LC4 steering head and fork service notes

Discussion in 'Thumpers' started by boyscout, May 14, 2007.

  1. boyscout

    boyscout sittin' down

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    THIS IS NOT A HOWTO

    This is more of a HOWDID. This post is merely things I noted while doing my first fork and headset service on my 2002 LC4 Adventure. I figure some of this info may be useful to others who are thinking of servicing their front end but haven't done it before. I have decent mechanical ability, but am far from an expert on the LC4. Suspension has always been taboo for me. I think it is because every suspension manual starts by emphasizing the cleanliness and organization of your work area. My work area is half of a garage filled with 2 motorcycles, too many bikes and various things that the previous renter has been "going to pick up" for a year now.

    Cleanliness and organization are its weak points. The same can probably be said about me.

    Well I finally bit the bullet and cleaned the garage. While I was at it I reorganized my tools so that everything I used would be in easy reach. The goal being that if it is as easy to put tools in their correct place as it is to lay them on the closest random horizontal surface, I might be able to cut out a large portion of my "where the heck did I put that" time.

    I had already done my "required reading" from the index.

    Required Reading - Fork oil change:​

    Neduro's non-LC4 specific howto. Contains pretty much all you need to know to change your fork oil.

    Good discussion of how to measure oil height and a basic outline of the fork oil change process.

    Discusses some tips and tricks that make doing the job easier

    Steering Head Bearings - Required Reading:


    Laramies Guide to Drunken Steering head maintenance

    Discussion on steering head bearing adjustment

    To get in the right frame of mind I flipped through "How to Keep Your Volkswagen Alive: Step-by-Step Procedures for the Compleat Idiot" whose sage advice had taken me from the compleat idiot stage all the way through to a complete engine rebuild while in college. I put on some Tom Waits to set the mood.

    The notes

    I found an easy way to work on the fork was to use a small stool to hold it up and a zip tie around a nail pounded into the workbench.
    [​IMG]


    The inner nut on my fork was a 22. Not having a 22 box end, I first tried a large crescent but ended up buying a 22 and grinding it down to about 7mm thick to make things easier.
    [​IMG]

    Neduro describes simply pushing the damping rod down to remove the adjusting rod. This didn't work for me, but it was pretty easy to get it out.
    [​IMG]

    The threads describe filling with oil to 25 mm below the holes between the inner and outer tubes. My manual said to always keep the oil above the holes while pumping the damper so that is what I did.

    This brings to mind a key point.

    Even though each fork leg only takes 450mL of oil, it will take more than 1L of oil unless you pay attention and conserve your oil when adjusting the oil height After filling the first fork leg with oil and then pumping the damper to fill the damping chamber, you need to remove a significant amount of oil to set the oil at 120mm (or whatever you are setting your oil height to). I had poured a lot of oil into the drain pan before realizing I should be preserving it for the second leg. Even after squeezing oil out of my paper towels I came up short on the second leg and had to put it off till I could go get more oil.:becca Would probably make sense to drain both fork legs first so that you can pour the overs from one leg right into the other.

    I found it useful to use my digital calipers as a dip stick to check oil height. I used a paper towel to absorb the last few mL and checked the height by setting the caliper to a little over my desired level and checking the oil height on the scale. I set it to 120mm from the top of the inner tube.
    [​IMG]

    The steering head bearings went really smoothly. Laramie tells you everything you need to know in his thread. I used special BMW grease for my headset. Hope that it doesn't have some sort of adverse reaction with my KTM. The only thing to note is that on my bike the ignition key on the top triple had some form of safety bolts that couldn't be undone. I just unplugged it from the wiring harness and left it attached to the triple the whole time. Make sure to take a good look at how all the wires and cables are routed before you start taking things apart. It'll make the reassembly go smoother.

