A practical review coming soon!
This post is to discuss the options, and real world tested opinions of what works best. First off, what is a DU bushing? Well, this is one of the most underrated and critical-to-bike-feel components of a full suspension bike. Most suspension designs utilize some form of bushing or bearing to provide a friction surface and allow a pivoting motion (via pin connection) between the mounting of the shock and the link connecting to it.
In its simplest form, this is what is known as a plain bearing or bushing. The term DU bushing is a carryover from the original OEM part number of the bushing itself, now a generic term much like how KLEENEX is used as a gerneric term. The picture above shows a new, INA EGBZ0808E40-Y bushing. This is actually an aftermarket bushing that uses a steel backing (press fit into the shock eyelet) and the friction (bearing) surface is comprised of a porous broze layer covered in a metal-polymer coating. This coating is what the connecting pin rotates in and acts as a self lubricating plain bearing or bushing. This surface is subject to wear.
It is through this bushing wear that a clunk, knock or free play can be felt in the suspension linkage of a bicylcle with every compression of the suspension system. Any play severely degrades from the “feel” of a bicycle, much like a loose headset, hubs or fork bushings.
Fox offers three types of bushings and eyelet reducers/pins:http://service.foxracingshox.com/consumers/Content/Service/Rear_Shocks/reducer_maintenance2011.htm
The newest iteration is the 5 piece plastic bushing, through pin, seals and delrin spacers. This is what came as stock on my Santa Cruz Tallboy LTc. After about a month of riding, this developed play that was very evident during riding and maintenance. I felt that this was insufficient service life since I had a lot of success with the through pin and sleeve style hardware. The 2 piece aluminum reducer style was never a great option as it did not allow full contact between the two aluminum spacer halves and as a result the pressure on the bushing was increased and life suffered. Being open to new ideas I decided to try the wheels manufacturing full complement needle roller bearing, pin and seal style bearing:
At first glance, this increases the complexity of the bushing system and adds a lubricated component, but the potential for greatly reduced suspension friction and better “feel” was worth a try.
I installed the roller bearing into hte shock eyelet (carefully as the outer race of the bearing is very thin and easily damaged by careless tooling…Installed the pin (slight clearance fit), seals etc and reinstalled into the bike. I did not even need to ride the bike to know that this was a poor “upgrade” since the clearance fit caused it to already feel like a worn out DU bushing. I removed the wheels bearing and looked for another option.
This lead me back to a solution that I used on my Santa Cruz Tallboy (not LT) from last season. It came equipped with the two piece reducer style that I upgraded to the Pin and Sleeve style. I installed this style of pin, spacer sleeves as well as a brand new INA bushing. The pin to bushing fit is very tight when new and you have to be careful when installing back into the bike to make sure that the pin does not rotate on the hardware and actually pivots in the bushing. This was the third time that I had made this same upgrade to this area of the bike (three separate bikes) and each time, it was the last bushing I had to install. The life improved many times over the other options and provided a tight fit as compared to wheels needle roller bearing option.