet spot ?

 

[FrankS29]

Bring it to a shop.

 

[smashysmashy]

So i should remove my XT and try to install this XTR again ? (i will add spacer too this time)

When i tighten it, ill attempt to remove it till it's getting harder to remove and leave it like that ? That's the ''tightened'' sweet spot ?

NO.
Take it to a shop, I agree here.

Leave the XT on for now.

 

[eri]

The torque spec is supposed to ensure the unit moves as a whole. If ridden with poor connection (not tight, or incorrectly seated) it can be hundreds of miles before some random peak force overcomes the connection and suddenly there is damage and unit is ruined.

Everything youve said makes me think the crank interface is ruined.

Examine crank interface closely and look for mushed metal or scarring, and bring to good shop.

edit: on inside interface pic above, the splines at 5,6 o clock are cheezed. Once it wont seat flat there is space for motion, no torque can save it now.

 

[ckspeed]

On my first xtr m9100 crank I did not tighten/torque it and the left crank came off and couldn’t install it. Basically busted so I have to buy a new left arm. Sounds like you going have to buy a new left.

 

[ualar]

This XTR install system is stupid, been using XT since 11 speed times and then 12 speed, installation of XT cranks much more easy and gives you ''strong'' feeling.

Loved the Q factor of XTR, it really noticeable, specially while climbing. Really i purchased this crank just for Q factor, there is no weight difference between XT, it's the chainring makes the difference, and my 34 t XTR chainring installed on my old XT crank now.

Screw this ****, going to send it for warranty, i did install and use it over 500 km without any problem, if it was really wrong installation from beginning it can't lasted this long. This is the first time ''Crank'' problem i am having, all kind of problems and replaces i had in the past, but the shimano crank, this is a first !.

Oh and i did used it pretty harsh, all kind of rock garden to some downhill drops, plus sprint mashing, it's a MTB after all.

 

[smashysmashy]

XTR 9100 is for light duty pro xc racing. 9120(?) is the more durable one.

The interface is bad though. It was bad in 1995 with XTR M950, and why they went back to it is a mystery because of all the cranks in the last 20 years, hollowtech 2 has been the most reliable and idiotproof (at the interface, some models have other problems).

 

[FrankS29]

Funny thing is, I’m pretty sure Shimano moved to this interface on the XTR; first because it somewhat differentiated it from XT and secondly because of people complaining that the normal Shimano interface was not secure enough.

Just goes to show, you can’t replace just doing it right the first time.

 

[smashysmashy]

Funny thing is, I’m pretty sure Shimano moved to this interface on the XTR; first because it somewhat differentiated it from XT and secondly because of people complaining that the normal Shimano interface was not secure enough.

Just goes to show, you can’t replace just doing it right the first time.

Hollowtech 2 is fundamentally a BMX crank. I have seen various complaints, but in practice, you really need to work hard to mess it up. Most failure I've seen don't have anything to do with the interface and are usually the bonded road cranks.

BB30 on the other hand, along with octalink and of course square taper will destroy themselves if you aren't meticulous with the first installation - and even then might destroy themselves anyway. If you put in on perfect, and never take it off, it may well last you forever, but for a fairly large amount of people, this will not be the case. My XTR m950s got warrantied twice, and my ultegra 6500's did last a good 10 years, but eventually developed play and died on the non drive side.

 

[FrankS29]

Hollowtech 2 is fundamentally a BMX crank. I have seen various complaints, but in practice, you really need to work hard to mess it up. Most failure I've seen don't have anything to do with the interface and are usually the bonded road cranks.

BB30 on the other hand, along with octalink and of course square taper will destroy themselves if you aren't meticulous with the first installation - and even then might destroy themselves anyway. If you put in on perfect, and never take it off, it may well last you forever, but for a fairly large amount of people, this will not be the case. My XTR m950s got warrantied twice, and my ultegra 6500's did last a good 10 years, but eventually developed play and died on the non drive side.

I’ve personally had nothing but great results with Shimano cranks using the Hollow Tech design.

Several of them removed and reinstalled several times.

I have also heard of the road cranks having some issues with bonding, but my sets of R8000 and R6800 cranksets have had zero issues.

 

[sacrefrancais]

Only if using a non-threaded PF92 BB is no spacer needed with the 9100. Threaded BBs 100% require 1 or more (2.5 mm) spacers.

https://si.shimano.com/en/pdfs/dm/MAFC002/DM-MAFC002-10-ENG.pdf

 

[thebenskiii]

Skimming this it sounds like you just replicated the spacing setup of your XT on your XTR rig. This may not work. If the preloader cannot take all the play out of the arms with some reserve travel on it you would need to play with spacers. I install a lot of wheels MFG BBs and I would say for most installs you are only using the tech docs as a guide, but I always end up testing different spacer combos if there is anything unusual going on … so many different BB, frame and crank variants.
if you’ve ridden it with the arms knocking due to too little preload and then you are talking about running it with the bolt backed partway out I would desperately suggest you seek a professional before doing any more with those cranks … good luck buddy.

 

[ualar]

Warranty changed the crank. Crank was faulty, shimano service said that they had several complaints of crank coming loose. Now installed same as before, no new BB. Same wheel manufacturing threaded BB as used with XT crank. Almost 1500 miles no problem so farm. Purchased a big torque wrench also. Tightened it 50 nm. (45-55) it says on it.

Sorry guys but almost all of you were wrong.