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Join Date: Nov 2007
Location: Finland
Posts: 68
Idler arm wear

I have later Carrera idler arms and everything else looks very good (bronze bushing in shaft shows no signs of wear) but areas that runs to tensioners are worn. Could these be re-conditioned (does it need hardening?) or could I just use these if I smoothen edges? First one have significant wear even thought it looks worse in picture but on other one its just on surface.
I know these are available but they are not cheap and also I know there is re-conditioned ones for sale and they must have had some treatment for these areas. As these are later idler arms, they already have wide bearing, I wouldn't bother with older un-reliable ones.




Also how teeth look in this wheel, are they OK? I can't really see much wear on this.


Old 04-25-2010, 08:43 AM
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The teeth are fine. The wear on the surface doesn't look that bad to me. As long as the amount worn off doesn't cause the tensioner to extend too far it should be fine.

-Andy
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Old 04-26-2010, 08:52 AM
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Is that the same idler sprocket in those two pics?

One side looks hardly used and like a new sprocket and the other side is out of focus so it's hard to say, but from what you can see it looks like the shim set behind the cam thrust plate may be wrong and the cam and idler sprockets are not aligned properly to the intermediate shaft chain sprockets... causing more wear on one side of the idler sprocket.
Old 04-26-2010, 09:09 AM
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In the second picture (middle) even though it is out of focus, the gear teeth at the bottom look J-hooked. If you look at the bottom of the gear the semicircular cutout between the any two teeth is accentuated on the left side of the cutout. (If you can imagine a radial line coming through the bottom of the slot the left and right side ramps should be mirror images of each other. This lower ramp is caused by long term wear from a stretched chain. Using a new chain here will cause premature wear because the new chain is shorter between the links and will be unsupported as the chain leaves the gear teeth.
Old 04-26-2010, 03:25 PM
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I believe the idler arms "float". That is to say they don't need to be aligned with the rest of the sprokets because the move themselves on the shaft to keep their alignment. In addition there is little wear on idler pullys in general as they provide no thrust or drag like the drive and driven sprokets.

-Andy
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Old 04-26-2010, 04:44 PM
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Thanks guys!
Pic 1 and 2 are different idler arms, other one have very little wear but on other one much more. Its very difficult to say what is acceptable wear and what is not.

Of course it would be nice to replace everyting but if its not needed, that I rather not.

Old 04-27-2010, 05:32 AM
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