F800 GS lowered suspension

Discussion in 'Parallel Universe' started by riverguy9, Dec 1, 2008.

  1. riverguy9

    riverguy9 Adventurer

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    With my 28" inseam, my new 2009 BMW F800GS is just too tall for me. I'm on my toes with it when stopped.

    I bought it anyway, after considering and rejecting the F650GS, which is available in a lowered version, because I couldn't pass up all the niceties of the F800 model. (BMW apparently does not offer the "lowered suspension" option on the F800, even though the parts appear to be compatible.)

    Now, to make this otherwise great bike useable...

    Rear suspension:
    I can buy the rear spring/damper unit for the lowered F650, and it will likely fit in the F800 bike (I've examined a lowered F650 alongside a standard F800).. But, that unit is actually overkill, and, on the F650 I've sat on, it puts my heels on the ground, and sacrifices more ground clearance than I am willing to give up. (I'd like to shorten, but retain my centerstand. I guess I'll also have to shorten my sidestand.)

    So, here is what I'm hoping that someone will have information on----

    Can that rear spring/damper assembly be disassembled, i.e. the spring removed from the unit, and reinstalled? It is not obvious from looking at the unit (still mounted on the bike), if this is possible.
    If this can be done, then I can shorten the spring by a turn or so to get to the "happy medium" that I seek.

    I did the same on a previous bike with conventional twin coil-over rear shocks. (Cut turns off with a torch, bent the remaining "tail" and ground it flat to seat properly.) The springs were much smaller, and yes, I may need to build a giant spring (compressor) removal lever tool for this big monoshock, but I would think that this should produce the desired result.

    Maybe someone out there has another approach. I'd love to hear it.

    Front suspension:
    It looks like the forks can be slid up into the triple clamps by about an inch, which would be just about perfect. The diameter of the part barely sticking out of the top of the top triple clamp is within about .01 inch of the diameter just below that clamp, so it looks like there's probably not a ridge inside the triple clamp acting as a stop.

    Can anyone confirm this for me?

    Also, any suggestions for a safe way to support the bike and _gracefully_ slide those loosened triple clamps that inch further down the fork legs? (Do we still call them fork legs even though they are the upper section, now?)

    I envision a block and tackle to a ceiling beam, plus a rubber hammer "persuader." Or, maybe I need to reverse my thinking and remove the front wheel and hook the forks to my ceiling support, and then coax them upward (whack, whack).

    Any suggestions or comments would be appreciated, especially if you have first hand knowledge from having had these things apart.

    Thanks!

    Greg

    P.S. Before posting this, I searched for anything on this topic and found none. Let me know if I missed anything.
    #1
  2. Ed@Ford

    Ed@Ford Long timer

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    Have you tried the lowseat? My dealer has a low seat just for the purpose of determining which seat works best for the customer. Although it is lower than necessary, I found the low seat more comfortable. Also, my dealer has both an 800 and a 650 demo. I find that the 800 has the spring preload WAY too much. I went for the 650 for $$ reasons, as the extra thousands of dollars was suspension capabilities I'd just never use. I have dirt bikes for bashing around in the woods and crap. Take all the preload out of the shock and ride it around first....I think you'll be amazed...plus you'll find the spring will limber up some. The fork legs will slide up someas well What you're suggesting to do would be $$$$$$$$$$$$ and you kiss your warranty away...and this is a bike that has the potential for lots of $$$$$$$$$$ warranty repair over it's lifetime that I don't want to pay for out of my pocket!!

    Finally, and no slight on your inseam, I have several biking ladyfriends who go to quality bootmakers and get their boots resoled with extra soles, a slight heel lift , with lifts inside and pick up a full inch of inseam. This cost, even with new boots is pennies compared to the suspension mods you suggest. Also....if you read the fine print on the F650 lowered suspension....you loose significant load carrying capacity...something that might matter if you ride 2-up or have lots of luggage.
    #2
  3. Bucko

    Bucko In a parallel world

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    I have a friend with a low seat on his GS8 who's thinking of trading for the standard seat. Seems like a good first step for you. PM me if you're interested and I'll hook you up.
    #3
  4. riverguy9

    riverguy9 Adventurer

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    I do already have the low seat option. And, the hydraulic preload knob for the rear damper is set at the lowest (max ccw) setting.

