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Author Topic: Strange fork thing goin' on...  (Read 1621 times)

Offline Justin B.

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Strange fork thing goin' on...
« on: May 24, 2009, 03:09:42 PM »
I pulled off the Dawg's fork sliders, cleaned them out, and reinstalled and noticed that the l/h side was about 3/32", or so, "lower" than the r/h side causing the axle to bind.  Loosening the triple tree clamps and raising the tube a bit allowed the axle to slide all the way home with finger pressure.

I need to take some measurements...
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

not-so-fast-ed

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Re: Strange fork thing goin' on...
« Reply #1 on: May 24, 2009, 06:37:04 PM »
Justin,  Anything to do with the rain you've been getting?

 ;D

Ed

Offline Justin B.

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Re: Strange fork thing goin' on...
« Reply #2 on: May 24, 2009, 07:15:37 PM »
No, it's in the shop BUT we did get a purty good turd-floater a bit ago...
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

Offline Bengt_Phorqs

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Re: Strange fork thing goin' on...
« Reply #3 on: May 24, 2009, 09:12:22 PM »
What's the prognosis on that? Sounds like one of the springs may have "compressed" a little bit.  Do springs do that?  I would think something mechanical would cause it to bind and not expand.  Is there a metallurgist in the House?
Bengt Phorqs, Jake R90/6, R80/7, R1200RTw, Moto Guzzi California EV , Triumph TR250W, Yamaha TY250A Trials, Suzuki DR650

Offline Justin B.

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Re: Strange fork thing goin' on...
« Reply #4 on: May 24, 2009, 09:25:52 PM »
No, I don't think a spring could cause this issue.  It's almost like one assembled tube/slider assembly as a bit longer than the other!
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

Offline nhmaf

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Re: Strange fork thing goin' on...
« Reply #5 on: May 24, 2009, 10:16:47 PM »
Maybe a spring is broken, or- something which is preventing one  side from extending all the way?  Or, maybe, one side was replaced with a new fork tube that wasn't cut right?   Did you get pictures of the top of the forks prior to disassembly?   This is an odd one..
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Offline Justin B.

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Re: Strange fork thing goin' on...
« Reply #6 on: May 24, 2009, 10:20:19 PM »
No, but when I serviced the head bearings I didn't loosen the lower tree bolts so there shouldn't have been any change there and when I put the top tree back on the tops of both tubes were at the same spot.  This is indeed strange...
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

Online Barry

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Re: Strange fork thing goin' on...
« Reply #7 on: May 25, 2009, 10:05:09 AM »
Topping out bushes could be different heights ?  maybe one slightly perished.
Barry Cheshire, England 79 R45

Offline Justin B.

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Re: Strange fork thing goin' on...
« Reply #8 on: May 25, 2009, 05:45:23 PM »
Hmmm, are they a fiber or plastic thing?  I did have some chunks of the "mystery crud" on that side that seems to wind up in the sliders...

If it is some sort of bump-stop bushing then I think I'll probably ride it as-is for a while and if it proves reliable then dive into the forks a bit deeper...
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

Online Barry

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Re: Strange fork thing goin' on...
« Reply #9 on: May 26, 2009, 06:37:20 AM »
Originals on mine were black rubber.  Motobins replacements seem to be polyurethane.

« Last Edit: May 26, 2009, 06:49:23 AM by bhodgson »
Barry Cheshire, England 79 R45

Offline Justin B.

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Re: Strange fork thing goin' on...
« Reply #10 on: May 26, 2009, 11:41:11 AM »
Hmmm...  Did you take tons of pictures when you rebuilt the forks?  There is little to nothing concerning this on the web, that I can find, and it would be nice to have fork overhaul in the Wiki.
« Last Edit: May 26, 2009, 11:47:28 AM by admin »
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!

Online Barry

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Re: Strange fork thing goin' on...
« Reply #11 on: May 26, 2009, 03:05:19 PM »
The only thing I did was take accurate dimensions so that I could make new shims and valve washers. The attached diagram is all I had to go on. Item 24 is the topping out bush.

Maybe the next rainy day I'll  pull one leg apart and take some pictures but it'll have to wait a while until after my holiday.

« Last Edit: May 26, 2009, 08:14:03 PM by bhodgson »
Barry Cheshire, England 79 R45

Offline nhmaf

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Re: Strange fork thing goin' on...
« Reply #12 on: May 26, 2009, 03:52:24 PM »
I think that is that part that I've seen disintegrate on an airhead fork before (that, and the "buffers" that were at the top of the fork legs on the older airheads).   My LS's legs didn't seem to have a problem with part #24 at the time I had them apart, but I am sure that time, temperature, and fork oil additives all play a part.
Airhead #12178 ? BMWMOA #123173 ?BMWRA #33525 ?GSBMWR #563 ?1982 BMW R65LS ?1978 BMW R100/7 1998 Kawasaki Concours

Offline Justin B.

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Re: Strange fork thing goin' on...
« Reply #13 on: May 27, 2009, 12:42:21 AM »
I've never had the need (or was never curious enough) to completely disassemble a fork leg before, maybe I'll do that at the next fluid change...
Justin B.

2004 BMW R1150RT
1981 R100RT - Summer bike, NEKKID!!!