Stardate 2016.263

Fresh Seals
In 2011 I blew the Nitrogen-charged portion of the rear shock on my Specialized FSR mountain bike. I can tear into suspension to change oil and air seals, but my shop isn't quite equipped to deal with Nitrogen charging – yet.



I also had just built-up a Giant XTS hardtail (no rear shock) 29er (29 inch wheels). So, the FSR has been stabled for a while – a long while; as in 5 years. Anyway, I finally sent the shock off to the FOX factory for a rebuild. In the process, I've decided to resurrect the FSR as well. The resurrection begins with new air, oil and dust wiper seals for the blown seals on the front Marzocchi MX Pro + TAS shocks.



This was the first time I'd torn into this model of Marzocchi fork. The left leg top cap required utilizing a free hub tool that normally is used to remove the cassette (rear sprockets) from the rear hub. I thought this was a good idea because you can get a good bite on the top cap.



After removal of bottom bolts, the air/oil-pumping element, spring and the extension travel adjustment (ETA) and travel adjustment system (TAS) cartridge can be removed. ETA allows fork rebound and damping to be controlled on-the-fly from full rebound, to lock out or something in between. TAS allows suspension travel to be preset at a minimum of 100mm (3.9 inches) or a maximum of 120mm (4.7 inches).




After draining the oil and pulling the sliders off of the stanchions, I let them drip residual oil overnight.




Residents of the left leg are the ETA/TAS cartridge, spring and top cap. Left leg pump is not shown. Oil is collected and given to appropriate handlers.




After popping the old seals out, the fork races are cleaned and await fresh seals to be pressed in.




New air/oil seals are pressed in tightly and further held in check with stiff snap rings.




The new dust wiper seals are also tightly pressed in. At times, it can be a battle to get seals pressed.



My basement floor is designed to "float", thanks to our local clays. To complicate matters, bicycle suspension performance characteristics are very sensitive to air pressure, oil weight and oil quantity. Hence, I use a tripod, 4-square metal blank and level to find level ground for measuring volume.






Into the forks goes the new elixir.




TA DA! The fat lady won't sing until I get to test everything.



Thanks to a recent "mini blizzard" dumping over a foot of snow, followed by yet another storm adding an additional 8 inches of very wet snow, conditions to ride are slow in returning. Trails have melted fast but require additional time to dry. Maybe I'll saddle up a road bike and venture into the foothills to see how wet and sandy the roads are.

Stay tuned, and thanks for reading!

Adios

Stardate 2015.310

New Fork Seals For The Black Pearl

I blew a front shock oil seal on the Pearl. This is quite normal. Occasionally changing seals actually is a general maintenance necessity.

Note: The following is not a "how to" post. There are a few more steps, specialized tools, et cetera required than mentioned. Moreover, there are many different models of Fox Shox. For a good illustrated "how to," consult the Fox maintenance website for your particular model of fork.

If you're uncomfortable tearing into new things, let your local bike shop do it for you.



The headset bearings like this task because they also get cleaned and repacked with grease.



A clean bearing is a happy bearing!



The culprit is hidden under the black dust wiper.



Our ultimate goal is some new refreshing oil for the oil bath...



...and a pair of new seals (the white foam rings) and dust wipers.



My first small battle was loosening this tiny 1.5 mm hex bolt without stripping it. It had been set at the factory with Loctite Blue. I normally don't have trouble loosening threads containing blue thread-locker. But this little guy was being a pest, oh my.



There is a method to the madness. The bolt had to be backed out without spinning any of the 3 control knobs with it, especially the top black lockout force knob, which wanted to spin with the bolt I was removing. I didn't want to use the knob stops as a wedge either. I attached the vice grips to the hex key for some leverage and to get my hand away from the other hand that would be holding the three levers in place.

I couldn't hold the black knob with my fingers. To remedy this, I taped Presta valve stem caps onto the legs of a pair of snap-ring pliers. The valve stem caps fit into the knob nicely without marring it. After heating the small bolt, I would try to break it free of its bonds. It took 5 or 6 heat-and-breaks to finally spin the bolt free.



In time, I had the old oil drained, the shock lowers pulled off and the FIT damper removed from the right stanchion tube. I left the air/spring assembly in the left stanchion because I wasn't going to mess with it this go around. I set aside the FIT damper as well. All I was planning to do is clean everything, install new seals/wipers and refill oil baths.



The fork lowers (white thingies), stanchions and fork crown (gold thingies) and FIT damper (silver/black thingie) await new seals and having a home again.



The new seal is not visible. It rests under a new dust wiper.



With the lowers in place, all I need now is to install and bolt dampers to lower shock legs...



...then add some 20-wt. oil to the stanchions. A 5cc pillow of a lighter Fox fluid was added to the air chamber (5cc oil pillow install not shown here).



Add some air to cause the stanchions to extend so the FIT damper can be installed and bolted to crown and lower fork leg. I'll set the air pressure to the proper sag and my liking when I'm finished.



When done I invert fork to get oil splashed around. This actually is how this fork should be stored. The seals are special foam that absorbs and retains oil. Upside down guarantees oil to be in contact with the foam seal. I don't store bikes upside down. However, before a ride I'll flip the bike onto its back to allow oil down into the seal area. While riding, the oil gets mixed around pretty good.

I'm off to the hills...

Adios