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Blown Fork Seal


barno68

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Due to the unique design of the front suspension on these bikes it is a breeze to do the fork seals.

 

I place a board under the centre stand to get a little more clearance then tie the back of the bike down.

 

Next remove the front brake calipers and tie them out of the way.

 

Remove the front wheel.

 

Remove the fender.

 

Unbolt the frok leg lower from the cross bridge.

 

The leg will now pull down off of the bike.

 

Carefully lever out the old seal - I use a blunt screwdriver

 

Clean up the area, oil the new seal and using a suitable drift (a large socket works) press the new seal into place.

 

Reverse the removal procedure then do the other side.

 

Andy

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Andy

 

I came across this reply of yours. I have just suffered an MOT failure due to a leaking fork seal (although why the fork seals are relevant on a telelever-operated suspension system is beyond me: a call to the local BMW shop confirmed their frustration, and a "that's the way it is" shrug of the shoulders.)

 

Anyway, to your succinct procedure: running it through in my mind's eye, it would appear that you are leaving the fork tube still attached to the upper fork bridge, and simply removing the slider from under it, seals and all. Have I understood you right? if so, then this seems a do-able job.

 

By the way, BMW quoted £36 for parts to do both fork seals (seals, dust seals and new oil), and a whopping £230 for labour. Hence the interest in your procedure.

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The way I do it the upper tube stays in the yokes as there is no suspension components tieing them together. You have to separate the lower tube from the A-Frame with the shock on it which, apart from the wheel, is all that holds it on. Use a heat gun on the bolts as they are loctited in place and use loctite to re-fit them.

 

The official BMW procedure is to drop the whole fork leg, which is not a lot more effort but needs the tupperware out of the way first hence 4 hours labour.

 

There is a slightly higher risk of damaging the new seals this way. You set the oil level by volume, which I think is 470cc per leg.

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I did mine a couple of weeks back without removing TW but I did remove the handle bars and top section of the fork, you will lose a small amount of fluid when you slide the two sections apart, you also need to loosen the bleed screw at the top to reduce suction/pressure, I found the hardest part was fitting the new seal, I had to go out and buy a 37mm socket, if you don't use something like this, (I initially tried a piece of plastic pipe) you will damage the delicate springs that are part of the seal

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Jerry Johnston

You can use the old seal instead to pound the new seal in place - it's a perfect fit. smirk.gif

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Look here http://www.ukgser.com/forums/showthread.php?t=97873 it's a GS in the pictures, but it's almost the same for an RT - There is no need to remove the fuel tank or fairing panels.
Exactly! About the only thing I do different is open up the air bleeder before pulling the slider out to eliminate the suction effect in it. Do one side at a time and the wheel and whole lower 'stuff' doesn't even have to come off!
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Exactly! About the only thing I do different is open up the air bleeder before pulling the slider out to eliminate the suction effect in it. Do one side at a time and the wheel and whole lower 'stuff' doesn't even have to come off!
On a GS maybe, but on an RT? It doesn't seem like there would be enough room to work with the front fairing assembly in the way.
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On a GS maybe, but on an RT? It doesn't seem like there would be enough room to work with the front fairing assembly in the way.

 

My business is working on BMW's - There is enough room to do the job on an RT without removing any fairing panels/fuel tank parts.

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On a GS maybe, but on an RT? It doesn't seem like there would be enough room to work with the front fairing assembly in the way.
No problems. One of these days I need to snap a picture of an RT with one side out and the front wheel cocked way to one side. It's the most discerning looking thing!
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Thanks again for the instructions, the job took all of an hour once I had the parts. There was a lot of white gunk in there so I took the extra time to remove the plastic tube inserts and run a rag down the tubes. All told, I think it was about $70 in parts (not counting the new front tire :-). As I had the bike torn down for a tune up and ABS modulator replacement, everything was already out of the way.

 

Brent

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Andy

 

Thanks for the clarification. One last point: where did you get your replacement parts from? Did you replace the seal and the dust seal both?

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Andy

 

Thanks for the clarification. One last point: where did you get your replacement parts from? Did you replace the seal and the dust seal both?

 

James Sherlock and I did just the seals - JS part number 012988 £14-69 the pair. He sell the dust covers at £4-11 each pt no 012980.

 

Andy

 

Andy

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  • 3 weeks later...

Andy

 

Parts arrived. Another query, which you may either have not addressed, or were able to work around: having determined you could do the job with the upper parts still in situ, how did you overcome the suction effect while removing the lower slide, and the opposite hydraulic lock effect when refitting the lower slide? Most threads point to the upper bleed screw needing to be opened to allow under/over pressures to be equalised, which requires the handlebars to be removed.

 

Or did you manage to get around the problem?

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it's easier if you take off the handle bars to access the bleed screw, if you separate the two halfs of the fork with the top section in situ, be prepared to catch the fork oil which will leak out.

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Eckhard Grohe

I noticed in the photos that there was a lot of grease in the seal when it was installed. It seems to me that grease could lead to future problems by filling the cavity between the wiping edges or preventing the edges from really wiping. Is this really necessary or do I just moisten the wiping surfaces of the seal with a bit of fork oil.?????

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Alan, probably the correct way is to pull the bars, lower the tube, then open the bleed screw.. I have done a couple now without pulling the bars or the opening the bleed screw by inserting a lubricated .001” feeler stock (long full length type) between the upper tube & seal when reinstalling the lowers.. That allows the air to escape as the lower is slid on & up..

 

Twisty

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