Results 1 to 35 of 35
  1. #1
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137

    Help needed identifying my DUC32

    I suspect my forks might be off a Trek 69er.

    I bought my bike used with a set of DUC's installed having a 28 spoke count Bontrager hub laced to a 26" rim. At full droop I have 6 1/8" (155.5mm) of exposed stanchion. I've read the A2C on a DUC is 521mm but I am unclear as to where the A2C measurement is taken. I only have about 19" (483mm) from the center of the axle to the bottom of the lower crown and 20 1/4" (514mm) from center of axle to the top of the lower crown.

  2. #2
    mtbr member
    Reputation: ragetty's Avatar
    Join Date
    Jul 2006
    Posts
    529
    is it the trek 69'er 'orange/brown' ?

  3. #3
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    That is about what I measure on mine. The 6 1/8" will go a little more if you put more air pressure in the air coil to fully compress the negative spring. I get about 6 1/4" (7 3/4" on the one's with the extenders) on mine. You may get this extra extension by pulling up on the stem while pushing down on the top of the tire.

    I believe the standard measurement is from axle center to where the bottom headset bearing race sets. Which appears to be about the same as the top of the crown on the DUC32.

  4. #4
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Thanks for the replies, once again I am grateful for Maverick owners and this section of the forum.

    They were black ano, but I wasn't sure all the Trek 29er DUC's were that cool copper/ bronze color.

    I'm relieved to here that it's improbable these are the 69er model. I began my initial look at these to consider putting a 650b up front as the frame these are on was intended for a 160mm travel 545mm A2C fork. I was hoping a 2.1 tire on a 650b would jive with the DUC, but it looks like in order to do so I must run either shortend 29er bumpers or make some stanchion extenders.

  5. #5
    mtbr member
    Reputation:
    Join Date
    May 2006
    Posts
    13
    shes a standard duc32 off a 2006 gary fisher fat possum. Im rolling the same fork and wheelset on my ml8

  6. #6
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Quote Originally Posted by orangedude View Post
    shes a standard duc32 off a 2006 gary fisher fat possum. Im rolling the same fork and wheelset on my ml8
    Great info orangedude, thanks.

    I have a pic posted in the Post your Maverick sticky, it's the orange Titus El Guapo. With the DUC installed the bottom brackets stands 12.75" from center to ground so it's rather low.

  7. #7
    mtbr member
    Reputation: savo's Avatar
    Join Date
    Oct 2009
    Posts
    739
    You won't know if it's a 29er (or 69er) version by mesuring the A2C, as it's the same for 26'' or 29'' (or even 650b) wheels. 29er reduction only limits the travel at something like 115-120mm, so you might let the air out and compress it all the way down to know how much travel you have.

    You can put a 650b front wheel on (do check if you need any travel reduction to avoid tyre-crown contact when bottomed out), it will lift your front end of a couple of cm and I think it would be a good move

  8. #8
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Thank you savo, I wasn't aware the reduces were merely travel limit stops. I will relieve the air, deduce travel, and post a follow up of the A2C at full jounce in case this info might serve another.

  9. #9
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137

    More perplexed than ever, please share any insights.

    I bled the air out of the fork and the A2C measures 15 3/4" (400mm) at full jounce. I have 1 3/4" (44.5mm) of stanchion exposed with the fork fully collapsed and I have about 1 9/16" (40mm) of tire clearance between the knobby of a 2.35 Kenda Nevegal and the bottom of the lower crown.

    It looks like these forks only have about 4 1/2" (110mm) of travel. I'm at a loss, when I asked Suspension Experts if these were equiped with the 29er travel stops they said no. Would this have been normal for certain DUC32's? It sure seems like these are set up for a 29" wheel.

  10. #10
    mtbr member
    Reputation: savo's Avatar
    Join Date
    Oct 2009
    Posts
    739
    I had a DUC32 in 29er configuration, it was 515 A/C with 115mm of travel. It seems like yours is in the same configuration. But if Suspension Expert said it was not... what to say? Did they actually check the fork? did you buy it from them? Anyway, if it has 29er travel stops, removing them is an easy job.

  11. #11
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Quote Originally Posted by savo View Post
    I had a DUC32 in 29er configuration, it was 515 A/C with 115mm of travel. It seems like yours is in the same configuration.
    I tend to agree. I'm having a hard time understanding how it could be anything else. The thing I find strange is that the travel adjuster works as normal, I thought that this function was lost when converted to 29" configuration?

