Page 1 of 2 1 2 LastLast
Results 1 to 25 of 30
  1. #1
    Just another FOC'er
    Reputation: .Danno.'s Avatar
    Join Date
    Jun 2005
    Posts
    2,222

    Cool-blue Rhythm Pressurizing a Romic twin tube

    I know it's a bit of a long shot, but I wonder if anyone out there has come up with a clever way to repressurize a Romic? The access screw is on the top cap and has to be flush because the bottom out bumper flattens out on top of it. I believe that there's no valve inside that access screw, just the IFP chamber because when I loosen it a bit of oil starts to seep out. Threading a valve into the cap won't really work because it has to be flush. All I can figure is that Romic must assemble them under pressure!?

    Mine's still working somewhat, but it lost a fair amount of oil due to that access screw being loose. I'd like to change the oil and repressurize it, but just looking at it I'm not sure how to proceed...

    I know I should just send it to Romic for repair, but where's the fun in that?

  2. #2
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Anyone knows???

    I was wondering the same thing myself... but I don't have a Romic to look at.
    I was thinking it has a membrane type fill port... but based on your comments, I think it doesn't.

    But then it has to involve some special tool... maybe??
    Check my Site

  3. #3
    Just another FOC'er
    Reputation: .Danno.'s Avatar
    Join Date
    Jun 2005
    Posts
    2,222
    Warp, I never got any input from anybody so I experimented a bit. The seal head has a hole drilled through it that comes out on the air side of the IFP ring. There's a fill screw, but no check valve of any sort. The screw has to be flat against the seal head because the bumper sits against it. For that reason there's no easy way to add a check valve.

    I've heard that Romic uses a pressure vessel to pressurize them.

    I found that I could use a small piece of electrical tape on the inner side of the seal head to act as a check valve. I wrapped tape around a basketball inflator needle to fit the fill screw hole tightly. Using this method I could easily fill it to 150 psi. I've rebuilt 3 now and they all are working perfectly. When I first took them apart I found the oil completely emulsified and the damping was shot.

    I'm using ~26 cSt @40 HVI shock oil.

  4. #4
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by .Danno.
    Warp, I never got any input from anybody so I experimented a bit. The seal head has a hole drilled through it that comes out on the air side of the IFP ring. There's a fill screw, but no check valve of any sort. The screw has to be flat against the seal head because the bumper sits against it. For that reason there's no easy way to add a check valve.

    I've heard that Romic uses a pressure vessel to pressurize them.

    I found that I could use a small piece of electrical tape on the inner side of the seal head to act as a check valve. I wrapped tape around a basketball inflator needle to fit the fill screw hole tightly. Using this method I could easily fill it to 150 psi. I've rebuilt 3 now and they all are working perfectly. When I first took them apart I found the oil completely emulsified and the damping was shot.

    I'm using ~26 cSt @40 HVI shock oil.
    Thanks, Danno... minutes later after I posted this question, I found your post on RM.

    Thanks for the detailed response. I'll try to snag a Romic.

    If you remember my perils with the Roco, I'vecame to the conclusion that the problem is the aggressive progression of it's spring rate (main chamber+IFP) paired with the raising rate of my frame.

    The Titus Switchblade with the rockers I have, goes from 3.1:1 to 2.1:1... So, when you get the sag set up, you end up automatically with a lot of bottom out "protection". I don't huck or do drops of any kind so it's kinda pointless.

    I'll be putting a coil-over. There is no space for a piggy back which is the most widespread shock nowadays, so I'm aiming at a Romic or Vanilla.
    Check my Site

  5. #5
    mtbr member
    Reputation:
    Join Date
    Apr 2006
    Posts
    257
    wow,

    you guys blow my mind...

    bahhhh...


    great stuff!!!

    i need hollydays so i can get my hands on some shocks!!!!

  6. #6
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by Marcolino
    wow,

    you guys blow my mind...

    bahhhh...


    great stuff!!!

    i need hollydays so i can get my hands on some shocks!!!!
    There are people who really know their stuff... Dougal, Danno, bmadau, Pushind, presslab, etc.

    I'm just learning from them. Danno's help was invaluable to sort out my Roco.
    Check my Site

  7. #7
    Just another FOC'er
    Reputation: .Danno.'s Avatar
    Join Date
    Jun 2005
    Posts
    2,222
    Quote Originally Posted by Warp
    Thanks, Danno... minutes later after I posted this question, I found your post on RM.

