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  • Title Page- Lowering the Valkyrie Forks
  • Original Author- Larry Heath

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Lowering the Valkyrie Forks

    

I purchased a new Valkyrie Interstate last year and had installed a set of Progressive 412 shocks and a Corbin seat to attain a lower riding position. I wanted to lower the front also, but was unable to find a source for a lowering kit for the Valkyrie forks. This year, through a friend, I posted a message on the Valkyrie Riders web site asking if anyone knew of a vendor that could supply a kit, or if anyone had lowered the forks and, if so, how did they do it? The responses were all the same; there is no vendor supplied kit available and the riders that had lowered the forks did so by slipping the fork tubes up in the triple clamps. One response, defining the process, stated that it is o.k. to go up to 1" lower by slipping the forks. It is my opinion that slipping the fork tubes up into the triple clamps, especially amounts approaching 1", is an unsafe modification. Let me try to explain why I am concerned.

The following elements exist in the stock setup.

When the forks are slipped in the triple clamps the amount of the move is equal to the amount of the triple clamp that is no longer holding the fork tubes. This can be equated to a proportional loss of bearing area and resistance to movement of the fork within the clamps. The condition is further impacted by the fact that aluminum is relatively soft and is easily deformed, which means that a fit the initially appears to be sufficient will eventually fail with use. How much can the forks be slipped and still maintain safety? This is a question for engineers to answer (obviously the Honda engineers set it up with some safety factor allowance).

I have had no personal experience with aluminum in compression fit applications. My background has been in compression fits of hardened steel pins fitted into holes bored in ductile iron, but I know that if you reduce the bearing area, you reduce the holding capacity. In other words, the force required to move the fork tubes in relation to the triple clamps is reduced. In addition, the cast iron on hardened steel fit is much more stable that of aluminum on aluminum. Aluminum will deform easily, further increasing the risk of failure.

Having said all of that, I have lowered the inverted forks on my Valkyrie internally using the same principles used for typical, (non-inverted), forks such as those on Harleys. The following sketches and steps define the process.

 

Lowering Valkyrie Forks

 Step by step process Both Forks:

Follow the disassembly process defined in the Valkyrie Service Manual, up to the point where you remove the dust seal from the fork tube. The complete disassemly of the forks is not required when doing the lowering modification. Do it only if you think the fork bushings and seals need maintenance. If you do not have a service manual, the following step by step process should get the job done.

  1. Raise the front end of the motorcycle off the floor high enough to remove the front wheel assembly and block it securely
  2. Loosen the front axle pinch bolts
  3. Remove the axle bolt, axle and wheel assembly
  4. Remove the brake hose clamps
  5. Remove the brake calipers (hang these up to relieve tension on brake lines)

    Note: Do not touch the brake lever while the brake calipers are off the bike

  6. Remove the front fender
  7. Remove the turn signal assemblies from the forks if your bike has them mounted there (GL1500C/CT)
  8. Loosen top triple clamp pinch bolts
  9. Loosen fork caps
  10. Loosen left fork lower triple clamp bolts
  11. Slide the left fork out of the triple clamps
  12. Loosen the right fork lower triple clamp bolts
  13. Slide the right fork out of the triple clamps

     Modification Process Left Fork

  14. Remove fork cap
  15. Slide the fork tube down the fork slider until it is all the way to the axle holder
  16. Slide the rubber stopper down
  17. Break the lock nut loose from the bottom of the fork cap and remove the fork cap
  18. Slide the fork tube down until the inner fork bolt is visible

    Caution!!!!!!! The inner fork bolt has spring preload pressure on it

  19. Remove the inner fork bolt

    Note: This requires a special 44mm lock nut wrench, Honda p.n. 07VMA-MZ0010A. I made one out of heavy wall pipe and welded an old " drive socket into it so I could torque it properly upon assembly.

  20. Remove the rebound rod assembly
  21. Remove the spring collar (a long thin wall sheet metal tube)
  22. Pour the oil out of the tube
  23. Remove the spring seat (looks like a washer), and the spring
  24. Determine how much you want to lower the forks.

    Note: You will be reducing the amount of fork travel available, but it will still bottom out at the same height so the fender will not hit anything. I lowered my Interstate 1".

    NOTE: Every dimension change made in this modification, the amount of material removed from spring collars, damper rod, and length of the spacer added to the rebound assembly must be the same for both forks

  25. Reduce the length of the spring collar by the amount determined (this cut must be square). I used a chop saw set up as square as possible
  26. Drill a new hole through the spring collar to replace the one lost when length was reduced
  27. Make a spacer with the length equal to the reduction of the length of the spring collar. This spacer will be put between the spring and the inner fork bolt, in the rebound assembly, during final assembly of the fork.