    Quote Originally Posted by savo View Post
    But if Suspension Expert said it was not... what to say? Did they actually check the fork? did you buy it from them? Anyway, if it has 29er travel stops, removing them is an easy job.
    I didn't buy it from them, I aquired the forks used and sent them to Suspension Experts for a rebuild, tune, and have their IFP and Headlock seal retainers installed. I wanted the fork professionally rebuilt so as to establish a baseline for how they ought to perform.

    I still want a 650B up front so if these have a set of travel stops installed I could leave them or safely cut them 1" (25mm) shorter. I guess I'll have to open these up and take a look inside.

  12. #12
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    They are easy to open up. I position the bike so the fork housing is horizontal then the bath oil will not drain out. It is not a biggy if it does drain out. Just a little mess and loss of 10 cc of oil. If you have ridden it very much and the bath oil looks like it has a little dirt in it then you want to replace it anyhow. I have been mixing a little Fox Float oil with the bath oil. Seems to make it a little smoother.

    I have a bike stand where I can rotate the bike to where the fork is horizontal. I have also laid it on the floor and by positioning the pedals and turning the tip of the seat been able to get the fork horizontal and remove the stanchions without the bath oil draining out. When you remove the stanchions the bottom out bumper and spacers may slide off the 10 mm rod so look inside the fork housing after you remove the stanchions. I tend to break these bottom out bumpers if I bottom out very much pretty hard.

    I have taken mine apart many times. When unscrewing the air valve bolt make sure the air valve stays centered. If the 10 mm rod pulls away then the air valve bolt can rub against the side of the top cap and tear the little o-ring. I have been there and done that. Use the same precaution when putting it back together. On the other side when putting the knobs back on make sure the o-ring on the drop-down knob doesn't get pinched. Be careful not to lose the little screw on the top of the rebound knob. I hold the knobs in one hand and have a phillips screwdriver in the other hand on the little screw to keep it from popping out when I position the knobs. After you get the knobs into the top cap turn the small screw in just a little and then make sure the rebound knob is seated properly before tightening the small screw. I turn the push down on the rebound know and turn it counterclockwise until it hits a stop then I know it is on correctly. Then I tighten the little screw. I have bought extra of these little parts from Ethan since I know I tend to need them.
    Last edited by geweber; 05-07-2012 at 02:30 AM.

  13. #13
    mtbr member
    Reputation: voob's Avatar
    Join Date
    Jan 2011
    Posts
    175
    Quote Originally Posted by Jon Richard View Post
    I didn't buy it from them, I aquired the forks used and sent them to Suspension Experts for a rebuild, tune, and have their IFP and Headlock seal retainers installed. I wanted the fork professionally rebuilt so as to establish a baseline for how they ought to perform.
    e.
    It sound like a set up/dampening problem.
    Ask them to provide you with the tune they did to the fork.

    Left leg/damper:
    Shim Stack?
    Weight oil?
    What is the mm depth setting of the IFP and Damper air pressure pressure?

    Right Leg/air spring:
    What nm negative spring? (too strong and the fork will not extend fully-lower A2C)
    How much oil in air spring below piston.
    What air spring pressure are you using?

    What is your ridding weight and what type of trails and ridding do you do?

    All the above information is needed in order to tune the fork to your needs and preferences.

    http://www.maverickbike.com/cms_images/file_8.pdf
    Last edited by voob; 05-08-2012 at 03:58 AM.

  14. #14
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Quote Originally Posted by voob View Post
    It sound like a set up/dampening problem.
    I'm a little taken back by that statement as I didn't even suspect anything wrong until I started measuring to see if I could fit a larger wheel. I'm not disagreeing, just saying I would not have suspected anything was wrong due to such a nice stable ride. I'm really impressed with these in spite of not getting a full 150mm of travel.

    damper:
    Shim Stack? Unknown
    Weight oil? TORCO racing fork fluid 10wt.
    Damper air pressure? 60 psi

    air spring:
    What nm negative spring? Stock 5 nm
    How much oil in air spring below piston and what is the mm setting of the IFP and air pressure? Unknown
    What air spring pressure are you using? 100 psi

    What is your ridding weight and what type of trails and ridding do you do? 180 lbs./ mostly hardpacked, semi technical. Steep, but not to knarly. I'm 39 and just getting back into riding, so not to agressive. I like attacking a good challenge, but I gas out quickly.

    When I called Suspension Experts it was about 2 weeks after they completed the service so it's possible they simply didn't recall these particular forks. I'll pull the stanchions to verify whether these have the 29er travel stops, it seems an easy enough first step. Thanks voob.

    geweber, as usual your a great help!

