Michael Hanslip Coaching

If you want to go faster, you have to pedal harder

Fork seal replacement time

Just before Covid changed 2020 so dramatically, as in about 2 weeks prior, I got my Ibis Ripley. As I wanted this to be my "Stromlo" bike and also my replacement XC race bike (the proper race bike was going up for sale) I specified the 120 mm Fox 34 SC fork rather than the more usually installed Fox 34 with 130/140 mm travel.
Meanwhile I had reached the end of the road with my hardtail's fork. A Fox 32 with a straight steerer, Fox hasn't supported these forks in years. The bushings were quite worn, the stanchions had bushing marks on them - it was past its best. Virtually nothing decent was available with the necessary straight steerer tube. And the Ibis convinced me that I needed updated geometry - a much longer reach being way more suitable for this tall and long-armed rider. I bought a Spot Rocker which came with the same Fox 34 SC 120 mm fork as the Ibis. The Spot was almost exactly 12 months behind the Ibis into my life, coming in March 2021. Yet the fork was the same on each bike (Fox usually changes stickers each year or so and they have the same stickers).
As mentioned in a prior entry, I swapped from Feedback Sports app to ProBikeGarage app to keep track of my maintenance. PBG told me instantly that my Fox 34s were past-due for seal replacements.
I picked up the two seal kits with one for the Ibis shock and used a recent weekend to attend to the two. My first problem was that the bolts holding the sliders onto the stanchions are highly recessed in the SC forks. And with the step casting (what SC stands for) the bolts are off-centre in the bottom of the leg even though they are dead centre to the stanchion's circle. I really needed a 10 mm thin-wall deep socket to get on the nut. Luckily, my 12-point shallow socket was just thin enough to sit on the nut.
The Ibis fork had lots of oil inside it, but it was moderately dirty looking. Not the golden syrup colour of new oil, but more like burnt butter. Still quite clear, but also rather dark. It was past time to replace these seals and given that PBG was telling me I'd almost hit 150 hours of riding, it really WAS by all accounts. The Spot fork was quite different. This exemplifies why some Fox forks work really well and others don't - the builds are not identical despite mass production. There was hardly any volume of liquid in this one in either fork leg, but it looked absolutely brand new.
Using a trick taught to me by a former sponsored-by-Fox racer (thanks Brent!); with the trick being to use a little Fox Float Fluid in each leg to increase the slipperiness of the splash oil and make the fork that bit smoother for longer. I don't use Fox Fluid. It is a viscous but fully soluble in fork oil liquid that is used primarily inside the shock bodies. Maxima has a great reputation for fork oil as a probable supplier of Fox fluids (which are reportedly made by a local-to-Fox company, which would be Maxima) and the definite supplier of Rock Shox's Maxima Plush used in current forks - so I use Maxima 10 wt and Maxima Assembly Lube (both more readily available and about 1/2 the price from MX shops than from bike shops).
To refill the splash lube I squirt about 1-2 ml of the red Assembly Lube into the syringe through the plunger side, insert the plunger, and then slurp up the correct amount of 10 wt (10 and 15 ml total for the 34 SC's two legs) and squirt it down the hose and through the bolt hole in the slider. Then push the sliders so the threads protrude, and tighten the nuts to 5.7 Nm and done!
One wrinkle in this whole process was I haven't used the seal press I bought for my 34 forks before. This one is from Unior. It was available locally, but it isn't as nice as the Real World Cycling presses I have in sizes 32 and 36 mm. They fit snugly in the bushing forcing the seal to go in straight. There is a long nose on the Unior tool, but it doesn't fit very snugly in the bushing and it requires operator diligence to get the seal in squarely. Also, the outer lip on the RWC tools give a strong indication (if not a positive stop) that the seal is pushed in the correct amount. I note that the new Unior seal presses proclaim a new design that bottoms out positively on the fork to prevent overdriving the seals.
The first seal I did with the Unior ended up too far in, by 2-3 mm, because there is no indication and I pushed too far. Knowing that, the other 3 went in the correct distance. I had to squeeze the foam ring in between the seal and the bushing because the gap wasn't quite the width of the ring. Hopefully everything will function fine for the next 100ish hours.