R1100GS Suspension Tuning & Troubleshooting

Discussion in 'GS Boxers' started by CoatsEast, Nov 6, 2018.

  1. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

    Joined:
    Apr 19, 2016
    Oddometer:
    660
    Location:
    Raleigh, NC
    Searched and there are a lot of R11GS threads on specific issues with shocks. I thoughts I'd start this one where others can add their issues and tuning tips to build up a knowledge base. My other bike is a G650X and its nice to have one or two main threads to follow so mybe this can become a main thread on suspension talk.

    I'll start!

    On, I decided to make my low mileage (20K) gem of 1999 a keeper bike so invested $$$$ in new Hyperpros set up for my weight (220lb loaded) and riding style (80/20 road/dirt). Installed them as they came from Klaus at EPM. Easy? Supposed to be set up just for me... maybe a few clicks this way or that. Despite making a dozen or so adjustments to sag both remote hydraulic preload and rebound

    Problem symptoms.
    • the rear skips and "chirps" over sharp bumps when taken above 40 MPH or so.
    • It also chirps on sharp deceleration - coming off full throttle in say second gear.
    • It seemed to eat up my last rear tire at about 2X the rate of the previous one.
    • It has gotten worse with time. I have only ridden maybe 2500 miles on the shock. Some gravel and dirt but nothing really rough. Certainly not catching any air!

    In my mind (I'm no suspension guru) its packing down and skipping (shock not rebounding). My tech and riding buddies all thought it was shock internals as it still does this withe the rebound dialed all the way back. But here's the catch! finally took the shock off to send back for internal inspection and repair (its basically new) and replaced it with the OEM Showa (in perfect condition) but STILL have the same issue. So maybe its not the shock ? Am I on the wrong trail??


    What else could be causing this? Some ideas
    • Something bouncing or rubbing somewhere. Shock mount? Center stand? Others
    • Swing arm bearings
    • Front suspension set up (I've messed with its settings as much as the rear) Right now I have Hyperpro on front , Showa on rear. Front spring is heavier than rear.
    • What else? Anyone else encounter this? Is the Paralever / Telelever system touchy?
    I feel like a dude trying to diagnose his own medical condition who is way off the trail. Help me think about what this could be and what to do. Thank you R1100GS inmates!!!
    #1
  2. TUCKERS

    TUCKERS the famous james

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    With the rear shock removed is the swing arm (drive shaft) ‘notchy’ or ‘catchy’ when you manually push it up and down through its area of travel? Does your rear wheel spin freely?
    #2
  3. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

    Joined:
    Apr 19, 2016
    Oddometer:
    660
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    Raleigh, NC
    I will test the swing arm next time I take of the shaft. without taking the wheel off, there is a little play at 9 and 3, not at 12 and 6. I don't feel any wobble on the road, just the chirpy skip over sharp bumps and on hard off throttle deceleration. could this be the elusive cause?

    the disc had a very small scrape when I put the wheel back on but otherwise spun freely. what would make the swing arm catchy or notchy? I haven't done anything to maintain it since I've had the bike.
    #3
  4. TUCKERS

    TUCKERS the famous james

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    Just want to substantiate there is nothing catching the travel of swing arm.
    #4
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  5. Gaazz!!

    Gaazz!! Adventurer

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    Hi, sounds like the swingarm is fine. Wheel play 1mm 3-6 oclock is fine. It sounds like the rebound is maybe a bit high back but more importantly, how is your front shock set up? Too soft maybe so the front dives too much?
    buy racetechs suspension bible to clear the bs from the facts as your evening literature.
    let us know how it goes! Good luck!
    #5
  6. Bill-66

    Bill-66 I don't even know... Supporter

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    Set your sag
    Set everything back to 15 and 20 clicks..
    Ride your chosen section of road..
    Adjust rebound. Over the same piece of road, same speed.You can do it as described in your manual but it doesn't work for me.
    When rebound is good, start with compression..compression has little to do with harshness, it's more, resistance to bottoming.
    Slow speed compression controls brake dive and rear squat. And PROBABLY won't need much, depending on how hard you ride the bike. High speed compression is for about everything else.