  15. #15
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    I just remembered when I had one of my forks serviced at Suspension Experts and had the IFP put in the oil damper that I lost about an inch of travel. When I took it apart the seal head nut on the oil damper was loose. The oil level in the damper was low. I assume some oil had leaked out due to the loose seal head nut. When there is not enough oil in the damper and high air pressure under the IFP the damper will hit the IFP before full travel is reached. I added more oil to the oil damper and tightened the seal head nut and it has worked fine since.

    This is not a hard limit to travel like the 29er spacers. When the oil damper piston contracts the IFP it could still push the IFP down. It would just take more force due to the air pressure under the IFP. However, it feels like a hard stop when you let the air pressure out of the air coil and stroke the fork. This oil damper tube has a diameter of 24 mm so with an air pressure of 100 psi this would be a force of about 70 pounds ((24/25.4)^2*PI/4 *100). I don't know how much air pressure they put in yours. With the air pressure out of the air coil (relieve the air when the fork is fully compressed or take the air core valve out to be sure) and your full weight on the fork will it compress beyond the 1-9/16 inch clearance between tire and crown? If it doesn't then it is probably the 29er spacers.

    It may have had the 29er spacers in it when you sent it to Suspension Experts and they tuned it that way. Did they know you wanted it set up for a 26 inche wheel?
    Last edited by geweber; 05-08-2012 at 01:37 AM.

  16. #16
    mtbr member
    Reputation: voob's Avatar
    Join Date
    Jan 2011
    Posts
    175
    180 lbs./ mostly hardpacked, semi technical. Steep, but not to knarly. I'm 39 and just getting back into riding, so not to agressive. I like attacking a good challenge, but I gas out quickly.
    [/QUOTE]

    It sounds like you might want to start with a stock set up on the fork and go from there.

    The stock tune is a bit too soft for aggressive/ fast big hit ridding with diving/bottoming out too much. I think the IFP helps with that and cavitation of the oil but it must make the fork harder to attain full travel under normal ridding. I decided not to install an IFP because I wanted a more linear feel, easier tuning and I don't do jumps or high speed down hill. I ride slow/technical/twisty/up and down singletrack.

    My current tune is: (no IFP)
    Damper Shims: From piston (flat *side) 8x21x.10 - 8x16x.10 - *8x14x.10 - 8x12x.15 - 8x 21x.15 *-
    damper Oil: 10wt(63mm from top)/100psi *
    13-15cc oil fluid (15wt) (more oil makes the travel more progressive)in air chamber *with 5nm (stock neg spring)/ 90-100 *psi).
    25 to 30 % sag and I almost get full travel

    I will most likely use 5 weight oil in the damper and 10ml of oil in the air spring next time as I find a bit too much hand slap/rebound. It's fun trying different tunes!

    It now takes me about 45 minutes for complete rebuilt of both legs!

    You can also contact Ethan at mavericksuspension@gmail.com.
    He will be able to rework the fork to your liking.

  17. #17
    mtbr member
    Reputation: voob's Avatar
    Join Date
    Jan 2011
    Posts
    175
    Quote Originally Posted by geweber View Post
    I just remembered when I had one of my forks serviced at Suspension Experts and had the IFP put in the oil damper that I lost about an inch of travel. When I took it apart the seal head nut on the oil damper was loose. The oil level in the damper was low. I assume some oil had leaked out due to the loose seal head nut. When there is not enough oil in the damper and high air pressure under the IFP the damper will hit the IFP before full travel is reached. I added more oil to the oil damper and tightened the seal head nut and it has worked fine since.

    When the oil damper piston contracts the IFP it could still push the IFP down. It would just take more force due to the air pressure under the IFP. However, it feels like a hard stop when you let the air pressure out of the air coil and stroke the fork. This oil damper tube has a diameter of 24 mm so with an air pressure of 100 psi this would be a force of about 70 pounds ((24/24.5)^2*PI/4 *100).
    I was considering installing an IFP in my fork but decided against it since I retune my (4) forks every 5 to 10 rides in order to try different tunes.
    I have retuned rear maverick ML8 dampers with IFPs and they can be tricky to set up without trapping air in the damper.

    For the fork I think you need to remove the Base Cap (attachment boss in rear damper) in order to bleed air/oil level. Then you set the IFP in the proper(desired) depth before reinstalling the Base Cap(with new o-ring) and pressurizing the damper to desired psi.
    Last edited by voob; 05-09-2012 at 04:18 AM.

  18. #18
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    voob, your probably right about starting with a stock tune, but I no longer have the stock piston. I do kinda bomb it when I point down hill if that makes a difference.

