How to service (some) LC4 forks

Discussion in 'Thumpers' started by meat popsicle, May 7, 2008.

  1. joekanter

    joekanter Been here awhile

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    ...from working graves last night.

    I have those fancy speed bleeders on the WP's. My bike likes to be fondled on a daily basis. Part of the fondling is hitting those bleeders for a WP fart. Just did it on my way through the garage. The bike even asked me "how was your night?" Then I had a brain fart. I always get a pretty good hiss out of the bleeders. There is no weight on the front wheel-then it accrued to me. Where is this hiss coming from. Could the change in barometric pressure be causing this? Seriously. If not-then what is. Again-no weight on the front tire. Fork unweighted and at full extension.

    Now-if the front axle is slightly misaligned, could this also cause uneven sealing and the drip, drip, drips? I read this valuable thread until my brain leaked. http://www.advrider.com/forums/showthread.php?p=7503930 Is there any relations ship?

    Lastly-do your rebuilds include new dust shield/scrapers. I have them on order but now I'm thinking I might not need them. It would be stupid, like Mr. Meat suggested: "probably why a suspension tuner told me he just goes ahead and changes the fork seals with every rebuild; it's cheaper than doing them later."

    Thank
    #41
  2. joekanter

    joekanter Been here awhile

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    ...from working graves last night.

    I have those fancy speed bleeders on the WP's. My bike likes to be fondled on a daily basis. Part of the fondling is hitting those bleeders for a WP fart. Just did it on my way through the garage. The bike even asked me "how was your night?" Then I had a brain fart. I always get a pretty good hiss out of the bleeders. There is no weight on the front wheel-then it accrued to me. Where is this hiss coming from. Could the change in barometric pressure be causing this? Seriously. If not-then what is. Again-no weight on the front tire. Fork unweighted and at full extension.

    Now-if the front axle is slightly misaligned, could this also cause uneven sealing and the drip, drip, drips? I read this valuable thread until my brain leaked. http://www.advrider.com/forums/showthread.php?p=7503930 Is there any relations ship?

    Lastly-do your rebuilds include new dust shield/scrapers. I have them on order but now I'm thinking I might not need them. It would be stupid, like Mr. Meat suggested: "probably why a suspension tuner told me he just goes ahead and changes the fork seals with every rebuild; it's cheaper than doing them later."

    Thanks folks in advance.
    #42
  3. meat popsicle

    meat popsicle Ignostic

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    I musta had a good night too... seeing double. :loaded

    joe, you should be able to visually inspect your dust shield/scraper assy for damage. Does it look worn out? Is the upper edge destroyed from prying it open to maintain the grease pack and/or clean the seals? When it "scrapes" the fork tubes do they look uniformly scraped or do they look really streaked? Just some things I thought of that might help you consider replacing them.

    Oh, are they cheap? :lol3
    #43
  4. joekanter

    joekanter Been here awhile

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    No, OEM. Original ones that came with the bike. I have ordered replacement wipers to be safe. I'll compare them when they come. Still don't get where the air is coming from when pushing the bleeders. I went to sleep after my last post. Some ten hours later-the forks were pressurized again with that tell tail hiss. Now back to work. Graves sucks.
    #44
  5. meat popsicle

    meat popsicle Ignostic

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    Ah, the question is why do forks build up pressure when the bike has not been touched? Mine do that too, and my guess was warming/cooling cycles over days.

    Or maybe it is an indication of something else? :dunno Here is a discussion of the "air spring" in forks:

    http://crfsonly.com/howto/230f/fork-air-valves/fork-air-valves.php

    and a statement of why pressure builds up:

    With that in mind I am guessing that night cools things inside the forks off, causing them to contract and creating a vacuum that sucks air inside the forks (much like fork extension after compression, but to a lesser degree).

    Then when things warm up during the day, and things inside the forks expand, the additional air inside the forks cannot escape. Night comes, things cool off, and repeat the above.

    Sounds good? :scratch
    #45
  6. meat popsicle

    meat popsicle Ignostic

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    #46
  7. failvanduck

    failvanduck Adventurer

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    Hi. I have stuck rebound needle and my mechanic will take forks and repair this and also look for other issues.

    CAN WE REUSE FORK SEALS IF THEY ARE NOT LEAKING YET?

    Bike is 2003 LC4 enduro, 43mm WP forks. New seals is quite lot of money so I was wondering about reusing old ones...
    p.s. bike has about 13k km
    #47
  8. Tseta

    Tseta Lost

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    No need to take the fork seals off to get to the internal cartridge (where the stuck rebound needle is located). In other words, the inner and outer fork tubes (thick grey aluminum upper tube and chrome, lower inner tube) do not need to be separated to service the fork internals.

    Cheers,

    Tseta
    #48
  9. twqqis

    twqqis Adventurer

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    since this is gonna be my first post and I wasnt able to find a "Hi all - from the newbs" section, Hi all !! :D

    Onto more serious matter. I realise that the answer to my question will probably fall into the "it depends" category, but anyways... I gather from some of the posts that time to change the oil would be before reaching 10k miles? Since one cannot really judge the condition (or can one?) it's gotta be around some mileage mark.

