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888 compression sleeve - tech q's

Discussion in 'Downhill & Freeride' started by Udi, Dec 14, 2005.

  1. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    EDIT:
    Just finished everything up and wrote a bit of a how-to with pics on my home forums (farkin.net). Let me know what you think. :)

    http://forums.farkin.net/showthread.php?t=44839




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    Old original post:

    Hi guys,

    I'm running an 888RC and decided to make my own custom sleeve to get a little more low-speed compression damping, but in action I don't seem to be getting quite what I expected. It seems to be ramping up slightly earlier, but it doesn't feel like I am getting much more compression damping in the first 4" or so of the stroke, which was what I wanted.... not to use less travel! (i've been spoilt ever since I rode a fox40)

    I used a piece of 20mm OD pvc pipe and filed out the inside carefully to get a nice tight fit on the fork and slid it on to cover the lower 3 holes in the cartridge (as per the go-ride articles recommendation) and the two larger ones are left open. The fit is tight enough for it to not go anywhere i'm pretty sure.

    Now my setup; its an 888RC, flat crowns, running motul factory-line 7.5wt both legs @ about 230ml per leg. I weigh 130lbs roughly. Compression knob all the way in (because I was trying to get more LS, but really it's just giving me more HS), and rebound knob one turn out from full in.

    I'm thinking I should drop the height to help me keep using all my travel, and maybe try 10wt oil in the compression side... but i'd like to hear how other users are doing it, I know a fair few guys on here use the sleeve. (i've been reading here for a while even though I don't post much :))

    Thanks a bunch in advance, sorry about the long post,
    Udi
     

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  2. S.K.C.

    S.K.C. Turbo Monkey

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    ...hmmm this sounds like a job for James from Go-Ride.

    :)
     
  3. vitox

    vitox Turbo Monkey

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    so basically what y ou want is a higher ride height?
     
  4. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Well not quite, but I think part of the idea is to stop the front diving under braking/cornering. I haven't given it a proper dh run yet, but just playing around in the park I can't see a difference other than that it's ramping up earlier and using less travel.

    I'm just asking other users of the actual sleeve (or a custom job) what I should be seeing, and I wouldn't mind some damping earlier in the stroke, how would I get that? Higher weight oil, cover more holes, etc.

    I know I should give it a real DH run but so far I can't see a huge difference..
     
  5. vitox

    vitox Turbo Monkey

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    yea that should be what happens.

    i might be wrong on this but it would seem to me you are covering the wrong holes, the lowest ones i think are the bleed ports for when you are close to bottoming the fork, so for your particular requirement you could try covering the uppermost ones.
     
  6. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    You might be right.

    I've attached a 2 diagrams, the 1st showing both (opposite) sides of the compression cart and the holes in them, and the 2nd is the same, except shading which holes i've covered.

    It sounds like covering the 2 large upper ones instead of the 3 small ones will get me what I want?
     

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  7. vitox

    vitox Turbo Monkey

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    yea thats about what i was thinking, give it a shot, cant hurt and it wont be any more of a challenge than what you have already done
     
  8. Polandspring88

    Polandspring88 Superman

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    When you finally get them complete either PM me with pictures and a description of how you made them or post it up here. I would be interested in trying to fabricate some of my own.
     
  9. motomike

    motomike Turbo Monkey

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    I've been running the Marz. comp sleeve all season, covering the same holes you are. Basically, I'm pretty sure that no matter how many holes you cover, the first 4 inches of travel are unaffected by the sleeve. That's what I've noticed. After that, it will started to ramp up, because that is when it forces oil through those holes. Which holes you cover affects how much it ramps up.

    Maybe you could adjust the spring preload a little to get what you are looking for.

    *I'm 125lbs and have stock springs and oil. My fork feels puuurrfect on DH runs.
     
  10. SKYWAYBUZZ

    SKYWAYBUZZ Monkey

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    I did the same thing but I used 1" PVC Heat shrink tubing from MCMaster Carr. Got the same results you did, next time I may just cover one top hole.
     
  11. Alloy

    Alloy Monkey

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    The best way to figure out what you want is too take the compression cartridge completely out and experiment with it submerged in oil. A 24 ounce water bottle made a good oil bath for me and I was able to figure out exactly where each setting on the comp sleeve makes the dampening kick in.

    I have the 7" 888 and it is possible to get complete compression dampening throughout the entire stroke with one of the sleeve settings. Although not recommened. I tried it with 5 wt oil and even with the comp knob all the way out I could still feel my teeth chatter over the bumps. This setting is only good for huckers who ride smooth trails with big drops. You can get the same feeling with higher wt oil.

    I run mine in the middle setting with comp knob backed off one click away from feeling it kick in. Then I lock it down with the allen screw This way it's doing the maximum bottom out prevention without any spike in the travel. This is what I would reccomend trying to duplicate with the pvc.
     
  12. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Well today I moved the sleeve up to just cover the two large upper holes, and that seems to be the ticket. It's not a day and night difference, but I can feel a bit more resistance in the earlier part of the stroke with the compression knob cranked down.

    I'm still running 7.5wt both legs, so maybe 10wt in the compression side would make the damping difference more noticeable, but for my weight (59kg/130lbs) I think this should be alright.

    I also noticed I can use 200mm quite easily with the comp knob wound all the way out, but can only get 185mm with it wound all the way in. Dropping the oil height should compensate for that though.

    Alloy - can you tell me the different settings the marzocchi sleeve has, and which holes they cover in each setting? You can rip my diagrams if you want, otherwise just in words is fine. Also curious how much you weigh, and what oil weight you settled on in the end.

    Polandspring88 - i'll get some pics for you and post them up here next time I pull it apart. I've got brand new seals and oil to put in yet, i've just been re-using the old stuff until I got my lsc setting right hehe. So i've still gotta open her up once more, hopefully for the last time.
     