    I just aired out the fork dropping it down to the 1 9/16" tire clearance and sure enough when I place a good share of my body weight downward on the bars it drops another inch or so and springs back when I let up. Good call geweber!

    I have all the manuals downloaded from the Maverick site, The only thing holding me back from cracking these open is not having the block vises or a proper tool to hold and unscrew any of the tubes.

    I've been meaning to get into these and I have a small lathe and mill to make the blocks, but man i'm overloaded with projects as it is and when the weekend rolls around I just want to ride.

    I'm sure i'm preaching to the choir. You folks have been so patient and helpful, i'm truly grateful and I will see this through and share the results.

  19. #19
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    Jon, you don't need any tube clamps to fix this problem. If your seal head nut is loose like mine was you want to get it tightened before you ride again. You just have to remove the stanchion and damper tube from the fork housing and you can tighten the seal head with a couple of wrenches or one wrench and clamp the drop out to your wheel axle.

    You can unscrew the damper tube from the stanchion by clamping the stanchion to your wheel if you don't have a piece of 24 mm tube to clamp it to. There is a wrench fitting on the damper tube. After you get the damper tube unscrewed from the stanchion then let all the air pressure out of the damper. You should be able to push the 10 mm damper rod all the way down now. With a wrench on the damper tube you can use a wrench or socket on the seal head nut to see if it was tight.

    Now you can remove the seal head nut and pour the oil out and remove the damper if you want to look at it. You would not have to remove it. You could just slide the seal head nut up the damper rod and add some more oil and then put the seal head back on just a couple of turns. Then you can put a small amount of air pressure below the IFP. Work the damper rod in and out a few times to get the air out of the oil. I screw the damper rod bolt in hand tight to make it easier to push the damper rod in. The small air pressure should push it back out. Adjust the loose seal head to let the air out. If you can't push the damper rod in all the way then add more oil. I let oil escape the loose seal head just until the IFP just starts to push up on the damper rod then I tighten the seal head.

    If you can push the damper rod in all the way except for about a 1/4 inch you should be okay. With the fork fully compressed the damper rod will be out by the thickness of the bottom out bumper plus the length the damper rod goes into the top cap of the fork housing. This will give you the maximum air volume under the IFP which will give more linear compression from the damper. However, you get most of your compression from the air coil in the other fork leg. This is where you would get most of your progressive compression if that is what you like by adding oil to the air chamber to have a smaller air volume(high air pressure) at the end of the stroke.

    Before you put the damper tube back on the stanchion you want to put the air in the damper. I noticed they put 60 psi in yours. I think that is normal. With air pressure in the damper tube I like to stay out of the line of fire if the snap ring at the bottom would happen to come out and the base cap propelling into my chest. I have pushed the damper tube in all the way with my shock pump still attached. You can get a high air pressure, like 300 to 400 psi. The snap ring has a correct orientation. It has a sharp edge on one side and a slightly rounded edge on the other side. If it was installed wrong I don't know if it could come out or not. But I don't push the damper rode in with the base cap end pointed at my chest like I have in the past before I realized how much air pressure could be on the other side.

    I don't think there is any big problem that your damper piston has been hitting the IFP since there is air volume under the IFP that allows it to move down. I would be more concerned about the loose seal head if that is why you are low on oil. If the seal head is tight then they just didn't get enough oil in the damper tube.

    When you remove the stanchion and damper tube from the fork housing note if there seems to be excess bath oil in the fork leg. The normal amount is 10 cc. If oil did leak out of the damper tube then the amount of bath oil may be larger unless you have been leaking oil out the stanchion wiper seal which you would notice.

  20. #20
    mtbr member
    Reputation: voob's Avatar
    Join Date
    Jan 2011
    Posts
    175
    In the Air Spring chamber side (Left leg), if you use 10 to 13 ml (cc) of oil you should have a linear feel and you should be able to compress the air spring fully to get full travel.
    If you use more oil (less air volume) you will get a progressive shock rate and make it harder to get full travel at the benefit of less brake dive. 5ml can make a big difference. I think the total oil you can put in the air chamber is around 20 ml.

    You can remove or add oil without taking the fork apart. Release air pressure while compressing the fork leg to remove all air. Remove the valve core and turn the fork upside down and almost all the oil should drain out. Now add 10ml of oil through the valve core hole and install valve core and pressurize to 90 to 100 psi. Try the fork. Add more oil to get the feel you want.

    If you are still having issues go to the damper/right leg for further adjustments.

