F-Twins Tech - F800GS Renewing Fork Oil

[drneo66]

Once all the fork oil is drained out, we are ready to refill. The 2013 and newer F800GS's WP forks call for an air gap of 61 mm when the fork is fully compressed and the plastic inner damper rod is full. To measure this air gap, you can purchase the proper BMW tool from your dealer (BMW Tool number: 31 6 551), use an aftermarket tool such as Motion Pro Fork Oil tool, or the newly-released Thom Rieck's multipurpose, eco-friendly, and dolphin-safe amazingly wonderful Fork Oil Poker Tool (Patent-pending 2019) available at only the most exclusive of motorcycle dealers for $24.95 , which is also known as a chop stick with a red pen mark at 61mm.

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[drneo66]

Measure out approximately 610 milliliters of fork oil and dump half of it into the fork leg.

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[drneo66]

Slowly draw the plastic inner dampener all the way up and push it all the way down several times to move the fork oil into the damper. You will notice that, as the damper rod is filled it becomes more difficult to move the damper rod.

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[drneo66]

Once the bubbles in the fork oil have settled and you have made sure the damper rod is all the way at the bottom of the fork and the fork is fully compressed, slowly fill the fork with the remaining oil until you achieve a 61mm air gap.

If you using the chopstick (DrNeo's wonder tool ), align the mark we made on the edge of the chopstick with the edge of the fork tube, and fill the fork with fluid until the fluid just touches the bottom of the chopstick. Take your time, as it's not easy to remove excess fluid.

Note: this picture shows the chopstick partially removed

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[drneo66]

Congrats - you've replaced you fork oil! We can now install the top cover to the fork and begin replacing the fork onto the bike.

First, screw the locking nut on the plastic piston dampener all the way down. Next, pull the piston rod all the way up, so it's fully extended. Then, carefully slide the fork spring over the dampener rod. Finally, screw the top cover back onto the plastic dampener rod. This may take take a little bit of coordination as the dampener rod has a tendency to want to slowly retract down.


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[drneo66]

Once the top cover is screwed all the way down, we can screw the locknut up tight against the top cover using the 13 mm open ended wrench and 24mm socket on the torque wrench. The torque for this locknut/top cover is 15 Newton Meters (11.1 Foot-Pounds, 133 Inch-Pounds)


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[drneo66]

We can now put the top cover back onto the fork. Slowly meet up the bronze-colored upper tube to the fork tube and screw the cap down until it's about 80% complete. Using a bit of fork oil and your finger, lubricate the o-ring on the top cover with a bit of fork oil, then tighten the top cover to hand tight.

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[drneo66]

We can now install the fork leg back into the bike. You'll notice that the top of the fork has a single grove machined into it almost at the top of the fork; this is where the fork should sit on the triple tree.

The process to torque the pinch bolts on both the upper and lower portions of the triple tree is a bit unique.

Tighten up the bottom set of two pinch bolts by using your T45 star bit. Each bolt is torqued to 19 Newton meters (14 Foot-Pounds, 168 Inch-Pounds) each time it is tightened. Starting on the top bolt, torque this pinch bolt, then torque the bottom pinch bolt, and continue going between each bolt for a total of six times (each bolt is torqued three times).
(In the picture below, you torque bolt A, then bolt B, then bolt A, then bolt B, then bolt A, and finally bolt B.)


and continue going between each bolt for a total of six times (each bolt is torqued three times).

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[drneo66]

Tighten up the top two pinch bolts by using using your T45 star bit and torque wrench.

This process is the same as the bottom pinch bolts:

Each bolt is torqued to 19 Newton meters (14 Foot-Pounds, 168 Inch-Pounds) each time it is tightened. Starting on the top bolt, torque this pinch bolt, then torque the bottom pinch bolt, and continue going between each bolt for a total of six times (each bolt is torqued three times).
(In the picture below, you torque bolt A, then bolt B, then bolt A, then bolt B, then bolt A, and finally bolt B.)


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[drneo66]

Now we can tighten the top cover of the fork leg. So using your 24mm socket, tighten the top cover to 40 Newton Meters (29.5 Foot-Pounds, 354 Inch-Pounds).

[drneo66]

Move on to the other fork leg and repeat the same process. (We will call this the "second fork" for the next process)

Second fork out, drained, refilled, and top cover screwed on hand tight.

To prevent the forks from binding as we ride, we will use the front axle to make sure that everything is aligned properly. Install the second fork leg so it's again properly lined up with the machined groove on the top of the fork leg/steering head yoke, and hand tighten the top two pinch bolts. Then install the front axle.

Next, loosen, and then tighten the top pinch bolts using your T45 star bit and torque wrench. Again the unique process: Each bolt is torqued to 19 Newton meters (14 Foot-Pounds, 168 Inch-Pounds) each time it is tightened. Starting on the top bolt, torque this pinch bolt, then torque the bottom pinch bolt, and continue going between each bolt for a total of six times (each bolt is torqued three times).
(In the picture below, you torque bolt A, then bolt B, then bolt A, then bolt B, then bolt A, and finally bolt B.)


Then tighten the bottom set of pinch bolts using the unique process: Each bolt is torqued to 19 Newton meters (14 Foot-Pounds, 168 Inch-Pounds) each time it is tightened. Starting on the top bolt, torque this pinch bolt, then torque the bottom pinch bolt, and continue going between each bolt for a total of six times (each bolt is torqued three times).
(In the picture below, you torque bolt A, then bolt B, then bolt A, then bolt B, then bolt A, and finally bolt B.)


You should be able to easily draw out the front axle without any binding. If you notice any binding, then loosen up both top and bottom pinch bolts on the second fork leg and torque them back down.

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[drneo66]

You can now reinstall the front wheel. Directions are located here on the forum: https://forums.bmwmoa.org/showthread...-Wheel-Removal

Then you can reinstall the front brakes by gently guiding each brake caliper onto the brake disc, being careful to route the speed sensor located on the clutch side to the correct position. Using your external E12 star (Torx) socket to torque each upper and lower brake caliper bolts to 38 New Meters (28 Foot-Pounds, 336 Inch-Pounds).



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[drneo66]

You can now reinstall the front fender - careful to route the brake lines and speed sensor wire to the correct locations. Using your T30 star bit to tighten each of the 6 total bolts of the fender to 4 Newton Meters (3 Foot-Pounds, 36 Inch-Pounds). Snap on the plastic pieces that cover the brake lines.

The speed sensor uses a T30 and is torqued to 8 Newton Meters (5.9 Foot-Pounds, 71 Inch-Pounds).

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[drneo66]

Replace the brake line to fork leg holding clamp with your T25 star bit and torque to 4 Newton Meters (3 Foot-Pounds, 36 Inch-Pounds).

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[drneo66]

Take a moment to make sure that everything is installed and tightened up correctly.

Finally, ride off into the sunset!