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CRF1000 shock rebuild

Discussion in 'Japanese polycylindered adventure bikes' started by Motociclo, Jul 27, 2017.

  1. Motociclo

    Motociclo Long timer Supporter

    Joined:
    May 18, 2017
    Oddometer:
    1,082
    Location:
    Oz
    A guide to revalving CRF1000 shock.
    This process is similar to many shocks.


    Tools required, with shock off.
    17mm spanner,
    Picks for circlips,
    Schrader valve tool,
    Spring compressor,
    Blade screw driver,
    Seal head depressor. (Use split pvc tube, if you don't want to buy tool).
    Torque wrench, preferer for proper nut tightening.
    Vice,
    Air compressor.
    Nitrogen. This can be recharged at auto aircon shop.


    Need to get the spring off. Will need a spring compressor for this task. Wind the preload adjuster to full soft prior disassembly.
    Be careful getting spring off. Lots of stored energy. Like wise when releasing gas.
    This spring isn't stock. There is an adapter on the preloader, Gold coloured thing sitting in preload adjuster.
    Stock Showa spring tapers at the top. This spring is straight up and down.
    I am now using a 9.8kg spring. This spring is 10mm longer than stock. If I got a stock length spring, 10.5 would have been the likely candidate.
    Heres what it looks like disassembled. Give it a clean also. Good Idea to turn both comp and rebound adjusters to full soft positions.

    20170724_123441.jpg
    20170724_141324.jpg

    Next, must release gas from chamber. Remove valve core to ensure all pressure is released.
    Push down on bladder to expose circlip. Remove circlip and bladder.
    20170727_094132.jpg
    20170727_094439.jpg
    #1
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  2. Motociclo

    Motociclo Long timer Supporter

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    Can now remove comp adjuster and drain oil.
    Get a punch and tap this seal guard up, clean around seal and then push seal head down to expose circlip. Extract the circlip, can then pull shock shaft assembly out. Might take a little bit, but will come out.
    20170727_094507.jpg 20170727_095013.jpg
    Next you can remove the nut. There are 2 small peen marks on nut. They can be drilled, but I found that it could be undone with out to much hassle.
    Take time, it has a bit of resistance, but will come off without damage to either thread.
    I used plenty of oil to lube nut and shaft. I found undoing with a back and forth motion on the nut until it loosened worked. I had no thread damage doing this. Take time and lube is the key. If you just need to try to unscrew at one hit and power through resistance, nut/shaft will gall and seize. Quite abit of heat is generated undoing nut.
    Lube, back and forth on nut and patience. It will come off.

    Take note that the nut locks down on the washer. If you remove the first washer after nut, you will see the chrome shaft below the thread. Important washer overlaps shoulder and thread area. The nut needs to lock down on washer on re assmbly. Don't bottom nut out on the shoulder of chrome shaft.
    20170727_103740.jpg

    Once you have it off, pull off rebound stack and measure up, followed by piston then comp stack. Measure up all shims. There are some spacer shims in pic, these are near the nut. Will explain later. This a picture of revised shim stacks to be used.
    For reference the ID of the shims is 12mm.

    20170727_101025.jpg
    #2
  3. Motociclo

    Motociclo Long timer Supporter

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    Good time to inspect everything now. Check for marks in shock body and bush on the piston for wear. Repair as required.
    I haven't removed the seal head from the shock shaft. Seal is not leaking. There is also a risk of seal damage when installing seal head without a seal bullet. Damage is caused by the shoulder on the shaft, the piston, shims etc sit on. It can be chamfered to make smoother. I prefer to use the seal bullet.

