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  1. #1
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    iMust SN04 Full Suspension Issue

    Noticed lately while pedaling I'm getting a clunking sound around the cranks area and have replace my BB bearings and chain, I've also check the pedals and chainring torque and checked my rear hub plus the bearings all feel good but the clunking sound is still there, I check the frame's joints torque which are within specs so I don't know what else could be causing the clunking sound.

    Now this is not a creaking but a clunking sound and only happens when pedaling. Also the drivetrain sensation feels nice and smooth.

    Any suggestions?

    Thanks

  2. #2
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    Just a sound? No loose/play in the pivots?

    If just a sound, possibly internal cables slapping around?
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  3. #3
    since 4/10/2009
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    Sounds echo in carbon.

    When was the last time you:
    removed and cleaned the seatpost
    removed and cleaned cranks
    removed and cleaned pedals
    dropped fork and cleaned/greased headset
    removed and cleaned cassette
    removed and serviced freehub

    If anything is dirty or the grease is old, it's a potential culprit. Chances are, you can get the bike to produce the noise without pedaling. You just have to isolate it.

  4. #4
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    The bike was just built 10 days ago and was on its third ride.

    Know the sound of cable contacting inside the frame and that's not the sound and it's only happening while pedaling where the cable sound is basically every time you hit a bump.

    Will check the Seatpost since I haven't done so but usually it would sound more like a creaking and not clunking sound.

    Thanks for the info.

  5. #5
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    I had cheap pedals on a new bike and it made a slight clunk every crank rotation. I had to ride it more to actually feel the earlier clunk in a pedal. One of the balls in the bearing spit in 2. Bought new pedals. Could be a freak bad bearing somewhere on your bike.
    Totem KDS-D fatbike, Brompton M2L-X Ti, 6kg Dahon Dove, 1998 GT Forte Ti road bike

  6. #6
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    Holy crap what a coincidence! I have an Imust FS bike doing the same thing. And I decided to spend the afternoon chasing down the ping. I have replacement cranks and BB (Race Face Next) because when I originally got the bike last year I wanted to drop the chainring down to a 26t or 28t. And I have changed the original wheels for the summer set up Nextie 29er plus rims w/ Fatlab hubs. So far I have tightened cassette and applied green thread locker to the Race Face threaded bottom bracket. I have checked the tension on the pivot bearings as best I could without a proper torque wrench. I have a 1/4" torque wrench and a 1/2" torque wrench. But unfortunately the BB wrench, and my hex and torx sockets, all require a 3/8" 5-80 foot pound torque wrench. I have one on order from Amazon. So hopefully I can be more exact on my torqueing in a week or so. If you figure this mystery ping out I would sure like to know. I went about eight months without any noise. I'm thinking perhaps it is in the bearing of the main pivot.

  7. #7
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    My bike sounds fine on flat ground. But when I climb it pings on both side pedal strokes. Doesn't matter if I am standing or sitting. I can stand next to the bike and push down on a crank on either side and get this ping. All pivot bearings feel sufficiently tight and without noticeable play. I am going to take these wheels off and replace them with the original 90mm Imust/ Powerway wheels to see if the problem is in the wheels.

  8. #8
    since 4/10/2009
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    Quote Originally Posted by Nash04 View Post
    The bike was just built 10 days ago and was on its third ride.

    Know the sound of cable contacting inside the frame and that's not the sound and it's only happening while pedaling where the cable sound is basically every time you hit a bump.

    Will check the Seatpost since I haven't done so but usually it would sound more like a creaking and not clunking sound.

    Thanks for the info.
    are you 100% certain it was built correctly with correct bolt torques, grease, antiseize, carbon paste, etc applied in the correct places, etc?

  9. #9
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    Take shock off and cycle suspension.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  10. #10
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    I have had headsets that did this because they were loose.
    ~~~~~~~~~~~~~~~~~~~~
    Nothing to see here, move along folks.

  11. #11
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    Quote Originally Posted by Harold View Post
    are you 100% certain it was built correctly with correct bolt torques, grease, antiseize, carbon paste, etc applied in the correct places, etc?
    Sure did, used the correct torque plus grease. Need to check the Joints.

  12. #12
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    Quote Originally Posted by endo_alley View Post
    My bike sounds fine on flat ground. But when I climb it pings on both side pedal strokes. Doesn't matter if I am standing or sitting. I can stand next to the bike and push down on a crank on either side and get this ping. All pivot bearings feel sufficiently tight and without noticeable play. I am going to take these wheels off and replace them with the original 90mm Imust/ Powerway wheels to see if the problem is in the wheels.
    My cranks/pedals doesn't have any play, the whole drive train feels real smooth during the whole time, it just have clunking sound while pedaling but as everybody suggested; will take the bike apart and rebuild it piece by piece. The clunking sounds more metal than plastic.

