Oil leak on my GSA front fork, due to hitting a bloody deep pot hole with hi-speed, however it’s about the time I need to carry out fork service.
Telelever suspension system of the BMW is an interesting invent. The main suspension is located deep inside, two obvious front forks, but their primary function is to make a stiff frame for the front wheel to sit in, and to allow the rider to steer the bike. So once a fork got leak, and you still need to keep riding, all you need to do is to try all means to hold the oil at the leaking point, covering by cloth with additional of some nylon on top of it. That will prevent oil drops onto front tire and especially brake discs. If you are confident enough about your skill, you can shorten the spring ring on the dust seal about 1cm, it will help the dust seal hold a little bit more tight to the fork tube, somehow reduce a bit oil leak.
Bike on center stand. Raise the engine to have front wheel freely spinning. Remove front wheel:
Loosen two bolt which holding the front fork on the lower triple clamp:
Carefully pull down the fork tube, slowly and straight down to avoid damage to the inner tube and residual oil pour out.
Remove all residual oil from the fork tube:
Remove the dust seal – it’s quite easy to remove, by screw driver or even by your thumb. Then remove the circlip:
Oil seal of the GSA front fork held very tight. Best if you have oil seal removal tool. If not, then you have to try your best DIY tool, either by steel hook, screw driver, or two screws to pull the oil seal out. Please remember the top side of each seal, as well as the o-ring.
Make sure the inside chamber is clean, you can use gasoline and then dry it by air blowing
Liquid came out from the fork after cleaning by gasoline:
Fill the new oil in. Put every parts back to the fork tube in order. Be noted that when you drive the oil seal, you need something with appropriate size, thickness and diameter. When you drive the oil seal in, do it firmly, equal.
You can either install the dust seal onto the fork outer tube or onto the inner tube first. The GSA fork is not so difficult as some other bikes’.
Note: You do not need to disassemble the inner tube from the upper triple clamp for changing fork seal and oil.