    Take notes, adjust ONE thing at a time.

    When you think you have it really close. Ride for a few days and concentrate on what it's doing and why. Make one or two click changes max.

    I'll post my settings in a bit..to give you an idea.
    #6
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  7. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

    Joined:
    Apr 19, 2016
    Oddometer:
    660
    Location:
    Raleigh, NC
    Thanks Bill. I have the Hyper pro with remote pre-load only. Do not have high/low speed compression settings, only rebound.

    Let me ask you a very simple question. From this image from the manual,

    1. Does turning the rebound left (counter clockwise) decrease the rebound damping (meaning increasing speed which tire rebounds).
    2. Or does it mean straight up rebound speed. In other words, am i correct in turning it to the left to decrease the rebound damping and therefore address the packing down ?

    Hyperpro Rebound.jpg

    Trust me, i have tried many iterations and agree to return to the same road. I Think I've been down that stretch a dozen or more times with different settings and no combination has eliminated the skip and chirp. But putting the old shock on and having the same issue is a clue. Gaaaz may have a good point, I have focused on the rear settings but they are definitely related. What would you change on the front to help with the packing down/chirping over speed bums and the chirping on sharp deceleration (off throttle, not braking)

    Thanks, I do plan to go over this with a pro, but am enjoying diagnosing and trying to understand suspension dynamics. I hope this is helpful to others doing the same. Much to learn.
    #7
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  8. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

    Joined:
    Apr 19, 2016
    Oddometer:
    660
    Location:
    Raleigh, NC
    For settings, here's what I have from EPM:
    • Front 1217 spring, 335mm length, 10mm preload, 35mm sag +/-5mm
    • Rear 1216 spring, 383mm length, 18mm preload, 20mm sag +/-5mm
    • Rebound for both 20 +/- 5 clicks open on the rebound.
    I will double check Sag.
    · The bike has 200mm (7.9") or rear travel so the recommend sag is only 10%.
    · The front has 190mm (7.5") of front travel so the recommended sag is 18.4%.

    Why would he (EPM/Klause) set this up so low? OK, on thinking this through, this must be the STATIC sag. And the manual says it should be about 10% rear and 20% in the front. So that checks out OK. Now on the bike I should be looking for about 30% dynamic sag (60mm (2.36") rear, 57mm front (2.25"). Will check that again !

    Since the shock was built for my weight and bike, I would have thought it would come out very close, but we’ll see!
    #8
  9. vagueout

    vagueout Long timer

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    The standout item not mentioned so far is the condition of the FD pivot bearings. You really should have the wheel off, then undo the brake torque arm and roll the FD drive up and down to feel if it is catching on seized/broken bearings.:*sip*
    #9
  10. Jim Moore

    Jim Moore "You ain't black!"

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    You just hit on a big part of the problem. People aren't disciplined with their terminology. Decreasing rebound, or decreasing rebound damping (which increases rebound)? Fuck if I know.

    Here's something else to look at. If the rebound damping is off you will develop a ridge at the front or the rear of the sipes, and a bevel on the other side. A ridge on the leading edge means one thing, the trailing edge means the opposite. I can't remember which is which, but I bet google knows.
    #10
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  11. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

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    Apr 19, 2016
    Oddometer:
    660
    Location:
    Raleigh, NC
    sipes? and the hyperpro manual is definitely hard to read... thx
    #11
  12. Jim Moore

    Jim Moore "You ain't black!"

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    The tire treads. Check out the vid. At about 5 minutes in.

    #12
  13. Bill-66

    Bill-66 I don't even know... Supporter

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    Yes..DECREASING rebound will allow spring to return to it's static length quicker.

    Many people think their compression dampening is off when the ride is harsh...USUALLY it's too quick of rebound and the bike is actually fighting the bumps.

