Torque Reaction Rods

[docc]

Many of us have been aware that the rubber part of the torque reaction rod can deteriorate or tear and become loose. It has always mystified me that the bushing appears captured by the "pivot" bolt creating (what has seemed to me) something like a "torsion rod" that would interfere, even limit, suspension movement. Seems to me it would be better for the spring and damping to work without that interference.

With the reardrive off and swingarm out, my torque rod has always just stuck straight out like a  . . . uh, well, stuck straight out from the bracket on the frame cross member.  Sliding the rear pivot bolt through without the reardrive, I realized there is clearance for the torque rod bushing to actually pivot without "capturing" the bushing and stressing the rubber part.

Upon removing the front bolt it occurred to me that I can't recall ever pulling it out . . . "OH, that's why [ it doesn't pivot ]" . . .

Cleaned it up, BelRay Waterproof Grease, and only set the tightness on the locking nut to allow the torque rod to pivot without clamping the bushing hard into the bracket. Proper Witness Protection Marks to monitor and a promise to add this to the Wheels Off Maintenance Checklist . . .

Friends don't let friends let their pivot bolts seize up! 

 

 

[Lucky Phil]

I don't know about this docc. These style of bushes are actually designed to work clamped up as standard and the rubber flexes. It's served you well for many many miles now. The issue now is that you have 6 additional wear points, 2 on each side of the internal bushes and 2 on each pivot bolt. Car suspension arm bushes work the same way as the Guzzi torque arm with the isolating bush clamped up tight and the rubber providing the flex.I know it "feels" like a good idea but I don't believe it actually is. It's not going to be an issue in the short term though. If you want to go the other route you should use a torque rod with rose joints at the ends as my bike has. I cant tell any difference in performance or "feel" to be honest. 

Ciao  

[docc]

Rose ("Heim") joints always seemed a good idea for this application. I know it has been done by some. FWIW, I didn't leave the bolts totally loose, but also did not crank them down as tight as possible. The rod will still stand straight out on its own, but will rotate under hand pressure. Maybe there is an actual tightening spec in the manual, but not likely.

At the very least, I should not have let all that corrosion build up in there.

[Lucky Phil]

46 minutes ago, docc said:

Rose ("Heim") joints always seemed a good idea for this application. I know it has been done by some. FWIW, I didn't leave the bolts totally loose, but also did not crank them down as tight as possible. The rod will still stand straight out on its own, but will rotate under hand pressure. Maybe there is an actual tightening spec in the manual, but not likely.

At the very least, I should not have let all that corrosion build up in there.

Thats what actually concerns me docc. You now have the end faces of the bushings rotating against the frame tabs and the bevels drive support faces as the rod rotates with suspension movement. I'm actually impressed with the condition of the bushes in your torque arm docc.

Ciao

[docc]

Thanks, again, Lucky Phil, for the thoughtful reply. True, I've been expecting the rubber to disappear from my bushes for a long while.

I cannot find anything on the "chassis rod" in the Workshop manual other than how to release the rear pivot bolt to remove the reardrive.

[Lucky Phil]

1 minute ago, docc said:

Thanks, again, Lucky Phil, for the thoughtful reply. True, I've been expecting the rubber to disappear from my bushes for a long while.

I cannot find anything on the "chassis rod" in the Workshop manual other than how to release the rear pivot bolt to remove the reardrive.

I think someone came up with a replacement bush for the arm a little while back as Guzzi dont sell them separately.

Ciao

[docc]

13 hours ago, Lucky Phil said:

I think someone came up with a replacement bush for the arm a little while back as Guzzi dont sell them separately.

Ciao

Yeah, Cabernet had some manufactured and offered to the community back in April, 2020. Others I know have made them from Delrin. Here is Tom M's solution from 2017. 

Is there any factory procedure for installing the reaction rod/ "chassis rod" on the Daytona, Sport 1100, Centauro, or 1100 Sport-i? (I'm pretty sure not all those models have the same cast reaction rod, only the Centauro and 1100Sport-i.)

These bolts look to be 10mm with a locking nut ("NyLoc").  in the absence of a specific torque specification, should they really be torqued to 50 Nm like any other 10mm fastener? No doubt, that much torque would pinch the forward frame bracket and "capture" the inner sleeve of the bush.

[Cabernet]

If we consider other bike's transmissions, every other bike I've owned over 125 has cush rubbers that act as a shock absorbed for the transmission. If we replace the rubber bushes in the reaction and with something solid like nylon or rose bearings, what else is in the V11 transmission is going to protect it from shock loads?

[docc]

By "transmission", Cabernet, do you refer to the gearbox or the rear(bevel)drive? I ask because the torque reaction/chassis rod only connects from the reardrive to the frame.

Otherwise, the movement of the swingarm is damped by the shock absorber while the drive line forces (acceleration/deceleration)  are damped by the cush drive in the V11 reardrive hub as well as the "cush drive" inside the gearbox itself.

My understanding (that is always evolving . . .) is that the torque reaction/chassis rod checks rotation movement of the reardrive by resisting motion along its axis (not rotation of the bushes) to limit, or eliminate, the tendency of shaft drive/ bevel box bikes' rear suspension to rise and fall rolling on and off the throttle.

BTW, your solution to having these bushes made is stellar, IMO!

 

 

[Lucky Phil]

7 hours ago, docc said:

By "transmission", Cabernet, do you refer to the gearbox or the rear(bevel)drive? I ask because the torque reaction/chassis rod only connects from the reardrive to the frame.

Otherwise, the movement of the swingarm is damped by the shock absorber while the drive line forces (acceleration/deceleration)  are damped by the cush drive in the V11 reardrive hub as well as the "cush drive" inside the gearbox itself.

My understanding (that is always evolving . . .) is that the torque reaction/chassis rod checks rotation movement of the reardrive by resisting motion along its axis (not rotation of the bushes) to limit, or eliminate, the tendency of shaft drive/ bevel box bikes' rear suspension to rise and fall rolling on and off the throttle.

BTW, your solution to having these bushes made is stellar, IMO!

 

 

Yes I agree docc, the torque arm isolators or lack thereof don't impact the transmission itself. It's a cost effective and maintenance free solution to the mechanical requirements not a better solution than rod ends. As I said swapping to rod ends made no difference to the feel or suspension performance it's just a more compact and neater solution.  

Ciao 

[Cabernet]

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. 

[Cabernet]

Also, what is the "knock" on effects on the swing arm bushes by hard tying the bevel box to the swing arm, that Guzzi have gone to great length to engineer out?

[docc]

32 minutes ago, Cabernet said:

Also, what is the "knock" on effects on the swing arm bushes by hard tying the bevel box to the swing arm, that Guzzi have gone to great length to engineer out?

Not knocking it, just trying to understand it (and share that the front bolt could get neglected).

I totally neglected to consider the rear tire as part of the "system!"

[docc]

I recall being instructed that control arm bushings on a passenger car should be torqued with the vehicle weight bearing, not with the suspension hanging, to index the bushings at ride height. Not sure if this is applicable to the V11 reaction rod if the bushings are designed to be part of the kinetic chain?

[Cabernet]

No knocking percieve.we're all just trying to backward engineer the designer's thoughts.