Is BMW killing it's famed shaft drive? | Page 3 | GTAMotorcycle.com

Is BMW killing it's famed shaft drive?

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Brian P said:
The swingarm on any production motorcycle is welded up of some combination of stampings and extrusions and castings with some simple machined parts involving where the swingarm pivot bearings and suspension linkage have to attach. Regarding the distance between swingarm pivot and axle center-line, it is not held to CNC-machining accuracy, it is production-welding-fixture-and-clamps accuracy.

Likewise ... the engine mounts (which is where the other sprocket is attached). You are not dealing with machined datum surfaces. You are dealing with clearance holes in the chassis for the engine mount bolts. They intentionally have a little bit of wiggle room in them to facilitate assembly.

All this means ... is that with conventional manufacturing methods, the dimension between the transmission output shaft and the rear axle center-line is not held to CNC-machining dimensions, it is held to production-welding-fixture dimensions - probably give or take a millimetre or two when you account for all the tolerance stack-ups.

"Could" you make those parts with machined datum surfaces to achieve CNC-machined accuracy so as to not need any means of adjustment? Sure, but it would cost more than providing a slotted hole and jack-screw for the axle (conventional axle adjustment) by a long shot. And it would screw up people who want to change the final drive ratio.
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Thank you. I was thinking about bringing up those points but people were having a hard enough time with how changing the final drive ratios on sprocket driven systems the distance between the sprockets has to change to maintain proper slack.......unless you get really lucky or run a ratio that works, but isn't near what you're trying to achieve.
 
FullMotoJacket said:
Thank you. I was thinking about bringing up those points but people were having a hard enough time with how changing the final drive ratios on sprocket driven systems the distance between the sprockets has to change to maintain proper slack.......unless you get really lucky or run a ratio that works, but isn't near what you're trying to achieve.
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As I recall, one of the big problems when they took the Harley-Davidson XR1200 road racing was the distance between the front pulley and the swingarm pivot. It made for some interesting handling issues. I think the cure was a kit to relocate the swingarm pivot. Please feel free to correct me if I'm wrong ?

Harley-Davidson-XR1200-Right-Side-5.jpg
 
Hack said:
No one buys a BMW motorcycle so they can show off their "made in China" label.

Yes, lots of stuff we buy is made in the PRC, but we do so fully aware of the fact and for things like phones and computers... Who cares?
BMW... or as my German father would say ...
Beh.M.Vey... has a branding that isn't as far as I've seen advertising...

BMW Motorrad... Proudly built in China.

It may be irrational, but... I've scratched the 850 off my short list.
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(This topic deserves a separate thread)
BMW = Beijing Motor Works

Globalisation allows companies to outsource the manufacture of components to countries that provide the best bang for buck. If this crosses your expectations, then as a consumer you have the option of talking with your wallet i.e. just don't buy. The fact is that every bike/car will have a component made outside of it's factory and possibly in another country. The key is having strict adherence to manufacturing standards.
In addition to BMW, you have KTM and "Thai-umph" among others, that engage in this practice.
What I do not like about this is:
(a) The savings are almost never passed on to the consumer, but then this is an economic fact as Companies exist to make money.
(b) Sometimes there is a lag in QC and at times the "build" is tailored to a price vs. a standard.
(c) Outsourcing leads to a loss in jobs in the parent country and to worker-exploitation in the "contracted-to" country.

* full disclosure for item (c), my job was outsourced, my MP agreed with the unfairness of it, but he was unable to move the Feds and claimed that the economic might of the "big company" made it impossible to reverse the outsourcing.
... story for another day and time.
 
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TK4 said:
As I recall, one of the big problems when they took the Harley-Davidson XR1200 road racing was the distance between the front pulley and the swingarm pivot. It made for some interesting handling issues. I think the cure was a kit to relocate the swingarm pivot. Please feel free to correct me if I'm wrong ?

View attachment 44874
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No idea what they did with the XR. Probably a squatting issue. They ran into the same problem in the 70s, along with excessive chain slop when they started extending the travel on MX bikes. There were some innovative solutions.

Jack shafts on swingarm pivots.
gupP7I0qrlrLFkm5o7nwSwex3omZAHpUAwDQdCaKibqP4HDaezzPPRFtngKOSby6nGHeSXwExHwHLuG-cE4x1dZ04yGjAAMbO4TwgwJvMCp9g4bWWZ0BsmVt4uZsuNBCkmjPj1z276Szadvkm9TTQ9gz5vHNav8Ua5qvSSTeV6gk_OYa-gzrbiOljYsFjYBzM0T9lMbdgJccB9bGBVyzCocO1CXNpw2YqusnCteTEPEGHQ_lUJtNKp6RruQgXRxEvAGCObkD3G0


ATK (Leitner) anti squat device
zbtF7QEv3yPrk-ktnuU1rakeO_uNWm2gNCO1SzlAYHCnJm_-JJR6RfzrsuFer_RHJwAqUDfpLEm2Lzqz8zsw0Ic


Boyesen link (virtual pivot)
MXA_feb08-AncientArtifactsweb_Page_.jpg
 
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Chris-CJ said:
(c) Outsourcing leads to a loss in jobs in the parent country and to worker-exploitation in the "contracted-to" country.
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I'm all for profit... It's what motivates innovation. And I'd pay more for say... A bike if it were built anywhere but PRC or a third world ###hole.
PRC claims to be a socialist/communist state yet needs to prop itself up through pure capitalism... What a joke.
Of course "western" companies aid them by lining up to exploit this fatal flaw in the PRC's system...

Anyway... You suck BMW Lol
 
Found a pic of a modded XR race bike. Moved the pivot up to help eliminate the suspension squat.

xr-right-730x544.jpg
 
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FullMotoJacket said:
Found a pic of a modded XR race bike. Moved the pivot up to help eliminate the suspension squat.
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Look at the difference in the angle of the swing arm. They jacked the rear end up so far, trying to kill steering head angle, to get the slug to turn, that there was no way the thing would pull out of a corner.
It looks like adjustable triples too
... then they put a steering stabilizer on the size of the shock on my Oldsmobile, so it would go straight

That's what happens when you race agricultural equipment.

My favorite was/is the Leitner setup, on the ATK with the 3 foot long shock. (No connection to Leitner-Bush)
I have a Leitner front end on TR3 racer, it works like emulators, but predates Race Tech emulators by 30 years.
 
bitzz said:
My favorite was/is the Leitner setup, on the ATK with the 3 foot long shock. (No connection to Leitner-Bush)
I have a Leitner front end on TR3 racer, it works like emulators, but predates Race Tech emulators by 30 years.
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ATK was Horst Leitner. He designed/built KTM's 89 125 prototype. Went on to form AMP Research. Built full suspension mountain bikes. Now they do bed extenders and extending side steps for pickups.

b6923901a0dbc54a86899843ccf1490f.jpg
 
Anyone have a link to buy the chain, or Regina chains in Canada? I think I need a new chain end of season and may try this one as its a 525
 
Does it not say; the rollers are coated and the rest of the chain is still a regular chain that still has rubber seals to hold in the original grease :/ how is this a forever chain, you are just going to have a heck of a time trying to wear out the rollers as I read it.

I think it might end up one of those if you have to ask the price it is too expensive items.
and I want a regular non sealed 520 with all of the chain covered in diamond treatment :cool: then I never need to lubricate it.
 
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