F800GT fork oil capacity/level - BMW F800 Riders Forum & Registry



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    Hi, newbie here with a 2015 f800gt. Does anyone know what is the fork oil capacity/level for the GT? I do not have a repair manual. Is it the same as the ST (520ml per fork, air level 120mm)? Not all the OEM part for the forks are similar for ST and GT, and I wonder if there's any difference especially in height among them.

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    590ml initial filling and 94mm air chamber (Forks fully compressed, compression spring and spacer removed).

    Click image for larger version. 

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    Quote Originally Posted by bembura View Post
    590ml initial filling and 94mm air chamber (Forks fully compressed, compression spring and spacer removed).

    Click image for larger version. 

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    Thanks so much for the information. You are a life-saver

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    Quote Originally Posted by silvermoon1407 View Post
    Quote Originally Posted by bembura View Post
    590ml initial filling and 94mm air chamber (Forks fully compressed, compression spring and spacer removed).

    Click image for larger version. 

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    Thanks so much for the information. You are a life-saver [IMG class=inlineimg]https://f800riders.org/forum/images/smilies/icon_smile.gif[/IMG]

    Glad I could help. Good luck!

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    Quote Originally Posted by bembura View Post
    Glad I could help. Good luck!
    Just an update. My right fork was leaking slightly (a busted oil seal I guess) so I decided to procure a set of dust and oil seals and went to my trusted workshop to do the fix and the fork oil change. When the mechanic poured out the oil from the non-leaking fork, it measured exactly 520ml, very far from the 590ml listed, and far too similar (in fact, same) to the ST which was 520ml. Granted not every single drop of oil will come out, but it would be hard to believe there's 70ml of oil still left around within the probably hard to flow parts of the fork. Besides, conventional wisdom suggests that the amount that comes out should be the amount to put back, so I didn't put 590ml. Neither did I put 520, decided that I want to try a 'stiffer' setup, so I told the mech to put 550ml instead, which translates to roughly 20mm lesser air gap.

    Also, it turns out that my right fork stanchion had some micro scratches around the area near the dust seal area. The mechanic was worried that even if the seals were replaced, I might still get leaks soon enough as the oil may seep through the grooves of the micro scratches

    I had my tyres changed as well on the same day, so I cant evaluate the performance of the serviced front suspension alone. Initial ride out feels so much better with new tyres and renewed fork oil. New seals held up well too, no initial leaks. I do hope that if the seals does its job today, it should continue doing its job well for hopefully a few years.

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    Quote Originally Posted by silvermoon1407 View Post
    Just an update. My right fork was leaking slightly (a busted oil seal I guess) so I decided to procure a set of dust and oil seals and went to my trusted workshop to do the fix and the fork oil change. When the mechanic poured out the oil from the non-leaking fork, it measured exactly 520ml, very far from the 590ml listed, and far too similar (in fact, same) to the ST which was 520ml. Granted not every single drop of oil will come out, but it would be hard to believe there's 70ml of oil still left around within the probably hard to flow parts of the fork. Besides, conventional wisdom suggests that the amount that comes out should be the amount to put back, so I didn't put 590ml. Neither did I put 520, decided that I want to try a 'stiffer' setup, so I told the mech to put 550ml instead, which translates to roughly 20mm lesser air gap.

    Also, it turns out that my right fork stanchion had some micro scratches around the area near the dust seal area. The mechanic was worried that even if the seals were replaced, I might still get leaks soon enough as the oil may seep through the grooves of the micro scratches

    I had my tyres changed as well on the same day, so I cant evaluate the performance of the serviced front suspension alone. Initial ride out feels so much better with new tyres and renewed fork oil. New seals held up well too, no initial leaks. I do hope that if the seals does its job today, it should continue doing its job well for hopefully a few years.

    I double checked and 590ml is correct volume for GT. Someone please correct me if I'm reading it wrong.
    Don't know why you measured 520ml. Did previous owner do any fork work?
    My understanding is that with less oil, you'll heave somewhat less preload and, depending on your weight, your sag might be off.

    Damir

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    Quote Originally Posted by bembura View Post
    I double checked and 590ml is correct volume for GT. Someone please correct me if I'm reading it wrong.
    Don't know why you measured 520ml. Did previous owner do any fork work?
    My understanding is that with less oil, you'll heave somewhat less preload and, depending on your weight, your sag might be off.

    Damir
    I'm the 3rd owner, and the previous 2 owners only put 23,000 km to the bike over the course of 4 years. whatever servicing records I got from the previous owners didn't reflect any fork work (since it's unlikely that one will do any fork work within 23k km if usage is just limited to light/occasional commuting)

    Maybe somehow the dealership in my country decided to only put 520ml (I believe bike imports are shipped dry, and fluids are added only at the local distributor?)

    Have you actually serviced the fork and put in 590? or just quote from the service manual?

    Anyway, while I'm not a suspension expert, but my current setup feels good, after already getting used to a 520ml oil level + old fork oil. I'm 90+kg, somewhat meaty by asian standards, but pretty much average by western standards I guess.