    Thanks for your response, but this bike needs a mechanical solution of lowering, and it's not going to be made up by adding an inch to my boot soles.
    #4
  5. MoToad

    MoToad Been here awhile

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    Hey Riverguy. In the same boat here. have lowered the front an inch. That's pretty much all that it will allow due to it champfering in after that. It is a simple task and can be done on the center stand. Use a rubber mallet and a steel ruler to measure, tap and adjust. I really only gained perhaps 1/4 of an inch at the seat. Mine came with the lowered seat but I had to get rid of it as they have just carved way too much foam out for my liking. Hyperpro progressive springs out of Holland,I believe, makes a lowering kit. Google it. But, for myself, I am going after the cobbler who will add an inch and a half to my riding boots. Cheapest. Easiest.
    #5
  6. WoodWorks

    WoodWorks House Ape

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    Tried one of these? :D

    [​IMG]

    David
    #6
  7. Nemesis

    Nemesis just ride the damn thing

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    :poser :poser :poser
    #7
  8. Bike4Fun

    Bike4Fun Smooth IS Fast

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    I've gotten use to stopping with one foot down, usually left cause I'm breaking with the right. I then just lean the bike over to be flat footed and with the right still on the peg its not that far. Takes a bit to get use to but I don't even think about it anymore. Unless its one of those lights from hell and left arm is all pumped cause I have to hold the clutch in forever. Otherwise, I have to switch feet after the stop to put it in neutral. My neighbors must have thought I was an idiot riding around the neighborhood stopping in the middle of the road perfecting my stopping, foot down maneuver.
    #8
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  9. RedHawk47

    RedHawk47 Adventurer Supporter

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    #9
  10. Gany

    Gany Been here awhile

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    I too am interested in this thread, as Im a short rider. My bike isn't due for delivery until March though so no chance to experiment yet. A couple of links to similar threads:
    F800GS lowering kit 30mm or 60mm:
    http://f800riders.org/forum/showthread.php?t=17573
    Lowering my F800GS:
    http://f800riders.org/forum/showthread.php?t=18444
    Lowering:
    http://f800riders.org/forum/showthread.php?t=20626
    Hyperpro suspension lowering kit:
    http://f800riders.org/forum/showthread.php?t=18368
    F800GS hyperpro lowering:
    http://f800riders.org/forum/showthread.php?t=19799

    F800GS: 19" front wheel:
    http://f800riders.org/forum/showthread.php?t=18474

    I also got these responses to my PMs from the guys (thanks guys!):
    Geir:
    I did not measure,but think about 1-1.5 cm lower seat by lowering 1" in steering crown,no effects on riding the bike.
    Preload set to minimum,to make it softer on the damper,but if your body weight is 60 kg you can have it at the lowest point all the time,just 1-2 turns on the adjuster.
    More if you load it up with luggage anothet 4-5 with 20 extra kilos or passenger.
    The bars will stay in the same place all the time,but the fork leges will come up 1 ",and it looks ok,no problems at all.

    The 800 gs looks very nice when lowered,and drives very good ,better in corners ,due to the fact that the center of gravety is lower to the ground.

    I did not use Hyperpro but Wilbers,you can get the Wilbers or Tourateck,or Wirth,they all comes from the same spring manufactor,in Europa.
    If you go for the lower springs up front,leave the front forklegs as is ,in the clamps.
    I also changed the aft shockabsorber,to a Wilbers with preload adjuster,as the original is a sealed unit and can not be modified(lowered)
    But if you only want 820mm seatheight,I think you will be ok wit only the front springs.
    As my bike is now custom tailored to my bodysize and fits me 100% I will not get a 19" front wheel ,no need,however I will try to get tubeless rims\wheels if possible.

    New springs is shorter and progressive.


    Toadride:
    I figure the 1" fork lowering got me 1/2" at the saddle. Absolutely no difference in the handling of the bike. Any little bit helps. with my new 1 1/4" work boot and this I am at the lower end of the balls of my feet. I opted out on the lower seat as there was just too much foam carved out of it for my comfort. Hope this helps.

    Lowering the forks really makes very little difference. As they chamfer after about an inch or so, that;s about as much you can do anyways. I have noticed some softening of the suspension after a few thousand kms. And loaded for travel lowers it even more. I've pretty much decided just to live with it.

