X-Challenge Air Shock Problems

Discussion in 'Thumpers' started by W8-4IT, Sep 27, 2007.

  1. R-dubb

    R-dubb Dubbious Adventurer

    Joined:
    Aug 4, 2001
    Oddometer:
    5,307
    Location:
    San Francisco
    I think it's now kind of a cross over from the bicycle world. Airshocks are lighter and more easily adjustable for various conditions. Not saying it's successfull, but you can't really judge from what happened in the 80's, can you? Materials, machine tolerances and overall designs have come a long way since then. I had plenty of Italian bouncies with air bladders. None them worked worth a damn. Best thing you could do was let all the air out and use stiffer springs and/or heavier oil.
    #21
  2. Lone Rider

    Lone Rider Registered User

    Joined:
    Jan 29, 2002
    Oddometer:
    25,130
    Location:
    out and about
    What's replacemnt cost of the BMW air shock?

    I could very well be wrong, but believe that BMW has done another BMW type of thing here.
    #22
  3. ctfz1

    ctfz1 been there

    Joined:
    Jul 8, 2006
    Oddometer:
    2,807
    Location:
    Waterbury, CT, USA
    Air shocks work on large vehicles, bicycles don't know. Harley used spring and air, reservoir and spring loaded diaphram.
    Size and air capacity effect air shocks, as does dialing in.
    Suspect Ohlins or equiv with proper spring choice better idea, being refined for 60? 80 ? years.
    #23
  4. GB007

    GB007 Been here awhile

    Joined:
    Aug 22, 2007
    Oddometer:
    284
    Location:
    Southern California, USA
    I paid extra to get a BMW with the new technology of air shock, figuring out that if it was being used by HP2, it was probably a good product. Why pay another $850.00 to get regular suspension set up? So far I am happy with my current set up. I can adjust it just the way I like it and any time. The draw back is that sometimes I have to adjust it in the middle of a ride depending on outside temperature. For the type of riding I do, and my weight (about 165 lb, I keep it at about 85lb pressure), seems to work great! :norton
    #24
  5. Hair

    Hair I am on my way. Supporter

    Joined:
    Sep 28, 2003
    Oddometer:
    20,030
    Location:
    Northern New Mexico
    I know almost nothing about an air shock.
    But since you brought up the topic of changing do to a change in air temp.

    What about altitude?

    What happens when one rides to the top of a pass? A change of several thousand feet.
    #25
  6. W8-4IT

    W8-4IT Been here awhile

    Joined:
    Dec 9, 2003
    Oddometer:
    300
    Location:
    Thornville, OH
    The Ohlins shock is $810 from TT. But the other choice is Wilbers will build you a custom valved shock for your weight for $540 and it is ride height adjustable. It will lower the seat height up to 2" and if you want the fork springs to lower the front of the bike they are $130 dollars from Wilbers.

    Does anyone know what the Ohlins unit does for the seat hieght?

    The only draw back to the Wilbers is it has rebound and preload adjustments only no compression adjustments where the Ohlins I believe is adjustable for all 3.
    #26
  7. boyscout

    boyscout sittin' down

    Joined:
    Oct 1, 2001
    Oddometer:
    1,336
    Location:
    Corvallis Oregon
    It's a sealed system. The air inside the shock will compress at the same rate independent of the outside air pressure.
    #27
  8. Hoots Magoon

    Hoots Magoon Hey ya'll, Watch this!

    Joined:
    Mar 22, 2007
    Oddometer:
    1,259
    Location:
    Redneck in New England
    Air pressure at sea level is 14.69 PSIG. The pressure inside the shock is 80 to 130 PSIG depending on the rider's weight and riding style. The outside air pressure would have to be higher than the shock pressure plus enough to compress the shock walls. So if the barometric pressure increased to 65 PSIG, I think you would have more to worry about than the G-650 rear shock.

