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Observation and Perspective
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| Ride Stats |
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Distance:
4.64 miles
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Time: 00:27:00
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Max Speed:
19.30 mph
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Avg Speed:
10.31 mph
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Temp:
Avg: 28
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Category: general: errand -
solo
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Route:
Adams Basin Post office
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Weight:
238
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Altitude Gain:
0 ft
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Avg Power: 0 W
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Calories Burned: 300
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Avg HR: 0 bpm
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Terrain: Road: Flat
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Bike: Specialized 40lb-Globe 700c Hybrid
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Club: USA Towpath and Trail Riders association |
| Weather Conditions: snow crusted driveways and roadway shoulders; damp, breezy, overcast; |
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After last Thursdays Ride I noticed the "wiper-seal" on the right side of the fork had become unseated. A 2-piece plastic "bearing sleeve" component, had also worked its way out of its normal position, directly under the wiper-seal.
Disassembled, the suspension fork is comprised of several parts. The two main components, the (lower portion) outer "sleeve assembly" and the (upper portion) inner "tine assembly" are attached to each other with two threaded retaining rods. The retaining rods act as the seating surface for the two main springs. The main springs are located below the pre-load adjuster units. The "tine assembly" slides in & out of the "outer sleeve assembly", with which springs, retaining rods, and pre-load adjusters, comprise the suspension fork.
The wiper-seals are held in place in the counter bore seating surface of the outer sleeve assembly, with a friction fit plus the interaction of the tines positioned respectively each in a 2 piece plastic sleeve. The 2-piece plastic sleeve acts as a bearing surface for the tines to slide in. The plastic sleeves are seated just beneath the wiper-seals in the "outer sleeve assembly". The wiper-seals can be easily removed or installed when the "tine assembly" is removed from the "outer sleeve assembly". In fact the only way to re-seat the wiper-seals is to dis-assemble the fork.
First, remove the front brakes from their mountings on the fork. Detach any other components that are attached to the fork and the handle bars, such as, a cyclometer, or generator wiring. Remove the stem and handle bar with as many components as possible yet attached. Tie-up those components as one unit, out of the way, to the bike frame. Remove the wheel. Slide the fork out of the headset. Carefully handle any shims, spacers, or small rings (bearing races). Tie shims, spacers and loose parts together in the sequence they will re-assemble.
Next, remove the two preload adjusters from the top are of the "tine" portion of the fork. Remove the (2) main springs. With a 5mm extension wrench or "T" handle wrench, unscrew the (2) retaining screws. Slide the tine assembly from the sleeve assembly. Carefully unseat the (2) wiper-seals from the outer sleeve assembly. Remove the (2) plastic "bearing" sleeves from each side, and look carefully for any "extra" shim pieces. There was a light spring in the left sleeve which was not in the right sleeve when I disassembled the unit. In addition, the main spring on the left side had a rubber travel limiter. Clean and reassemble.
!["Photobucket]("http://i98.photobucket.com/albums/l242/migliore_photo/tn_suspensionfork.jpg")
A good mechanic always uses the proper hammer...an essential tip in watch repair too!
I did the tear down on the porch. What a mess the suspension fork had become after 2 years & 4000+ miles. I removed a lot of water. There was substantial corrosion on the Left side's springs and both tine attachment bolts. Although messy (I am a sloppy worker), it was an easy but somewhat time-consuming bit of maintenance. I was surprised by the quantity of sand-like grit in the sleeve component (bottom portion of the suspension fork). It was sort of "mucky" too. I wouldn't think the wiper-seals could allow so much material to migrate into the fork, especially on the left side of the fork where the wiper-seal was still properly seated. I believe the "preload adjusters" are where most of the water and grit get in. Those adjusters are the 2 knob components at the tops of the tine assembly. Overall, the fork seems to be of good design.
Though I expected to order a re-build kit, it was not necessary!
In spite of the fact there was substantial corrosion on the springs and both retaining bolts I was able to re-use all parts -and no extras! I soaked all the internal components in kerosene, scraped corrosion from the springs and retaining rods, and re-lubed with an "anti-seize" lubricant.
I think the disassembly, cleaning and re-lubrication needs to be done more frequently than once in 4000 miles. I was grateful that all the parts seemed re-usable. I do have some corrosion/pitting remaining on the right tine, I will need to monitor it closely in the future. I expect to disassemble these components, clean, check and re-lube on a yearly basis.
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