Results 1 to 11 of 11
  1. #1
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    78

    monarch 4.2 creaking and where to get IFP air adapter tool?

    Just got a monarch 4.2 rear shock. I love it except for an annoying creaking or popping that Im getting from the shock. I get it at the very top of the travel and only when the shock is pumped to 200 psi. Lower pressures - say 100 psi - and the noise goes away. I triple checked all my hardware and pivot points and know for sure its coming from the shock. I can feel the piston bump when I hear the creak.

    I called RS and they were not aware of known issues with this... They suggested that maybe its a loose can or damper assembly... Im tempted to rebuild the shock just to insure everything is lubed.

    Has anyone experienced this?

    If I go thru with the rebuild, does anyone know where I can get the air valve adapter tool at the the bottom of the piston? I dont want to disassemble anything until I have all the tools.

  2. #2
    LDH
    LDH is offline
    mtbr member
    Reputation: LDH's Avatar
    Join Date
    May 2007
    Posts
    762
    add a few cc's of fork oil to air canister before you try anything else.

  3. #3
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    78
    Thanks for the information LDH. I think I found the problem. The piston bump I was feeling was actually play between the shock eyelet and pivot bolt. The eyelet opening is 8mm diameter and the pivot bolt is 7.85mm. That is enough play to cause the popping. I put some teflon tape wrap and grease around the lower pivot bolt and creak was eliminated. BTW, with no air pressure in the shock, you can feel the looseness in the shock and frame when the shock is topped-out.

    Im now reading on other threads that this kind of play will cause this symptom...

    Im suprised that these bolts are so sloppy on tolerances...

  4. #4
    mtbr member
    Reputation:
    Join Date
    Dec 2005
    Posts
    44
    Quote Originally Posted by tj90
    Thanks for the information LDH. I think I found the problem. The piston bump I was feeling was actually play between the shock eyelet and pivot bolt. The eyelet opening is 8mm diameter and the pivot bolt is 7.85mm. That is enough play to cause the popping. I put some teflon tape wrap and grease around the lower pivot bolt and creak was eliminated...
    IMO it is not a solution. These things should not move against each other. Look here
    http://www.tftunedshox.com/info/moun..._bushings.aspx
    What sort of mounting hardware do you have? If Heavy Duty - just squeeze it harder. Theoretically you can do the same in case of Standard Kit but it may happen to be out of spec and that would cause increased friction so more attention is required.

  5. #5
    mtbr member
    Reputation:
    Join Date
    Mar 2005
    Posts
    2,029
    No 8mm bolt will ever measure 8.00mm (unless you coughed up for a precision ground custom shoulder bolt). The number is the nominal thread diameter, not a measurement of the bolt shaft. If the bolt did happen to be a press fit tollerance (to both the shock hardware as well as the frame mount tab holes), how would you get through the mounting hardware?? Put you bike in a press and press the bolt through? What would you do when the mount tab holes wore from pressing in the bolt?


    As mentioned above, the simple solution and the way bike shock mounts are designed...is to pinch the frame mount tabs tight against the shock mount hardware, thus eliminating movement at the mount without requiring any sort of precision parts or press fit assemblies that one would not have at home (or a bike shop).

    Tighten the bolts....

  6. #6
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    78
    The shock has a heavy duty 1-piece axle style. Manufacturer recommends the bolt should be tightened to 115 in-lbs - not alot of torque! The manufacturer also says "Ensure
    that the shock reducers are not rotating on the shock axle - the shock
    should be rotating on the reducers." Im not sure what that means... Reducers are used on standard duty mount kits...

  7. #7
    mtbr member
    Reputation:
    Join Date
    Dec 2005
    Posts
    44
    It seems the manual has been written for standard kit and addresses another issue which is not the one you have experienced. Anyway the Axle/Pin must not move in relation to frame/link/swingarm (wherever it's mounted). It's a similar story as with qr axle/dropouts the axle is not immobilized by the fact it protrudes into the dropouts, actually you can cut it off right at its nuts so it would not protrude into dropouts at all and after fastening the qr it will stay in place. The force which keeps it there comes from the qr mechanism. Similarly rear shock absorber is not kept in place by the fact that the bolt which goes through it protrudes into the frame tabs (/link/swingarm...) but by a squeezing force. Thus you can use a bolt of smaller diameter say 5mm instead of 7.85mm and it will work as well (assuming its tensile strength is high enough and it doesn't elongate too much).
    The question is: what is the maximum clamping force the system can withstand? IMO it depends mostly on frame (/link/swingarm...) material aluminum should accept a lot, CF perhaps less or some washers would be required. Sorry - I can't provide any numbers.
    BTW some intriguing associations came to my mind:
    - qr mounted shocks used to be found in some frames (e.g. Rocky Mountain ETSX), perhaps the qr leverage was higher,
    - Iron Horse 10 mm shaft standard what for is that?
    - wheel axle nuts and drop outs are more sophisticated although they carry less load.
    Have more thoughts on this?

  8. #8
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    78
    OK, I think Im understanding now. Provide enough compressive force to the frame to squeeze the hollow axle between the frame. If you put enough compression on the hollow axle, the bolt - even if its smaller diameter than the hole in the axle - will not see any shear loads from the shock hardware. If the shock hardware is moving in relation to the frame its too loose and will cause the condition Im experiencing. This explains why RS puts some type of bushing material on the eyelet so it can easily rotate around the hollow axle.

    Why do they provide 2 bushings that slip over the axle on both sides of the shock eyelet? Is it to keep the shock centered? You definitely dont want the bushings to bottom out on the frame or you will prevent rotation of the shock around its pivot point. Maybe it keeps dirt out of the eyelet /axle interface?

  9. #9
    mtbr member
    Reputation: nagatahawk's Avatar
    Join Date
    Jun 2007
    Posts
    1,190
    This may or may not be related, but the lbs intalled a rearshock on my bike. I had an unusual creak during pedaling the no one could locate. I removed the shock and lubed the spacers that centered the shock with some with lube. End of Creaking!

    I lube any and all metal to metal mounts. stem, seat post, shock spacers, and pedals.

  10. #10
    mtbr member
    Reputation:
    Join Date
    Dec 2005
    Posts
    44
    Quote Originally Posted by tj90
    Why do they provide 2 bushings that slip over the axle on both sides of the shock eyelet? Is it to keep the shock centered?
    Yes. They are spacers.

  11. #11
    mtbr member
    Reputation:
    Join Date
    Oct 2006
    Posts
    78
    Thanks for the clarification. Im always amazed about how little I know about something right under my nose!! Thanks for the knowledge!

Posting Permissions

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