Longitudinal motorcycle engine - torque effects 1

[amorrison]

Lateral engine torque reactions are produced at the wheels.
Where are the reactions for a longitudinal engine ?
Rider sidewise lean?

 

[NormPeterson]

Fore and aft compliance movement of the lower ball joint should not.

Wouldn't that imply zero Ackermann correction / true parallel steer?

There would still be vertical effects and bumpsteer.


Norm

 

[BrianPetersen]

If the steering tie-rod is not absolutely parallel with the main lateral lower suspension link (not the trailing link) then fore/aft compliance movement certainly could have some steering implications.

 

[patprimmer]

Unless the tie rod and lower link are very seriously out of parallel, it would take a substantial fore and aft movement to create a very small toe change. I have never seen one that is more than a few degrees off parallel.

It also depends on the upper lateral arm and how the steering arm is positioned relative to both arms as they are often out of parallel in both plains to control camber and anti dive.

Regards
Pat
See FAQ731-376 for tips on use of eng-tips by professional engineers &

http://eng-tips.com/market.cfm

for site rules

 

[LadaTrouble]

I don't notice the torque reaction much on my '87 BMW R65,it's only when starting and taking off that I notice it,otherwise it rides just like a normal motorcycle.The R65 has a lighter flywheel and shorter stroke than the bigger BMW's,but I don't even notice on them.

I have noticed it much more on Moto Guzzi's - they actually require opposite lock under hard acceleration at low speeds (1st gear),and will pull the bike down under power exiting right hand corners,and are self righting exiting left hand corners.Even though the effect is noticeable,there is no problem riding the bikes,you just adapt.

 

[pontiacjack]

Lada- Please don't lump all Guzzis together. I've done a one-on-one comparison with a friend's R65, and my Guzzi V50 has less polar inertia of flywheel/clutch.

 

[swall]

I have noticed that my BMW's give you an interesting torque reaction if you have backed up to a curb, then go to start up and leave. The rear wheel being pinned increases the reaction to the machine that can be somewhat disconcerting if you're not expecting it.

 

[LadaTrouble]

I didn't mention the V50 - because people tend to lump all Guzzi's together.I have a Stornello 160 - even Guzzi riders don't know what I'm talking about.I've ridden the V50,and it has almost no torque reaction at all...I just notice squat when backing off in corners,but that's more a shaft drive thing.The V50 has a different engine package to the bigger bikes,the R65 is basically a short stroke 750,particularly my mono which has the same frame as the bigger engines.