Author Topic: Changing fork oil  (Read 12523 times)

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Offline shotgun

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Changing fork oil
« on: June 28, 2011, 07:58:13 pm »
How hard is it to change fork oil on an 03. I want to change to 15wt. Thanks
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Offline 2linby

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Re: Changing fork oil
« Reply #1 on: June 28, 2011, 08:28:49 pm »
Keep in mind that everything is simple, nothing is easy.  Some folks just vacuum out the old fluid with a mity-vac, however in order to do it right you should remove the forks from the bike and thoroughly drain and clean them purging all the old fluid out. This is a relative easy thing to do.
1. Support the bike under the engine
2. Remove the front wheel, fender and if you have a fork brace remove this too and tie up the calipers (I also place a wood wedge between the brake pads in case someone squeezes the front brake!)
3. Back off the pre-load adjusters and carefully remove the top fork tube caps (they are under spring pressure) Pull the springs out (have a rag close by) and put the caps back on to prevent making a bigger mess.
4. Loosen the upper and lower triple tree clamps and pull the tubes straight out.
5. Remove the caps and drain the tubes by pumping them several times. If you can hang them over a pan this works well.  Drain them thoroughly. I flush them out with some new fluid until the fluid coming out is clean.

While you are here this is the best time to replace the seals and wipes and consider either racetech or sonic springs as replacements for the stock springs. I know there is a tech write up on it.
When you reinsert the tubes make sure they are even with each other in the triple tree and check the torque spec for those nuts so you don't under or over tighten them. Also make sure you do not cross thread the top caps (clean and inspect the caps "O" rings) as the thread is very fine and you will be doing this under the pressure of the springs and fluid.

Best of luck!

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Offline John Sperger

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Re: Changing fork oil
« Reply #2 on: June 28, 2011, 08:33:23 pm »
I like to free up the fork tube caps before I get too far.  Don't take the caps off until you have them off the bike, otherwise it's a pain to try and free them up off the bike.  I bought a breaker bar to make it easier.

Otherwise it's an easy process.
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Offline WillyP

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Re: Changing fork oil
« Reply #3 on: June 28, 2011, 08:48:08 pm »
Get a 19mm deep socket for the fork caps. You can take the fork caps off after if you have an extra upper triple to use as a fork wrench. Or I suppose a lower or a fork brace would work. If you don't, forget it, loosen the caps first. But, no need to take out the springs until you have them on the bench. Then put the cap end over the end of the bench with an oil pan on the floor.

Put some pressure on the caps as you take them off! Otherwise the spring pressure could pop them off prematurely, wrecking the first couple of threads.

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.
« Last Edit: June 28, 2011, 09:01:29 pm by WillyP »
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Offline Slybones

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Re: Changing fork oil
« Reply #4 on: June 28, 2011, 09:48:42 pm »
Personally i vote for the suck out the old oil, and dont worry about the left over. yes many will tell you do it right you have to remove the forks and purge every last bit of old oil. But come on, when you change your engine oil do you remove your engine and get every last drop of engine oil. Same applied to many other fluid changes on your bikes, cars, trucks, etc. You just dont get every last drop and what ever is left over always mixes with the clean new stuff and delutes it some. I dont see why we cannot live with that on the forks when we do with with the engine, drivetrains, power steering and everything else. 

Brake fluid is one exception.
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Offline WillyP

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Re: Changing fork oil
« Reply #5 on: June 29, 2011, 12:42:18 pm »
That's true for a routine oil change. And it might be 'good enough' in this case. But he wants to change weights, and as the weight is crucial to the characteristics of fork dampening, knowing what weight you end up with is kinda important. And if you have emulators there could be a pretty substantial amount of oil left if you don't remove them first, as your siphon tube won't go down past the top of the emulator.
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Offline connie_rider

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Re: Changing fork oil
« Reply #6 on: June 29, 2011, 01:07:14 pm »
Shotgun, I see you have instructions on the project. But I have a question. Thy are you changing to 15 wt?

NOTE: If you opt to suck the oil out and change it you should add oil to a specified level not a specified amount. (You can not accurately use voulumn as you will not have all the oil out).

I can send details on how to do this if you need it?