  13. Bacardi

    Bacardi Monkey

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  14. Jm_

    Jm_ Turbo Monkey

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    you're not trying to attain the impossible are you? A "plush" fork that reacts to small bumps at low and high speed is going to dive, due to minimal compression damping. If it doesn't dive, it's going to be harsher, no way to get around it except with a linkage fork or interia valve.
     
  15. leprechaun

    leprechaun Turbo Monkey

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    Yeah,just keep covering more holes till you get enough damping.

    Leaving the 2 large holes open would be 3 out of 5 closed.This is still a lot of oil flow.The 2 large holes are fairly large. In order to make custom changes,like leaving small holes open,etc would require custom drilling or a do it yourself jobbie.

    Now that i see people doing shring wrap etc,i did a sweet coke can shim with 4 zip ties to cover the 2 holes on one side leaving 3 holes open on the other a long time ago.This is light damping, which i wanted.

    Leaving the 2 large holes open may not feel that different on the lot but it does help on the trail.

    Don't ever ride DH trais with the comp knob alll the way up.It will ride like a 6" fork and will have a serious spike in the travel which could cause deflection in steering,pinch flats,etc.It seems to me that 1/2 way up is about as much as you can go and still have a smooth transition. Turn it up more for drops/big jumps and turn it back down again.

    Add oil,not ending stroke damping,that may help.If you run lower oil and more damping you'll be running in circles trying to figure out why it's not doing what you want it to! It will sink deeper with less ramp up and the spike hard with the heavy ending stroke damping.Poo.

    PS James no longer works here,So feel free to call me out on Q's.

    Krispy
     
  16. Internal14

    Internal14 Monkey

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    "PS James no longer works here,So feel free to call me out on Q's.

    Krispy"



    Wha wha wha what? Who what when where why how dat happen?
     
  17. leprechaun

    leprechaun Turbo Monkey

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    James is persuing school.
    He found a part time job near school so he could get in a few hours between and after classes.

    The spew that came out of James' mouth was info regurgitated from Scott and I.It sure did make him sound smart!!


    He did have more time to spend here as it was part of his job,i'm spendin a little more time surfin here and MTBR now.I hang out in the mgf forums at MTBR,but the DH board there is difficult for me to cope with (which adapter for my jrt,how big can my HT huck etc) so i hang out here for DH/FR action!!
     
  18. george

    george Chimp

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    what's the word on the Boss cartriges - any updated reviews?
     
  19. leprechaun

    leprechaun Turbo Monkey

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    Scott is running the Boss carts still.He really likes them.

    there are some positives and negatives to them,just like the stock system.

    for people not getting the desired effect from the Sleeve the traditional compression circitry of the Boss does the job of holding the fork up in it's travel very well.

    We haven't had a single complaint yet from people upgrading to them.
     
  20. banj

    banj Monkey

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    Other than the price ;)

    Mojo's offering an "upgrade" cartridge now as well.

    http://www.mojo.co.uk/888_Cart.html

    It's pretty pricy though as well.
     
  21. Alloy

    Alloy Monkey

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    I'm not sure exactly what holes are covered up on which setting. The Go-ride article has some pics you could probably figure that information out with best.

    Anyways here's what I do know. As far as I could tell the 3 settings on sleeve with the 7" 888 either start the compression dampening at 4" into the travel, 5" in, or with all holes covered up it's absolute compression dampening throughout the entire stroke.

    As far as my settings, I weigh 175 and run one firm spring and one stock spring, I have the comp sleeve in the middle setting and run 5-wt oil at a high level, something like 180mm.

    With this set up the fork has unbelievable small bump absorption, never bottoms out, and doesn’t dive in excess of 4" in the turns. I highly recommend it. The sleeve makes it possible to run lighter oil without the usual negatives that come with running lighter oil.

    Also note if you try this set up it's crucial to put the 5wt in both sides -As the rebound side does displace some oil on the downstroke as well.

    More babble.

    I'm one not hundred percent sure on this, but what I remember from screwing with the internals, is that it's not possible to get any other dampening combination without using the sleeve to cover up all holes and then drilling new holes in the compression cartridge itself.... As you've probably figured how it works. The oil is relieved through holes on the sides of the compression cartridge, until the piston passes the holes leaving no other place for the oil to go except through the piston itself, which has the externally adjustable shim stack. And there are only so many holes already.
     
  22. freerder56

    freerder56 Chimp

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    Just got my new sleeve from marz.I bought my fork used, when I took it apart I found I already had a LS sleeve in the fork. The old sleeve is like the one on the Go ride page, w/ 3 holes on each side , the new one has 5 holes on each side. Which ever way you turn it , it's either all 5 holes open or it's fully closed. Need some input before I call marz.:help:
     
  23. DHDror

    DHDror Monkey

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    I am finally happy with mine !

    I did'nt like it for almost a year but I think I just got it right .
    I have tried the LS sleeve and was still not happy.
    Only when I moved to ATF things got a little better -
    I am now running ATF on both legs (180cc !) and the sleeve covers one hole only.
    It is a little rough on small hits but much better than with 7.5W oil and with the sleeve covering 3 holes .
    With this set up the compression knob seems to make a difference on the early stages of travel as well .
    BTW , I am 180lbs , standard springs with the heaviest preload , the fork is on a Sunday with Go-Ride crowns.
     
  24. Udi

    Udi RM Chief Ornithologist: “I Brake for Birds”

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    Finished it all up and wrote a how-to here with lots of pics for those that asked:

    http://forums.farkin.net/showthread.php?t=44839

    I may try 10wt oil later but for now i'm quite happy with how it turned out. All details are in that thread.