Pinkbike visited the SRAM pits at Crankworx, where local legend Shawn Cruickshanks was working his way through a line of suspension forks tagged with the names of many top competitors, as well as the lucky ones who stood in line to receive Pro RockShox service during the week-long festival. Shawn made time to run Pinkbike through the process of replacing the seals and dust wipers of the very popular 2011 RockShox World Cup fork. Watch and learn.
What you’ll need:-Clean shop towels and working environment
The 2011 air-sprung RockShox World Cup fork is fork of choice for downhillers who are both weight and performance minded. This one needs some love and attention.
-Plastic-tip hammer to tap the slider’s foot-bolt loose
-Allen keys: 5mm and 2mm
-Bike-stand (helpful but not essential)
-Light, high-quality grease like Pedros Slick Honey
-SRAM seal driver for 35mm forks or a large, clean socket wrench that matches the diameter of the seals.
-Isopropyl alcohol in a spray bottle
-15-weight suspension fluid (Shawn uses Torco brand)
-Pan to catch dripping suspension fluid
-Sturdy wire, looped on one end to hold shop towel for cleaning inside of fork sliders.
-New seals and dust wipersTips:
While you can change the fork seals and wipers while the fork is on your bike, the easiest way is to remove the fork stanchions from the triple-clamps and then use a bike stand to hold the fork while you do the work. Jot down your high and low-speed rebound settings before you get started so you can return the dials to their proper place after the rebuild. As with all suspension work, take the time to clean the external fork parts to ensure that your results are actually improving the fork’s performance, not sentencing it to death.
Release all of the air pressure from the spring side of the fork, clamp the spring-side fork stanchion in your work stand, and then loosen the ‘foot-bolt’on the bottom of the spring-side slider with a 5-millimeter Allen key about half way out. Tap the foot-bolt with a plastic hammer to free the damper shaft inside the slider and then remove the bolt completely. Oil will flow from the open hole, so have a pan ready
Pump the slider a few times to get as much suspension fluid from the fork leg as possible (there’s only 10 CCs inside, but it will look like a lot more on your Persian Carpet). Slide the stanchion tube out of the slider and put it somewhere where it will stay clean.
Clamp the damper-side stanchion in the work-stand and then hold the rebound dial on the bottom of the right slider with one hand and use a 2-millimeter Allen key to remove the retainer screw. Slide off the low and high-speed rebound dials to expose the 24-millimeter wrench flats on the rebound adjustment body. Don’t lose the black washer that separates the two dials or you will be sad later.
Use either a 24-millimeter open end wrench, or a RockShox approved BFC (Big Fernie Crescent wrench) to unscrew the aluminum rebound adjustment body half-way out and then give it a sharp tap with your plastic hammer to release the damper shaft. Remove the adjustment body and then pump out the suspension fluid, remove the slider and store the stanchion tube as in step two.
Make a visual inspection of the inside of the slider tubes. Look for gouges, scoring or excess wear in the upper and lower bushings, as well as dirt or metal chips that may be polluting the fork’s internals. Next, give the stanchion tubes a look for scratches or dings that could cut the new seals. If your fingers can feel any significant scratch, your stanchion tube may be a candidate for replacement, as the scratch will eat through the seals quickly.
Shawn uses a Pedros tire lever to remove the seals because its smooth, flat, working end will not damage the thin walls of the slider tubes. There are two seals in the World Cup slider, the gray dust wiper and the black oil seal. Slip the tire lever under the seal until you can feel the magnesium wall of the slider and pry the dust wiper out. Next, repeat the process with the black oil seal. Be sure to pry on the outer diameter of the seals were they are reinforced with an internal metal band. A large, flat-blade screwdriver will work, but use caution to avoid gouging the sliders.
Spray the inside of the slider tubes with isopropyl alcohol and then use a lint-free shop towel threaded into a looped wire or a slotted wooden dowel to clean the bushings and internals.
: Reassembly – Shawn uses Pedros Slick Honey grease to lightly coat the upper and lower bushings and then he puts a thin layer on the walls of the slider where the seals will press in. The key here is to use a sparing amount of light, viscous grease. Too much grease will impair the fork’s action and the stuff will seep out of the seals for weeks.
The seal-lips and numbers face upwards on the fork slider. Slide the black oil seal on the 35mm SRAM seal driver and, using firm hand pressure, slide it inside the seal cavity until it bottoms out firmly. Repeat the process with the gray dust wiper seal.
Plan B – The optional install method is to find a large (clean) socket with an outside diameter that will just slip into the seal cavity of the sliders. Be sure that the socket contacts the reinforced outer rim of the seal to avoid damage. Place the seal on the slider and then use the socket to press the seal into the cavity.
Lightly lubricate the seals with lightweight grease and then carefully work the stanchion tubes into the lips of the dust wipers. Slide the stanchions in only about 1.5 inches, so they stop just short of the lower bushings. When you fill the sliders with lubricating oil, this will ensure that you get some fluid between the upper and the lower bushings.
Inject 10 CCs of 15-weight suspension fluid into each fork leg (note: inject 40 CCs into the spring side of a coil-sprung Boxxer fork) and then work the oil around the internals by gently compressing the stanchions into the slider assembly.
Clamp the right stanchion tube in the work stand, screw in the rebound drive body and then tighten snugly with a BFC or 24mm wrench (7.3 Newton-meters). Next, install the aluminum crush washer on the foot bolt and tighten it snugly (7.3 Newton-meters) into the left-side slider. Use a fresh crush washer if the original appears jagged edged or damaged.
reassemble the high and low-speed rebound dials making sure that the black washer separates the two. Please don’t over-tighten the 2mm Allen screw.
Put the slider on a padded surface and cycle the stanchion tubes full-travel ten times to ensure that all the parts are sliding perfectly. Wipe down the excess lubrication from the stanchion tubes, reassemble your fork, return the rebound dials to your personal settings and then go ride.
Pinkbike thanks Team RockShox and especially, Shawn Cruickshanks for taking the time from their hectic race schedule to lead us through the Boxxer World Cup fork seal replacement process. If anyone has a tip that may make the process easier, we’d love to hear about it.
Master of suspension Shawn Cruickshanks poses with Pinkbike's revitalized RockShox Boxxer World Cup fork. Shawn can get through a complete Boxxer fork in about a half hour.
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