    Check condition of shims. They do wear and get marks on them. If they look like this, replace it. Ensure shims are flat also and not bent.
    20170727_095610.jpg
    Stock comp stack.
    40*0.15,(4)
    38*0.15,(2)
    36*0.15
    34*0.15
    32*0.20
    30*0.20
    28*0.20
    26*0.25
    24*0.30
    22*0.30
    20*0.30

    This is a revised stack also, have had a few variations, trying different things.
    40*0.15,(12)
    28*0.10
    40*0.15
    38*0.15
    36*0.15
    34*0.15
    32*0.20
    30*0.20
    28*0.20
    26*0.25
    24*0.30
    22*0.30


    Stock rebound stack,
    36*0.25,(4)
    34*0.25
    32*0.25
    30*0.25
    28*0.25
    26*0.25
    24*0.25
    22*0.30
    20*0.30
    18*0.30
    16*0.30

    Another revised rebound stack,
    36*0.15,(16)
    34*0.25
    32*0.25
    30*0.25
    28*0.25
    26*0.25
    24*0.25
    22*0.30

    I have used a lot of thinner shims. They are more tolerant to bending than thicker shims. Feel nicer too.
    Have also taken out some of the smaller shims. This makes clamp shim bigger. This stiffens entire stack.

    (Edit, I like experimenting and trying to improve on what have, so both these stacks have now changed. I have experimented and now use dual stage stacks on some rebound setups. Havealso gone back to 0.25mm shims on rebound setup. Use less and getting good results. Generally stick with a single stage stack on comp side.)


    Dress up piston with 800 wet and dry to get sealing surfaces cleaned up. Ensure you clean up everything as you go. No grit, no lint or anything.
    Comp side of piston.
    20170727_102148.jpg

    Rebound side of piston.
    20170727_102152.jpg

    Piece together your shim stacks. Should look something like this.
    The spacer shims I mentioned earlier take up most of the gap to this shoulder. The washer will locate and still leave enough thread for the nut to adequately tighten down.
    In pic below you can see a little bit of the chrome shaft and then the thread. It is important the chrome shaft is covered by spacer shims or washer and over lap on to thread. The nut needs to be tight against washer etc.
    20170727_103300.jpg

    Prior to torquing down nut, use compressed air to ensure everything is clean. I leave nut loose, and spray with contact cleaner. This way shims move a bit and can pretty well clean individually.
    Torque nut to 35Nm, using a dab of blue Loctite.
    #3
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  4. Motociclo

    Motociclo Long timer Supporter

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    Can start filling up the shock body. Ensure you have cleaned out all of old oil prior to this.
    I use Motul VI400, this is a 2.5 weight oil. Use an shock specific oil with a viscosity index no less than 350. Shocks work pretty hard in a hot environment.
    I put body on angle, pour a bit in, install comp adjuster, then ½ fill gas chamber with oil.
    Put bladder in, want oil to over flow, then install circlip. Install valve core and add a bit of compressed air helps seat the bladder and purge any air in comp adjuster.. No more than about 30psi. Don't add air to quick, try to not go over 30psi. Don't want to over extend bladder to much. The air pressure helps to purge any air in comp adjuster into shock body.
    20170727_104557.jpg 20170727_104827.jpg 20170727_104935.jpg





    Top up shock shaft chamber with oil and insert shaft assembly and start bleed process.
    You want a little overflow. Push down quickly and pull up slowly for rebound. You can cavitate the oil if try to go to quick on rebound. Also, don’t let bleed hole on rebound side of shock shaft come above oil line, otherwise you will need to start bleeding process over. It doesn’t hurt to give a little whack with mallet to open comp shims a touch, you will get bubbles come out. Continue this process until no bubbles com up. May take a bit, be patient. Vacuum bleeding is better, I don’t have access, neither do most people. I do try to warm oil also. May or maynot make a difference. But i feel cold oil is likely hold more air in fluid. Doesn't need to be scorching. 30 deg C max.
    I also leave shock for abit after bleeding air.
    Shine a torch into fluid, it has a lot of tiny air bubbles. I leave shock for about half hour or longer. When you come back, fluid will have nice clarity. Slip seal head down, not enough to seal, just to stop any potentual flying crap going into shock.