    Thanks for the detailed response. I'll try to snag a Romic.

    If you remember my perils with the Roco, I'vecame to the conclusion that the problem is the aggressive progression of it's spring rate (main chamber+IFP) paired with the raising rate of my frame.

    The Titus Switchblade with the rockers I have, goes from 3.1:1 to 2.1:1... So, when you get the sag set up, you end up automatically with a lot of bottom out "protection". I don't huck or do drops of any kind so it's kinda pointless.

    I'll be putting a coil-over. There is no space for a piggy back which is the most widespread shock nowadays, so I'm aiming at a Romic or Vanilla.

    I always liked the feel of the Romic shocks, certainly more than the older Vanillas. You could set the IFP pretty deep to make it as linear as possible for your Switchblade.

    I worked out the whole pressurizing problem without any guts in the shock to make it easy. Once I got the method worked out I assembled everything and filled it with oil. It seems kind of tricky, but it ended up working out perfectly. Kind of surprising.

  8. #8
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by .Danno.
    I always liked the feel of the Romic shocks, certainly more than the older Vanillas. You could set the IFP pretty deep to make it as linear as possible for your Switchblade.

    I worked out the whole pressurizing problem without any guts in the shock to make it easy. Once I got the method worked out I assembled everything and filled it with oil. It seems kind of tricky, but it ended up working out perfectly. Kind of surprising.
    Thanks, Bro!

    I'm getting one, get it rebuilt by Romic... but if then it craps out on me, I now I can repair it myself thanks to you.
    Check my Site

  9. #9
    mtbr member
    Reputation:
    Join Date
    Sep 2004
    Posts
    28
    Hi guys,
    I've just bought an unused Romic Twin Tube for 100$ including spring and bushings. However I don't think it has pressure. Without the spring, I can push the piston in completely and there's nothing to push it back out.
    This shock is without warranty and I feel comfortable playing around with shocks innards.
    So I guess I'm going to give this electrical tape thing a go.
    I have 16 Cst Kayaba oil, will that be good enough, or is it maybe not viscous enough? Seing you used 26..
    Did you use a special tool to open the piston chamber, to rotate the two holed threaded thing?
    Cheers

  10. #10
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by RoelantVDL
    Hi guys,
    I've just bought an unused Romic Twin Tube for 100$ including spring and bushings. However I don't think it has pressure. Without the spring, I can push the piston in completely and there's nothing to push it back out.
    This shock is without warranty and I feel comfortable playing around with shocks innards.
    So I guess I'm going to give this electrical tape thing a go.
    I have 16 Cst Kayaba oil, will that be good enough, or is it maybe not viscous enough? Seing you used 26..
    Did you use a special tool to open the piston chamber, to rotate the two holed threaded thing?
    Cheers
    Normal service at Romic is like 40 bucks... Give it a go. I just received a shock from them.
    Check my Site

  11. #11
    mtbr member
    Reputation:
    Join Date
    Sep 2004
    Posts
    28
    Thanks for the suggestion. I would do that, however I live in Switzerland and postage to the US is going to be very costly.
    Does your shock stay compressed if you compress it without a spring? No squishy noise?
    Cheers
    Roelant

  12. #12
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,480
    Quote Originally Posted by RoelantVDL
    Thanks for the suggestion. I would do that, however I live in Switzerland and postage to the US is going to be very costly.
    Does your shock stay compressed if you compress it without a spring? No squishy noise?
    Cheers
    Roelant
    FWIW, I just sent a small package the weight and dimensions of a shock to Zurich and it was only like $12. Hopefully the contract charge is somewhat reflective of what it might cost to send the shock to the US. It took four business days, including customs.

  13. #13
    Just another FOC'er
    Reputation: .Danno.'s Avatar
    Join Date
    Jun 2005
    Posts
    2,222
    Quote Originally Posted by RoelantVDL
    Does your shock stay compressed if you compress it without a spring? No squishy noise?
    Cheers
    Roelant
    I'd have to go find my notes again for the Romic, but I think the IFP/Shaft area ratio was a bit over 3. I put about 150 lbs in the ones I rebuilt which means I was getting ~50lbs of force pushing the shaft out at full extension. It takes maybe a couple seconds to extend and that of course depends on how your rebound is set.