    On the flip-side, when going up in altitude, the pressure is lower. At 7000 ft the pressure is at 11.34 PSIG, so only a difference of 3.05 PSIG which shouldn't effect a metal container engineered to hold more than 200 PSIG.:norton
    #28
  9. PacWestGS

    PacWestGS Life Is The Adventure!

    Joined:
    Aug 28, 2005
    Oddometer:
    10,863
    Location:
    A Worldly Traveller
    I certainly need to spend more seat time before I can form an opinion. I think it's working just fine, it's just different.

    I recently spoke with Jimmy Lewis about the air shock and the problems they've had while racing the HP2. All of the "Extra" travel one's had one problem or another, blown bladders, broken internals, etc. During last years Baja race (I think the 500) they blew the race preped shock, changed back to the stock (air) shock and finished the race, Jimmy said they have never had a race related failure from the stock air shock.

    I think it is important to make all adjustments while the shock is cold and just ride with what you got until the next time you can make a cold adjustment.

    Remember to make notes for what works best on-road, off-road, and serious trails than adjust properly.

    I think its design gives into a not-one-size-fits-all-conditions. What is comfortable on-road may not provide the best off-road suspension. I don't think any shock will truly live up to that requirement.

    I've been pretty happy at 110psi (I weigh close to 220 geared up) Damping - Soft=Highway, Hard=Off the beaten path
    #29
  10. Metteke

    Metteke Beemer beat in me

    Joined:
    Jul 8, 2007
    Oddometer:
    209
    Location:
    Flanders Fields
    Just to make things clear, Max has it right. Do not use the air bubble.
    BMW has said in an internal document that the bubble is not placed well.
    Instead, get on your bike (in riding gear) and put full weigth on the bike on the position you ride it (some on the rear end of the saddle, some more to the steer etc.). Then ask a buddy to measure the distance between the top of the rear axle and the most rear bolt for the luggage rack. It should be between 55 and 56 cm. This is the ideal static sag according to BMW.
    #30
  11. Venteuri

    Venteuri I don't give a shit

    Joined:
    Sep 3, 2007
    Oddometer:
    20,514
    Location:
    Queretaro , Mexico
    For those who had the shock problem: how much the replacement cost?
    #31
  12. W8-4IT

    W8-4IT Been here awhile

    Joined:
    Dec 9, 2003
    Oddometer:
    300
    Location:
    Thornville, OH
    The Ohlins is listed at $810 through TT which has remote compression adjustment, rebound adjustment and preload (static sag) adjustment.

    Wilbers makes one for $539 that has rebound adjustment and preload adjustment but no compression adjustment. For $899 they make their race shock that has low and high speed compression adjustment, rebound adjustment and preload adjustment.

    Both companies make them valved and spring selection according to your weight. Wilbers is ride height adjustable up to 2", so it would lower seat height by up to 2". The TT web site says the Ohlins is taller then the factory air shock but does not address seat height. Just because the shock is taller doesn't mean the seat height will be, because you will still set the static sag.

    Now you know what I know.:D Scarry isn't it.:lol3
    #32
  13. GSL

    GSL Team Big Wheel

    Joined:
    May 13, 2002
    Oddometer:
    1,751
    Location:
    Albany, OR
    Air shock problems? You betcha!

    I posted this in the threadfest but will repost here - just cuz I want to get enough people pissed off about the GX's that BMW will actually do something about this. Don't get me wrong, I LOVE MY GX!!! It's hand down THE best bike in the garage. It just has a few design flaws (and I seem to be finding all of them first :lol3 ).

    If you ride much off road, this is what your air shock is gonna look like just short of 5000 miles.