    20170727_105329.jpg
    #4
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  5. Motociclo

    Motociclo Long timer Supporter

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    Once bled,top oil up to near circlip seat and then push in seal head far enough to get circlip in. Will need to release pressure in bladder as you push down on seal head.Once clip is in, use a little compressed air to seat seal head.
    20170727_112226.jpg 20170727_112243.jpg


    I like to push shaft through stroke a few times to ensure it is smooth. Add compressed air to bladder. At this point I use what ever air compressor will deliver for pressure, around 100psi. Push shock shaft through stroke, It should return by itself, if it doesn’t, need to find out why. May need more bleeding or not enough oil in shock. So out with the seal head again. Naturally check for any oil leaks.
    If this is ok, release compressed air, refit seal guard and hook up nitrogen.
    I use about 180psi, stock is 150. I fill once, release then fill again. Pedantic, yes but I like to know it is pretty much just nitrogen in chamber.
    20170727_113110.jpg
    Now your pretty well done.
    Install spring and and reset comp and rebound clickers. I use stock settings as a starting point. Adjust to taste.

    Take your time, inspect everything as you go and understand how it fits, measure, take a picture and keep it clean.
    I will add more if not enough detail. This is a bit of a guide anyhow. Shim stacks may or maynot work for you, I found them ok.
    Hope this is of some help.

    Just for reference,
    Shim ID is 12mm,
    Stock spring is 238mm long,
    The preload adjuster offers about 8mm of additional preload. This will give you around 17 to 18mm of ride height at the swing arm.

    https://advrider.com/f/threads/crf1000l-spring-and-valving-data-base.1363798/
    #5
  6. michaeln

    michaeln What're YOU lookin' at? Supporter

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    Great write up! I'll never do it myself, but some folks will find this really useful.
    #6
  7. vgreno2000

    vgreno2000 vgreno2000

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    Oddometer:
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    Thanks for shearing!! When I reach about 25kkm I'll rebuild the suspensions following your steps

    Enviado desde mi Nexus 5 mediante Tapatalk
    #7
  8. cyclopathic

    cyclopathic Long timer

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    7,742
    How many miles on shock and what is the reason for rebuilt? How dirty was OEM fill? thnx!
    #8
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  9. Motociclo

    Motociclo Long timer Supporter

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    No worries. Hope it helps.
    If only giving shock an oil change, don't need to disassemble valving etc.


    Shock had 20000km when I first revalved. Oil was quite good. I think from memory oil was a light blue colour. Since then I have had apart 2 more time, only to revalve. Nothing mechanically wrong with shock, just wanted a firmer ride and to sort rebound out after fitting higher rate spring.
    Stock rebound damping on current spring, 9.8kg, is pretty worthless.
    #9
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  10. Big Willy

    Big Willy Gen. Italia

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    Great work MC. Very easy to follow.

    I bought a cheap vacuum bleeder a few years back. Consists of a converted water filter housing and a commonly available vacuum pump off Ebay.
    Works a treat and it's fun too.
    Don't have nitrogen but found no detriment in using compressed air via handpump to 150psi.
    Will service the AT shock one day. Thanks for this
    #10
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  11. Motociclo

    Motociclo Long timer Supporter

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    Cheers.
    I have seen some diy vac pumps people have made. Good Idea indeed. They are the better option if available.
    Plenty of people use air to charge bladder. Never heard of any issues.
    #11
  12. Junglejeff1

    Junglejeff1 Long timer

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    Nice write up.I would add in that when sliding seal head back into shock have shaft fully retracted into seal head.I put 30 psi in bladder after I reinstall bladder.Have had issues where it sucks bladder and bladder insert into shock when bleeding shock if I don't.Also forces any air caught up in compression adjuster into piston chamber for easier bleeding.Have to release pressure as you are putting in seal head of course.I would never use air in bladder when finished as on a hot shock will build up huge pressure.
    #12
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  13. Motociclo