    In the damper side (right leg) as geweber said but also check the Damper Base Plate O-ring and air valve core (the part that the snap ring is holding down) for air escaping through the bottom. I have had this happen to one of my forks. Replacing the O-ring and tightening the valve core solved the problem.

    Allways Use Safety as geweber said. Trapped air can turn the fork into an air rifle.

  21. #21
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    I disassembled the damper side and found that:

    There are no 29er length travel stops, only the stock bumpers

    The seal head nut was tight

    The damper cylinder was full to 40mm shy of the top

    There was no excess of bath oil in the fork leg

    upon reassembly following the Maverick instructions (fill damper cylinder to 63mm from the top and cycle the damper rod) I yielded the same sprung resistance at the bottom of the stroke as it did before disassembly. I unscrewed the seal head nut and added oil several times until the damper rod would push down all the way, this seems to be quite a bit more oil than Mavericks recommendation. Is it possible to over fill?

    As it is with 80psi in the damper I can push the damper rod all the way down and it springs back about half way up. I now have a full 6" of travel.

    I am not understanding how not enough oil limits travel, must there be a proper ratio of air/ oil volume to allow for emulsification? I thought it was just a matter of routing the oil through an orifice to create motion resistance, but there is something i'm not getting. If I had a better understanding of the principle of operation and what it does when functioning properly, I would feel much more confident about how this was accomplished.

  22. #22
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    The Maverick instructions are for when there is no IFP (internal floating piston) in the tube. The Maverick instructions for the rear shocks are more appropriate since they have an IFP. The position of the IFP depends on how much oil is in the tube above the IFP. The oil above the IFP is not compressible and the air below the IFP is compressible. There has to be enough oil in the tube so when the the damper rod is pushed in all the way the piston doesn't hit the IFP.

    I am puzzled why the damper rod doesn't extend all the way when you put air pressure below the IFP. When I put air pressure in mine the damper rod always extends the full length (approx 6-3/8 I think).

    You said "The damper cylinder was full to 40mm shy of the top". When was this? I assume you let the air pressure out the air valve core. The level of the oil from the top doesn't mean much without knowing the level of the IFP. If air leaked past the IFP then when you let the air out below the IFP the air above the IFP will push the IFP down some. When you unscrew the seal head did some air come out? If no air leaked past the IFP then the oil should have been at the top of the tube when you took the seal head off.

    There should only be oil above the IFP. When you put the seal head back on did you bleed all the air out of the oil?

    Yes, you can put too much oil in. If the IFP was at the bottom of the tube and you fill the tube to the top with oil and then put the damper rod in and tighten the seal nut with the damper rod half way in and no air in the oil you would not be able to push the damper rod in any farther. There would be no space for the damper rod to go any farther into the tube since the oil is not compressible and the IFP can't move down since it is already at the bottom of the tube. So putting a little air pressure below the IFP will move it up when you loosen the seal head to let out any air and the excess oil. But if you let too much oil out then the IFP will move up too much and the damper piston will hit it when you push the damper rod in all the way. So I let oil escape just until the IFP hits the piston with the damper rod in all the way. Then I tighten the seal head. If I let a little too much oil out and I can't push the last 1/4 inch of the damper rod in that is okay. The last 1/4 inch will not need to be pushed in because of the bottom out bumper thickness and the damper rod goes into the top cap a little bit. If you have more oil in than this then the air volume below the IFP will be smaller and you will get more progressive compression. I would rather get my progressive compression by tuning the air coil in left fork leg. The smaller the air volume below the IFP the higher the air pressure will go when the damper rod gets pushed in all the way. I can't say why but I would rather not have 500 psi in this chamber when the damper rod gets pushed in all the way.
    Last edited by geweber; 05-13-2012 at 05:16 AM.

  23. #23
    mtbr member
    Reputation: voob's Avatar
    Join Date
    Jan 2011
    Posts
    175
    Filling oil 63mm from top allows for proper function of lockout feature. Do you still have use of this feature? Does installing an IFP (the IFP separates the oil and air charge and prevents mixing of the two preventing foaming and therefore more consistent dampening) remove the lockout feature? Adding more oil should decrease the air chamber and give a more progressive feel but should allow for full travel as there is less air to compress.

    You might want to contact Ethan at mavericksuspension@gmail.com for a better explanation on the use of an IFP in the DUC.

  24. #24
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    The IFP doesn't affect the lockout feature. The lock tube has two small holes that let the oil pass around the damper piston on the rebound. When this tube is turned a quarter of turn the holes are block. Then the oil can still return through another hole untill the fork is within 2 inches of full extention and then this hole is covered by the sleeve of the seal head which is nearly 2 inches long. Now the oil can only return through the port adjusted by the green rebound knob.

