Forks

Got a technical query? Found another 0.02bhp? Ask/tell the world.

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yamagar1
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Forks

Postby yamagar1 » Tue Aug 19, 2014 8:57 pm

Have just bought R1100S, 2001 36k miles and going through it and tidying up and has usual problems broken exhaust studs etc.

However, one of the forks has a long plastic tube insert that is 'floating' in the tube and the other has not. I have read some models have these but were discontinued at some point but should both tubes be fitted with one?

:?:

dave the german
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Postby dave the german » Wed Aug 20, 2014 5:23 am

Welcome to the forum - put a search in - I seem to recall some discussion on the "tube" but cannot for the life of me think what the conclusion was
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omg1010
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Postby omg1010 » Wed Aug 20, 2014 7:27 am

I cannot say as I never owned a 11S (only 11R). However I believe it is irrelevant as the fork itself has nothing to do with damping. The fork ensures the wheel guidance and the oil inside is only for lubing purpose. The damping is ensure only by the front damper ...

The parts can be seen here http://www.realoem.com/bmw/showparts.do ... 42&lang=en

and here http://www.realoem.com/bmw/showparts.do ... 42&lang=en

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Corvus
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Postby Corvus » Wed Aug 20, 2014 8:09 am

This has cropped up before, fairly recently. Bout a year ago. Ish!

I'm pretty sure what you're describing is a device to raise oil level in the fork, but at the same time lowering oil volume without adding additional weight. Although an ingenious solution in principle, apparently it was flawed in practice. It was subsequently scrapped and the oil level raised back up! If you're keeping it, then really you'll need two. Although I'lll bet the bike would function ok with only one as long the oil levels were adjusted accordingly for each leg. Let us know if you can feel the offset unsprung weights!

I'd check the condition of the bushes and fork legs (stanchions).

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nab 301
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Postby nab 301 » Wed Aug 20, 2014 8:00 pm

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Corvus
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Postby Corvus » Wed Aug 20, 2014 8:27 pm

Yes, read the largiader link. The toob is nothing to do with damping. Just to get the oil level up near the top bush without using a large amount of oil. The only reason oil is in there is to lubricate the sliding action of the forks, and the top bush is a fair way up. The oil doesn't perform a damping role.

IMO.

Merecat's take on oil viscosity sounds very plausible to me.

A mates r1100s had the lower oil quantity in, but no plastic tubes. The bushes were worn and the stanchions had picked up material.

"Deary me" we said.

yamagar1
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Location: Bedford

Re: Forks

Postby yamagar1 » Wed Aug 20, 2014 8:46 pm

yamagar1 wrote:Have just bought R1100S, 2001 36k miles and going through it and tidying up and has usual problems broken exhaust studs etc.

However, one of the forks has a long plastic tube insert that is 'floating' in the tube and the other has not. I have read some models have these but were discontinued at some point but should both tubes be fitted with one?

:?:

Thanks for all of the replies - as I only have one tube (it was not screwed into the bottom of the fork leg so was filling with fork oil) I will remove it and fill with 0.49l oil ……….. and check the bushes cause I don't know how long it has been used like this!

Richard


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