Assembling the fork:

  1. Clean everything making sure that there is no grit or metal shavings on any of the modified parts
  2. With the fork vertical and compressed, pour the fluid in until the fluid is at the recommended level, measured from the top of the compressed fork tube. Add the oil incrementally, pumping the fork up and down a few times to get air out between each measurement.
  1. Install the fork spring into the fork slider with the tapered end up
  2. Install the spring seat (this is the thing that looks like a washer)
  3. Install the spring collar
  4. Assemble the rebound rod assembly, placing the new spacer between the rebound spring and the inner fork bolt
  5. Compressing the fork spring, thread the inner fork bolt into the fork slider
  6. Holding the fork in a soft jawed vice, torque the inner fork bolt to 72 ft lbs
  7. Install the fork cap onto the rebound rod assembly
  8. Hold the lock nut and torque the fork cap to 14 ft lbs
  9. Slide the rubber stopper up and screw the fork cap into the fork tube. This will be tightened later when the fork is in the triple clamps.
  10. This fork is now ready to put back on the bike

    Modification Process - Right Fork:

  11. Remove the fork cap from the fork tube
  12. Slide the fork tube down onto the axle holder
  13. Loosen the damper rod lock nut and remove the fork cap from the damper rod
  14. Back the lock nut off on the damper rod to reduce spring pressure, but do not remove the nut. Be careful because this assembly is under spring pressure!!!!!!
  15. Push down on the spring collar to compress the spring and remove the spring seat stopper
  16. Remove the spring collar
  17. Remove the spring
  18. Pour the fluid out of the fork
  19. Holding the fork in a soft jawed vice remove the bolt in the bottom the fork that retains the damper
  20. Slide the damper and the oil lock piece (a sheet metal cap on the bottom of the damper) out of the fork
  21. Reduce the length of the spring collar by the amount determined ( this cut must be square). I used a chop saw set as square as possible
  22. Drill a new hole through the spring collar to replace the one lost when length was reduced
  23. Reduce the length of the damper rod

You have a couple of options here:

 Cut and weld process:

 

If machined:

Assembling the fork:

  1. Clean everything making sure that there is no grit or metal shavings on any of the modified parts
  2. Hold the fork in a soft jawed vice and insert the oil lock piece and the damper into the fork
  3. Apply locking sealer to the threads of the damper retaining screw and install the screw and sealing washer
  4. Torque the screw to 14 ft lbs
  5. With the fork vertical and compressed, add about half of the required oil to the fork
  6. Work the damper up and down until the air is out of the damper
  7. With the fork vertical and compressed, pour in the fluid in until the fluid is at the recommended level measured from the top of the compressed fork tube:

-5.3" for GL1500C/CT

-5.4" for GL1500CF

  1. Install the spring with the tapered end up
  2. Install the nut on the damper rod, threaded about half way into the nut
  3. Attach two feet of wire to the damper rod
  4. Thread the wire through the spring collar and pulling the damper rod up, install the spring collar
  5. Pulling up on the damper rod and pushing down on the spring collar, install the spring seat stopper (this is tough to do alone)
  6. Remove the wire and tighten the nut down by hand until it bottoms on the damper rod
  7. Screw the fork cap onto the damper rod
  8. Holding the damper rod lock nut, torque the fork cap to 14 ft lbs
  9. Screw the fork cap into the fork tube. This will be tightened later when the fork is in the triple clamps.

    Putting it all back together:

  10. Install the forks back into the triple clamps.

    Note: The dimension from the top of the fork tubes to the top of the upper triple clamp must be the same for both forks

  11. The lower triple clamp pinch bolts are tightened first
  12. Torque lower triple clamp pinch bolts to 18 ft lbs
  13. Torque the fork caps to 25 ft lbs
  14. Torque the upper triple clamp bolts to 41 ft lbs
  15. Complete assembly in reverse order of disassembly

Note: During assembly tighten the left axle pinch bolts first after the axle and speedometer drive are seated correctly. Next tighten the axle bolt. After making sure that everything is aligned and working freely, tighten the right axle pinch bolts. The brake pads must not drag.

Note: Torque specs for screws/bolts in assembly

This modification will improve the low speed handling of the Valkyrie for two reasons:

On the down side:

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