Author Topic: Changing fork oil  (Read 12461 times)

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Offline GF-in-CA

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Re: Changing fork oil
« Reply #50 on: July 09, 2011, 06:35:22 pm »
For whatever reason, the service manual specifies that the oil level on the pre '94 to be 14 inches with the forks fully extended.  For the later models, the spec is 6.75 inches with the fork fully compressed.  I agree with Willy, the numbers are a starting point, and if an aftermarket spring company recommends a different value, then use that as a starting point. I would recommend not moving too far from the spec, e.g. 1 inch either way, since if the volume is too small, you can end up blowing seals due to overpressurizing the fork.  The oil level doesn't affect damping, but affects the fork's resistance to bottoming by introducing a secondary spring (the air).  The higher the oil level, the smaller the air volume, and the stiffer the secondary spring.  If you are interested in optimizing oil level, I found a good article on suspension tuning.  Scroll down to find the section on oil level.

http://www.strappe.com/suspension.html
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Offline connie_rider

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Re: Changing fork oil
« Reply #51 on: July 10, 2011, 12:38:59 pm »
Well said Gary! Plus good info on how to determine proper setting of the oil level.

I see that the original spring setting for later models is 6 3/4". So my memory wasn't as bad as i thought. I started with 6 3/4" and changed to 6 1/2" to get the ride the way I liked it.

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Offline Buddy

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Re: Changing fork oil
« Reply #52 on: July 21, 2011, 05:44:45 pm »
Just hung up with Race Tech. If you have emulators. 150mm - Forks collapsed - Emulators in - Springs out.

Offline WillyP

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Re: Changing fork oil
« Reply #53 on: July 21, 2011, 09:48:14 pm »
Thanks, I was going to call them myself.
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Offline willb

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Re: Changing fork oil
« Reply #54 on: March 21, 2012, 02:32:21 pm »
Changed my fork oil yesterday for the first time on my 2004 (20k miles).
First thanks for all the tips in this thread, they made it a much easier job.

Some notes from the experience:

15 weight fork oil does make a difference in reducing "nose dive".

Get a Mighty Vac if you don't already have one. It has plenty of suction to get the old fluid out, the container that comes with it is graduated so you can use it to measure the new fluid going in. Got mine at Harbor Freight $34 and got 20% off with coupon from Rider magazine.

The tip about marking the thread engagement point really is a good one. Even with the front raised off the ground, you have to push down pretty hard to get the fork caps back in. Mark the cap and the fork with a Sharpie at the point at which the threads start to catch. Do it with the spring in but without the washer. I used the deep well socket to push down and started my turn just before the the Sharpie alignment marks. Still took a couple of tries to get them to catch, but not that hard.

Caution....Use one of the plastic tips from the Mighty vac to help get the suction tube all the way down to the bottom of the fork tubes. Otherwise you won't get all of the old fluid out and you might end up overfilling and get to do it the job again.

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Offline connie_rider

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Re: Changing fork oil
« Reply #55 on: March 21, 2012, 10:34:52 pm »
DO not put a measured volumn of oil in the forks.
Not as accurate as measuring the fluid height and you do not have to do it multiple times if you use too much.

See Gary's note above...
6 3/4" forks compressed/springs out....
EZ to do..

Ride safe, Ted
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Offline xjdaver

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Re: Changing fork oil
« Reply #56 on: April 05, 2012, 11:28:49 am »
My Clymers manual lists a few tools required for this job. Damper rod T-handle and Damper rod holder. They also list a fork seal driver but I read elsewhere of using PVC pipe.

What is the shop workaround for the T-handle and Damper rod holder?
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Offline WillyP

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Re: Changing fork oil
« Reply #57 on: April 05, 2012, 11:37:41 am »
Some have used a broom handle, some have used 15/16 nuts, welded, pinned or double-nutted to both ends of a length of threaded rod. I used a nut sticking out of a socket with an extension, some tape to hold the nut from falling out, and a smaller nut inside the socket to keep the nut from sliding inside the socket.

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Offline Daytona_Mike

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Re: Changing fork oil
« Reply #58 on: April 05, 2012, 12:07:32 pm »
Yup, broom handle works great. I dont remove the forks from the bike. Just drain from the bottom and I can clean and rinse any left over residue while on the bike.
The easiest way is to  use an air impact driver for the bottom bolt  and and  to hold the tube by  using  bottom of an old spark plug socket. Pull the rubber out of the spark pug socket  and flip the socket  over and it fits on an extension and a little duct tape to keep them together but a broom handle works just a s well when you have an impact driver.
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Offline xjdaver

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Re: Changing fork oil
« Reply #59 on: April 14, 2012, 12:34:14 pm »
Some have used a broom handle, some have used 15/16 nuts, welded, pinned or double-nutted to both ends of a length of threaded rod. I used a nut sticking out of a socket with an extension, some tape to hold the nut from falling out, and a smaller nut inside the socket to keep the nut from sliding inside the socket.

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I don't have an air impact driver so I'm not confident about the broom handle method. What size nuts? I wish I knew what this thing looked like.
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Offline Daytona_Mike

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Re: Changing fork oil
« Reply #60 on: April 14, 2012, 02:20:37 pm »
Some have used a broom handle, some have used 15/16 nuts, welded, pinned or double-nutted to both ends of a length of threaded rod. I used a nut sticking out of a socket with an extension, some tape to hold the nut from falling out, and a smaller nut inside the socket to keep the nut from sliding inside the socket.

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I don't have an air impact driver so I'm not confident about the broom handle method. What size nuts? I wish I knew what this thing looked like.


You would need to cut a 10mm allen key and use the straight part (cut the bend off ) and use a 10mm socket  and you remove the front wheel axle. The allen bold is above the  the axle shaft. Maybe borrow an electric impact driver. I dont know how well it comes out with out one. It goes back together  fine with out one. See part number 92001. Dont loose the copper washer. Sometimes it stays in the fork, sometimes it comes off with the bolt.
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Offline WillyP

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Re: Changing fork oil
« Reply #61 on: April 14, 2012, 04:26:30 pm »
I've never used an impact wrench. I bought a socket with the allen part already in it, and I just give the ratchet a sharp jerk and it breaks free. Once it is loose the pressure from the spring holds it enough to unscrew it the rest of the way.
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Offline xjdaver

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Re: Changing fork oil
« Reply #62 on: April 21, 2012, 12:48:15 am »

If the forks are hard to slide out of the triples, you can tap a screwdriver into the gap in the triple to open them up slightly.
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I tried this. Still won't budge. It was getting late and I decided to give up for the evening before I resorted to measures I would regret.

On another note, is there a tool or special method for removing the seal retainer ring? One was easy, the other a complete struggle.
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Offline xjdaver

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Re: Changing fork oil
« Reply #63 on: April 23, 2012, 01:06:47 am »
A little trick I heard from someone on the zggtr.org site on getting the fork caps back on is to start them in the tube without the springs in, to mark or put tape on as an index on the caps and tubes at the point just before the threads begin to mesh with the threads on the tube. 

Then when you re-install them with the springs in, you won't have to spin them around guessing, while keeping everything straight due with the back pressure from the springs. 

I think it minimizes the chance of cross threading the caps.

I did this and it saved a lot of frustration. I removed the o ring before marking. I could'nt very easily feel when the threads were starting with the o ring in because it is a tight fit inside the tube.
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