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Author Topic: How to internally lower your forks. Updated with better pics. 6/20/09  (Read 66916 times)

Offline Coryonbusa

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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!
« Last Edit: June 20, 2009, 10:42:51 AM by Coryonbusa »

Offline atticdog

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Re: How to internally lower your forks.
« Reply #1 on: December 20, 2008, 05:29:57 PM »
Thanks Cory!!
01 Black/Silver,08 GSXR fork/wheels, Pyramid DB, Corbin seat, gsxr1K footpegs, spedo healer, PCIII USB, 6 over Trac arm and Boosted!!

Offline Mike-Nightrider

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Re: How to internally lower your forks.
« Reply #2 on: December 21, 2008, 04:13:06 AM »
Dragraceteam NIGHTRIDER
1/8: 5.101s..........1/4: 7.801s
227.7mph Woodbridge/GB 2013

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #3 on: December 21, 2008, 05:40:19 AM »
You're welcome guys. :thumb:

Offline piratediverjefff

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Re: How to internally lower your forks.
« Reply #4 on: December 21, 2008, 07:03:23 AM »
Nice post Cory. :thumb:
Build a man a fire and he'll be warm for a day,light a man on fire and he'll be warm for the rest of his life.

Offline squirel6025

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Re: How to internally lower your forks.
« Reply #5 on: December 21, 2008, 09:46:06 AM »
Excellent post,thanks for the info. :thumb:

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #6 on: December 21, 2008, 10:39:06 AM »
Y'all are welcome! :thumb:

Online sportbikeryder

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Re: How to internally lower your forks.
« Reply #7 on: December 21, 2008, 11:04:15 AM »
Great write-up cory.

You wrote "Don't remove less than 1/2 difference, spring binding may occur." for the difference in spacers.

Do you really mean "Don't remove MORE than 1/2" difference, spring binding may occur.
Any day on a motorcycle like this that ends just needing parts and labor is a good day.
4.82, 158.67mph 1/8th mile 7.350, 200.32mph 1/4 mile Riding

4.51, 171.75mph 1/8th mile  6.908, 212.83mph 1/4 mile Tuning

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #8 on: December 21, 2008, 11:37:33 AM »
Great write-up cory.

You wrote "Don't remove less than 1/2 difference, spring binding may occur." for the difference in spacers.

Do you really mean "Don't remove MORE than 1/2" difference, spring binding may occur.


If you removed more of the factory spacer, you would have a spongie front end.
Removing less of the factory spacer put's more preload on the spring.
Removing less than 1/2 of an inch of the total legth of the spacer you add, would put the spring in a bind.

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #9 on: December 21, 2008, 11:38:56 AM »
It is worded tricky. I'll change it.
Thanks. :thumb:

Offline Mike-Nightrider

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Re: How to internally lower your forks.
« Reply #10 on: December 21, 2008, 12:17:08 PM »
Cory, I hope it is fork oil in your hand and no blood  :?
Dragraceteam NIGHTRIDER
1/8: 5.101s..........1/4: 7.801s
227.7mph Woodbridge/GB 2013

Offline Pinky

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Re: How to internally lower your forks.
« Reply #11 on: December 21, 2008, 12:35:24 PM »
Cory, I hope it is fork oil in your hand and no blood  :?
thats what needs to be watched out for
the forks will bite you if you arent careful
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Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #12 on: December 21, 2008, 04:12:27 PM »
Cory, I hope it is fork oil in your hand and no blood  :?

Yep, it's blood. They do bite back! :lol:

Offline Rocketgeezer

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Re: How to internally lower your forks.
« Reply #13 on: December 25, 2008, 09:51:37 PM »
Nice write up Cory pics make it much more understandable if its a newby trying it :thumb:
The older you get do you notice you start chickening out way before the bike does

Offline TYSON

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Re: How to internally lower your forks.
« Reply #14 on: January 10, 2009, 07:11:59 PM »
Does anyone know the length of the standard spacer at the top of the fork? Just have to return a set back to stock height and can't remember the length to make the spacer.