    No squishy noises after the rebuilds, lots of noise beforehand.

    I built a tool out of an old cone wrench and a couple machine screws to take off the top cap.

  14. #14
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by Jerk_Chicken
    FWIW, I just sent a small package the weight and dimensions of a shock to Zurich and it was only like $12. Hopefully the contract charge is somewhat reflective of what it might cost to send the shock to the US. It took four business days, including customs.
    However Romic only goes UPS.

    I paid 60 bucks for shipping to Mexico. He can get it sent to someone in the US and then back to CH by USPS and it'd come cheaper.

    To Roelant.... No, actually I can't compress the thing with my hands completely without the spring (not that I'm strong anyways) and no squishy noises.

    Actually, any shock with noises and easily or totally compressible by hand is way too low in IFP pressure. Maybe the CCDB is different in that regard, though.

    I was watching that auction where you won the Romic (if it was the one that ended last week)... it surprised me to see someone paying 100 dollars... They have been going at around 60. But that one you got was advertised as "just rebuilt" (I was about to bid on it, but I had mine coming at Romic already) and I would make a claim to the seller. Sorry to hear your troubles.

    Agreed with Danno... Use a pin spanner to remove the cap. I have yet to try his method of inflating the shock (if mine ever gives up the ghost), but I used a similar tip to inflate a Roco and it can totally work.
    Check my Site

  15. #15
    mtbr member
    Reputation:
    Join Date
    Sep 2004
    Posts
    28
    Actually, the one I got is a refurbished one directly from the swiss importer. They advised it as a no warranty item, with new bushings (of the size I wanted) as well as a new spring with the rate of choice... I think 100$ is not a bad deal all things considered, even if it IS out of pressure. I guess this one was lying around for too long and air got into it, creating the slurping noise. It does look brand new... And anyways, I love tinkering... ;-)

  16. #16
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by RoelantVDL
    And anyways, I love tinkering... ;-)
    Check my Site

  17. #17
    Equal opportunity meanie
    Reputation: DHidiot's Avatar
    Join Date
    Aug 2004
    Posts
    2,784
    Quote Originally Posted by Warp
    If you remember my perils with the Roco, I'vecame to the conclusion that the problem is the aggressive progression of it's spring rate (main chamber+IFP) paired with the raising rate of my frame.

    The Titus Switchblade with the rockers I have, goes from 3.1:1 to 2.1:1... So, when you get the sag set up, you end up automatically with a lot of bottom out "protection". I don't huck or do drops of any kind so it's kinda pointless.
    Which Roco were you using, the Air WC? I've been encountering a similar problem on my DH bike (R9, it's a 10" bike from a 3" stroke shock, goes from somewhere around 3.5:1 down to 2.5:1, not sure exactly but it stays progressive through the whole stroke). What I've been trying to fix is the high speed blowoff past the sag point. Between the linkage and the progressiveness of the shock, it can get harsh on really big bumps. I removed some shims from the compression side of the piston and used heavier weight oil (5w) to compensate, and it feels AMAZING on drops and jumps and high speed undulations, and better on rocks, but not as good as I'd like it to feel. I was thinking of removing a couple of the shims from stack at the base of the reservoir in similar fashion to the piston shims. I don't want to mess with the IFP depth too much because I like the progression of it on drops and big slow hits.
    805

  18. #18
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by DHidiot
    Which Roco were you using, the Air WC? I've been encountering a similar problem on my DH bike (R9, it's a 10" bike from a 3" stroke shock, goes from somewhere around 3.5:1 down to 2.5:1, not sure exactly but it stays progressive through the whole stroke). What I've been trying to fix is the high speed blowoff past the sag point. Between the linkage and the progressiveness of the shock, it can get harsh on really big bumps. I removed some shims from the compression side of the piston and used heavier weight oil (5w) to compensate, and it feels AMAZING on drops and jumps and high speed undulations, and better on rocks, but not as good as I'd like it to feel. I was thinking of removing a couple of the shims from stack at the base of the reservoir in similar fashion to the piston shims. I don't want to mess with the IFP depth too much because I like the progression of it on drops and big slow hits.
    No, bro.. the plain Roco Air R from 2007.

    I'd keep the stack you're using now, use lighter oil and compensate the low speed by preloading the compression shim stack. The piston is dished on the Roco Air R, I would expect at least the same from any of the WC's.

