Shock bushings - the weakest link in a smooth system?

[LazyTrailRider]

OK, so my Intense 5.5 has a new bushing in the bottom shock eye. The old one, together with hardware, was trashed and had probably 2-3mm of very annoying (and harmful) play, so now everything's rattle and vibration-free again. While the mechanic was fitting the new one, I asked him to check the top bushing. I'd noticed with the main linkage taken off and the shock just hanging off its top mount that it didn't rotate smoothly on the frame, and my thinking was "surely this should be smooth, it's a moving part of the suspension?"

 

The mechanic explained that it's supposed to be tight and not move smoothly (and I believe him), because that's how they're made... But I'm thinking that:

 

1) Yes, the shock mounts aren't exposed to nearly as much rotation as the main pivots, but they DO pivot.

2) That little bit of movement (see my totally inaccurate diagram below, illustrating that the bushings in red do actually encounter rotation) that they are exposed to causes stiction, probably not much, but it still does.

3) This stiction is really, what's the word... *stupid*... if one takes into account how much effort has gone into making the rest of the system buttery smooth, what with expensive pivot bearings, shock seals, tuneable-to-infinity compression damping rate, fancy teflon shock shaft coatings, etc.

 

 

Surely all the incredible small-bump compliance made possible by my bike's super-slick-8-bearing-running VPP suspension design is being hampered by two silly little DU bushings?

 

So I started searching around, and found this: http://enduroforkseals.com/id275.html

 

 

What do the suspension gurus think? Are bushings inefficient? Is it worthwhile (I'm thinking it must be) to put something better in place? I'm worried about the fact that the hardware (spacers) seems to also be an issue, the more I tighten the top mount, the less movement there is. It's almost like it's not just the bushing that's causing the friction.... Is this maybe the spacer being incorrect?

 

Any input appreciated!

[LazyTrailRider]

Eish, I just realised after scrolling to the bottom of the Enduro page that they're selling exactly what I'm saying. OK, so it seems I'm logically on the right track!

[Capricorn]

yep, anything that rotates could do with a bearing. Hell, you get bearings for coil shocks so the coil can rotate freely when it's being loaded and unloaded. However, sometimes, the simpler option gets you 99% of the way, hence the DU bushing. Using bearings on the shock pivot, considering just how little the shock pivots to begin with (nb: that 'test' of yours "with the main linkage taken off and the shock just hanging off its top mount that it didn't rotate smoothly on the frame", it's akin to testing a bike suspension in the car park), so it's a case of bearings for shock pivots being on the wrong end of the a severe case of diminishing returns.

 

But, there's nothing technically wrong with the concept. So go wild!