Ride safe, Ted

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Offline Stasch

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Re: Changing fork oil
« Reply #7 on: June 29, 2011, 01:20:43 pm »
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.
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Offline smithr1

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Re: Changing fork oil
« Reply #8 on: June 29, 2011, 02:03:14 pm »
I suck it out and then add some new, work it around and suck that out sometimes more then once.  There is always more oil in the container then I need and this gets it mostly changed, clean, correct wt.  But then again I do this almost every valve adjust.
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Offline GF-in-CA

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Re: Changing fork oil
« Reply #9 on: June 29, 2011, 02:42:00 pm »
I say either way will work fine.  Even with removing the forks, it is hard to get all the contaminated oil out without totally disassembling the fork tubes, and the oil gets contaminated fairly quickly, anyway.  I'm sure none of us would be able to notice a difference in viscosity between the two methods, since the variance between oil manufacturers and even with the same manufacturer is probably greater than the difference that would happen with mixing a small amount of old oil with new oil.  I would recommend removing the forks because in doing so you have an opportunity to check some things that you might not otherwise, like the condition of the fork tubes and triple clamps and whether the forks slide smoothly or not.  Plus you get to learn more about how to work on your motorcycle, which is always high on my list.  Again, JMHO.
« Last Edit: June 29, 2011, 03:10:07 pm by GFinCA »
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Offline connie_rider

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Re: Changing fork oil
« Reply #10 on: June 29, 2011, 02:48:01 pm »
Bob, maybe I'm wrong about using the level method. How do you know "how much" oil to add?

I also prefer the level method because I use fluid level more than oil viscosity to adjust the front end.

NOTE: I always loosen the caps before I remove the Forks, becsue it can be difficult to do.
Be sure to loosen the pinch bolts before loosening the Caps.

Ride safe, Ted
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Offline GF-in-CA

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Re: Changing fork oil
« Reply #11 on: June 29, 2011, 02:53:26 pm »
Ted, the level method is correct, you are establishing the volume of air at the top of the fork that gets compressed when the fork compresses, which affects bottoming resistance.  The amount of oil in the fork should always be established by the level, and not how much oil goes in.

HTH,
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Offline Slybones

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Re: Changing fork oil
« Reply #12 on: June 29, 2011, 03:07:37 pm »
I believe the instructions for the emulators tell you to set the oil level with the emulators removed. Just like you normally would. So I think you need to remove them anyway when doing a oil change such that you can set the level of the new oil correctly. Emulators being in the way to remove the old oil is not a problem. At least if you are following the instructions.
« Last Edit: June 29, 2011, 03:09:41 pm by Slybones »
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Offline Daytona_Mike

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Re: Changing fork oil
« Reply #13 on: June 29, 2011, 03:56:25 pm »
Why not remove the shock tube bolt and let the oil drain out?
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Offline Slybones

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Re: Changing fork oil
« Reply #14 on: June 29, 2011, 04:02:43 pm »
You mean the bolt on the bottom that holds the dampening rod in place?
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Offline SAS Mayhem

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Re: Changing fork oil
« Reply #15 on: June 29, 2011, 05:35:39 pm »
Just my 0.02 cents. If you go to the trouble of removing the fork tubes, you might as well make drain holes.  When I did my Emulators install a few weeks ago,  it only took 10 minutes max to do the drain holes.
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Offline Daytona_Mike

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Re: Changing fork oil
« Reply #16 on: June 29, 2011, 07:30:55 pm »
You mean the bolt on the bottom that holds the dampening rod in place?
Yes, just remove the dampening rod bolt and the oil drains out. No need to remove the forks, no need to drill holes.
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Offline SAS Mayhem

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Re: Changing fork oil
« Reply #17 on: June 29, 2011, 08:04:53 pm »
I believe the instructions for the emulators tell you to set the oil level with the emulators removed. Just like you normally would.

I went over the instruction that came with mine and it reads on page 2 step 7 "...Remove spring and use the recommended oil....Bleed fork by pumping them.  Install Emulator and then set the oil levell with the forks completely bottomed out..."

They "Race Tech" might have changed up on the instructions.

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Offline SAS Mayhem

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Re: Changing fork oil
« Reply #18 on: June 29, 2011, 08:09:00 pm »
You mean the bolt on the bottom that holds the dampening rod in place?
Yes, just remove the dampening rod bolt and the oil drains out. No need to remove the forks, no need to drill holes.

