TECHNICAL > MODS
How to internally lower your forks. Updated with better pics. 6/20/09
Coryonbusa:
This is step by step instructions on how to lower inverted forks.
You'll need:
30mm socket
10mm Allen socket. 3/8 drive
3/8 drive extention
Impact Gun
2 Pipe wrenches
2 sleeves: 7/8" o.d. x 5/8" i.d. (for busa) or 3/4" o.d. x 5/8" i.d. (for gsxr) (the length of the sleeves will determine the amount lowered)
Hack saw (or something to cut the factory sleeves)
We are starting with a fork that I've previously cut 2"s. We're wanting to cut it to 2.5"s. The process is the same for starting with an uncut fork.
First, turn the fork upside down and hit the 10mm Allen bolt with an impact.
Turn it right side up in a drain pan and let it drain for about 10 minutes.
Use the 30mm on the top to unscrew the assembly.
Slide the assembly out of the fork tube.
Let it drain off.
Unscrew the lower cartridge housing using the 2 pipe wrenches.
Drain it out.
Next, compress the spring. This is a crude spring compressor I've built. Works great though!
Now, with the spring compressed, put the 17mm wrench on the nut under the top hat and remove the top hat with the 30mm socket.
With the top hat removed, loosen the spring compressor and remove the spring. Use a pipe wrench and a 3/4 wrench to remove the valve assembly.
Now install your spacer. This is a 2.5" spacer with a washer on top.
Here's what we used for a spacer. You can get it Home Depot. Just measure and cut. :thumb:
Now cut the the factory spacer. If the lowering sleeve you have made is 2", cut 2" off of the factory spacer.
If you want to add more preload to your front suspension (heavy hitters), remove less of the factory spacer.
Example:
Normal: 2" sleeve, remove 2"s from the factory spacer.
Heavy hitter: 2" sleeve, remove anywhere from 1.5" to 2" from the factory spacer. A 1.5" factory spacer, in this example, will add the most preload.
Don't remove less than 0.5" from the factory spacer than the total length of the spacer you added to lower the fork.
Spring binding may occur.
We've already taken 1.75 off of this one previously, when we lowered it 2". Now that we're lowering it another .5"s, we'll take .5" more off of this spacer.
Put the cartridge all back together in the spring compressor. Be sure to loosen the preload all of the way out on the cap and turn the rebound screw all of the way out. before you reinstall the top cap. Tighten the cap just hand tight, then tighten the 17mm nut up to the top hat.
The inner cartridge reassembled with 2.5" lowering spacer and cut factory spacer.
Reinstall the lower cartridge housing using the pipe wrenches.
Slide the cartridge back into the fork housing, turn it upside down and start the Allen bolt by hand. Then tap it with the impact gun.
Turn it right side up and add the fork oil. 16 oz. per fork.
Be sure to pump it after every 4oz. you pour in.
Once you've got 16 oz. in there, let it sit for about 10 minutes before tightening the top hat to let all of the air bubbles escape.
Reinstall the top hat and pump it until you feel the rebound working. Then you're done!
(Insert sweet pics of Dave's bike here once the motor is back in. :D)
Big thanks to Pinky for coaching me through this! :thumb:
And a big thanks to Dave3.4 and Katie for the pics!
atticdog:
Thanks Cory!!
Mike-Nightrider:
--- Quote from: atticdog on December 20, 2008, 05:29:57 PM ---Thanks Cory!!
--- End quote ---
+ 1 :thumb:
Coryonbusa:
You're welcome guys. :thumb:
piratediverjefff:
Nice post Cory. :thumb:
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