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Fork Oil Replacement - Classic/Roadster with adjustable compression and rebound

6.2K views 26 replies 11 participants last post by  cgilfond  
#1 ·
I have searched the forum and youtube looking for a procedure for changing the fork oil in a Classic / Roadster with gold inverted forks and adjustable compression and rebound. I haven't been able to find one. This will be my first time changing fork oil in any bike.

I do all of my own maintenance on my R Nine T and my R1200RT so I'm sure I can do that job, I'm just wondering about what awaits me when I remove the caps from the fork tubes and any gotchas with respect to performing this service and getting it right. If BMW sold the service manual for the 2021 model I could look there, but we know how that goes at this point. I have seen some vids of people doing bikes BMW bikes with ESA, etc... but some of that doesn't apply here

Can anyone help with a pointer to a write up or video?
 
#2 · (Edited)

@alegerlotz Good how to for that fork here.
 
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#3 ·
Thanks, lots of info in this writeup... I didn't realize that the forks were essentially the same as on the early S1000rr, which is good to know.

This job seems a little intimidating when reading it and looking at tiny pics, but as with most things, I think when you're in the middle of doing it, it seems more straight forward.
 
#4 ·
Not done r 9 t yet, but drain and re fill open cartridge forks are fairly straight forward,
set compression and rebound to minimum settings to allow oil flow, slacken top caps before removal,
for a change without stripping the springs out, an extra litre of oil for flushing and pumping through helps,
for stripping the top caps off and removing springs for a change i have managed with help to pull the spring spacers down and use an open ended wrench/spanner on the spacer to push it down enough to remove the top cap,
not got any measurements as my bike is not ready, so will be watching with interest
dont be intimidated, an oil change is a little messy, but pretty straight forward,
Good luck,
Forest
 
#7 ·
I am actually getting close to the point of doing this as I have my 12K service coming up and figured I'd tackle it then. I know that the maintenance interval is 18K, but I did a suspension clinic with Dave Moss and he had some recommendations for new fork oil so I'd like to do it along with the major service.
 
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#9 ·
Do you have any instructions on how to do it? I can't find anything online.
I don't, that's why I created this posting in the first place. I've checked on some YouTube vids, etc... so I might just have to start the job and see where it goes.
 
#10 ·
I am just in the process of changing the fork oil on my 2018 classic,
its a straight forward process if you are able to remove a front wheel,
i have everything stripped out and forks drained, will post up how i did it once the oil arrives new year,
first thing i noted was both forks had 600 ml, spec in haynes 525 ml,
current miles 9500
Forest,
 
#11 ·
I am just in the process of changing the fork oil on my 2018 classic,
its a straight forward process if you are able to remove a front wheel,
i have everything stripped out and forks drained, will post up how i did it once the oil arrives new year,
first thing i noted was both forks had 600 ml, spec in haynes 525 ml,
current miles 9500
Forest,
Great, hearing more about your experience would help. I'm at 12K miles now and still haven't changed my fork oil. Knowing more about how to disassemble those cartridges in the forks would be helpful.

Thanks,
-Al
 
#12 · (Edited)
I finally got the fork oil changed, on my 2018 classic at 9500 miles,
slacken fork caps, 30 mm , note damping settings and set to 1,
remove abs sensor, brake calipers, front mudguard and wheel,
note the position of the top of the fork protrusion, marked the leg position in the lower yoke bolt gap to align reflectors, release the last bolts and remove the fork legs,
have a measuring cup ready, i used disposable paint mixing cups,
unscrew the leg from the cap create approx a 1 inch gap and drain the oil, periodically screwing the tube to the cap a few threads and pump the forks, then repeat the draining,
i noticed the left fork took much longer to drain,
i initially got to a measured 600 ml, after a while,
but decided to leave them draining into measuring cups overnight laid with the axle ends propped up, the final amount was an equal 625 ml,
you could stop when you get to 600 each if time is limited , assuming you have the same quantity from each leg ,
Haynes state 525 ml and oil level 65 mm below the inner tube which required the fork spring etc removing,
i went with re filling the exact 625 ml quantity removed , which is visible at the top of the inner tube with the outer slid all the way down,
when re filling keep the outer tube app 2 inches below the cap and pour slowly,
then loosely screw on the caps again and pump until you get resistance on full stroke,
the right side leg took much longer to get the damping back full stroke, i let them settle upright for 20 mins once they had damping, then slid the outer tubes down to see the oil levels at exactly the top of the inner tubes,
i reset the damping settings before re installing
i hope this helps, this is just how i did it, putting back exact oil quantity that came out,
you may prefer to strip the forks or find different oil quantities to mine,
as i found it requires some time to drain the legs completely,
being the owner from new it is a factory set amount i trust,

