Main Motorcycle: 2018 Kawasaki H2 SX SE
Join Date: Sep 2008
Location: Indiana, USA
Other Motorcycle: 1973 Yamaha RD350
Extra Motorcycle: 1974 Kawasaki 500 H1E
Sprint Forks Maintenance and Upgrade – Oil, Seals, Bushings, Springs & Gold Valves
This post describes the work I did to upgrade the suspension on my ‘06 Sprint ST. I hope my photos and description will help others who want to maintain or upgrade or simply enlighten those who are curious about what’s inside their forks. This information does not apply to pre-’05 Sprints that use old-style damping rod forks. For more photos check my album.
There are several alternatives available for upgrading Sprint suspension. I’ll review the various options in a separate post
and focus on the maintenance tasks in this post. To upgrade my forks I used new straight rate springs and revised the damping by replacing the compression and rebound valves with Race Tech
Gold Valves. I also replaced the bushings (Teflon-coated bearings) and seals. While the forks were removed I took the opportunity to inspect, clean and lube the steering head bearings too.
Rebuilding Sprint forks is not difficult but does require more than just basic levels of skill and experience. I would recommend having a manual to hand. For coverage of suspension maintenance I consider the Haynes manual superior to the factory manual. I’ve broken the description into sections so even if you’re not doing a full rebuild there should be enough information to help with each of the following operations:
- Fork oil change
- Replace springs
- Upgrade with Race Tech Gold Valves
- Install new bushings and seals
For fork overhaul your selection of tools should include the following:
- 24mm wrench or socket for fork caps.
- Leak-free tray for collecting/cleaning parts.
- Torque wrench.
- Bushing/seal driver (or suitably-sized piece of pipe).
- Fork oil level tool.
Tools required for installing Race Tech Gold Valves are listed in the instructions for the valves.
- Fork Dust Seals - Triumph Part # T2046234 (if replacing)
- Fork Oil Seals - Triumph Part # T2046232 (if replacing)
- Fork Bushings, Outer - Triumph Part # T2042889 (if replacing)
- Fork Bushings, Inner - Triumph Part listing not available (if replacing)
- Sealing Washer for Damping Cylinder Bolt - Triumph Part # T2042907 (optional)
- Fork Cap O-Rings - Triumph Part # T2042905 (optional)
- Preload Adjuster O-Rings - Triumph Part # T2042933 (optional)
- Fork Springs (for upgrade)
- Race Tech Gold Valves (for upgrade)
1 - Remove Forks
- Plenty of Paper Towels
- Kerosene (Paraffin) or Cleaning Solvent
- Suspension Fluid
- Grease for Seals (if dismantling forks)
- Loctite 271 – Red
- Plastic Bag or PVC Electrical Tape to put over end of fork tube to protect seals (if dismantling forks)
2 - Remove Spring and Drain Oil
- All of the tasks described were performed with the forks removed. The forks can be removed with the fairing in place but removal is a good precaution to reduce the chance of damage.
- Before removing the forks I loosened the fork caps. The fork caps mark very easily, as I discovered on a previous occasion, so I wrapped some masking tape around the hex before using a socket.
- In the base of the fork leg there is a bolt that holds the damper cartridge in place. It doesn’t need to be touched for oil change or spring replacement but I planned to completely dismantle the forks. To make it easier to remove later I loosened the damper cylinder bolt slightly while the fork was still held in place.
- After loosening the bolts on the bottom triple clamp, top triple clamp and handlebar the fork leg pulled out with a little bit of twisting.
3 - Remove Damper Cartridge
- With one fork on the bench I unscrewed the fork cap. There is some spring preload tension but minimal force pushing on the cap when it’s released.
- The cap is held on the damping rod by a locknut screwed against the preload adjuster. To loosen the locknut I screwed in the preload adjuster to expose the flats on the threaded end of the adjuster. With a pair of 14mm wrenches I undid the locknut & removed the fork cap/pre-load adjuster from the damping rod.
- The spring is held in place by a cupped washer. A slot in the washer allows it to be removed from the damping rod. I lifted out the spring slowly to allow oil to drain from it.
- I poured the oil out of the fork tube into a container, pumping the damping rod a few times to help oil flow out of the cartridge. I inspected the oil for any debris that could indicate excess wear and/or damage that should be investigated during strip down of the forks and damping cartridge.
- The following sections describe work to the damper cartridge and replacement of bushings and seals. If the aim is to simply change fork oil or replace springs then skip these tasks and jump to Section 8.
- My next step was to remove the damper cartridge. I removed the bolt, loosened earlier, from the bottom of the fork leg and lifted the cartridge from the fork. The bolt came out easily without the need for a cartridge holding tool.
- It is recommended that the cartridge and valves are stripped and cleaned. If you are not comfortable with that and simply want to replace bushings and seals then make sure the cartridge is cleaned thoroughly before moving on to fork dismantle in Section 5.
Damper cartridge removed from fork tube.
It's amazing how fast you can go when you take your time.
Last edited by champ87; 12-10-2010 at 03:23 PM.