Dang !!! that would work too.
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Offline connie_rider

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Re: Changing fork oil
« Reply #19 on: June 29, 2011, 09:54:45 pm »
Yes, removing that bolt will drain the oil.
BUT: that bolt can be a real PITA to get out.

I use an Impact and a proper Metric Allen Wrench Socket to remove.
Can be done with an Allen wrench but be careful to keep fork tube from rotating.

Ride safe, Ted
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Offline Slybones

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Re: Changing fork oil
« Reply #20 on: June 29, 2011, 11:16:02 pm »
I believe the instructions for the emulators tell you to set the oil level with the emulators removed. Just like you normally would.

I went over the instruction that came with mine and it reads on page 2 step 7 "...Remove spring and use the recommended oil....Bleed fork by pumping them.  Install Emulator and then set the oil levell with the forks completely bottomed out..."

They "Race Tech" might have changed up on the instructions.

Cheers
Ron


hmmm... ok, split the difference..... set the level with the emulators in, as adding the emulators adds mass and increases the height of the oil in the tubes. Even then reading what is written here reads to me you pour the oil in when the emulators were out. Also did the pumping thing to bleed, etc when the emulators were out. You installed them after all that. Then set the level.  -- Gonna go and see if I can find mine.  Don't recall what I did a year ago, but a few weeks ago I am pretty sure I set it before adding the emulators. So I might want to go and recheck. Might need to take a few mm oil off the top. 
« Last Edit: June 29, 2011, 11:19:41 pm by Slybones »
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Re: Changing fork oil
« Reply #21 on: June 29, 2011, 11:35:34 pm »
That's what mine say too. Nice catch. I probably have a bit too much oil. Probably not too bad as the emulators are not that big. But I'll readjust this weekend for sure. -- Now that I read it myself, I recall looking that up before. But I know just a week or two ago when I switched to the blue springs on the emulators and changed the oil I did not.

Thanks!!
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Offline Daytona_Mike

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Re: Changing fork oil
« Reply #22 on: June 30, 2011, 01:27:13 am »
Yes, removing that bolt will drain the oil.
BUT: that bolt can be a real PITA to get out.

I use an Impact and a proper Metric Allen Wrench Socket to remove.
Can be done with an Allen wrench but be careful to keep fork tube from rotating.

Ride safe, Ted
You are correct, you really need to us a an impact driver and cut a piece of the correct 10mm allen and the 10mm  6 point point socket. I have a old  13/16 spark plug socket and I think the other end of that socket fits the top of the fork tube.
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Offline WillyP

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Re: Changing fork oil
« Reply #23 on: June 30, 2011, 11:30:23 am »
How do you get the emulators out without removing the fork? Magnet?

For the Allen bolt holding the rod you can get an Allen socket. Nearly every parts store has them because they are used on GM disc brake calipers.


Lisle 33920 3/8 Drive Hex Bit Socket 10 mm for 2 bucks!

To hold the rod, I used a nut I stole off my jack, stuck in a 15/16 socket. The nut I taped to a 3/8 to 1/4 drive adapter, to prevent the nut from going to far into the socket.

In the bottom of the fork tube there is this aluminum piece the the rod slides into to when the forks are collapsed. If you remove the bolt and the forks are extended, will this piece drop out? Will it be difficult to get it back into the bottom of the fork? When I put my forks back together that piece fell out. Because the forks were of the bike I could turn the forks upside down and shake that piece back into where it belonged.
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Offline wild man

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Re: Changing fork oil
« Reply #24 on: June 30, 2011, 11:46:15 am »
I've got the emulators and here's what I do when it’s time to change the fluid.  With the forks installed on the bike and the caps, springs, spacer, and emulators removed I insert a 2' long 1/4" copper tube that's attached to a mity vac down to the bottom, past the dampener rod until it touches the bolt that holds the dampener rod, fluid is then removed.

Fill the forks with your favorite 15w a couple of inches past the top of the dampener and give a few pumps to expel air.  Drop in the emulators and fill the tubes to 150 mm from the top with the forks completely bottomed out, and then let everything set overnight. If all goes well the level shouldn’t change much.  If it does use the suction tool to correct it.

I should also mention the front wheel and fender is removed and the bike is supported from tipping forward by a floor jack placed underneath and just behind the coolant overflow tank… 
 
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