Drive Shaft Angle? Blowup?


Information and questions on GL1200 Goldwings (1984-1987)
Post Reply
Cwrhine
Posts: 1
Joined: Fri Jun 09, 2017 6:21 am
Location: Columbus, Ohio
Motorcycle: 1985 GL1200 Aspencade

Drive Shaft Angle? Blowup?

Post by Cwrhine »



I posted a picture on Reddit of my 85 Gl1200 cafe/dragger style. I have after market shocks on it, and a guy said my dive shaft WILL blow up at that angle. I can't find any info on this.... What's the proper angle? It's not exactly parallel to the ground. If anything, it's slightly angled up towards the engine like I thought it should be?


User avatar
WingAdmin
Site Admin
Posts: 23616
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (sold)
1998 XV250 Virago (sold)
2012 Suzuki Burgman 400 (wife's!)
2007 Aspen Sentry Trailer
Contact:

Re: Drive Shaft Angle? Blowup?

Post by WingAdmin »

Cwrhine wrote: Fri Aug 11, 2023 12:26 pm I posted a picture on Reddit of my 85 Gl1200 cafe/dragger style. I have after market shocks on it, and a guy said my dive shaft WILL blow up at that angle. I can't find any info on this.... What's the proper angle? It's not exactly parallel to the ground. If anything, it's slightly angled up towards the engine like I thought it should be?
Maybe post the picture here so we are able to give an opinion?
User avatar
Rambozo
Posts: 3088
Joined: Sun Apr 01, 2018 8:36 pm
Location: Disneyland
Motorcycle: 1992 GL1500 Aspencade
Ducati Monster

Re: Drive Shaft Angle? Blowup?

Post by Rambozo »

U-Joints are typically happiest when run at 7 degrees or less. (Don't tell the off-road guys) ;)
User avatar
Sadanorakman
Posts: 475
Joined: Tue Sep 19, 2017 1:42 pm
Location: Midlands, ENGLAND
Motorcycle: 2000 GL1500 SE (Blue)
1991 GL1500 SE (Gold)

Re: Drive Shaft Angle? Blowup?

Post by Sadanorakman »

Rambozo wrote: Fri Aug 11, 2023 7:56 pm U-Joints are typically happiest when run at 7 degrees or less. (Don't tell the off-road guys) ;)
Yes this. A simple (single cardan) universal joint is not a constant velocity joint, so when it's not running dead straight, it causes a small amount of acceleration and deceleration with every single turn! This loads the joint with dynamic forces, and will increase wear.
The greater the angle of operation, the greater the velocity shift.

This is mitigated somewhat if you have a UJ at both ends of a driveshaft, each carrying identical angles (e.g. rear-wheel drive vehicle with traditional live axle or similar) because then that non-constant velocity is cancelled out by the second joint before it gets to the rest of the drivetrain, and it's only the mass of the driveshaft undergoing the velocity changes.

Unfortunately on a gold wing, you just get a single UJ, so when it's not running straight, those velocity variations have to be absorbed by the rest of the drivetrain including cush-drive and tire.

If they had room for a double cardan joint, or a CV joint like those used in a front-wheel drive car, then this would tolerate running at a constant angle much better.
Measure twice, cut once.
User avatar
WingAdmin
Site Admin
Posts: 23616
Joined: Fri Oct 03, 2008 4:16 pm
Location: Strongsville, OH
Motorcycle: 2000 GL1500 SE
1982 GL1100A Aspencade (sold)
1989 PC800 (sold)
1998 XV250 Virago (sold)
2012 Suzuki Burgman 400 (wife's!)
2007 Aspen Sentry Trailer
Contact:

Re: Drive Shaft Angle? Blowup?

Post by WingAdmin »

Sadanorakman wrote: Wed Aug 16, 2023 5:57 pm
Rambozo wrote: Fri Aug 11, 2023 7:56 pm U-Joints are typically happiest when run at 7 degrees or less. (Don't tell the off-road guys) ;)
Yes this. A simple (single cardan) universal joint is not a constant velocity joint, so when it's not running dead straight, it causes a small amount of acceleration and deceleration with every single turn! This loads the joint with dynamic forces, and will increase wear.
The greater the angle of operation, the greater the velocity shift.

This is mitigated somewhat if you have a UJ at both ends of a driveshaft, each carrying identical angles (e.g. rear-wheel drive vehicle with traditional live axle or similar) because then that non-constant velocity is cancelled out by the second joint before it gets to the rest of the drivetrain, and it's only the mass of the driveshaft undergoing the velocity changes.

Unfortunately on a gold wing, you just get a single UJ, so when it's not running straight, those velocity variations have to be absorbed by the rest of the drivetrain including cush-drive and tire.

If they had room for a double cardan joint, or a CV joint like those used in a front-wheel drive car, then this would tolerate running at a constant angle much better.
100% correct. The amount of angle it is required to push through is not large, as the universal joint is right at the pivot, and Honda designed it such that when the motorcycle is loaded (and adjusted) properly, for the vast majority of time, the universal joint is straight through, with no angle at all. Only when the suspension is moving, or...the bike is overloaded, particularly on the rear seat (and that's as far as I will go on that topic!) is the universal joint held at a constant angle that makes it harder on the entire driveline.


Post Reply