Fork R&R.
Parts and Supplies:
Fork Oil Seals, 2each
Fork Dust Covers (also called wipers), 2 each
Fork Fluid, 2 qts (might get away with one, better safe).
Springs*, spec’d for your weight and preference street or track
Valves*, optional but from all told, very nice to have
Bushings upper and lower*, if yours are worn out
Ultrafine emery cloth/wet sandpaper
Tools needed:
¼â€ Drive ratchet and 12mm socket shallow
3/8†Drive: Ratchet, extension, 4mm & 6mm hex head (allen drive), 12mm socket
½â€ Drive Breaker bar (ratchet or torque wrench) and 30mm “Axle Nut†socket
11mm, 13mm, 17mm wrenches
#2 or 3 Flat tip screwdriver
Drain pan
Some rags
Tape measure
Marker
Following the basics in the Service manual, pages 299-307. Front end supported, I used a stem stand. Remove: under-nose panel, front fender 4mm hex head, brake calipers 3/8†x 12mm socket (hang them by cut coat hanger, zipties etc to keep weight off the line itself), axle bike tool kit and 6mm allen, and wheel.
Loosen fork cap nut 1/2†x 30mm socket, just break it free a turn or two
Loosen lower triple clamp bolts ¼â€ x 12mm socket and ratchet for easy fit from underneath, and upper clamp 6mm allen.
Slide forks out from under clamps and bike. Fully loosen top fork nut 30mm socket. The upper tube will now slide down over the lower tube. The fork nut is held onto the internal cartridge, it is screwed onto the stem of the cartridge via a lock-nut underneath the spacer (aluminum tube with 2 holes on upper end and lower end. The Suzuki spring compressor tool is similar to a “tap and die†handle set, having two pins on opposite ends that sit inside the spacers holes, and a handle extending out to the sides for leverage. I used the axle clamp bolts, one in each hole, angled down with a rag wrapped around them for cushion on my hand. At this point you will need a friend to grab the 13mm wrench, as you push the spacer down, against the weight of the forks spring, the locknut will be exposed. Slide the open-end of the 13mm wrench UNDER the locknut and wedging the spacer in the compressed position. Now, you can release pressure on the two bolts you used to press the spacer down. Using the 17mm wrench hold the locknut, and use the 30mm socket to spin the fork nut off the cartridge rod end. Once removed, place the fork nut aside, and depress the two bolts hanging out of the spacer, remove the 13mm wrench and carefully let the spring uncompress, bringing the spacer off the cartridge end. Reach in the tube and pull the spring seat out, and spring. If replacing the spring, discard. If keeping the spring and only replacing seals fluid, go to FLUID FILL.
If replacing springs, also replace fluid. So skip to the FLUID FILL.
Seal Replacement. Now that the spring is out, pull the top tube off the lower tube. Invert the lower tube over the oil pan to drain the garbage fluid out. Once it seems the fluid is all out, begin pumping the cartridge via the locknut and threaded portion, until all available fluid is gone. Thoroughly wipe down the lower fork tube, and inspect to ensure there are no nicks, scratches etc, if there are, gently use wet-sand paper or emery cloth to wipe the surface removing any defects. Flip the upper tube so the seal is on top. Using a pick, or flat tip, carefully pry the dust wiper off and discard. Remove the seal stop ring, simply pull up on open end and walk it out working your way around, keep this part. Next, using the same wiper prying technique, pop the seal out. Be careful so you don’t scratch/gouge the inner fork wall where the seal resides. Remove the seal and discard. Remove seal stop, looks like a large washer, wipe down and reinstall. Carefully tap new seal in with the PN’s facing up towards you. Next install the seal stop ring. Now, slide the dust wiper on, this doesn’t require any tapping or pressing, simply slide onto the tube end. Use grease on the tip of a finger, and generously lube seal inner lip a edge of wiper to prevent tears during reinstall. Also, smear a small amount on outer end of lower fork tube, where the seal will first meet it for reassembly. CAREFULLY slide the upper tube over the lower tube, taking care to not tear wipers and seals. During the assembly, the tube will have to slide into the internal bushing. Once completely slide onto lower tube begin the Fluid Fill.
FLUID FILL: With the upper tube slide over the lower and collapsed, have assistant hold it up right (open end topside). Pull the dampener adjustment rod out from the center of the cartridge, it’s a small diameter long skinny aluminum rod. Using a measure tape, make a mark 3.9†from one end. (since I didn’t have a micrometer, I used one marker tip width below 4â€). With the lower tube clean, pour in almost half a quart of fork fluid. Looking into tube, once it over the cartridge end, pump the cartridge to remove the air, and continue filling, until the fluid is up to the 3.9†mark on the dampener rod, when the mark is held at top of lower tube, the rod end should meet the tip of the alum rod. Again, pump the cartridge to ensure all air is removed, and let sit a few minutes (beer or smoke time, whatever). Now, insert spring with the smaller end up, followed by spacer seat (the smaller lip facing into the spring to locate the seat).
Now for the fun part. If using new heavier springs, again, using the 2bolts into the spacer, a friend with a 13mm wrench at the ready… Steady the fork tube in the upright position. Pull the cartridge end up into the fully extended position, and quickly place the spacer/bolt/rag assembly over the cartridge end pushing down (what a PITA with a heavier spring) until your assistant can wedge the 13mm wrench under the locknut to hold the spacer in the compressed position. Once wedged, carefully measure that the locknut is 11mm down from the top of the threaded end of the cartridge. I used an 11mm wrench for this, and eyeballed it. If its not 11mm, you wont have complete adjustability of your rebound. Once the nut is down 11mm, add a drop of locktite to the threads, and screw the fork nut on, torque to spec in SM. Press down on spacer bolt to remove 13mm wrench and allow the spacer to ride fully up the fork nut stem. Lift the upper tube to the fork nut and screw together hand tight. Insert into triple clamp, adjust for desired height, and lock into place using the clamp bolts. Once clamps are tightened, tighten the fork nut using the 30mm socket and torque wrench to spec. Repeat for opposite fork. Reinstall wheel, axle, brakes, fender, under-nose panel. Set preliminary suspension settings, compression, rebound and pre-load. If using 10wt fluid, rather than 3.5-5wt, you can expect to not need as much compression, as the weight of the fluid will dampen more than lighter fluid will, same for the spring. Measure and set sag etc…
If you follow this way, it’s a PITA to compress the spring, your hands will hurt, but when you go for the test ride, and adjust you will feel so proud of yourself! I will be buying the Suzuki spring compression tool and locknut holder tool.
If you need to replace the cartridge, you will need a 10mm Allen socket, extension, and ratchet. Loosen the 10mm hex head bolt in bottom of lower fork tube, while holding the cartridge rod over to one side of the tube, this keeps just enough tension on the cartridge to prevent it from spinning while loosening. I used the impact wrench while holding cartridge to one side, then realized I didn’t need to remove the damn thing! Install, slide cartridge into tube, clean washer area on bottom of tube, insert and tighten 10mm allen bolt. Have fun.
I hope I’ve got it written well enough to supplement the SM. I wanted to get pics, but ran out of hands. If I do another set for my friend we’ll get the pics.
Charlie