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[Closed] Who does my non driveside arm keep dropping off

 hora
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Cheapest place for new XT's currently? Think I'll leave the world of SLX and used market alone. The last descent yesterday was ass on rear tyre stuff so wouldnt have been fun if it fell off there


 
Posted : 14/11/2016 3:53 pm
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I would get on Ebay and try one of the ali bolts, £3 on ebay and located in Huddersfield. A lot cheaper and may save you pounds. Still got a nearly new set of XT cranks in the garage that we got just in case. Even took them out to the Alps this year just in case. They will be kept just in case we need any in the future.


 
Posted : 14/11/2016 3:58 pm
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In the end they worked loose and damaged the splines. He replaced them with the new XTs and has since had no problems. Personally I think they were cursed.

You'll probably find that the splines, in either the crank or on the axle, were damaged after the first incident and it was a losing battle thereafter


 
Posted : 14/11/2016 3:59 pm
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I got shown how to fit HTII cranks about 10yrs ago and the advice has worked every single time. I wrecked a set of LX cranks when they first came out within a few rides and was gutted.

The plastic tension cap is basically doing the bearing pre tension. So you do this up by hand etc to set them without any noticeable wobble....... Then you go through the process of tightening the little bolts and tighten them down being carefull to alternate so you get spread load on the bolts etc.

Trouble is you haven't then got a hope in hell of removing that plastic tension cap because it has been crimped by the closing of the bolts. Imagine a headset design and after tightening everything down you can pretty much remove the stem cap and it wouldn't effect anything. Well your cranks are now being held on by the tension bolts on the arm but also slightly by the cap being squashed. Once the plastic gives up after a while the fit becomes loose and they come off.

I tension, nip the bolts up so they wont slip/move off, then I REMOVE THE PLASTIC CAP. Then I nip the bolts up fully and refit the cap at the end. No difference in the use but has been 100% on a set of original XT HTII cranks fitted and removed probably 20 times.

If you cant easily remove that cap at the end, its under pressure from the nip bolts. This also answers why the alu one is more reliable than the plastic ones. They withstand this pressure better.


 
Posted : 14/11/2016 4:12 pm
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There is also the possibility that there isn't enough spline interface, ie BB shell width is quite wide, and maybe a couple of BB spacers fitted too, all of a sudden you're only looking at half of the splines engaging.

I had a similar issue on an old bike, fitted Saint cranks with their alloy cap, sorted.


 
Posted : 14/11/2016 4:20 pm
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Oh god... Bodgemagedon


 
Posted : 14/11/2016 4:31 pm
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I think I've lost the tension bolts on all my cranks. They are all ten years old, never come loose. I just tap them on with a rubber mallet to get tension.


 
Posted : 14/11/2016 4:35 pm
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[quote=Nobeerinthefridge ]There is also the possibility that there isn't enough spline interface, ie BB shell width is quite wide, and maybe a couple of BB spacers fitted too, all of a sudden you're only looking at half of the splines engaging.But then the pin in the plate wouldn't fit in the hole in the crank axle.


 
Posted : 14/11/2016 5:13 pm
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got some new FSA on the FS if you interested in something different?


 
Posted : 14/11/2016 5:31 pm
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NHS arm refit? Go private - better stitches....

🙂


 
Posted : 14/11/2016 5:37 pm
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Maybe the crank is fine and it's the rest of the bike falling off.

Made me laugh anyway.


 
Posted : 14/11/2016 5:58 pm
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Hora,

I noticed [url= https://www.canyon.com/en-gb/factory-outlet/#category=parts-transmission&id=19078 ]THIS[/url] the other day. May be of interest if you are looking to replace your current cranks.


 
Posted : 14/11/2016 6:38 pm
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But then the pin in the plate wouldn't fit in the hole in the crank axle

Granted, but he doesn't mention this, unless I missed it.


 
Posted : 14/11/2016 6:41 pm
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Leprosy. Buhdum Tish.


 
Posted : 14/11/2016 8:31 pm
 hora
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As with life, the answers and clear voices sit in a mire of poo 😆

Cheers all.


 
Posted : 14/11/2016 8:42 pm
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This had happened once to me and I realised I'd got one spacer on too many so the non drive side crank didn't have enough spline to grip on to. User error 😳 Otherwise all Shimano cranks, mountain, road and CX have been bombproof.


 
Posted : 14/11/2016 9:11 pm
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They only come off if

A. They've not been tightened correctly.
b. The spline is damaged.
C. The crank arm spline is damaged.
D. Not enough preload.
E. Too many spacers.
F. Out of width BB shell.

I always preload them, tighten the inside bolt, remove the preload tool, fit a metal cap-tight !, then do up the other bolt, then repeat the bolts until done. I've probably fitted a hundred various road and MTB shimano chainsets, never had one back.

The plastic cap is crap.


 
Posted : 14/11/2016 10:43 pm
 hora
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Never had one back..

Ok but if you did you could just get it warrantied with Shimano UK your supplier I guess.

As for badly fitted-my XTR rear mech lasted 10yrs on various bikes, my only bike. Saint chainset 5yrs+.

Yet a Zee rear mech's casting failed at the known Zee failure point, my SLX fails and my SLX brakes (twice) seals don't to be the best/100% serviceable. I think lower end Shimano kit IMO nowadays is lower quality.


 
Posted : 14/11/2016 11:16 pm
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They only come off if

A. They've not been tightened correctly.
b. The spline is damaged.
C. The crank arm spline is damaged.
D. Not enough preload.
E. Too many spacers.
F. Out of width BB shell.


But it is very easy to do A or D (my comment about the design) which leads to B or C and there is no way back from there.


 
Posted : 14/11/2016 11:20 pm
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There is also the possibility that there isn't enough spline interface, ie BB shell width is quite wide, and maybe a couple of BB spacers fitted too, all of a sudden you're only looking at half of the splines engaging.

And all the others talking about wrong spacers/width - the plastic spacer that can only be put into place when the arm is in the correct position is to stop this sort of thing being possible. Or do people just ignore the instructions?


 
Posted : 14/11/2016 11:29 pm
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Or do people just ignore the instructions?

have you read some of the mechanical help posts in here? At times I wonder if some people have actually seen some instructions, it's bike mechanics though not as complicated as lego n stuff....


 
Posted : 14/11/2016 11:34 pm
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the plastic spacer that can only be put into place when the arm is in the correct position is to stop this sort of thing being possible.

A [b]lot[/b] of people think it's just an annoying pointless thing that needs to be removed if it won't go into its hole properly...

🙂


 
Posted : 15/11/2016 3:28 am
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But it is an annoying pointless thing that needs to be removed, if you know how to fit a crank/bottom bracket.


 
Posted : 15/11/2016 7:50 am
 hora
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NEW XTs ordered. I'll also fit a ALU bolt anyway.

Things like crank arms- I don't want to muck about. The last descent to the car at the bottom was one of Peaks cheekiest and it'd been a bust ankle


 
Posted : 15/11/2016 1:47 pm
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well good luck but I would suggest calibrating your torque wrench, and following the instructions to the letter (and video it) so you can claim warranty. Just whipped my cranks off to fit the warranty replacement chainring this afternoon in the office, 10 mins with an 8mm and I'm away again.


 
Posted : 15/11/2016 1:50 pm
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Use 2 allen keys for ht2 ,tighten both bolts at the same time after finger tight preload , had 5 sets 1xdeore, 2xslx and 2x xt. No crank boo boo's so far


 
Posted : 15/11/2016 6:49 pm
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