    If there are others who corroborate this 590ml confirmation, then maybe I will do a top up next time when I decide to pop in some hyperpro progressive springs, who knows?

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    You have to be careful about lubricant refill quantities specified in service manuals. Unless otherwise specified many times they are for completely dry components when filling at the factory and not for refilling engines or forks when the fluids are being replaced. In many cases those fluid quantities will be less than what is called for in the service manual.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2005 Triumph T-100 Bonneville, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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    Quote Originally Posted by silvermoon1407 View Post
    Quote Originally Posted by bembura View Post
    I double checked and 590ml is correct volume for GT. Someone please correct me if I'm reading it wrong.
    Don't know why you measured 520ml. Did previous owner do any fork work?
    My understanding is that with less oil, you'll heave somewhat less preload and, depending on your weight, your sag might be off.

    Damir
    I'm the 3rd owner, and the previous 2 owners only put 23,000 km to the bike over the course of 4 years. whatever servicing records I got from the previous owners didn't reflect any fork work (since it's unlikely that one will do any fork work within 23k km if usage is just limited to light/occasional commuting)

    Maybe somehow the dealership in my country decided to only put 520ml (I believe bike imports are shipped dry, and fluids are added only at the local distributor?)

    Have you actually serviced the fork and put in 590? or just quote from the service manual?

    Anyway, while I'm not a suspension expert, but my current setup feels good, after already getting used to a 520ml oil level + old fork oil. I'm 90+kg, somewhat meaty by asian standards, but pretty much average by western standards I guess.

    If there are others who corroborate this 590ml confirmation, then maybe I will do a top up next time when I decide to pop in some hyperpro progressive springs, who knows? [IMG class=inlineimg]https://f800riders.org/forum/images/smilies/icon_biggrin.gif[/IMG]
    My bike just got out of the warranty with 6,000 miles when left fork seal started leaking.
    I bought the bike used with only 1,000 miles and 2 years old.
    I never drove it on any unpaved roads.
    Don’t know about first owner but based on bike’s shape, I doubt he did that as well.
    He made only 1,000 miles in 2 years.
    It seems it was just bad seal quality.
    I fully disassembled the forks and put 590ml and took out the excess with hose and syringe to get 94mm air gap as per manual. To be honest cannot remember how much went out but I doubt it was 70ml. It was much less.
    590ml is just initial filling. More important is to get 94mm of air gap.

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    The air gap between the top of the oil and the top of the fork tube with the springs removed, and the fork tubes fully collapsed, is the proper way to set the oil level. Don't pay any attention to the quantity, unless you can't measure the fork oil level for some reason or you are buying the fork oil and you want to make sure that you will have enough to replace the lubricant.
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    Fair points from many of you. I guess at the end of the day, neither 590 ml nor 94 mm are magic numbers, but are reference points to start with. Different rider weight and riding style would require different amount of suspension adjustment. I'm pretty satisfied with my current setup, although I might tweak it a little next time.

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    I think I'll attempt to change my fork oil. First time I've ever done it. So it appears like I'm supposed to use 10 weight fork oil, right? Is there anything special to look for, or should I just get the cheapest fork oil I can find at the local store?

    Richard mentions something about measuring the air gap. I watched the F800 Service DVD on YouTube and he only covers draining the oil and the reassembly. Nothing about filling the oil level, and when he's doing it, the front wheel is off the ground. So do you lower the front back to the ground, or strap the front wheel to pull it to the frame and compress it?

    I love the way the bike handles now and don't want to screw it up.

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    Quote Originally Posted by Daboo View Post
    I think I'll attempt to change my fork oil. First time I've ever done it. So it appears like I'm supposed to use 10 weight fork oil, right? Is there anything special to look for, or should I just get the cheapest fork oil I can find at the local store?

    Richard mentions something about measuring the air gap. I watched the F800 Service DVD on YouTube and he only covers draining the oil and the reassembly. Nothing about filling the oil level, and when he's doing it, the front wheel is off the ground. So do you lower the front back to the ground, or strap the front wheel to pull it to the frame and compress it?

    I love the way the bike handles now and don't want to screw it up.

    Chris
    To compound the problem, the SAE number we are used to seeing on fork oil isn't very helpful. Apparently the range is too wide, and there are other considerations that are more important in fork oil compared to motor oil. So each brand's 10 weight might be considerably different. That said, if you know what brand was in there to start with, you can match it's properties to another brand very closely by utilizing a bunch of the comparison charts out there. More info here: https://www.peterverdone.com/wiki/in...spension_Fluid If you just pick up any 10W fork oil, the feel could be noticeably different. I don't know that I would be able to tell the difference, but I'm sure some people can.