    I plan on getting the bike first and trying to lower the forks 1" and see how that goes before throwing any money at it. The dealers are going to do that for me and said it would have no affect on the bike's warranty (I'm in Australia if that makes any difference to warranty!). I'll probably add bar risers to bring the bars back up to normal height and give some buffer between the top of the forks and the bars. But I'll have to wait for delivery before reporting any successes or failures. Hope that helps some.
    #10
  11. wbrisett

    wbrisett hmmm....

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    I'll be honest with you after the experience I have with lower a bike (my wife's R1150R) via suspension changes, I'm not a fan. The work was done by the local BMW dealer, and once you get the bike up above 20 MPH, it handles fine, but at low speeds, the bike really feels like you are fighting with it and not really riding it. The dealer has looked at it and everybody agrees that the bike simply doesn't feel all of a piece at low speeds. But everybody also seems to think that is pretty normal for bikes that get lowered via suspension changes. I'm no expert, but if every bike handles this poorly at lower speeds after suspension changes to lower a bike, I wouldn't do it. Of course I'm spoiled since my RT handles like a dream at low speeds, and the Uly is no slouch either.

    Wayne
    #11
  12. GOROVN

    GOROVN Adventurer

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    anyone who wants my F650 lowered rear shock just PM me. I am selling it cheap. I really think you will be disappointed with it though...it is VERY low. If it were me and I had an 800 that was too tall, i would look for a standard length F650 shock. It is shorter than the 800, but not crazy short like mine.

    by the way, Ohlins are about $40 cheaper than BMW OEM. i would skip the dealer and get a good one.
    #12
  13. riverguy9

    riverguy9 Adventurer

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    Thank you to everyone for your helpful responses.

    WoodWorks -- That's hilarious, but too painful, I think!

    GOROVN and RedHawk47
    Yes, I agree, the lowered F650GS is way too low, so (GOROVN) I'm not going to take you up on your offer. Interesting, however, that you say the standard length F650GS rear shock is lower than that supplied on the F800GS, though. That might be an (expensive but ready made) alternate choice though, if that's true.

    There are about 7 spring turns on the F800GS unit and about 5.5 turns on the lowered F650GS unit. The wire diameter looks similar, but not identical (I didn't measure it).

    wbrisett
    Bad handling at low speed? That's bizarre. But your wife's bike is quite a different animal, though, than the 800GS. I think I'm looking for about 1.5 inches at the saddle.

    Bike4fun
    Yes, I've "practiced" also at reading the slope of the "landing pad" and putting the correct foot down. But that's no way to live. The bike's gotta fit ya, and not just by loading it up with luggage, or getting elevator shoes.

    Toadride
    Thanks for confirming that the 800GS forks will, in fact slide up thru the triple clamps, just like every other bike I've encountered. Yes, there's slightly less than an inch of cylindrical fork leg before the leg taper starts.

    Most of the lowering will be with the rear unit. But, sitting on a lowered V-Strom, I noticed that it felt pointed "up hill." Sliding the stock forks will level this bike back out without changing the travel or spring rate. (I'm not a fan of progressives. Too much sag.)

    Gany
    Thanks for the thread links and the helpful quotes.

    The one that disturbs me is the remark from Geir: "I also changed the aft shock absorber to a Wilbers with preload adjuster, as the original is a sealed unit and can not be modified (lowered)."

    They had to install the spring somehow. I'm counting on it not having a (one time) crimped fastener, so I can remove and reinstall the shortened spring.

    In one of the threads on this topic (maybe on the F800riders.org site, someone mentions using modified auto spring compressors to remove and replace the spring. Not sure if it was this specific unit, but that's what I'm talking about. (Actually, I'd expect to make a large version of my lever style compressor.)

    Having not confirmed this, I guess I'll just start taking it apart. I'll take pics of the process (cut off the spring and reinstall it). If it's successful, this is the "free" lowering solution, without that progressive nonsense.

    Wish me luck.
    #13
  14. spookytjw

    spookytjw Adventurer

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    #14
  15. riverguy9

    riverguy9 Adventurer

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    HOORAY! I now have a suitably lowered (read stop-able, backup-able, turn-around-able, actually use-able, and how about ENJOYABLE) F800 GS, and the mods to make it so cost me some measurement research, a few hours of work and one package of black cable ties.