  13. #13
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    "Take shock off and cycle suspension."

    That could be a good idea. I may try another 200mm shock to see if the sound is coming from the shock.

  14. #14
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    Quote Originally Posted by Nash04 View Post
    My cranks/pedals doesn't have any play, the whole drive train feels real smooth during the whole time, it just have clunking sound while pedaling but as everybody suggested; will take the bike apart and rebuild it piece by piece. The clunking sounds more metal than plastic.
    I have a feeling that the main lower pivot is responsible. It has a long single bolt (axle) carrying the main bearings on either side of the chainstays, and going through the hollow area behind the bottom bracket cup. My next move is to remove this axle and see if the bearing cups are tight fitting around the bearings. Other than this problem, these are really good bikes. I hope there is an easy fix for the problem.

  15. #15
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    Quote Originally Posted by endo_alley View Post
    "Take shock off and cycle suspension."

    That could be a good idea. I may try another 200mm shock to see if the sound is coming from the shock.
    I'm using the shipping bracket that hold the suspension together while it's taken apart.

  16. #16
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    Well took the suspension brackets apart and all looks good, the bearings are of good quality; Enduro 6801 but did noticed my paint is chipping on the bottom suspension hinge but can't do nothing about that and all is good. The headset is brand new and torque to manufacture's specifications.
    Again, this issue is only happening while pedaling which is weird. Can't test the bike due to awaiting some DT Swiss grease for my rear hub to arrive.

  17. #17
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    Well, we've heard a lot of different "noises" claimed in this thread, from clunks, to pings, to what seems like creaks. These usually mean something different to me, so it's sometimes hard to diagnose from afar. A "clunk" sounds like something way loose, a rock hitting the BB area, a coil spring preload blacked off too far, rebound glide-ring broken on the shock piston, etc. The cinch cranksets are very picky about torque on the chainring collar, and to get that collar to the specified torque takes a LOT of force, get it to that force and the noise usually goes away.
    "It's only when you stand over it, you know, when you physically stand over the bike, that then you say 'hey, I don't have much stand over height', you know"-T. Ellsworth

    You're turning black metallic.

  18. #18
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    Quote Originally Posted by Jayem View Post
    The cinch cranksets are very picky about torque on the chainring collar, and to get that collar to the specified torque takes a LOT of force, get it to that force and the noise usually goes away.
    When I am tightening that lockring, I put my crank arm in a vise with soft jaws and put my torque wrench on it. The fixing bolts (crank arm to spindle) are the more tricky ones for me, as the crank wants to rotate.

    I am suspicious that OP has a crack somewhere. Or that the bike was not assembled properly. Impossible to judge someone's mechanical acumen on here.

  19. #19
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    iMust SN04 Full Suspension Issue-img_0772.jpgiMust SN04 Full Suspension Issue-img_0773.jpg

    When I removed my shock, I noticed something interesting. The rearward shock bolt has a tapered "flat head" bolt to attach the rear eye of the shock. When this bolt is loosened by a couple of turns, it wiggles back and forth freely about 1/16". The only other bike I have owned with a similar linkage was an old Ventana El Saltamontes. And I believe Ventana used Cap head bolts. Which were barrel head and fit nicely into a machined bore of similar size. I think this flat head bolt works fine for applying tighteneing pressure. But is not as well suited for side to side shear force. And as one of my photos shows, the paint is chipping in the taperd bore. rearward of the force applied to the shock by the seat stay. This may be allowing the shock bolt a little bit of side to side movement. Now the problem is how to address it.

  20. #20
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    Quote Originally Posted by Jayem View Post
    The cinch cranksets are very picky about torque on the chainring collar, and to get that collar to the specified torque takes a LOT of force, get it to that force and the noise usually goes away.

    I agree with that statement. The only thing I can say in my defense is that I have installed Next SL cranks on two other bikes. A Pivot Les Fat, and a Pivot Mach 6. And both of these bikes work quite well and don't (presently) make any unusual pops, pings, clunks or creaks. However, I expect that if I give these bikes sufficient time and poor treatment, they will start acting up too. From what I can remember from experience, there are bikes that creak, and bikes that don't creak (yet).

  21. #21
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    I am thinking that if I sand the tapered bore down I can fill the very loose bore for the bolt shaft, and the tapered countersink bore itself with JB weld. And let it cure over night. And hope for the best that this will fix the issue. I might put some cellophane tape on the bolt shaft so that the glue will break loose easy when I nee to remove the shock in the future. Another fix might be to find the proper sized Cap Head bolt to replace the flat head bolt. And use a drill press to carefully create a cylindrical bore where there is presently a countersink tapered bore. But first I wish to be sure this is the cause of the problem. As I said before, there is a lot to like about this bike. But just a few bugs to fix.

