OzVMX Forum
Clubroom => Tech Talk => Topic started by: Ji Gantor on June 21, 2010, 07:01:25 pm
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This is a modern upsidedown fork.
Should be pretty similar to a Pre 90 fork.
Any way like all forks they started leaking oil last ride so today I purchased a pair of new fork seals and a litre of 5w oil.
I already have all the tools required to service these forks.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP1a.jpg)
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First turn your rebound and compression clickers clockwise to find out what your current setting is.
Then grip the fork and undo the cap with a pin spanner.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP2a.jpg)
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Lower the outer tube down.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP3a.jpg)
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they are nothing like the pre 90 fork ji ;)
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Sorry Holeshot I don't have a pair of Pre 90's to see.
I just guessed that they should be similar.
Okay these are just modern forks.
Nothing like any VMX bike including Pre 90.
Tight nuts
Ji
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Grasp the spring and pull down so a 22mm open spanner can be fitted to the hex.
The hex has a steel plate top and bottom so when the spring is released the spanner is kept in place.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP4a.jpg)
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Place a 24mm socket or ring spanner on the cap nut and loosen.
Tight nut
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP5a.jpg)
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Remove the cap.
Then remove the spring and let drip into a pan.
Now we can pour all the old oil into a measuring container.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP6a.jpg)
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Hi Wasp,
Yes I use Stahlwille, Snap On, KC Pro and Repco spanners.
I like the Stahlwille because they are so light and thin.
Tight nuts
Ji
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With the spring out, the outer tube pushed down and the oil drained it is time to place the fork into a vice.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP7a.jpg)
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With the fork held securely in a vise pry the rubber plug off the bottom of the fork.
Place a 19mm socket onto the compression cap and loosen.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP8a.jpg)
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Now that the cartridge is free both ends we can lift it out of the outer tube and place on a drip tray.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP9a.jpg)
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Gently pry out the mud wiper.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP10a.jpg)
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Lever out the circlip.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP11a.jpg)
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With the circlip removed the inner and outer tubes are now free.
This said they do not just come apart, you have to use the two tubes like a slide hammer.
Two or three slides and the seal will pop out of its recess and the two tubes will come apart compleatly.
Remove all the parts and place on a drip tray in order so they will go back on the way they came off.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP12a.jpg)
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With the tubes seperate take note of how all the parts go back on.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP13a.jpg)
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Also check to see if there are any problems, scratches or worn out parts.
When removed they need to be cleaned ready for reassembly.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP14a.jpg)
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Now that all the parts are clean we are ready to reassemble.
So we don't scratch the new seals on the sharp edges of the inner tube, wrap a few layers of sticky tape over all the sharp edges.
WP do have a tool for this so if sticky tape is not for you please ask Walter where you can get one.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP15a.jpg)
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smear some fork oil over the sticky tape and gently slide the mud wiper circlip and new oil seal over the end of the inner tube. After oil seal is on remove sticky tape completely.
I have read the manual for this fork, and today asked my local KTM Team Moto mechanic what level should the oil be.
The manual states 100mm down from the top, the KTM fellow told me 140mm down from the top.
I tried 140mm down from the top but as I slid the cartridge up and down to remove trapped air I could hear cavitation, so I gave 100mm a try and no more cavitation. This is not a recommondation just logic.
Please use specified amount.
Reassemble forks in reverse to strip down.
Make sure you turn your compression and rebound clickers counterclockwise before you reassemble.
After assembly set compression and rebound back to their original positions.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP16a.jpg)
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Hey Jock if you have any questions or need some advice please let me know.
These forks are pretty easy to service.
It took me about an hour to strip, clean and reassemble one fork.
Tight nuts
Ji
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i just used the plastic bag the seal came in as a protector ;) ;D
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Part number for the seal tool is T1401
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I am sure there are heaps of ways to skin that cat Matt.
Tight nuts
Ji
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Hi LWC,
Yes my manual states all the tool numbers but where can you buy them?
most of these special tools I have found can not be purchased.
Not even the bike shops use them when servicing your bike because again they don't have them either.
The split seal driver is needed to install the seal back into its seat.
The oil level tool makes things easy but not required. You can just use a stick.
WP have inner and outer tube vise tools and all sorts.
Walter probably has a few for sale if any one is interested.
Tight nuts
Ji
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JI they are available, just try any KTM dealer. I made some tools my self but i like the genuine WP tools because a lot are made in Germany and good quality.
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Ji,
What year ktm are the forks from?
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Hi Evo,
The forks are off a 2003 KTM.
I thought that the Pre 90 forks could be similar but as Holeshot said they are not.