    [​IMG]

    That little shiny spot has a hole in the center of it. If you look at this hi-res version of the photo, you can actually see the wearing through the threads that wrap the bellows. This is the point where the rear mud flap rubs up and down on the shock (photo has mud flap removed).
    https://eurobikedenver.smugmug.com/photos/203381447-O-1.jpg

    There's just not much material there and 110 psi comes out pretty fast when it finally goes. This has got to be a serious safety issue for anyone that has converted the GX for 2-up riding. Imagine dualsporting, and coming in a little hot into a paved corner and you suddenly find yourself sitting just on top of the rear wheel. You'll have the maneuverability of that little Big Wheel in my avatar...
    #33
  14. GSL

    GSL Team Big Wheel

    Joined:
    May 13, 2002
    Oddometer:
    1,751
    Location:
    Albany, OR
    I see beefjerky posted something to this effect back on page 2 of this thread. But it sort of went un-noticed...
    #34
  15. GSL

    GSL Team Big Wheel

    Joined:
    May 13, 2002
    Oddometer:
    1,751
    Location:
    Albany, OR
    hhhmmmmm... :confused I wonder what would happen if I pumped some Fix-A-Flat into the shock...
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    .
    :poser
    #35
  16. smithy1

    smithy1 been here a while

    Joined:
    Mar 28, 2006
    Oddometer:
    1,218
    Location:
    eastern pennsylvania
    Sounds like keeping the plastic mud flap from rubbing the bladder would be an easy fix for BMW and myself. I will take a close look at mine tonight.
    #36
  17. JimC

    JimC Long timer

    Joined:
    Aug 28, 2003
    Oddometer:
    1,039
    Location:
    Sacramento, CA
    GSL,

    Thanks for posting this information, your doing so has probably saved many of us from the same fate. This clearly is a design issue with the mud flap, much to hard a material. We hopefully will be seeing a BMW recall to address the problem soon. I guess a few layers of duct tape until the official fix is released will keep us from the same ending as you had. This has got to be covered under warranty.

    Jim in Sacramento
    #37
  18. GSL

    GSL Team Big Wheel

    Joined:
    May 13, 2002
    Oddometer:
    1,751
    Location:
    Albany, OR
    Hi Jim,

    Well, good news, bad news. Just got off the phone with my BMW service guy up in Denver. I gave them the link to my pictures, they sent the link to BMWNA, and everyone is in agreement that this is a warranty issue. Parts are on order, life is good. However, BMW stated that they've seen this before. However, as of now, there is no recall.... You heard right. They've seen this before (I wonder if it was beefjerky's), and there is no recall.

    So far, of the people that have replied in the GX threadfest thread, that have checked their mudflap and shock, both (100%) have reported a rub/wear spot. This tells me that it is simply a matter of time before every bike suffers this fate.

    Please, if you have at least 2000 miles on your bike and check the shock/flap and you don't see any wear, please post here that I'm wrong. Believe me, I would love to be wrong. If you do see any wear, talk to your service guy, point them to this thread or my pictures and let's get BMW on the right page.

    Again, I love this bike! And I'm not trying to provide any negative publicity that I don't have to. In fact, I want to see this bike succeed! By getting better.

    Cheers y'all!
    #38
  19. GB007

    GB007 Been here awhile

    Joined:
    Aug 22, 2007
    Oddometer:
    284
    Location:
    Southern California, USA
    I checked out mine tonight and also saw the air shock is wearing out on the same spot as yours. As a temporary fix I put some washers on the whole system trying to move it a little farther away from the air shock. I don't like the fact that my air shock is already showing signs of wearing off... I'm going to discuss issue with dealership, and I want a new air shock with a permanent fix by BMW. I'll report how dealership deals with issue. I can understand having a few bugs here and there since it's a brand new design, but this is an important issue they have to come up with a fix ASAP. I can't see myself riding on a twisty road at 50 mph on a turn when the suspension goes all the way down suddenly. That could be very dangerous.
    #39
  20. Hoots Magoon

    Hoots Magoon Hey ya'll, Watch this!

    Joined:
    Mar 22, 2007
    Oddometer:
    1,259
    Location:
    Redneck in New England
    I just checked mine. At 1600 miles I have the same issue. On mine, the rub is showing the cord. I guess I'll be calling about a replacement tomorrow. I guess I'm kind of lucky. Next weekend, I'm rideing the bike to through Maine. I wonder if they can deduct the cost of a new air shock from the cost of a Ohlins?
    #40