signalnc

I am trying to install new jockey wheels for the first time. So I made the mistake of just taking the old ones off and tossing them out, without paying attention if there are differences to the two wheels...I have installed them, re-installed them..etc....one of them seems to have some friction while the other spins free. Is this normal? or does one of the new wheels have bad bearing already?

Jamminatrix

For the 6600, the bottom tension pulley is directional. Make sure it is going the correct direction. The top G-pulley has those rubber seals. Make sure they're installed correctly or they can bind.

EDIT: reference this diagram: https://si.shimano.com/php/download.p...6600-2358A.pdf

Andrew R Stewart 

I always (as best as a human can. Always is a big claim...) set the lower pulley as the rotational direction states. But I fail to understand why the bearing aspect needs this directional spec. Can you educate me? I have installed them reverse before for experiments and found no difference in chain run or spin smoothness. I do agree on the guide pulley's seals as being a factor if installed inside out. Andy.

signalnc

ok, so the bottom pulley has an arrow on it, which should be pointed toward the front of the bike?

Andrew R Stewart 

As I reply to these rotational direction statements- When the arrow is above or below the rotational center? Not to nit pick but when instruction I find "righty loosen, lefty tighten" answers are lacking. Sorry if that is harsh, just trying to be exact.

In this case the arrow indicates the rotational direction of the pulley, not which is the front or back of the bike. So using the chain's motion as one pedals forward the pulley rotates clockwise as it is viewed from the RH side of the bike. The arrow, if below the center, will point rearward, then forward as the pulley rotates 180*.

But my question still is out here. Why is this a need? I have my own reasons to think so. It might have to do with the tooth profile and how the chain meshes with the teeth, of the pulley, and nothing to do with bearings or seals. Or maybe more likely it's because this way, of rotational direction, the pulley's labels are facing outward so the rider can read them like when reading the der's logos. Andy.

Jamminatrix

10/11 speeds have the directional pulley because the tooth profile is directional, not the bushing. With the tension pulley having to deal with the chain coming in at extreme angles, and with the narrower width of 10/11 chains, the chain would be more apt to jump off the pulley than that of its predecessors. The direction profile helps 'thread' the chain onto the pulley.

Andrew R Stewart 

I understand all this. I have profiled my Campy NR pulleys, back in the day, to accommodate this chain meshing angle. But they had rather "square topped" profiles. Current Shimano tension pulleys have a more knife profiled shape, much like what I made years ago. But when I reverse current pulleys I get no difference in chain meshing.

I'm just trying to still learn more details after a life of doing this daily. Is there a bushing aspect to the claims of a direction spec? I don't think so. This was the your statement. Andy.