    And, I only gave up a minimum amount of ground clearance, compared to using a shorter F650 shock. My sidestand needed no modification (it was too short before, anyway), and my centerstand is still functional without modification.

    Here's the offending bit that, removing it, transformed my bike.
    [​IMG]
    This posting is to show what I did so you can do the same thing, knowing beforehand that it will be successful.

    Before doing this, I examined a standard height F650GS and a factory-lowered version of the same bike. The rear shock assembly has a different installed spring length for each, and, though I was not able to measure it directly, a different eye-to-eye length for the uncompressed unit.
    The installed but uncompressed spring lengths for each model are approximately: F800GS=19.5 cm; F650GS standard=17.2 cm; F650GS lowered=16.2 cm. It would certainly be possible to use the rear shock assembly from one of those other bikes, but at a mighty steep price (about $900). Both of these units would make the bike way too low.

    It was clear that I could make the free length of the spring no shorter than the installed length of 19.5 cm. Shorter than that, and it would be loose when the rear wheel is off the ground. So that was the limit of what I could get. OK, I'll take it.

    Upon removing the rear wheel and shock, it was easy to move the swingarm and measure the difference in eye-to-eye shock length required to effect the lowering of the rear of the bike.

    Upon removing the spring from the shock, I found the spring to have a 20.8 cm free length. With a 19.5 cm installed length, I have only 1.3 cm to remove at the most. This is .51 inches. Let's call it .5 inch, as I'll be lucky to be within 10 mils on the cut, anyway. Sorry for the mixed units- a result of my measuring devices. (A tailor's measuring tape with a centimeter scale turns out to be a very useful around this hardware. You can thread it up into tight places.)

    Here are pics of the sequence.
    Remove the seat. Unclip the round connector and its wire from the plastic retainers. Unlatch the small two pin plug and unplug it. Unlatch the small two pin socket and slide it off its mount. Cut the four plastic cable ties. Remove the four small nuts and two side screws and lift out the plastic kludge.
    [​IMG]

    Here's what's under it. Unfortunately, no opportunity to offset the top shock mount upward.
    [​IMG]
    Remove the rear wheel. I put shims between the brake pads to keep them apart.
    [​IMG]

    Remove the chain guard. While you can loosen the lower shock bolt through the access hole in the plastic chain rub-rail (correct term?), you can't pull the bolt out without moving that rail to the side. So, remove the two screws to allow you to do that. Shoulda' dusted for these pics.
    [​IMG]

    [​IMG]

    With the shock unit held in a bench vise (with wood blocks to grip softly), back out the preload adjuster set screw. Compress the spring until the retaining ring can be removed.
    [​IMG]

    It's amazing. This thin snap ring supports not only the entire static weight of the rear of the bike and its luggage, but also all the tremendous shocks of riding over bumps. Good metalurgy, and under compression.
    [​IMG]

    Now to measuring the cut. Set spring upright on your flat bench, and measure dimension A. Rotate the spring clockwise until you get to the point where B is 0.5 inch greater than A. Note also dimension A1. The dashed line is where to cut. This 0.5 inch will correspond to about a 1.6" lower rear suspension.
    [​IMG]

    A 32 teeth per inch hacksaw blade fails immediately, the teeth are wiped off. But, a 24 teeth per inch blade takes a bite, and cuts fairly easily, considering spring steel. Here's what I removed.
    [​IMG]

    I only decided to document this with pics after I "bent" the remaining tail of the spring, so the next pic is just to show the approach of my "benchtop blacksmithing." This took a third hand with my right hand holding the spring, left hand on the vise handle, and my wife playing a propane torch along about a 1.25 inch section of the spring.

    The idea was to bend the tail until demension B1 is about the same as the previous dimension A1. I got mine close, maybe a slightly larger gap, but decided to err on the side of minimum heating.

    Vise jaws are about 90 degrees from cut end, with heat applied over about a 1.5 in length of coil at about 180 degrees from cut end.
    [​IMG]

    I didn't plunge the hot spring into the rain barrel ala Burt Monro. I don't think I got it that hot, anyway. I see the only failure mode as a possible slight additional sagging, but that will be easily taken up with the shock preload adjuster, if it's ever needed. And, that thing has quite a large range, about 6mm, to easily compensate for any spring settling.

