reaction rod

[andy york]

Anyone had any problems with the Reaction Rod? This is the rod that bolts to the top of the rear dif and to the frame.

I just took mine off and noticed that the bushings are shot!!!

I thought I noticed some crude around the hole and it was rubber. I can press the steel insert all the way out with my finger.For some reason it looks like it has been heated. I cant imagine the rear dif transmitting enough heat to melt the bushings!

Anyway, something you guys might want to keep on eye on.

later....

Andy

[al_roethlisberger]

Yeah, we had one fella... I think it was John and his Scura, that had the torque arm bushings(well the rear one) fail. He had it replaced under warranty. His whole arm had a lot of play after the bushing failed.

 

I don't think this is a regular problem though, as I've rarely heard of it on other bikes(yours is only the second). Perhaps you just got a bad bushing, or otherwise defective assembly

 

I suspect the "melting" is probably just because once it started "moving around" abnormally, it tore up the rubber surround. It may have also seized at some point, and that could have "melted" the rubber much like an eraser comes apart under vigorous use??

 

 

I wouldn't worry too much about it unless it does it again once you have the bushing replaced.

 

al

[guzzi323]

Yup, that was me. Both bushings were worn by the time I noticed it. I had heard a faint click noise when I transitioned from on to off throttle under very light load for quite some time. I was worried it was something in my clutch I never checked the rear end. Once that was replaced the noise went away.

I've got probably 4 or so thousand miles on the new one and it's just fine. It seems silly that Guzzi won't sell you the bushings which could be easily replaced. If I recall it's about $170 for the arm. Guzzi paid for it so I don't remember.

If it goes out again (post warranty) I'm going to have some bushings made out of delron and replace them myself.

[Baldini]

Same bush on my Scura has shown chewed up bits of rubber since new. The bush looks like it was badly fitted - the metal pressing is kinked - It's chewed up a bit more over 6K miles but I don't feel any play....yet.

 

KB, Cymru

[roberto]

I also had the rod replaced under warranty. The rod worked its way off the bushing and wore a groove in the diff as well - I got the diff case replaced also. The rubber was OK, but the bolt that held the rod at the rear showed signs of galling (an uneven, shiny, torn-up surface) due to relative movement and I reckon that the bolt was not torqued up enough - the bolt should be tight enough to prevent any pivoting of the arm on the bolt surface - the rubber is there to provide the required movement.

 

My theory is difficult to explain, but if the arm pivots on the bush, and galling happens at the end of rotation, temporarily siezing the parts in this position, the rubber will be subjected to excessive stresses at the other end of the stroke and may begin to shear. Alternatively, the bush-to- reaction rod interface (a press fit) slips - and repetition of this action can work the bush out (as happenned to me).

 

Note that after I had the rod and diff case replaced, I checked the bolt - it wasnt torqued up at all - just finger-tight.... that's a dealer problem though... I think I go to the same shop as Foxbat.. (and I'm not joking.)

[andy york]

So what would ya'll (i just had to do that:D) say to some delrin bushishings for the reaction rod? Any ideas on the type of design?

What I'm making is a delrin bushing,30mm dia to press fit into the old bushing hole. B - the bushing will be 32 mm in width which is the same as the steel insert in the stock bushing...C - a 10mm hole through the center for the mounting bolt.

I don't think this will put any unusual load on the gearbox mounting...the other end just mounts to the frame...

lemme know!!

[twhitaker]

I went out and looked at mine and sure enough it is disintegrating too. It looks like it may be a swivel rod end bushing. I would suggest taking it to a bearing supply house for a cross-over. INA makes some high quality bushings. My guess the bearing house price would be a third of what the dealer wants.

[twhitaker]

Oops. I meant to say spherical instead of swivel. They are used in all kinds of control arm and motion control applications.

[guzzi323]

I thought about replacing the bushings with spherical bearings as well. I doubt it makes too much difference either way. I know the Daytona's used bearings there. Maybe Delrin has some (very) slight amount of give for dampening shock during on/off throttle transitions? I don't know.

[docc]

After spending some time with Andy looking at his chewed up torque rod bushings it made me wonder: the torsion on the rubber is obviously enough to eat them up after a while. If the ends were allowed to pivot freely wouldn't there be less restriction in the travel of the rear suspension? Are the torque rod bushings one reason the rear end is so harsh on these bikes?

[Baldini]

Are the torque rod bushings one reason the rear end is so harsh on these bikes?

Looks like the bushings are a cheapskate solution but I think harshness is just cos of so much unsprung wt there - can't see bush making it much worse. Is there any reason that there needs to be some damping on these pivots or would a freemoving bearing always be better?

 

KB, Cymru

[Paul Minnaert]

Well if you have problems with the rod, you can always change it againt the one from the first daytona/sport. or make one yourself. Needed a pipe, and 2 from the things on the picture. Called ball and socket joint?

 

I can't figure out why the rubber thing fails, it should get push and pull froces only.

[twhitaker]

I believe the push pull forces in combination with the small rotational movements inside the bearing as the rear of the bike moves up and down cause fretting of the elastomer in the bearing. Maybe a bronze lined spherical bearing would work better. That's likely what Paul has on his. They make them as press fit units like ours as well as rod end units like Pauls.