VFR CARTRIDGE FORK SERVICE Part One of Four ---------------- Version: 1.0 Author: Robyn Landers, rblanders@math.uwaterloo.ca Copyright (c) the author, 1996 Distribution: May be copied as long as this header is retained. Improved versions will appear on my web page. --------------- 1. Introduction --------------- Being the maintenance keener I am, and having coincidentally come across an article in May 1993 _Motorcyclist_ magazine regarding the necessity of servicing cartridge style forks, and being confident that my '93 model bought used with 15,000 km on it had never had its fork oil changed, I decided I'd better remove the forks and disassemble them for cleaning and oil change, rather than simply draining and replacing the oil. One weekend in February 1996 I finally got started. Mileage at the time was 17,000 km. This series of four articles started as just an off-the-cuff description I sent to a friend, but then I started thinking of it more for general distribution. So, although I've been over it a couple times for improvements, the writing style varies from informal narrative to step-by-step instructions, and it's not what I'd call well-written. Oh well. 2. Fork Removal --------------- 2.1 Support the Bike I have installed the optional centrestand on my VFR. If you don't have a centrestand, this part is trickier. Thanks to previous experience I knew enough to ignore the manual when it says the first thing to do is jack up the bike. 'Fraid not! How about slightly loosening axle nut, pinch bolts, caliper bolts, fork cap bolts, and triple clamp bolts while the front end is still firmly planted on the ground so that sufficient force can be exerted without knocking the bike off the jacks. I used two hydraulic jacks, one beside the drain bolt on the RHS of the oil pan, and one near the left rear corner of the oil pan. Jack up each side a few mm at a time and be careful that the bike doesn't tip over or lift a centrestand leg too far off the ground. Not much height is needed to get the front wheel clear of the floor. You need remove no plastic other than the front fender to remove the forks, and you may need to remove the belly pan in order to jack the bike up. 2.2 Remove Handlebars, Fender, Calipers, Brake Line brackets Following the shop manual procedures, removal of all the required bits went fairly smoothly and of course I was working very slowly and carefully seeing as this was the first time working on this bike for me and I want to keep it scratch-free. The only problem was another incident with those nice looking allen bolts with the dome shaped heads. I don't know what it is with those things but they sure seem to want to seize in place. A pair of these hold the front fender on and it was a real struggle trying to get one of them out. I was sure I was going to strip the head of the bolt out. Mercifully it broke free at last. 2.3 Remove Forks From Triple Clamps Removal of the forks from the triple clamps was actually fairly easy. There was enough room (just enough) to get my socket wrench in there and loosen the bolts. The torque was low enough that I could crack the bolts loose with one hand in the close quarters. Then the forks easily slid down and out. Next I removed the drain bolt at the bottom of the fork leg and pumped out the fork oil. There was a fair bit of dark sediment in the formerly red fluid. Overall the jar of drained fluid looked quite dark with particles. What is this stuff? It is metal particles worn off the fork springs and other moving parts, as well as wear particles from the Teflon(R) fork bushings. 3. Fork Disassembly (overview) ------------------- I took the fork legs to my friendly neighbourhood shop where they happily loosened the damper rod bolt for me at no charge. This step requires an air impact wrench according to the manual. The mechanic disassembled one fork for me, and pumped the remaining oil from the cartridge. He felt the oil didn't look so bad compared to what dirt bikes are subjected to, but when I showed him the jar of fluid he agreed it certainly needed replacing. Seeing how the cartridge is assembled and how much more oil got pumped out after disassembly that I couldn't get out before made me believe that in addition to say a yearly simple fluid drain and fill, disassembly for complete draining and cleaning is certainly warranted periodically. We inspected the cartridge components and his opinion was that things weren't dirty enough to have necessitated the full disassembly at this point. But hey, I've gone this far, and it certainly won't hurt. Without some point of reference I wouldn't know how often to do it. All set with a bottle of new fork oil I returned home to disassemble and clean everything. I did find a piece of metal flashing jammed between a couple of the "valves" in one cartridge, and got a fair bit more sediment out of the various internal components when flushing them with solvent. So my conclusion at this point is that I needn't have fully disassembled the fork at the current mileage, but I will do the fork oil yearly, and save the full disassemblies for perhaps every 24,000 km or so (which is about the valve adjustment interval if memory serves). Details of fork disassembly appear in the next section. ---------- Footnotes: [1] DuPont's lawyers have warned that this footnote must be shown. "Teflon(R) is a registered trademark of DuPont for its fluoropolymer resins."