    My first attempt at getting the whole thing together didn't go so well. I put the triple clamps on and then had a hard time lifting the fork legs through the clamps. My second attempt went much better. I assembled the whole fork away from the bike, tightened the lower triple a bit, removed the top triple and then lifted the whole thing into place.
    [​IMG]

    I finally found a use for that thing that KTM gave me in place of a seat.
    [​IMG]

    I settled the suspension by only tightening the large nut on the axle and pumping the forks up and down, then tightening the disk brake side and pumping the forks up and down before finally tightening the non-brake side.

    That's it. Big Thank you to Creeper, Nedura, Laramie and everybody else whose instructions and advice I followed in getting this done.
    #1
  2. meat popsicle

    meat popsicle Ignostic

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    How did this slip into oblivion without nary a peep from la Familia?!? :scratch

    I just need some thumbs from the rest of the Committee on this before inclusion, but I am thinking that we might need a section on "overviews"? :ear

    Thanks boyscout, I am getting into this myself and I appreciate your work organizing some of index into one clear HOWDID with links. I would like to see more of this folks!

    PS - Which Tom Waits album?
    #2
  3. meat popsicle

    meat popsicle Ignostic

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    Hey ML,

    I wish I would have looked back at your HOWDID before I proceeded with my work... I took the manual at its word (ca 420 ccm) and found out the hard way that depending on your chosen oil height it can be up to 600 ccm! :becca

    This is also an FYI for you on your rebound adjustment rod. When opened up the rod should sit a bit above what you are calling the dampening rod (piston rod?). If you were to push on it it would spring a bit (the rebound needle's spring).

    If it does not then you may have WP's #1 fork issue: rusted rebound needle seized in the bore... I know this because that is where I'm at right now with my forks - can't put them back together because I now have to deal with this joy. :becca
    #3
  4. ChrisC

    ChrisC Amal sex?

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    OK Meat. First off it's a "damping" rod. Dampening would make it wet and that is not a requirement.

    Secondly, this surely belongs in the Holy Indexed Thread. Maybe an overview section is needed for those who produce concise guides without Hickson's penchant for verbosity... :deal
    #4
  5. Zerodog

    Zerodog Long timer

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    The oil height should be checked from the top of the outer tube. Not the inner tube. So the oil level in this example is very very low. Another thing if you don't want oil pouring out of your rebound knobs do not put oil down the center of the damper rod.

    What is up with your rebound needles Meat? Are they stuck in there and not budging for you? Are they as rusty and nasty as something pulled from the bottom of the ocean?
    #5
  6. meat popsicle

    meat popsicle Ignostic

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    As discussed they are stuck (your allen key trick didn't work, or I chickened out first) so the local fella offered to take care of them. And since I don't have anything to hold the, er, damn-ping rod (how's that Chrissy? :smooch) I want to avoid removing/remounting the rebound assembly.

    Since my fork oil was a gorgeous clear red I wonder if my rebound needles might have come fuct from the factory... unless condensation can get in through the rebound clicker and not contaminate the fork oil? :dunno

    So my Infinity Machine & Design resprung and revalved shock is back on the bike, as is my restored rear suspension. Just waiting on this rebound business so I can get the forks back together and try it out!
    #6
  7. meat popsicle

    meat popsicle Ignostic

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    I think I put it in there, but I have been mulling over the idea of adding a HOW-DID section just below the HOW-TOs :ear

    BTW, I'm the chatty fooker, not Hickey...
    #7
  8. ChrisC

    ChrisC Amal sex?

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    I surrender... :huh
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  9. meat popsicle

    meat popsicle Ignostic

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    but I really wanted your opinion on the HOW-DID section... :cry
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  10. Luke

    Luke GPoET&P

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    Well how's it supposed to rust, if it doesn't get wet?
    :hide


    3rded on the index thread. I'd say no to a how-did section. Keep all the fork threads together.
    #10
  11. meat popsicle

    meat popsicle Ignostic

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    already under Section 5.b of Post #1... thanks for the feedback Luke. Maybe just a different presentation so that these types of thread with process info - bold font, their own color, or?