    In that way you'll get less HSC while keeping the LSC acceptable.
    Check my Site

  19. #19
    mtbr member
    Reputation:
    Join Date
    Sep 2004
    Posts
    28
    okay; well, I took the shock apart (there was 0 pressure left) and rebled the thing, new oil, reassembled but didnt get the electrical tape thing to work quite yet. (it's not sticking the the inside of the chamber head properly). So i'm basically at starting point except that I now have less air in the oil chamber, which is already a definite improvement
    I will look into the pressurizing later. Maybe with a sort of shim...

    To Danno: How deep did you set the IFP? Because now I set it all the way in. I'm pretty sure that's wrong for progresiveness, but I didn't want to end up with the IFP topping out and creating a hydraulic lock. I guess I can calculate the oil displaced by the piston shaft easily and the distance the IFP would travel measuring the inner tube outer diameter and outer tube inner diameter, then setting an average value, but there is nothing like experience

  20. #20
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by RoelantVDL
    okay; well, I took the shock apart (there was 0 pressure left) and rebled the thing, new oil, reassembled but didnt get the electrical tape thing to work quite yet. (it's not sticking the the inside of the chamber head properly). So i'm basically at starting point except that I now have less air in the oil chamber, which is already a definite improvement
    I will look into the pressurizing later. Maybe with a sort of shim...

    To Danno: How deep did you set the IFP? Because now I set it all the way in. I'm pretty sure that's wrong for progresiveness, but I didn't want to end up with the IFP topping out and creating a hydraulic lock. I guess I can calculate the oil displaced by the piston shaft easily and the distance the IFP would travel measuring the inner tube outer diameter and outer tube inner diameter, then setting an average value, but there is nothing like experience
    While waiting for Danno to come up with the correct value, check out this thread too...

    Vanilla RC service
    Check my Site

  21. #21
    Equal opportunity meanie
    Reputation: DHidiot's Avatar
    Join Date
    Aug 2004
    Posts
    2,784
    Quote Originally Posted by Warp
    No, bro.. the plain Roco Air R from 2007.

    I'd keep the stack you're using now, use lighter oil and compensate the low speed by preloading the compression shim stack. The piston is dished on the Roco Air R, I would expect at least the same from any of the WC's.

    In that way you'll get less HSC while keeping the LSC acceptable.
    The tension on the shimstack shouldn't affect the behavior of the shims at the very tips right? Or are you referring to the actual compression adjuster?

    What part is "dished"? Do you just mean the two faces are concave or are you referring to the spaces in it?
    805

  22. #22
    banned
    Reputation: Jerk_Chicken's Avatar
    Join Date
    Oct 2005
    Posts
    16,480
    Come on guys, install a shraeder!

  23. #23
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by DHidiot
    The tension on the shimstack shouldn't affect the behavior of the shims at the very tips right? Or are you referring to the actual compression adjuster?
    No, you got it right... I was talking about the shims.

    AFAI Understand, the preload of the shims will only affect the force required to open them, not at their behaviour when they're open.

    Quote Originally Posted by DHidiot
    What part is "dished"? Do you just mean the two faces are concave or are you referring to the spaces in it?
    On the Roco Air R, the compression face of the piston is dished... meaning indeed that the surface of it is concave relative to the shims on that face. I haven't messed with the compression ports... Nor do I plan to.

    Check out the rebuild manual for the WC at the windwave.co.uk site if you haven't already.
    Check my Site

  24. #24
    mtbr member
    Reputation:
    Join Date
    Sep 2004
    Posts
    28
    Quote Originally Posted by Jerk_Chicken
    Come on guys, install a shraeder!
    Would have been done straight away, but unfortunately the port of filling up is on the face where the bottom out bumper ends. Cannot have anything sticking out.
    Next time I go diving i'll just take the shock with me, go extra deep, and seal it when my depth gauge reads 150 PSI.

  25. #25
    "El Whatever"
    Reputation: Warp's Avatar
    Join Date
    May 2004
    Posts
    18,645
    Quote Originally Posted by Jerk_Chicken
    Come on guys, install a shraeder!


    We need one that has ZERO height!!!

    After all, is not that bad of an idea, but requires some machining (tapping at the very least).
    Check my Site

Page 1 of 2 1 2 LastLast

Posting Permissions

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