    You have to give the shock TIME to absorb the bump, bring compression to a halt and return. If rebound is too fast, it has no chance to absorb the impact.
    #13
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  14. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

    Joined:
    Apr 19, 2016
    Oddometer:
    660
    Location:
    Raleigh, NC
    Interesting Bill! I have my mechanic checking out the chassis for issues. Hopefully none will be found and I can go back to suspension tuning. I really didn't expect to have to do much with them built for me... the guy that sold them to me said put it in the middle and ride. Will let you know.

    This shock only has rebound adjustment. I think if you increase that it also increases compression damping making it stiffer all around.
    #14
  15. CoatsEast

    CoatsEast 1999 R1100GS, 2007 G650X

    Joined:
    Apr 19, 2016
    Oddometer:
    660
    Location:
    Raleigh, NC
    Jim, excellent video. When I got the shocks the new rear tire wore out super fast and I got half the mileage as I did on the first Karoo3. However, I did notice severe cupping on the front tire (see image) on the trailing edge of the tire. This was not a new front but I never got this before the suspension. According to your video, if its on the back edge, the rebound would be set too fast (under damped). So maybe that's a clue too if its not just how this tire wore as it got to the end of its life. (tactic: increase front rebound damping). I wonder if the front was out of tune what effect this would have on the rear>

    [​IMG]
    #15
  16. tzracer

    tzracer Been here awhile Supporter

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    Doesn't look like a damping issue. Only on the center blocks, not on edge. Looks like wear caused by squirm. When you brake, you cause the tread blocks to move (squirm) which causes the wear pattern. Much like a pencil eraser, pull across paper in one direction, you will get a similar wear pattern. Common with tall soft tread blocks that are not supported by nearby tread blocks.
    #16
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  17. Bill-66

    Bill-66 I don't even know... Supporter

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    Sort of, yes. It goes back to how quickly the spring is trying to get back to zero..

    Say we have it set up to perfectly absorb a 4" bump at 40mph...no chassis movement, the suspension soaks up the whole bump, and returns the tire to contact perfectly.

    Now, hit that same bump at 10 mph, the spring compresses very little and, the chassis rises up and rides the back side of the bump down..almost as if the rear were solid.

    Now, hit the same bump at 75, the load moment is much faster. The bike and rider at the higher speed, in effect, weigh more, you blow through the shock stroke and bottom out, the stored energy in the spring releases at the same moment the rear tire loses contact with the bump/ground. On the back side of the bump, the tire is not in contact with ground and starts rebounding but with no resistance, it's TOO fast. So now you've made it harsh on compression and, violent on rebound.

    It's all a balancing act.
    #17
  18. Bill-66

    Bill-66 I don't even know... Supporter

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    Do you have the hyper pro set up books?

    There is NOTHING about tire wear reading in there...I'd not use that as much of an indicator.

    Personal opinion.
    #18
  19. Knob Slinger

    Knob Slinger The Anti-Poser

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    Location:
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    I have two R1100GS’s right now and have owned 5 all together as well as several other BMW’s. My boy and I did a 600 mile trip last Saturday to hit the Tail Of The Dragon in TN. We rode home in the dark and my boy commented that my headlight was very bouncy. I don’t know why I had not noticed it until then but I realized the ride was very harsh after him saying that. The next time we were stopped I looked at the front suspension travel and could not get the shocks to move more than about 1/4” even with a lot of downward force, braking, jumping/bouncing on it (all things that would normally get some movement). My other GS that my boy was riding easily moved with similar force. My front suspension seems froze up. I changed the preload all the way up and down and it changes the ride height but the shock won’t seem to actuate normally. Anyone experienced anything like this before? The only thing I can think of is the valve/valves inside the shock are messed up. Any help would be appreciated.
    #19
  20. TUCKERS

    TUCKERS the famous james

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    Probably no fluid in the shock. Any signs of leakage? If not the fork legs could be jammed, easy to check. Take the wheel off see if each leg moves independently.
    #20