    Motociclo Long timer Supporter

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    Never had any issues with bladder getting pulled down. Good to know.
    I part fill shock body on an angle and install comp adjuster to minimise chance of air being stuck.
    I don't use air, only nitrogen.
    I wouldn't recommend air in a shock because it does react to heat.
    There some that have, hasn't had ill effect, certainly don't recommend.
    #13
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  14. Junglejeff1

    Junglejeff1 Long timer

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    How is the 2 stage compression stack working for you on small sharp hits?wondering because that is alot of face shims.I am used to using the .20 shims and have yet to experiment with .15 shims.
    #14
  15. Motociclo

    Motociclo Long timer Supporter

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    Feels fine to me. The thinner shims seem give a softer feel. Even with many of them. You could get a similar level of stiffness from 5 * 0.20mm shims.
    0.20 shims about 2.5 stiffer than 0.15 shims on paper. Thick shims have a higher opening pressure and snap shut quicker.
    Some say that there's a big friction increase with to many thinner shims, I can't say I have really noticed it, but I also don't use shock dyno or tune to Gp levels!!!!!!!!
    #15
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  16. Junglejeff1

    Junglejeff1 Long timer

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    When I have time to not ride bike I need to get into shock.Not sure what they did but getting a spike on small sharp hits that I cannot adjust out.In woods hitting roots slower do not notice.When shock speed increases on road hitting rough stuff it is pretty spiking.
    #16
  17. Motociclo

    Motociclo Long timer Supporter

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    I run a 9.8kg spring. It is 10 mm longer than stock. So installed preload is 20mm before adding additional.
    Given I like a higher rate spring, if using a stock length, for my weight, i would/could use a 11kg spring.

    I could only hazard a guess to your harshness issues, harshness can be too hard and to soft. You have mentioned have a 10.4 kg shock spring. I am guessing your ride sag may be pretty close if not ideal. Long shot guess, but comp may be too soft. If shock blows through stroke too quick, can feel harsh.
    Rebound an play into also. I always tune rebound first, then comp when fiddling the clickers.
    #17
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  18. Motociclo

    Motociclo Long timer Supporter

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    A small addition to the shock revalve.
    I have given the comp adjuster a revalve as well.
    To compare a shock to a fork, similar components different location.
    On the Af Twin shock, the comp adjuster is the base valve and the shock piston is the midvalve.
    Same rules of revalving aplly to not having to stiff a midvalve as this can promote cavitation in the rebound chamber during comp stroke.
    These are the shims for the comp adjuster,
    17*0.20
    16*0.20
    15*0.20
    14*0.20
    13*0.20
    12*0.20
    11*0.20
    10*0.20
    9*0.20
    8*0.20

    The changes I made are an extra 17*0.20 and removed the 8*0.20.
    On the restackor this made a difference by firming up the base valve and pushing cavitation limit out further.
    This will firm the overall comp damping also.
    #18
  19. NSFW

    NSFW basecamp4adv Super Supporter

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    nice and valuable write up...:thumb
    #19
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  20. Motociclo

    Motociclo Long timer Supporter

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    Another revision to shock.
    This is mainly to firm up rebound, which was a touch quick. Not much, but enough to warrant change. I have gone back to the 0.25 shims from the 0.15.
    In the case on paper, difference is 0.25 shim is 4.6 times stuffer than 0.15.
    I did have 16*36*0.15 shims, This is roughly 3.5 of the 36*0.25. I did this Manly to tidy up stack, rather than having 18 or 19 36*0.15 shims.
    I have taken cross over shim out of comp valving.

    Revised comp.
    40*0.15, (11) Taken out cross over. Back to single stage stack.
    38*0.15
    36*0.15
    34*0.15
    32*0.20
    30*0.20
    28*0.20
    26*0.25
    24*0.30
    22*0.30

    Revised rebound.
    36*0.25,(4), went back to 0.25 shims.
    34*0.25
    32*0.25
    30*0.25
    28*0.25
    26*0.25
    25*0.25, Added shim. This makes quite a difference to balance low and high speed rebound.
    24*0.25
    22*0.30
    Removed 20*0.30 shim.
    #20
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