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General Category => General Discussion => Topic started by: Alfetta on November 29, 2021, 01:45:55 PM

Title: When is it logical to get shafted ?
Post by: Alfetta 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.
Title: Re: When is it logical to get shafted ?
Post by: Kiwi_Roy 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
Title: Re: When is it logical to get shafted ?
Post by: JC85 on November 29, 2021, 08:10:51 PM
I'm very confused...Guzzis and BMWs are transversely mounted, are they not???
Title: Re: When is it logical to get shafted ?
Post by: lucian on November 29, 2021, 08:28:01 PM
Apparently when you pull up to a gas pump lately  :sad:
Title: Re: When is it logical to get shafted ?
Post by: nc43bsa 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.
Title: Re: When is it logical to get shafted ?
Post by: Dimitri_Harkov 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.
Stranger things have happened on bikes & cars.

Cheers,
D.
Title: Re: When is it logical to get shafted ?
Post by: guzzista 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
(https://i.ibb.co/GJFcVrQ/Screen-Shot-2021-11-30-at-10-24-44-AM.png) (https://ibb.co/GJFcVrQ)
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
Title: Re: When is it logical to get shafted ?
Post by: Dimitri_Harkov 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.

(https://upload.wikimedia.org/wikipedia/commons/thumb/0/04/Yamaha_XS_750.jpg/1280px-Yamaha_XS_750.jpg)

Cheers,
D.
Title: Re: When is it logical to get shafted ?
Post by: Huzo on November 30, 2021, 05:02:30 AM
The XV 750 Yamaha was another.
(https://i.ibb.co/w6NmR7x/CCEF3-CB8-677-E-4-F61-81-F3-73677-D15-E8-AD.png) (https://ibb.co/w6NmR7x)
Title: Re: When is it logical to get shafted ?
Post by: Dave_NWTrophy 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
Title: Re: When is it logical to get shafted ?
Post by: moto-uno 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
Title: Re: When is it logical to get shafted ?
Post by: smsw 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.