Forest,
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#15 · (Edited)
Due to the lack of maintenance by the previous owner, I will also replace the fork oil now that the fork is out. Do I actually need any special tools? or will the top part of the fork fly through the roof when I loosen it
The fork caps will not fly off on the classic with USD forks,
they are connected to the cartridge internals, the outer tubes slide freely
you only need regular tools, a measuring jug and plenty of time to allow the forks to fully drain,
hope this helps, Forest,
 
#17 ·
I still haven't replaced my fork oil, but its about time for me to do that. As with any job of this nature that I haven't done before, I'm a bit apprehensive. I'm sure it will work out fine, though. The clutch on my wethead RT is working fine after I replaced it, and this job looks eaiser. I guess I'm going to find out!
 
#19 · (Edited)
The Haynes manual states BMW Fork Oil Type 2 (10W)

RnineT Capacities....

2014-16 = 575ml/80mm

2017 on = 525ml/65mm

Other models use different capacities, but the same spec/weight of oil.

But please may I advise that not all fork oil specs are the same......one brand's 10W may be very different to another brands of 10W.......there is no standardisation of fork oil viscosity.

However, there is something called a Centistroke (cSt) value, and it's this to look for when cross referencing brands.

Check here for comparisons >>>>

 
#20 ·
thanka. Beemerbonyard sells Liquid Molly which is not on your list. Is that stuff pretty good? They just have 10w “medium”. Does not indicate “type 2”

any thoughts on if just changing oil is all I need to do if the seals are not leaking or should I try to replace those while I have the forks out. Never worked on forks or seals before so don’t want to get in over my head…
 
#23 ·
Thanks for the info,
The forks are better fully stripped and new seals etc and oil levels are critical, i agree,
the reasons for me showing a drain and re fill,
some on here are wanting to change their fork oil and not comfortable with a full strip,
new oil at the specified or adjusted to your levels, is better than old,
i am good with setting up my suspension and the oil quantity was working for me,
the seals and bushes are good and i did not leave the oil until it turned to black sludge,
so a regular drain and re fill is my choice, when i have my rear shock serviced,
this is something many bike shops offer as a service so why not maintain it if you can,
i am able to fully disassemble the forks when the need arises,
Safety is the big issue, poorly functioning suspension due to degraded oil can be avoided,
Forest,
 
#24 ·
i am good with setting up my suspension and the oil quantity was working for me,
the seals and bushes are good and i did not leave the oil until it turned to black sludge,
so a regular drain and re fill is my choice, when i have my rear shock serviced,
this is something many bike shops offer as a service so why not maintain it if you can,
i am able to fully disassemble the forks when the need arises,
Safety is the big issue, poorly functioning suspension due to degraded oil can be avoided,
Forest,
Do you have the necessary fork spring compresser so you can remove the springs and do it right?
 
#26 ·
...shouldn' need any special tools if I am just changing the oil right? I am not sure about doing the seals myself.
Has nothing to do with replacing seals.
If you want to just do the "dump and run" shown you don't need any special tools. The video is really meant for guys that have already gone thru the process of figuring what viscosity fork oil and what levels they need.
To set the oil levels you do need a fork spring compresser. That really should be done once. The levels as delivered are all over the place.
You also need the fork spring compresser when you get to the point of replacing seals. It works on a lot of bikes. It's not an R9T specific tool.
 
#27 ·
Very helpful comments on this thread thanks for your patience!
I will not be able to compress the fork etc so will need to rely on refilling based on the specified amount of oil (525ml) or replacing whatever comes out of the exisitng set up.

But if fully drained, shouldn't adding the 525ml of oil result in the desired "stock" 65mm air gap? Why would the air gap vary if the volume of the internals are all the same?