  22. #22
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    Quote Originally Posted by endo_alley View Post
    ..... From what I can remember from experience, there are bikes that creak, and bikes that don't creak (yet).
    So true! And the more moving parts, the sooner it happens.
    Latitude 61

  23. #23
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    iMust SN04 Full Suspension Issue-img_0774.jpg

    For better or worse, I epoxied the shaft of this bolt in tight. And I epoxied the oblong shaped nut on the other side, tight to the frame pocket where it fits. I also applied blue Loktite threadlocker to all threads I could get to. And I cleaned and properly re-torqued all pivot, linkage and bearing points. I let the epoxy dry over night. I didn't touch the cranks. And voile! No more pings, pops or clicks. I had been having a little buyers remorse thinking the frame was wearing out. But now it is fine. I noticed the bearing nuts at the rear Split-Pivot (24mm or 15/16 socket size) were the ones most out of spec. I think they need to be threadlocked and kept torqued to fairly tight specifications. I really don't know if the glue (JB Weld plastic epoxy) was absolutely necessary. I hope this will be useful to thers with this bike.

  24. #24
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    iMust SN04 Full Suspension Issue-img_0775.jpg

    I noticed, when trying a different shock, that it looked as if a 200mm x 57mm rear shock would clear on this frame. If so, one might be able to get 12% more travel out of the bike. I didn't have the proper bushings to put the shock through all its motions. So this is just speculation presently on my part. But I have heard that the Imust/Ican P8 frame will easily take a longer stroke shock than it's spec. And as a 27.5 plus bike, will handle 29" wheels too. Just sayin.

  25. #25
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    Thanks for the info, will be replacing the pivot's bearings hopefully today and loktite them.

    Are those wheels 29 or 27.5?

  26. #26
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    29+ Chupacabras. Those split pivots seem especially touchy when it comes to proper torque.

  27. #27
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    Love those tires, have a 29+ on the front and 27.5+ in the rear on my Stumpy and both are great.

  28. #28
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    Quote Originally Posted by endo_alley View Post
    Click image for larger version. 

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ID:	1155986

    For better or worse, I epoxied the shaft of this bolt in tight. And I epoxied the oblong shaped nut on the other side, tight to the frame pocket where it fits. I also applied blue Loktite threadlocker to all threads I could get to. And I cleaned and properly re-torqued all pivot, linkage and bearing points. I let the epoxy dry over night. I didn't touch the cranks. And voile! No more pings, pops or clicks. I had been having a little buyers remorse thinking the frame was wearing out. But now it is fine. I noticed the bearing nuts at the rear Split-Pivot (24mm or 15/16 socket size) were the ones most out of spec. I think they need to be threadlocked and kept torqued to fairly tight specifications. I really don't know if the glue (JB Weld plastic epoxy) was absolutely necessary. I hope this will be useful to thers with this bike.
    What did you do so you could remove the bolt im the future?
    Latitude 61

  29. #29
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    Quote Originally Posted by sryanak View Post
    What did you do so you could remove the bolt im the future?
    ER.UH. UMM. good question.

  30. #30
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    I am hoping that the plastic epoxy is not as strong as regular slow set JB Weld. And maybe I can break the bond when I need to. That might not be a good assumption.

  31. #31
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    Quote Originally Posted by endo_alley View Post
    I am hoping that the plastic epoxy is not as strong as regular slow set JB Weld. And maybe I can break the bond when I need to. That might not be a good assumption.
    Yeah, you are going to hate yourself when it is time to service that shock.

    Sent from my SM-G900V using Tapatalk

  32. #32
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    Quote Originally Posted by Harold View Post
    Yeah, you are going to hate yourself when it is time to service that shock.

    Sent from my SM-G900V using Tapatalk
    I guess the whole "Live for the moment" philosophy may not be a good long term strategy. Anyhow, I don't recommend this fix to anybody else. I was going nuts chasing down the clunk. Now it has gone away. I will bask in my happiness till something else comes along and needs attention.

  33. #33
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    Quote Originally Posted by endo_alley View Post
    I guess the whole "Live for the moment" philosophy may not be a good long term strategy. Anyhow, I don't recommend this fix to anybody else. I was going nuts chasing down the clunk. Now it has gone away. I will bask in my happiness till something else comes along and needs attention.
    Like wearing out your lower shock bushings that you can no longer get to? That will be a fun clunk to chase.

