Obviously 'Work in Progress' and not sorted yet....
Fork Stanchion recall?
- Thread starter gerarddwatts
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POL382
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Received a letter from the Spanish Interior Ministry yesterday requiring me to contact BMW for the forks to be examined etc.
Obvious answer is drill through the stanchion and top fitment , then knock either a 6" nail though the hole and bend it over on the other side or perhaps use a nice monkey metal 6mm spout bolt and one of those square nuts on the other end .
Sounds as good as Munich are managing
Sounds as good as Munich are managing
'Monkey metal' - a common expression used by bikers in the 70s about the material used to build Japanese motorcycles. I didn't really understand what this mysterious substance was back then and still don't - can anyone enlighten me as to to the elemental composition of 'monkey metal' and explain the derivation of the term?
Excellent vid, thanks for posting, its saved me reading the entire thread.
Perhaps it should be made a sticky??
Perhaps it should be made a sticky??
Deleted account 181015003
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Its slang for die-cast zinc commonly used in old toys and prototypes before using a better metal for the production run
Just seen this
http://www.motorcyclenews.com/news/2017/july/bmw-r1200gs-recall-suspension/
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http://www.motorcyclenews.com/news/2017/july/bmw-r1200gs-recall-suspension/
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DC
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What's different here from the normal recall?
fred_jb
Registered user
Maybe they've now decided that if they stiffen the top of the stanchion too much it might crack below the reinforcement. It looks like there is already a rubber bushed fitting that the top bolt goes through, but perhaps they have decided to replace that with a more compliant one to allow more movement and reduce the tendency for the stanchion to flex? Presumably there has to be some give in this system to accomodate a change in angle of the forks, because as the wheel moves up and down the telelever forward attachment point is going to describe a shallow arc which will push and pull on the fork, changing its angle slightly.
fred_jb
Registered user
I found an description of the Telelever system here that confirms the arc movement which causes the movement at the top of the stanchions: http://www.motorcyclistonline.com/conventional-vs-telelever-forks-drawing-line
Interestingly this says that on the HP2 the top mounting has a spherical bearing to accommodate the angle change at the top of the stanchions caused by the suspension design. I've not been able to find any evidence in parts lists and drawings that the less exotic models have this, so I think they must make do with simple rubber bushes surrounding the top fixing bolts, so it could well be that they have decided to also replace these with modified versions.
Interestingly this says that on the HP2 the top mounting has a spherical bearing to accommodate the angle change at the top of the stanchions caused by the suspension design. I've not been able to find any evidence in parts lists and drawings that the less exotic models have this, so I think they must make do with simple rubber bushes surrounding the top fixing bolts, so it could well be that they have decided to also replace these with modified versions.
alp
Registered user
Had a quick chat to my local dealer about this and he mentioned that either they or another dealer had found that when they offered up the new press fit sleeve to a stanchion tube it was a loose fit!!! Guess the parts are made by Marzocchi after all!!
fred_jb
Registered user
You would think they could at least get the fix parts made properly, knowing how high profile this has become! Maybe it's not that, and there are sloppy tolerances on the size of the stanchions fitted to bikes, which could cause the same problem? If that is the case, then BMW have a really big problem!
fred_jb
Registered user
I'm kind of thinking it's about time someone did one of those Hitler in the bunker films with spoof dialogue about this. I can just imagine it:
Hitler: Why are these f**king sleeves not fitting correctly - this is making us a laughing stock. Bloody Italian engineering.
Cowering generals: Herr Fuhrer - we asked the Italians and they say our engineers only specified a close tolerance on the inside diameter of the stanchions, so the outside diameter could easily vary by enough to allow the sleeves to be too tight or too loose.
Hitler: Well don't just give me problems - give me solutions
Cowering generals: Well we could replace the stanchions on every bike with more precisely engineered ones - we are looking into the cost of this, but the Italians say it would bankrupt them.
Fred
Hitler: Why are these f**king sleeves not fitting correctly - this is making us a laughing stock. Bloody Italian engineering.
Cowering generals: Herr Fuhrer - we asked the Italians and they say our engineers only specified a close tolerance on the inside diameter of the stanchions, so the outside diameter could easily vary by enough to allow the sleeves to be too tight or too loose.
Hitler: Well don't just give me problems - give me solutions
Cowering generals: Well we could replace the stanchions on every bike with more precisely engineered ones - we are looking into the cost of this, but the Italians say it would bankrupt them.
Fred
Godzilla
Registered user
I've just spoken to my dealer about this. They looked up the latest communication about this and said there is nothing about the rubber bit for the shock. The only rubber parts needed are the small O rings on the fork air vent screws.
Could this be a rubber bump stop of some sort? I think until this becomes factual it needs ignoring.
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fred_jb
Registered user
There has to be some give in the system because the angle of the forks varies slightly with suspension travel. If you look at the video posted earlier showing the mod being done, it looks like the inside of the top yoke where the top of the stanchion is bolted on has a bush with a rubber surround. It may be this that provides the small amount of movement required and if so BMW may have decided to replace it with one that has a bit more give. I guess they can't overdo this though or it could start to make the steering feel a little vague.
fred_jb
Registered user
Just been reading the article in MCN about this and it occurs to me that the fix had better be 100% effective, because by covering the top of the stanchion it makes it impossible to check for any future movement. If the stanchion did still separate the first you would know about it would be when it popped out from under the sleeve applied as a fix, and the front wheel fell over. I think I'm going to be making a mark on my stanchion at the bottom of the new metal sleeve so that I can be sure it is not moving.
No, BMW are ensuring the stanchion tube does NOT move relative to the bit at the top of the tube which DOES move in a rubber pivot fixed in the top yoke.
fred_jb
Registered user
That's exactly what I said, so why quote me and say no? Perhaps try reading it again!
( I wrote in response to a post saying that a rubber bush was being replaced as well as the sleeve being fitted.)
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