    The Achilles Heel of the WP USD forks: the rebound adjuster leaves a channel for moisture to enter the forks. Maybe we don't need external rebound adjustment? :amazon
    #11
  12. Zerodog

    Zerodog Long timer

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    I think what it is from is condensation caused by temperature changes. The cartridge rod has no oil, and thanks to KTM or WP no grease on this item either. 02 USD forks had a little Oring at the top of the aluminum rod to help keep the water out too. Every 02 fork I have taken apart has had very nice needles. On the other hand I have seen 07 forks start showing signs of getting nasty. This is something easily overlooked when servicing a fork and I have seen it overlooked by lots of tuners. A funny deal with the shocks on all real KTM dirtbikes is they have a problem with the rebound adjuster and needle. Again, no grease from the factory, water, and tuners not addressing it. They get stuck or broken frequently.

    Some nice waterproof grease goes a long way in these dry areas to prevent corrosion and seal out any moisture.
    #12
  13. meat popsicle

    meat popsicle Ignostic

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    When I first started tearing down my forks I saw that o-ring noted on the service manual for my forks. It wasn't there so I asked about it on ADV and Luke said it was on the '02 forks but not '03-

    It would be easy to add the buggah eh? But Luke said they discontinued that very o-ring... those same engineers reading Bill the riot act for questioning their suspension tuning decisions musta decided that o-ring was useless...

    :pep
    #13
  14. Luke

    Luke GPoET&P

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    Huh. I even looked in the index before suggesting it. Must'av missed it.

    Fortunately for us, KTM doesn't make o-rings and they use standard sizes. This one is nominally 6.3mm ID and 2.4mm thick. That's a standard size (specifically -108) It's made of NBR/Buna-N which is also standard.
    In inches, it's 1/4" ID and 3/32" thick.
    ACE Hardware has an excellent selection of o-rings in with the plumbing stuff. I got half the o-rings needed for a shock rebuild there. I'm sure they'll have this one. Just bring a ruler so you know the ring you fish out of the drawer is the size marked on the drawer.
    #14
  15. sherpa

    sherpa ...Robert

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    This explains why I have weepage out of my rebound adjusters...when I serviced them the first time there was corrosion on the dampening rods just like you mentioned, so I polished them up and when reassembling filled them with oil. I'll use a light coating of grease next time. :thumb....thanks Zerodog...
    #15
  16. boyscout

    boyscout sittin' down

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    Wow, look at this. I'm in the index :clap

    Thanks ZD. I'm pretty sure I set the oil level right and then goofed when taking the picture by trying to get the calipers to stand up on their own.

    Either that or I've been riding for the last 50k with very very low fork oil without noticing. :huh
    #16
  17. meat popsicle

    meat popsicle Ignostic

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    Yep, and your thread helped me do this:

    how to service (some) LC4 forks

    It's not very popular... not as step by step and directional as Laramie's stuff but I thought it would be better for anyone who did dig into their forks to know what/why/how from a number of sources and be sure of themselves. That is how I did it, and I am sure they are fine. Well, I hope they are! :D
    #17
  18. CBR

    CBR Adventurer

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    I have some fork oil weeping from the adjuster behind the rubber plug at the bottom of the fork too. i suspected an o ring failure but could this issue just be oil in the wrong place in the fork as described below? The bike has been on its side a few times with the wheels above the bars ( I am a terrible rider..lol) so I wonder if oil has got into dampening rod because of this??

    Dealer said the whole adjuster has to be replace when I described the problem...not convinced of that though.


    #18
  19. Luke

    Luke GPoET&P

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    Probably not, to all questions.


    First thing to try is tightening the bottom adjuster body. AKA the compression bolt. It's the 19mmish hex part you want to turn, not the little screwdriver adjuster. If it turns without tightening then have someone compress the forks while you are tightening it.
    #19
  20. dhally

    dhally Hammerhead Supporter

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    Or use an impact wrench.
    #20