I have serviced RM125 1994 forks and they are pretty similar.
Oh well I hope it helped someone.
Tight nuts
Ji
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Hi LWC,
I will ask my local KTM dealer and see what they say.
The original tools are always the best to use.
Thanks mate.
Tight nuts
Ji
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Check the oil that came out of your fork.
The oil will be discoloured, that is normal even after only one ride.
Check the volume.
I caught 450ml in the container and lost on the vise about 100ml and the drip tray has about 50ml so roughly 600ml came out.
I don't let a weeping seal go because I have seen what that does. The outer tube can become worn on the inside to the point were it clunks and has to be replaced. The amount of new oil poured into the fork was about 600ml.
Don't over fill the fork with oil or it will go hydraulic. That is oil can not be compressed but a gas like air can. If you fill your fork to much you will not be able to compress it, try that over a jump. Also I have seen one pair that has an internal buldge, I am not sure why but it may be from over filling, but that said I would expect the seals to just blow.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP17a.jpg)
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If you have not seen one of these great tools it is a fork seal installer.
It fits over the inner tube and slide hammers the seal into place.
They cost about $70.00 and can be purchased in all fork sizes, this one is 47 - 48mm.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP18a.jpg)
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A tool that is not totally required but saves time is the fork oil level device.
Geoff Ballard sells them for about $35.00 and I can not tell you how many times I have used this one.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP19a.jpg)
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The pin spanner I use is made in Japan by Super.
They sell replacement pins that have two different diameters.
I purchased a few more and lathe them to the size I require.
This is the best one I have found. It cost about $120.00 but it works on all pin hole nuts.
So many people just grab a screw driver and thump it with a hammer similar to the castle nut on a shock pre load.
The right tool makes the job fun and leaves no trace.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP20a.jpg)
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The oil that came out was pretty thick so I think it may have been 15 or 20 w.
5 w sloshes like water.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP22a.jpg)
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The Compression bolt at the bottom of the fork is made of aluminium.
The second fork I serviced today gave a little problem when we discovered that the previous owner had rounded all the corners on the hex.
This bolt houses all the compression shims so if it won't come out there is a real issue.
I changed over from a standard 12 point socket to a 6 point socket.
The six point sockets grab more of the hex than the 12 pointer.
The 6 point socket did the job and we were able to strip the fork.
Both these sockets are 19mm.
I rang and ordered a new bolt from KTM, it will take a week to get here and cost $116.00.
Tight nuts
Ji
(http://i726.photobucket.com/albums/ww268/Jigantor1963/WP23a.jpg)
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Are these used for your tight nuts Robert?
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The two sockets above that I used are Snap On.
Snap On make some really great sockets which are cheaper than Stahlwille.
Of course Stahlwille are aircraft grade where Snap On is not, but they are great to work with just the same.
Tight nuts
Ji
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Hi GOD,
The hands in the images are my hand models.
My hands are all wrinkly, hairy and arthritic no good for pictures, but of course you would know that.
The lead does have exposed insulated wires, thank GOD, I will get my sparky to fix that next time he is passing.
World Peace
Ji
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good observation GOD. i would never have picked that one up. and by jove is it that cold over there that you need to wear thermals??
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When separating the top and bottoms it is a good idea to heat the top tube with a HEAT GUN (not gas or oxy) until they are uncomfortably hot ie require gloves to handle. This allows the bushes to slide out more freely as they are a light interference fit and the mild heat from a heat gun provides some expansion so the sliding action doesn't belt the shit out of the edge of the bushes. Usually they pretty well fall apart.
On the subject of spanners, a thread in itself, yep Stahlwille are my favourite QUALITY brand. Snap On rhymes with Crap On and for what they ask for their tools, no matter how good they supposedly are, the prices cannot be justified! Up to 19mm Ballard T's also do a pretty good job and are six hex.
What is it with 'tight nuts' by the way - you can fix that with the right woman you know!
Dave Mac :)
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Hi Dave Mac,
That is a great add to this thread.
Snap On are expensive but Stahlwille sockets are off the chart.
That is why I have both.
Tight nuts
Ji
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Hey Ji
Ebay + Stahlwille equals affordable good gear.
Ebay + Snap On ? Well scored a brand new Snappy torque wrench for next to nothing so not all bad...........
Dave Mac :)
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I get brand new Snap On 1/2" socket set on Ebay for $150 same in Stahlwille is about $400.00.
I plugged away a few years back on Ebay US and purchased all my tools cheap. It took a while but it was worth it.
I do like Stahlwille open end spanners they are light and thin they also have a different attack angle which in tight engine areas is a big help.
Tight nuts
Ji