    As voob suggested, contact Ethan. Tuning these forks is an art and he is good at it. He sent me a light force negative spring which gives me less linearity which is what I wanted. I want to use most of my fork travel on the light bumps because that is what I mostly ride. If I do a tight switchback on a decline I have to remember I have a soft fork setup and be prepared for that type of response. (I should say lack of response from the fork. "The dive!") But if that is what I want that is what I can get with a DUC 32.

  25. #25
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    The lock out is working properly. The fact that the damper rod does not rebound all the way out has me thinking the position of the IFP was to near the bottom upon reassembly and thus regardless of air pressure there is not enough air volume below the IFP.

    I was not understanding that the Installation of an IFP creates two separate chambers partitioning the oil and air. I read the Maverick manual for the rear shock and that clearified a lot.

    The 40mm to the top measurement was after having bled the air out and removing the damper rod, in hindsight I realize this information tells me nothing without knowing the position of the IFP.

    I bled all the air out of the oil the second time, but I failed to do so on my first attempt. I think I came close but need to do it again with a tad more air below the IFP to position it higher.

    I like how the procedure is outlined for the rear shock, I'm wondering if it would be beneficial to remove the base cap or make some sort of depth stop that could be inserted through the hole in the base cap for the shrader valve so that one could accurately postion the IFP for this operation? It seems doable as it is but it's like finding the light switch in a dark room

    I appreciate your patience with me. I'm learning a lot and feel if I continue in this manner i'll be equiped to tune and diagnose the DUC proficiently on my own, which is exactly what I want out of a fork.

  26. #26
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    Glad you are getting it figured out. The more you work on these forks the more you will understand them and they are pretty easy to work on.

    I have used a wood food skewer to put through the air valve core hole to measure where the IFP is at. The Maverick manuals give dimensions for setting the rear shocks. The IFP will move 1 inch when the damper rod moves 5.76 inches. This is assuming the ID of the damper tube is 24 mm and the damper rod OD is 10 mm.

    The IFP I got from Suspension Experts is aluminum and the ones I got from Ethan are a non-metallic and they are a different length.

    I think the next time I will let the damper piston contact the IFP with about 1/2 inch of damper rod sticking out. Then the piston will contact the IFP just as the bottom out bumper is starting to be compressed or a little before. The damper piston can move the IFP but the force on the damper rod will increase about 5.76 times(24mm^2/10mm^2) when the piston contacts the IFP. This may take some pressure off the bottom out bumpers. I have bought a few used DUC's and about half of the bottom out bumpers have been split. I have split a couple myself. When you believe in using all the travel of your fork you tend to bottom out a little more.

    So if the air pressure under the IFP is 200 psi when the damper piston makes contract with the IFP the force on the damper rod will immediately increase from 24 pounds of force to 140 pounds of force. So less of the force of my 175 pounds riding weight will go into the bottom out bumper when I screw up my riding. I guess if you tune correctly and ride correctly you should never bottom out. That's not me.

    The next time you have your shock pump on the oil damper notice how the pressure increases when you push the damper rod in all the way. Remember to stay out of the line of fire of that base cap if the snap ring gave way. This will give you an indication of where the IFP is positioned. If the pressure is real high then there may only be 1/4 inch or less of space between the base cap and the IFP when the damper rod is pushed in all the way.

  27. #27
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    I took the damper assembly out again and noted the pressure when the damper rod was fully collapsed raised to 250psi. I dropped the pressure to 30psi when collapsed and loosened the seal head nut and bled the oil til 1/4" of damper rod was exposed. This dropped the pressure to 200psi when compressed with 80psi static in the damper and the damper rod would now fully extend on it's own.

    Your idea about the split bump stops made sense, so I bled it down to having 7/16" (11mm) of the damper rod exposed when bottomed out and with 80psi static loaded in the damper the pressure reaches 170psi fully compressed. The only problem I see with this is that, although raising the height of the IFP will share the load of the bump stop when bottomed, it wont be as effective having less pressure. I wonder what the difference would be between the SuspensionExperts IFP an Ethans in this regard.

    I have 10ml of bath oil in each leg and 15ml of oil in the air spring hoping for a bit more progression to resist dive, coupled with the damper set up in theory bottoming out shouldn't be an issue. I'm using 7.5wt oil everywhere as this is all I have. I imagine I may end up playing with heavier wt oils but I won't get a chance to ride again til next weekend so the jury is out on how these will perform.