    What's the suggestions?
    #49
  10. komatias

    komatias Been here awhile

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    If you are thinking of changing the oil, change it. The more you use the bike the more the oil will degrade so a simple oil change will transform your ride.
    #50
  11. Tseta

    Tseta Lost

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    I've been changing my fork oil as often as my motor oil, which equals to 5000 kilometers. The last few times it has started to look like the forks would benefit from more frequent oil changes.

    Changing fork oil is obviously important. One should also consider the procedure used in changing the fork oil. Much of the "crap" will collect to the bottom of the fork, and if you wish to get most of this stuff out before pouring new oil in, you should let the fork drain for a considerable amount of time. Pumping the cartridge and the fork legs also help in getting all the old oil out.

    During the winter I've usually taken the cartridge unit out of the fork for a good cleaning. Even after a good drain, lots of dirty fork oil spills out when unscrewing the compression valve holder.

    Cheers,

    Tseta
    #51
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  12. meat popsicle

    meat popsicle Ignostic

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    I recommend if you are doing a full fork service to replace the seals. If you don't and they don't leak then congratulations! If you don't and they do leak then you have to open them up again (don't ask me; I don't wanna talk about it :bluduh). The fork seals are relatively cheap eh, considering the cost of "another service".
    #52
  13. meat popsicle

    meat popsicle Ignostic

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    Oi twggis! Welcome, and I hope you find everything you are looking for on ADV. :beer

    tseta already gave you a good answer, but if you do want to "judge" your oil you would need to take a sample and send it out for testing. There are motor oil testing labs in the US (and probably Europe), but I don't know about everywhere else. And I don't know if any of them test the hydraulic properties of suspension fluids, and I am guessing the "Viscosity Index" would be an important test.
    #53
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  14. wrk2surf

    wrk2surf on the gas or brakes

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    Ok .. has anyone come across good 43mm kits with all seals and bushings lately?
    #54
  15. bmwktmbill

    bmwktmbill Traveler

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    Works, everyone,
    You could try MX Tech and see what they can put together for you.

    http://www.mx-tech.com/

    or

    https://www.enduroeng.com/ProductDetail.jsp?LISTID=80000CBC-1276719311

    Last time I spoke to Z-dog at Infinity Machine he indicated that several brands of fork seals were available but that WP seals were the longest lasting.

    I put 20K miles on a set of WP fork seals going RTW through Russia and Mongolia using short fork boots for extra protection and grease inside the wiper seals to start out.The fork oil went the same distance without a change.

    I used Infinity's subtanks and kept the air well bled off in the rough stuff(3-4 times a day). I felt the forks worked as well at the end of my trip as at the beginning.

    http://www.infinitymachineanddesign.com/

    When I pulled everything apart after returning home, the bushing were in great shape and were reusable, in fact all the interals were OK, the shims were a little cupped, especially the mid valve, but they were put back in service.

    Running on the ATV trails around northern Wisconsin everything is working fine after an oil/seal change.

    The rear shock was redone for Guatemala when it leaked cause I compressed it in sub zero weather(That really isn't a good idea but it probably would have failed me on the road somewhere in Mexico).

    I think the rear shock is much more fragile than the forks and should have an oil change every 15K miles.

    I carry my old seals as spares as well as the rebuild guts of the rear shock. If you have one done ask for your old parts if you plan to travel.

    Much of this has been covered in old threads but I repeat for those who don't know.
    bill
    #55
  16. meat popsicle

    meat popsicle Ignostic

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    Just did a fork oil change and noted that both rebound adjustment rods not springing so I assume both rebound needle springs are shot. I can't deal with them right now (getting ready for a ride this weekend) so what should I expect if the rebound needle springs are shot?

    I am guessing that the rebound needle will be loose and I should close (tighten?) the rebound adjuster to compensate - anyone have any tips? :ear
    #56
  17. laramie LC4

    laramie LC4 flying something...

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    if your replacing your seals, i would HIGHLY recommend the SKF fork seals and wipers. they are awesome and really smooth things out, and do not leak. My suspension guys had tried the Race Tech and WP seals but mine kept weeping after a few rides. with the SKF's in i haven't seen a drop of oil since. they aren't cheap, but neither is your time pulling and working your forks every month or so...

    laramie :beer
    #57
  18. meat popsicle

    meat popsicle Ignostic

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    Just in case anyone wondered I am still wondering what influence weak or failed rebound needle springs will have on my forks, and if there is a way to compensate. I guess that cranking them down (closed) might help, but I haven't tried anything yet (this weekend is a big ride :ricky)
    #58
  19. Tseta

    Tseta Lost

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    Meat, I had a similar experience with the thin aluminum tube sticking down. In my case, corrosion was to blame, but the spring itself was not totally shot yet. I managed to salvage all the parts and make things work out again by disassembling the components and by cleaning and lubricating them well. Especially the needle itself seemed to easily get stuck inside the rebound tap. I changed the needle o-ring as well. Perhaps also some light honing (with some fine sandpaper?) on the inside of the needle seat will help smooth any corrosion out also. Then the needle action (and thus the aluminum tube's movement) should be nice and smooth again.

    Cheers,

    Tseta
    #59
  20. meat popsicle

    meat popsicle Ignostic

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    Thanks Tseta, that was last time to make them last a while longer... I forgot and didn't plan on replacing them this time, but knew the fork oil had to be changed before a big weekend ride. I'll crank down the rebound to see if that helps compensate for the spring not springing.
    #60