Pivot bushings

[Di.R.T.]

On the evo frame, I note that it appears to me that when the pinch bolts are properly tightened, the part that rotates is not the bushing around the cups, but the swing arm clamps around the bushing.

I've yet to actually remove a bushing, but I assume the nylon surfaces are on the outer surface of the bushing and contact the pinch/clamps.  The cup never contacts the nylon bushings, just the inner part of the bushing (metal to metal).

Thus, it would seem greasing the outer surface of the cups and inner metal surface of the bushings (that contact the cups) really does very little to alleviate dry bushings since the nylon around which the clamp rotates is not greased.

Am I wrong?

If this is true, then the 5-minute jiffy lube needs revamping.

[Oz-SUB]

I purchased a new bushing kit for my 5500c and it included K2 Goo (silicon mixed with PTFE) a special grease.  When the main pivot bolt is tightened, the metal bearings (pushed in from the outside of both sides) are locked onto the frame, and the swingarm nylon bushings rotate on these metal bushings, so a little grease ia a good idea.

When you tighten the swingarm pinch bolts, ensure there is no wheel in the swingarm, and tighten each equally until the arm just moves down under gravity.  Somewhere it is written that the wheel should be fitted - this is wrong, as the pinch bolts have to be so tight that the rubber spacer is almost squeezed out!

Hope this helps.

Oz-SUB

[Di.R.T.]

Oz-sub,

When you say, "locked onto the frame" do you mean into the frame or do you mean pushed up against the frame?  

As I understand it, the bushings are fitted inside the swingarm clamp.  There is also a pivot insert that goes into the frame and connects to the bushing surface on the inner swingarm side.  But I always thought the actual bearings were pinched inside the swingarm clamps.

The bottom line Q here is, what part of the pivot/swingarm inserts (metal parts) actually rotate if any when the swingarm moves?

Thanks for the reply

[Old Proflexer]

the pivot inserts are the plates on the sides of the downtube of the frame that the pivot axles (i call them axle cups) set into and all is held tightly in place by the crossbolt.  one cup is threaded, the other is not.  when tightened down to 250 inch pounds, the crossbolt holds this entire unit in place as a single unit, nothing is to move, up, down, with the pivot movement or not - no movement at all.  like a sandwich, from the inside out it is the frame, pivot insert, pivot axle and crossbolt.  when not tight - this is the cause of much creaking.

the nylon bushings / pivot bearings, that reside in the inner ring of the swingarm, slide over the surface of the now immobile pivot axles - these are the dark grey nylon pieces that periodically need to be replaced as they can become worn if not properly attended to via proper lubrication etc.   if adjusted via the pinch bolt too loose or too tight, they can become worn and create slop in the back end of the bike.  this would be a nylon on metal contact were it not for a thin film of lubricant in this area.

the dark grey nylon bushings / pivot bearings are not supposed to rotate inside their housing in the swingarm and should not move in that respect.  the pinch bolt tightens or loosens these nylon units against the axle cups and should be adjusted via the 'drop' method with the shock and rear wheel unattached (imho) - k2 says do it with the wheel attached but i think that's too tight and can be affected by the overall weight of the rear wheel and components.  

different k2 / proflex texts use the terms bearings and bushings for these nylon units interchangeably and they probably shouldn't - there are four of them - two on each side of the swingarm, one on the inside and one on the outside of the internal section of each swingarm hole.

one should not be able to see the internal bushings when the swingarm is installed as the exterior flange of the pivot axle cups on each side completely covers the units and are sealed (hopefully) from view and contamination via the quad rings, one that sits in the groove in the part of the swingarm next to the pivot insert and the other in the groove under the flange of the axle cup.


http://k2bikes.com/tech_library/service_manuals/98evo.pdf

OP

just a few, sunday morning, sucking on my coffee, trying to wake up before church, thoughts