  28. #28
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    Jon, I do a lot of experimenting. Maybe you want to let me try this first in case something goes awry. I have 8 of these DUCs so if I damage one it is not a big deal. I am a little concerned that maybe you could get too much stress in the damper rod when it contacts the IFP. However, the air pressure under the piston in the air coil goes to 300 or 400 psi when the fork is fully compressed and it appears to have the same 10 mm rod configuration. The other configuration would be how the piston contacts the IFP that could cause an issue.

    On the other hand you have already been hitting the IFP with the oil damper piston with that first setup when your stroke was 1 inch shy.

    The purpose of the oil damper is to force the oil through the restrictions to create some damping. If the air below the IFP compresses then less oil will be forced through the damper. So with the larger air volume under the IFP we may need more air pressure to get more damping. This is what happens when there is no IFP. Air mixes with the oil and gets below the damper piston and then compresses, which results in less volume going through the damper and the air oil mixture going through the damper also has less viscosity than all oil.

    What you might try to do to compensate for your light weight oil is partially close the lockout. This will increase the damping in both directions. If you do it too much your rebound may be too slow.

    Another way to put the oil in may be to move the IFP all the way to the bottom and then fill the tube with oil to within 63 mm of the top. Then when you put the damper in and bleed all the air out the volume of air below the IFP would be the same as when you don't use the IFP.

  29. #29
    mtbr member
    Reputation: voob's Avatar
    Join Date
    Jan 2011
    Posts
    175
    Hi Gerald you seem to be buying all the ducs out there!
    I have 4 of them and have being looking for a 5th.
    I ride at 200+ lbls and my current tune is:
    Damper Side:
    (no IFP) I am considering ordering some from Ethan.
    Damper Shims: From piston (flat *side) 8x21x.10 - 8x16x.10 - *8x14x.10 - 8x12x.15 - 8x 21x.15 *-
    damper Oil: 10wt(63mm from top)/100psi *
    Air Sring:
    13-15cc oil fluid (15wt) (more oil makes the travel more progressive)in air chamber *with 5nm (stock neg spring)/ 90-100 *psi.
    25 to 30 % sag and I almost get full travel

    I will most likely use 5 weight oil in the damper and 10ml of oil in the air spring next time as I find a bit too much hand slap/rebound. It's fun trying different tunes!

    I ride tight offcamper/smooth with some roots and short bridges, It is slow and technical with a lot of up and down (short steep climbs and drops) These trails require a more progressive/stiff fork to get rid of the sloppiness feel and less fork dive. However I like a more linear feel.

    Would the IFP help?

    What is your set up and what is your weight and your ridding style? Have you altered your shim stack? What depth is your IFP fully bled (rod 1/4" above seal head in your case) before air pressure and what oil weight and pressure are you using?

  30. #30
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Hey geweber I hear what you're saying, I wish I had a top cap in my hand to deduce exactly how much space is there when bottomed out.

    I failed to mention that these were torn into by my LBS after they came back from Suspension Experts because the lock out wasn't working, you probably remember my other thread with the pic of the custom orange stanchion guards. I think what happened is the LBS weren't aware that an IFP was installed and put them back together according to the Maverick doc. which rendered pretty much the same results as my first attempt.

    All that to say that before I tore the damper down they were under filled with 5wt. oil and 60 psi. Now I am running 7.5 wt. oil and 80 psi plus an added 5ml to the air coil. I understand your concern as you wouldn't want my forks to be damaged because of following your untested suggestion, but given the above if I wasn't bottoming out before it would seem even less likely to do so now, what do you think?

    Also-
    Quote Originally Posted by Jon Richard View Post
    The only problem I see with this is that, although raising the height of the IFP will share the load of the bump stop when bottomed, it wont be as effective having less pressure. I wonder what the difference would be between the SuspensionExperts IFP an Ethans in this regard.
    The reason I bring this up is because I still aim to put a 650B up front so I believe Ill end up tuning these with less air volume/ more oil volume when I get to that stage anyway.

  31. #31
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    I like using the IFP because by keeping the air and oil separated the fork response is consistent. On my first ride with this fork on a rocky down hill it got so spongy I had to stop and put in some more air. It was fine at the start but when the air and oil mix it changes things. Fox went to the FIT to keep the air and oil separate. When I took my 2005 Marzocchi apart I noticed they keep the air and oil separate. They fill the tube completely with oil. There are holes in the side of the tube at the end. There is a hose clamped around the tube. When the rod goes into the tube the excess oil exit the holes into hose area around the tube. Their fork housing contains the air pressure for the air coil. When the rod retracts then this air pressure pushes on the hose and the oil flows back into the tube.