    As for how to fill them, I have only done them on my ST, so it might be different. I removed the forks from the bike with it on the center stand while I had a bucket or water tied to the rack on the back along with a 50 pound bag of bird seed in my topcase. I might have put the center stand on a thin piece of wood for extra clearance, I can't remember. Either way, with the forks off, I held them with my bench vice so that I could push down on the tops to remove the circlip. Once that is out, everything comes out easily. Once I just dumped it upside down after pumping it a bunch and let it drain for an hour. The first time I changed it, the oil was really dirty and smelly. The second time I removed the damper, seals and everything. You'd be surprised how much oil and junk hold on to all those parts. I replaced them with hyperpro progressive springs and new seals. To fill them, I put it back in the bench vise and filled them, then pumped until all the air was out and I had the proper air gap. I think it was 120mm, but that's just from memory. I remember that it used a perfect 1 Liter bottle. I used Maxima 15W fork oil. It was only $14 from Amazon. I was looking for less nose dive on braking. After putting the circlip and cap back on, they just bolt back on the bike.Click image for larger version. 

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    08' F800ST- side panniers & Shad SH45 top case, Russell Day Long seat, MRA Vario Windscreen, SW Motech crash bars, ZTechnik exhaust, PC-8 fuseblock, Stebel Nautilus horn, Throttlemeister throttle lock, SW Motech handlebar risers, LED fog lights, highway pegs 

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    I don't have specific information for the GT, but on ST models use 10wt oil (any name-brand fork oil will be fine) set to a level of 120mm measured from the top of the fork tube with the forks fullly compressed and the springs removed. In order to drain the forks they have to be removed from the bike, after removing the front wheel first. Place the bike on the center stand and raise the front of the bike with a support under the engine. Remove the forks from the triple clamps after removing the fork caps, then turn them upside down to drain the old oil. Refill with the new oil. Reinstall the springs and spacer, install the forks into the triple clamps, upper torqued to 20NM, the lower to 25NM. Press down on the spring spacer, install the fork caps, torque to 20NM and reinstall the front wheel. It should take you about 2 hours to perform this task. I would think the process would be the same for the GT if it uses a right-side-up fork like the earlier models did.
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    I changed the fork oil last night. Probably the hardest thing of the whole process was deciding to start and getting the tools out.

    The forks do drain from the bottom if you decide not to remove the forks from the bike. Getting the two drain bolts to thread back in was time consuming. You're doing it all by feel. The other time consuming part was removing the circlip at the top of the fork. My suggestion is to put pressure on the cap so that it shifts the cap slightly off-center. That gave me the space needed to get the circlip out of the groove.


    Now a question...I followed the process in the F800 Riders Service Companion DVD. The video says to use 500 ml of fork oil, which I did. Then I came across this thread again and see that it says I should've used 590 ml of fork oil. The bike seems to ride fine. What do you think? Should I leave it as is? Or buy another bottle of fork oil to add 90 ml to each fork?

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    Sounds like you removed the damper bolts at the bottom of the fork as there are no drain holes on the GT that I can see. Would also explain why you had a lovely time putting them back in.

    Capacity is listed as 590ml for a GT, other variants have slightly different capacities. Access to a service manual is helpful and time saving in these situations.





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    I would set it per air chamber gap. The service manual states, initial fill - 590ml, then set the gap to 95mm with forks fully compressed, spring and spacer removed. The initial fill of 590 is just to make sure you have enough to purge all the air and then pull some back out. Cycle the fork as many times as it takes to get all the air purged from every nook and cranny in there. Then pull off the extra to the specified measurement and you're done.

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    Daboo,
    Out of curiosity, I have just studied the parts fiche and my copy of BMW repair manual.
    The bolts on underside of slider are not drain plugs but retain the damper rods. Correct method of draining is to remove fork and invert.
    The specified oil is BMW fork oil type 1 10w ref 31 42 9062 158.
    The manual quotes 590 ml as a nominal initial fill then procedure to exercise fork, allow oil to settle then siphon off to achieve the critical 94 mm air gap. Bembura describes well in his posts above and shows extracts from repair manual.

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    Thanks for the feedback, guys. Yes, I have access to a service manual. I've found YouTube to be a great source also. The founder of this forum, created a 90 minute DVD covering many of the maintenance things we'd encounter on our F800s. Later, he published it on YouTube where it can be accessed for free. It's good. Not only does he show you how to do everything, but he also shows you the little tips that help make things easier, plus he lists the torque values to use.

    In this case, he was changing the fork springs. Perhaps the 500ml he references is there because of the change in springs?

    Chris
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    Yes have watched some of videos before and thought them very useful and appreciated the effort that was put into producing them.

    You'll note in the video, it they're working on what looks to me to be an F8S or ST. Manufacturer states a capacity of 520ml for these variants while the F8GT shows as a capacity of 590ml. (Check your service manual for confirmation of other difference's between variants.)

    In the video, I'm guessing they may have thought that a difference of 20ml when using a standard 500ml bottle of fork oil would have a negligible noticeable difference in damping for the average rider?

    Who knows...





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    My recollection is that the GT uses different forks than the old ST and F8S. So I wouldn't depend upon that video for fork maintenance.
    Richard - Current bikes: 2016 BMW R1200RS, 2018 16.6 kWh Zero S, 2011 Royal Enfield Bullet 500 Classic, 2009 BMW F650GS, 2005 Triumph T-100 Bonneville, 2002 Yamaha FZ1 (FZS1000N) and a 1978 Honda Kick 'N Go Senior. 

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