Author Topic: When is it logical to get shafted ?  (Read 726 times)

Offline Alfetta

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When is it logical to get shafted ?
« on: November 29, 2021, 01:45:55 PM »
So while reading another post, I noticed a bike with a transversely mounted V-twin, utilizing a shaft drive system. I know that this is nothing new, and there are several machines out there that are configured such.... But I'm not sure why.

In the case of a GOLD WING, BMW, Guzzi, or other Longitudinally mounted engines, the shaft drive system makes sense as the 90 orientation is required to drive the rear wheel. but in the case of transversely mounted engines, I don't know why any manufacture would opt for changing the drive direction TWICE ??  not to mention that the bevel drive gears carry higher transmission losses than conventional gears.

In todays world of belt drives and o-ringed chains, there is no need to lubricate, hygiene and longevity is much improved. thus the added weight, cost and complexity of a shaft system (esp. a dual bevel gear type) only seems to be a burden.
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Offline Kiwi_Roy

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Re: When is it logical to get shafted ?
« Reply #1 on: November 29, 2021, 05:55:14 PM »
Yes, I used to own a nice Suzuki Boulevard S50 that did that, Change Direction twice.
I think it makes no sense, they should have used a belt drive like the S40
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Offline JC85

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Re: When is it logical to get shafted ?
« Reply #2 on: November 29, 2021, 08:10:51 PM »
I'm very confused...Guzzis and BMWs are transversely mounted, are they not???
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Offline lucian

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Re: When is it logical to get shafted ?
« Reply #3 on: November 29, 2021, 08:28:01 PM »
Apparently when you pull up to a gas pump lately  :sad:

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Re: When is it logical to get shafted ?
« Reply #3 on: November 29, 2021, 08:28:01 PM »

Offline nc43bsa

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Re: When is it logical to get shafted ?
« Reply #4 on: November 29, 2021, 09:27:02 PM »
I'm very confused...Guzzis and BMWs are transversely mounted, are they not???

From the engineering point of view, the orientation of the crankshaft determines whether an engine is transverse or longitudinal.  If the axis of the crank is across the frame (parallel to the axis of the wheel axle) it is transverse.  If it is perpendicular to the wheel axle, it is longitudinal.
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Offline Dimitri_Harkov

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Re: When is it logical to get shafted ?
« Reply #5 on: November 30, 2021, 01:31:26 AM »
My only explanation (why isnt' it explaination by the way? Makes no sense):

The designers/engineers think they have power to spare/can afford the extra weight and want to make sure the bike is no hassle on even the longest tour (belt/chain-wise).
Of course with the trade-off of a more costly rebuild/maintenance procedure on the shaft drive now and then.

Or maybe they just liked the idea of a shaft drive and that's it.
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Offline guzzista

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Re: When is it logical to get shafted ?
« Reply #6 on: November 30, 2021, 04:26:30 AM »
Back when chain drive was the default design for motorcycle drivetrains and  only BMW , Guzzi  and Honda GW were configured with a shaft drive, the MV750 was the only bike that had  a transverse

crank and shaft drive. That gave Magni an opportunity to simplify the drivetrain, regain a bit more  power from less torsional losses and make the MV's more appealing (imo) with his  chain drive conversions
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Offline Dimitri_Harkov

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Re: When is it logical to get shafted ?
« Reply #7 on: November 30, 2021, 04:41:41 AM »
There was also the Yamaha XS 750 (and 850).

Very nice machines with transverse engine and shaft drive.



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Offline Huzo

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Re: When is it logical to get shafted ?
« Reply #8 on: November 30, 2021, 05:02:30 AM »
The XV 750 Yamaha was another.


Offline Dave_NWTrophy

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Re: When is it logical to get shafted ?
« Reply #9 on: November 30, 2021, 04:42:11 PM »
Chains, even x- and o-ring ones, still require cleaning and maintenance, and will last about 12,000 miles or so if maintained:

https://www.revzilla.com/common-tread/bmws-maintenance-free-m-endurance-chain-put-to-the-test

Belts will last about 50,000 miles or so, but tension has to be checked every 2,500 to 5,000 miles.  They also don't work well for off road or even gravel, as a stone picked up in the belt will blow through it when it hits the sprocket.  Ask me how I know....

Shaft drive components will last tens of thousands of miles, usually outlasting engines and gearboxes.  I've had mostly shaft drive motorcycles for the last 20 years (Yamaha XV920J, Triumph Trophy, now two Guzzis), and it is still the final drive of choice for the riding I do.

Dave

Offline moto-uno

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Re: When is it logical to get shafted ?
« Reply #10 on: November 30, 2021, 05:08:32 PM »
  Something else that's been ignored , is , let's be honest , chains and sprockets are cheap to produce .
  Peter

Offline smsw

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Re: When is it logical to get shafted ?
« Reply #11 on: December 01, 2021, 08:14:29 PM »
  Something else that's been ignored , is , let's be honest , chains and sprockets are cheap to produce .
  Peter
Lot of reasons for a chain drive, more efficient, lighter weight, as well as cheaper, etc.  Mfr's do not generally care about an owner's maintenance problems.

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