    My shim stack is the 21x0.01-12x0.02-15x0.01., I also found a lighter negative spring than Ethan had that I like better. I am using 10 wt oil. I only run about 45 to 50 psig in the air coil on the ML8 with the 29er on front. The head angle is about 66 degrees and when I roll the bike over a scale I have about 65 pounds on the front and 130 on the back. I run about 60 to 65 psig in the air coil on the Niner Rip 9. I like to set the air pressure for plush travel for the first 2/3s of fork travel. Then if I am bottoming out I put in more oil instead of more air pressure. If I put in too much air pressure then my arms will ache after a 2 hour ride. I have a brass bell on one of my bikes. When I have the air pressure set to my liking then I very seldom ring the bell by hitting hard stuff.

    I think the shims should pop open when I run into a 6 inch curb but hold when I go into a turn with some speed. That is one of my tests is to run straight into a curb without pulling up on the front wheel. The shim pops open and you hear the oil go pussshhhh.

    I am not an aggressive rider. I don't have the legs, ankles, or skill to take big air and I want to ride tomorrow. I don't like to use my brakes on a rocky downhill. This is where this fork on the ML8 with the head angle of 66 degrees and 29er front wheel seems to shine. I don't have near as many end-overs as I used to. My motto is "Ride today like you want to ride tomorrow." My number one concern is having an accident that would put an end to my bike riding.

    When I switched to the 29er in the front I have had a stick get kicked up into the wheel just behind the fork and I went over the bars. The first time I thought it was a fluke, then it happen again. Now I ride with a piece of coreplastic between the spokes in the front wheel. I got the idea from Legit Bike Polo .
    Last edited by geweber; 05-16-2012 at 05:30 AM.

  32. #32
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    Yes, you should have less bottom outs. But with the better performing fork you will want to take bigger air and miscalculate just that one time and come down hard on the front wheel. When we get tired we don't ride as good and you could take a dip wrong and do a hard bottom out.

    I just looked at a top cap. There appears to be about only 1/16th of an inch of metal above the top of the 10 mm rod. The bottom out bumper puts pressure accross the top cap. The rod just pushes on that 1/16th inch lip at the center hole. The worst would be the rod will punch through this and you would need a new top cap. If this happens and you have trouble finding one you know where you can get one.

    I plan to try a 650b also. I will just put it on one of my forks setup with the extensions I have. I may also cut one of the 29er spacers I have in half and try that. What are you going to do to get the space for the 650b wheel/tire?

  33. #33
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Quote Originally Posted by geweber View Post
    I plan to try a 650b also. I will just put it on one of my forks setup with the extensions I have. I may also cut one of the 29er spacers I have in half and try that. What are you going to do to get the space for the 650b wheel/tire?
    Probably cut down some 29er spacers unless I can figure out what the material is in which case I could make some, any idea, Buna N? Butyl rubber? Urathane?

    I may try machining some 19mm extenders at some point, I would prefer a whole new stanchion but I am unsure about trying to bond to the dropouts.

    I think a 540mm A2C DUC with a 650B may be a tad tall so I need to verify before I decide.

    Perhaps I should contact Ethan for the travel stop limiters as an excuse to pick his brain.

  34. #34
    mtbr member
    Reputation:
    Join Date
    Jan 2008
    Posts
    121
    I reduced the amount of oil in the damper until I had almost one inch of rod extending when the piston contacts the IFP. I went on a couple of two hour rides with fairly low air pressure in the air coil and let it bottom out intentionally. You can definitely hear the piston hit the IFP. It must have hit about 100 times. I had about 1/2 inch of travel after the piston made contact with the IFP. The top cap was not damaged. I didn't have a real hard bottom out as in a crash or big air.

    I put some more oil back in until I had about 1/4 to 1/2 inch of rod extended when the piston makes contact with the IFP. I will note if this keeps me from splitting bottom out bumpers.

  35. #35
    Registered text offender
    Reputation:
    Join Date
    Dec 2011
    Posts
    1,137
    Yes, please post your findings. Thanks for the follow up. Did you feel the rate increase when the piston contacted the IFP? and do you think it is a viable anti bottom out strategy?

    Mine have behaved absolutely great since rebuilding the damper, and after adding 5mil to the air spring the rate has become more progressive which I like. My last ride the DUC only traveled 5"- perfect as I did not really go to aggressive.

    It's odd that I build a new bike and these old forks are one of the few components I'm enthralled with.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •