Torque Reaction Rods

[Lucky Phil]

3 hours ago, Cabernet said:

Moto Guzzi have gone to a lot of effort to allow the bevel box to rotate on needle roller bearings when the bike is buttoned up in a riding state.

Lift the rear wheel with the reaction arm in place with OEM or my sourced bushes installed and we can see with bike in gear, the whole bevel box move rotationally compare to the swing arm when the throttle is sharply applied.

That move movement is exponentially restrained  as the rubber bushes compress in one direction and move to an eccentric off set. Once the load is released the bushes re-concentrsize.

Should the bike be in a situation when ridden where the rear will lifts whilst under load, the rear wheel will accelerate to greater than the road speed. Upon landing, the rear tyre will shock load through the transmission from rear wheel to little ends. The torque arm bushes will absorb in part some of the shock load through the transmission, along with the other features the bike has that Docc mentions and also the tyre. Even in normal contact conditions, restraining of the movement of the bevel box will load up the other shock absorbing components including the rear tyre. Could a spirited or track day rider like myself over heat the rear tyre by over restraint of the bevel box?   

Thank you for the endorsement of my solution. 

A V11 rear wheel coming off the ground under spirited riding! Like wondering if a 50lb dumb bell might float away if it's not tied down:)

But seriously I understand your point but in the real world it's not about such finite issues. If I were Guzzi I'd have gone with the standard setup because it's almost totally bulletproof and requires zero maintenance and gives the additional albeit remote benefit in the scenario you have described and Guzzi will traditionally over engineer most stuff and prioritise that over weight and style. 

Once again we enter the rhelms of  theory over practical experience. I have my views on the two but that's a whole other topic.

The rear drive unit is like everything on a Guzzi, about twice the weight and strength it needs to really be. 

I'm just reading Dave Richardsons New book on being a Guzzi dealer and aficionado for 35 or so years. It's a great read and I highly recommend it. The stories of the balls Guzzi has dropped over the years in marketing and engineering are amazing and i'm only a quarter into it.

Ciao  

[Cabernet]

[R.I.P. Mikko]

YupI here’s a very cool video of a Moto Guzzi getting very squirrelly while under heavy braking. The reason he couldn’t keep the lead imho...

 

[Lucky Phil]

2 hours ago, Cabernet said:

Standard reaction rod?....No. Cadwell a typical race circuit? ...No. A 50cc Scarabeo scooter takes off there. 

Ciao

[docc]

"Cadwell" . . . I had to look that up.  Just nuts!

 

[Lucky Phil]

2 minutes ago, docc said:

"Cadwell" . . . I had to look that up.  Just nuts!

 

Like 90% of British circuits docc, narrow and a bit scary. Most haven't fundamentally changed at all since the days of the Manx Norton, Hailwood, Surtees, Bill Smith etc. 

 

Ciao

[docc]

So, the Moto Guzzi reaction rod appeared on the SpineFrame Daytona c. 1992?

When I had decided to move on from my café '75 GoldWing because I had run out of ground clearance (and it weighed 650 lbs/295 kg), I rode a GreenFrame 1000S. I had heard of "shaft jacking", but never experienced it before that. The GW didn't do it for some reason (maybe those 650 pounds!). It was one of the things that kept me away from the 1000S; did not feel good to me rolling on out of the corners trying to stand itself up and go straight.

Gosh, but it was a lusty looking thing, though . . .

[R.I.P. Mikko]

 Magni developed the “Parallelogrammo” in 1985. I think it was Dr. John who convinced MG to use the rod that he developed for his race bikes.

 

[GuzziMoto]

I see someone already mentioned that the early versions of the spine frame with the floating rear drive unit used a reaction rod with heim joints and not bushings, so the rear suspension moved smoothly. That is how my Daytona is, and I am pretty sure the reason later versions of the design used the rubber bushing was mainly due to cost reasons. The Daytona and Centauro were much more expensive motorcycles than the V11Sport. They had to reduce the manufacturing costs and while this was only one small part of that it was likely part of it.

I think switching to something more free floating, something more like it was originally designed, would be an upgrade.

[R.I.P. Mikko]

 

 

Starting on page 53, bottom of the first column, they describe the Dr. John rear suspension...

[LowRyter]

Torque Rod? 

I am getting to the point of being afraid to sign on here afraid that I'll learn something else breaking on my bike that'll kill me.

So far as my EV California (Tonti), it handles great and has zero rear end jacking issue when I corner.  I mean I've never experienced it ever.  In any gear, at any rpm and  at any speed.  None.  My guess, if the geometry is right and correct stiffness dialed for the right torque, that perhaps a simple setup might work fine after 40 years of refinement.  

I could be wrong.

[Cabernet]

Cadwell is my track of choice. Plenty of opportunity to mix it with some high tech stuff and show them up.

[Nihontochicken]

6 hours ago, docc said:

So, the Moto Guzzi reaction rod appeared on the SpineFrame Daytona c. 1992?

When I had decided to move on from my café '75 GoldWing because I had run out of ground clearance (and it weighed 650 lbs/295 kg), I rode a GreenFrame 1000S. I had heard of "shaft jacking", but never experienced it before that. The GW didn't do it for some reason (maybe those 650 pounds!). It was one of the things that kept me away from the 1000S; did not feel good to me rolling on out of the corners trying to stand itself up and go straight.

Gosh, but it was a lusty looking thing, though . . .

And why can't current production MGs look this good??? 

[Lucky Phil]

10 hours ago, docc said:

So, the Moto Guzzi reaction rod appeared on the SpineFrame Daytona c. 1992?

When I had decided to move on from my café '75 GoldWing because I had run out of ground clearance (and it weighed 650 lbs/295 kg), I rode a GreenFrame 1000S. I had heard of "shaft jacking", but never experienced it before that. The GW didn't do it for some reason (maybe those 650 pounds!). It was one of the things that kept me away from the 1000S; did not feel good to me rolling on out of the corners trying to stand itself up and go straight.

Gosh, but it was a lusty looking thing, though . . .

Interestingly on modern sports bikes and all road race bikes the rear end jacks on acceleration as a consequence of swing arm droop and the swing arm pivot positioned where it is (within adjustment capability) It's actually a benefit from the apex of the corner to the upright transition to keep the front tire on the ground and the rake steep and prevent understeer. You can see how it works from on board cameras these days. Interestingly Ducati with others following now have engineered a squat mechanism to compress the rear after the transition to the almost upright for traction and anti wheelie. So you get the jacking initially to help the steering and when you need the traction and anti wheelie you get the opposite via a dedicated system to produce the squat when it's needed. It's really apparent on the Ducati MotoGP bikes as they look like a chopper at the last phase of corner exit.

As an aside Dr John's original degree was as a mechanical engineer and after 2 tours of Vietnam he transitioned to Dentistry as it was the fastest way at that time with his qualifications to translate to a decent paid job.

Old bikes with skinny little crossply tires look weird to me these days docc. They actually look a bit scary to be honest as i grew up on them and remember how appalling the suspension and brakes were. Riding something where a degree of your concentration was simply absorbed by making allowances for mechanical shortcomings doesn't appeal anymore.  

Ciao   

 

[docc]

Looking closely at the images in the article Mikko posted, seems that Daytona racer has a chassis rod on both sides?