    Sent from my SM-G900V using Tapatalk

  34. #34
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    Heat the bolt end with a soldering iron, it'll come loose fine.

  35. #35
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    I really don't think the glue is that strong. Has the original poster fixed his problem? I kind of hijacked the thread. But only because I was getting ready to ask the same question on the same day he posted. Hope he has had good luck quieting his bike.
    Last edited by endo_alley; 2 Weeks Ago at 06:55 AM.

  36. #36
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    Not yet! Still waiting for my bearing to show up

  37. #37
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    Quote Originally Posted by Nash04 View Post
    Not yet! Still waiting for my bearing to show up
    Which bearing went bad? On a new bike, it must have been a manufacturers error. Was there play in the bearing?

  38. #38
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    Found 2 of the bearings on the pivot arm to be moving lateral (side-side) but still feels good while rolling them but decided to replace them.
    Funny thing is that I brought the H bracket to my LBS so they could replace 2 of the bearings since I already had removed 2 of them and asked them to install the new ones and they were going to charge me $ 50 for labor and $12 per bearing so I told them Thanks but No Thanks. I'm able to purchase the bearings between $6-8 per bearing and wanted you all do it so I can bring in some business but that's outrageous. Takes maybe 10-15 minutes to do the whole job?

  39. #39
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    Hmm. Is it the bearings themselves or the machining of the frame where they seat? On my bike, there was a little slop in the seat of the bolts. Hence my reason for taking up some of the space with plastic epoxy.

  40. #40
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    No it's the inner race of the bearing was moving side to side but I replace 2 of them since Amazon didn't deliver in time (again) and issue is still persisting, have swap pedals, cassette and again new chain (Shimano) this time and noticed it's coming from the rear of the bike but the DT swiss hub has been rebuilt. The only thing that I've not touch as of yet is where the axle attaches to the frame but am not going today since I want to ride this afternoon, perhaps tomorrow. Getting real fed up especially since most of the parts came from my other CC fatbike frame and never had that issue but that one was a hardtail.

  41. #41
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    I can only say, my Imust Sno4 developed some clunks. And I retorqued everything with a 3/8" drive 5-80 lb/ft range torque wrench, to specifications. And I used blue thread locker. I also epoxied the black oblong threaded nuts on the opposite side of the bolts, into the frame. I will show a photo of one of them. The concentric bearing which surrounds the rear axle is particularly important to torque properly. Anyhow, since doing all this, my bike went from a clunk monster to being quiet as a mouse. And as I said before, I put a little epoxy on the caps of the shock bolts. Although, that is a last ditch thing to do.



    iMust SN04 Full Suspension Issue-img_0776.jpg

  42. #42
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    This is a very important bearing/ bolt to torque properly.
    Attached Thumbnails Attached Thumbnails iMust SN04 Full Suspension Issue-img_0778.jpg  


  43. #43
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    Have created a MPG and sent to iMust, they responded to my email pretty quick, very impress.

  44. #44
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    Well! Finally found the issue.

    Took the rear axle attaching points apart and noticed on the NDS that the C-Clip was just hanging between the nut and flange and you can see some damage on the nut's surface where the clip was just rotating each time you either put some weight/torque on the swing arm.

    From I can see, there's no lip for the clamp to secure onto.

    Sent the pictures to iMust and we'll see what's the next step to resolve.
    Attached Thumbnails Attached Thumbnails iMust SN04 Full Suspension Issue-ndsdamage.jpg  

    iMust SN04 Full Suspension Issue-nds-dsnut-clamp.jpg  

    iMust SN04 Full Suspension Issue-ndsrearaxle.jpg  


  45. #45
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    All that stuff could use locktite after you replace the warn parts. Prone to loosening. Don't let it loosen.

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    Bought some tools and was able to re-install the C-Clip and torque the nuts IAW and issue is persisting so took whole swing arm apart then put it back together one joint at a time with carbon grease and loctite and now the sound is not as noticeable but still there especially when I put a load on the suspension, sounds like it's coming from the H bracket connecting the suspension together. One thing that I also noticed is when I removed the rear shock then installed a 0.75" square piece of wood and secured it to the frame, I noticed the rear attachment point if off from the center point, basically the temp piece of wood was dead center in the front but off by about 0.25" to the right at the rear, wonder if it's putting pressure on the rear shock when installed. The piece of wood is totally straight so it must be the rear attachment point that is off center.

  47. #47
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    I think the bushings are offset - thicker on one side than the other. So that may not be the issue. I don't completely trust those oblong shaped nuts which the pivot bolts thread in to. So I epoxied them on my bike.
    Last edited by endo_alley; 5 Days Ago at 05:26 PM.

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