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #15 on: January 11, 2009, 05:49:32 AM »
From Shcnitz Racing's instuctions, it says it's 4 1/4".  I dunno if that's right or not?

You could just order new ones.  :idea:

Offline squirel6025

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Re: How to internally lower your forks.
« Reply #16 on: January 29, 2009, 10:46:49 PM »
Followed your instructions, worked perfectly. :D

Offline squirel6025

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Re: How to internally lower your forks.
« Reply #17 on: January 29, 2009, 10:47:50 PM »
Does anyone know the length of the standard spacer at the top of the fork? Just have to return a set back to stock height and can't remember the length to make the spacer.

4.285" :shock:

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #18 on: January 30, 2009, 07:52:31 AM »
Followed your instructions, worked perfectly. :D

:woot: :woot:

Offline Patterson

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Re: How to internally lower your forks.
« Reply #19 on: February 17, 2009, 06:50:36 PM »
now you need to do a write up with pics to change a seal.... :lol:


mines leaking and i have never took one apart

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #20 on: February 18, 2009, 05:01:29 AM »
now you need to do a write up with pics to change a seal.... :lol:


mines leaking and i have never took one apart

:lol:

Seals are easy.

Remove the fork.
Remove the top 30mm top cap.
Hit the 10mm Allen bolt on the bottom with an impact.
Drain the oil. Slide the cartridge out and set it aside.
Slide the outer fork tube off to access the seal.
The rubber grommet just pops out.
Then, you can pry the seal out with a screw driver.
Push the new one in and put the grommet back on and you're in business.
Repeat the steps in reverse to put it back together.
Just remember to slowly pour in the oil while pumping the fork, to get all of the air bubbles out.

:thumb:


Offline Patterson

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Re: How to internally lower your forks.
« Reply #21 on: February 18, 2009, 03:37:24 PM »
now you need to do a write up with pics to change a seal.... :lol:


mines leaking and i have never took one apart

:lol:

Seals are easy.

Remove the fork.
Remove the top 30mm top cap.
Hit the 10mm Allen bolt on the bottom with an impact.
Drain the oil. Slide the cartridge out and set it aside.
Slide the outer fork tube off to access the seal.
The rubber grommet just pops out.
Then, you can pry the seal out with a screw driver.
Push the new one in and put the grommet back on and you're in business.
Repeat the steps in reverse to put it back together.
Just remember to slowly pour in the oil while pumping the fork, to get all of the air bubbles out.

:thumb:



thanks buddy, if i mess it up you can take a trip up and fix it. i'll buy you some taco bell  :lol:

Offline lowrider99

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Re: How to internally lower your forks.
« Reply #22 on: February 18, 2009, 04:25:04 PM »
Good explanation! :thumb:

Offline Coryonbusa

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Re: How to internally lower your forks.
« Reply #23 on: February 18, 2009, 04:40:43 PM »
now you need to do a write up with pics to change a seal.... :lol:


mines leaking and i have never took one apart

:lol:

Seals are easy.

Remove the fork.
Remove the top 30mm top cap.
Hit the 10mm Allen bolt on the bottom with an impact.
Drain the oil. Slide the cartridge out and set it aside.
Slide the outer fork tube off to access the seal.
The rubber grommet just pops out.
Then, you can pry the seal out with a screw driver.
Push the new one in and put the grommet back on and you're in business.
Repeat the steps in reverse to put it back together.
Just remember to slowly pour in the oil while pumping the fork, to get all of the air bubbles out.

:thumb:



thanks buddy, if i mess it up you can take a trip up and fix it. i'll buy you some taco bell  :lol:

:lol: Yo quero!

Where are you? I don't mind helping, if you're close to south GA. :thumb:

Offline BATTMAN

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Re: How to internally lower your forks.
« Reply #24 on: February 18, 2009, 04:44:07 PM »
Where is everyone getting seals the cheapest from?  Are you going to the dealer or where?  I need to change 2 sets of seals before riding season.
« Last Edit: February 18, 2009, 07:35:44 PM by BATTMAN »