    Then, on to the bench grinder to put a square surface on the modified end that matches the original. My ground flat extends a little further than it needs to. 260 degrees was about right, just like the original ends. Grind down the end to restore the original "A" dimensioin at the tip. As you go, set the spring on a flat surface and put a square against it and rotate it to confirm that it stands up straight. A cheap bench grinder removes the material easily.
    [​IMG]

    Paint the mangled end of the spring and reassemble the shock. Here's the cut spring reassembled.
    [​IMG]

    Reassemble everything.

    To level out the bike, I slid the forks up into the triple clamps as far as the cylindrical part of the forks would allow (slightly less than an inch).

    Hold up the weight of the bike with a support under the engine. Loosen the triple clamp pinch bolts and tap on handlebar clamps with a rubber mallet. Incrementally lower the engine support until you're there. Tighten everything.
    [​IMG]

    [​IMG]

    The most technically correct way to effect this lowered suspension would have been to shorten the eye-to-eye length of the shock unit from 43 cm to something between 1.25 and 1.5 cm shorter than that (for a corresponding 1.56" to 1.875" change in height). So, if I ever shopped for an aftermarket unit, that's my first question: What range of eye-to-eye adjustability?

    But, doing it this way was nearly zero cost (the replacement cable ties), AND, I get the benefit of not having to modify my centerstand. This is because, when levering the bike onto its stand, you lift on the rear handles as you step on the stand "pedal," you tend to lift the rear toward its original height, and the length of the centerstand is still "right" for that still-unchanged maximum eye-to-eye shock length.
    Without a load on the bike, the effort feels about the same as before. Loaded up with luggage, the effort required will be greater. Small price to pay.

    The mod doesn't seem to have affected the handling. It's a nimble ride.

    I hope this is useful to other shorter riders who want to enjoy this terrific bike without having it be an intimidating too-tall beast.

    This is the bike I bought.

    --Greg
    #15
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  16. Ed@Ford

    Ed@Ford Long timer

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    CRAIG:
    One ballsy job hacking up a $$$$$$ spring, but a great sucess making the $14K bike what you like!

    A few notes for others:
    1. The spring compressor some other guy used is from Harbor Freight and is currently on sale for $9.99. It required some grinding, I assume to keep from hitting the shock tube.
    2. I would suggest being careful grabbing the spring with a vice. A nick in the spring creates what is called a "stress riser", and could over time be a place where the spring will break
    3. Heat the spring only till its blue, then allowing it to air cool would minimize the loss of temper in the steel. Heating it to cherry red and air cooling will soften it. Heating it cherry red and quenching it in water will make it brittle and probably lead to rapid breaking. Soft is better than brittle. Not loosing temper is more desirable.
    #16
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  17. llamapacker

    llamapacker Mr. Conservative

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    Riverguy9

    Very good DIY job, well documented. I will jump all over a project bike but don't mess with new in warranty bikes. Congrads.


    ED@FORD

    Thanks for the engineering followup on the spring steel and tempering. Think he did okay with propane torch, now if it would have been me, pulled out the old acetylene torch and gone red, not good!
    #17
  18. riverguy9

    riverguy9 Adventurer

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    I borrowed this spring compressor, with permission to grind it a bit to keep it from pressing against the shock sleeve. Only my NAPA store had an automotive unit that could have been ground down for this size spring. It was sold under the "Performance Tools" name, and has one fixed end and only left hand threads, unlike my borrowed unit. Other auto stores' units were either the wrong style (internal) or way too big, even as a starting point.

    Yes, I'd agree on not nicking the spring. Doing it again, I'd use my aluminum jaw covers on the vise. But, I barely scratched the paint (powder coat?) on this spring, in any case.

    Thanks for the review on temper. I basically squeezed the coil and heated it only enough to cause it to sag a little. Likely only got to the cool side of dull red.

    --Greg
    #18
  19. spookytjw

    spookytjw Adventurer

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    Finished product of an Elka shock install.
    If you have questions on the shocks or what they run for email me at Twilliams@goaz.com

    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    [​IMG]
    #19
  20. TierHawg

    TierHawg Herder of the J-Cats

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    Nice work Riverguy9. Hope this catches on and helps out other vertically challenged riders.
    #20