Left crank suddenly coming loose - what to replace?

[brucem76]

So my SLX pedal crank is suddenly working it's way loose on my MTB, no matter how much I tighten the bolts. This is after an increase in creaking noise while pedaling - try as I did, I never found the source, but I think this explains it.

 

I assume there is wear and tear from some play between the crank and the bb.

 

I know the right answer is probably "replace crank and bb at the same time" but I'm needing to avoid unnecessary cost.

 

Can anyone help:

- is there a way to see wear on crank or bb or both?

- is it possible to buy just a crank arm in SA?

 

 

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[Mongoose!]

Think your bike is trying to tell you something. It wants a Stages power meter crank arm...

[brucem76]

Think your bike is trying to tell you something. It wants a Stages power meter crank arm...

Lol yes, thanks that's really going to help keep costs down!

 

 

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[Jewbacca]

Is your preload black plastic thing screwed in properly?

 

Fitting a Shimano non drive side crank goes in 3 stages....

 

loosen all bolts and lift the little pin insert.

 

slide onto spindle.

 

flick insert into hole. 

 

Screw in the black plastic preload untill tight but the cranks still spin freely.

 

Tighten bolts.

 

That should keep you sorted for endless hours of riding... 

 

If there is wear, you can buy a non drive side crank alone but it may not work as the wear could be on both the spindle and the crank arm.

 

Good luck... this is a weird one. I find shimano cranks last forever

[brucem76]

@Jewbacca Ok, um there is no preload cap there.... is this something that is only used when installing, or should it be permanently there?

 

 

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[Jewbacca]

there is your problem.....

 

It holds the whole system in place. It must have fallen out or your lbs didn't tighten it in properly..

 

You can buy them for a couple hundred bucks.

 

Just google Shimano Pre Load cap, print out the picture and take it to your lbs.

 

A heads up that the mtb ones are different to the road ones!

[brucem76]

@Jewbacca - a google search shows that it can actually be removed once the bearing preload has been done, and should be involved in actually holding things in place. But it is possible the preload needs to be there when the crank is reattached

 

To thicken the plot - the little plastic clip thingy is there, but the clip has broken off. I find it hard to believe that a little piece of plastic can be involved in preventing the crank coming off.... but it must perform some function??

 

 

 

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[BaGearA]

Thats how it should look, one bolt goes over and the other goes through so it can lift slightly

 

please post some pics of the end of the spindle where the left crank arm gets attached , then we can probably give the correct advice

 

 

But n couple of 100 buks at a local bike shop should sort you out. ( I highly doubt you need a new crankarm) 

[brucem76]

@BaGearA thanks. The plastic piece doesn't have the little metal pin that goes through spindle - it broke off.

 

Here a pic, and also a pic of where I think there's supposed to be a little rubber ring (but isn't?)

 

Do you think reattaching the crank with the pre load properly in place could make a difference? Does a removed crank mean the tension has to be done again?

 

 

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[Butterbean]

I strongly suggest you search YouTube for some videos of shimano crank installations. You clearly need to see this in action to understand the mechanics.

 

 

The little plastic clip has a small wire piece sticking out, yours has broken off. This wire goes into the little depression on the crank spindle,and adds extra protection for the crank arm to not come off

 

The previous tension nut is vital for the system. It preloads the bearings in your BB, and is the main factor in keeping your crank on. Think of it like your headset top cap. Its there to get everything lined up, and normally, the tension of the two brand arm bolts should keep everything together. However, the previous tension nut still operates post bolt tensioning, unlike the top cap in your headset.

 

Again, watch some videos, understand it, and go buy a new nut, and the tool you will need to tighten it.

[brucem76]

@DragoRosso thanks - as always with the interwebs there are a lot of conflicting views, particularly around what role the preload part and retainer pin play, many people confidently declaring things that contradict with other confident declarations. Such is the Internet. I was hoping to fix myself so I could ride on Sunday, but seems an LBS visit on Monday is in order...

 

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[shaper]

http://www.pinkbike.com/video/150764/

 

Watch the last part of the video with regard to clip and preload cap. You need to go buy a preload cap and install, probably easier to ask you lbs to do it

[Butterbean]

@DragoRosso thanks - as always with the interwebs there are a lot of conflicting views, particularly around what role the preload part and retainer pin play, many people confidently declaring things that contradict with other confident declarations. Such is the Internet. I was hoping to fix myself so I could ride on Sunday, but seems an LBS visit on Monday is in order...

 

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Yeah, unfortunately sram and shimano cranks need bearing preloads in different ways, so you'll get some differing opinions. However, this one is for sure. I'll try to find a link that will instruct you correctly. Alternatively, where you based? Maybe I can assist if you're in Cape Town.

[Butterbean]

Check this out

[brucem76]

Yeah, unfortunately sram and shimano cranks need bearing preloads in different ways, so you'll get some differing opinions. However, this one is for sure. I'll try to find a link that will instruct you correctly. Alternatively, where you based? Maybe I can assist if you're in Cape Town.

Thanks, so helpful - as you can tell I have no experience with any of this - I'm in the Northern Suburbs of CT

 

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[BaGearA]

only saw now the pin is broken off....sorry