F800GS Fork Seal Replacement
So, I noticed my fork seals were leaking. How could I tell? Hmm...
This is a pretty simple operation, but I knew nothing about it before I tried it. So this one is dedicated to weekend warrior garage mechanics who are also inept like me. :D
Edit (31/10/2012): The seal sizes I listed below are correct for my bike, which is a 2009. It appears that the forks on 2013+ models may be different (43mm WPs instead of the 45mm Marzocchis).
I opted for SFK seals from Dual Sport Armory. The size of the stock seals is 45 x 58 x 14. Stamped on the inside of the dust seal are the measurements 45 x 58.4 x 4.0 x 14. The SFK kit has the same dimensions, save what I guess is the overall height (11mm for SFK versus 14 for the NOK). The lip insertion depth appears to be the same on both seals (~4mm).
1) Unbolt your ABS sensor (if applicable), and remove the front wheel.
2) Unbolt the brake calipers (2 e-torx bolts) and zip tie them to the frame to keep weight off the hoses.
3) Unbolt the fender (2 torx bolts on the fork legs plus 1 bolt near the brake calipers on each side) and pull it off of the fork legs. Zip tie it to the frame if needed or make sure the weight is supported by the calipers.
4) Loosen ONLY the top triple clamp bolts (2 torx bolts). Use whatever size necessary on your top cap to pop it loose, but don't completely unscrew it.
5) Loosen the bottom triple clamp bolts and slide the fork tube out of the bottom.
6) Unscrew the top cap and slide the stanchion down to reveal the spring.
7) Drain the fork oil. You can optionally remove the fork spring by pushing the spring down, putting a 13mm open end wrench on the nut, and using your top cap wrench or socket to break the top cap loose from the damper rod. Then pull the spring off along with the plastic washer. (You'll have to do this at some point in order to pump the damper to get rid of the old oil and make sure it's purged of air when you refill the forks).
8) Use an impact wrench to unbolt the damper unit from the bottom of the fork leg (8mm allen bolt in my case, I can't remember if this is the stock bolt or not). Pull the damper unit out and lay it aside somewhere clean.
9) CAREFULLY use a screwdriver or pick to pull the dust seal off. This should come out pretty easily, if you have manly fingernails you can probably use those as well. Make sure you don't slip and scratch your fork tubes!
10) Once the dust seal is off, look under the upper stanchion. There is a lock ring with a couple of indentations where you can pry it out with a flat blade screwdriver or pick. Again be careful of your fork tubes, this should also come out pretty easily.
11) Once the lock ring is out, you need to unseat the oil ring. The easiest way I found on youtube to do this is to pull the upper and lower fork tubes apart like a slide hammer. It will take a few whacks but the oil ring should pop out along with a flat washer, the lower bushing and the upper bushing all on the lower fork tube.
12) Use a flat blade screwdriver to spread the upper bushing apart and slide it off the top of the fork leg. It is set into a small indentation, so it may take a little convincing. Still don't scratch anything!
13) Slide the rest of the pieces off, making a note of the order and orientation of everything. (I think the bushings and the washer are bi-directional, but obviously the seals are not!)
14) Clean up the fork tubes and bushings, if you plan to reuse them.
1) Slide the fork seal bullet over the top of the lower fork leg. The goal is to cover up the sharp edge of the indentation where the upper bushing sits. Use tape if you don't feel like spending a few buck for the fancy plastic thingy.
2) Slide the dust seal onto the fork leg. Make sure the metal ring is facing down towards the ground.
3) Slide the snap ring onto the fork leg.
4) Slide the oil seal onto the fork leg. On the inside of the seal there is a double ridge, make sure this is on the upper side of the fork leg, i.e. on the side closest to the handlebars. I put a dab of oil on the inside of both seals before I put them on to help lubricate them, not sure if it's entirely necessary but I figured it couldn't hurt.
This is a really bad picture of the correct orientation, but you can also sort of tell by the indents on the inside of the outer ring.
5) Pull the bullet off, or remove the tape. The rest of the parts won't fit over it. Slide the washer on.
6) Slide the lower bushing on.
7) Slide the upper bushing on, and make sure it is seated into its groove.
8) Slide the upper fork tube over the lower fork tube. Use the seal driver to individually seat the lower bushing. You should be able to hear when it bottoms out.
I actually put the washer between the driver and the bushing in order to drive it in since the tool I have has a gap that the bushing fits into perfectly, making it not fully seat.
9) Use the seal driver to seat the oil seal. If the oil seal is properly seated you should be able to see the groove that the lock ring goes into.
10) Reinsert the lock ring. I had to use my flat blade to get it all the way in because my fingers were too fat.
For reference, the bottom of the ring is in the groove but the top isn't quite seated.
11) Slide the dust seal in. You should be able to do this by hand.
12) Put the damper back in, refill it with oil. Pump the damper until the oil height doesn't change. Set your oil height, reinstall the spring, and button it up with the fork cap.
13) Put everything back together on the bike in reverse order. Tada!
Great job on the tutorial, that will definitely help all the first timers! :clap
Very nice, Lukas. Thanks for sharing:clap:clap.
Thanks for the tutorial. I have Kriega fork seal protectors on my F800 but also 43K miles. Been wanting to change the fork oil anyway. Time to go for the seals.
I was also due for a fork oil change. Only about 10 or 12k on the oil, but there was a little bit of sludge in the bottom after I pulled the dampers out. You'll probably have lot more at 43k. :eek1
Great job, thanks for sharing! :clap
Fantastic step by step ,how do like the SKF's?
I don't remove the cartridges to change the oil and dust seal. That step is optional. I use a thin sandwich bag for a condom to slide the new seals over the tube.
Good write up man :thumb
I noticed mine are starting to leak and I'm right at 20k.
I'm up in Farmington, hit me up if you're ever in my neck of the woods.
The stock seals didn't really seem to be inferior. The SKF's just happened to be a lot cheaper than buying a set of stockers from a BMW shop.
What year is your bike?
I have a 2010, and I noticed that this EBAY listing shows that they are different size---- INSIDE DIAMETER=42mm OUTSIDE DIAMETER=54mm THICKNESS=11mm
And the sizes you list are different...
Just wondering if these were different between years or not...
I'll keep that thread warm in my favorites. Thanks for the upload<label for="rb_iconid_24">http://d26ya5yqg8yyvs.cloudfront.net/cooltu.gif</label>
So, thanks for the write up, I used it this weekend, but had some questions for all you veteran riders out there.
First off, this was about the 4th fork seal job I have ever done, and it was much easier than any other bike I have ever done.
This is on the leg that was leaking. I cannot feel anything, no change in resistance, no edges, uneven surfaces, nothing.
It looks like the chrome is rubbed off.
Something I should be worried about?
Bike has about 21,500 miles on it. The leg was only leaking for about 200 miles and for about a week. It still had lots of oil In it, and it was still producing oil while riding around and sitting, so it wasn't dry.
By the way, I used the 45mm Marzocchi Kit from www.dualsportarmory.com and it fit like a charm. Exact same size seals as the stock ones.
Bump on my last question
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