Tonti Throw out Bearing Knock

[ozarquebus]

I have a knocking coming from my g5 gearbox/clutch area when in neutral which completely disappears when clutch lever is pulled. Any recommendations? It gets better when motor is hot, but comes and goes somewhat unpredictably. Rebuilding the assembly myself appears extremely complex from looking at the exploded diagrams.

Should I just ride it on short trips and keep it full of oil?
Add some heavier oil or additive to gearbox?
Will a clutch rebuild encompass a fix?
 Is it not as complicated as it appears?
 Is it a sign of poor ignition timing?

[Rolf Halvorsen]

What is your rev. when in neutral?

Between 1000 and 1100 should be correct.

Rolf

[guzzisteve]

If you go to hdwr store buy a large key ring. Drill hole in knob of clutch lever & put ring through it. Now pull it in & swing it over handle bar grip. Lever on all the time & no knocking. Old crap is old crap, 40yrs or so. Won't last forever but then fill trans w/85/140 and see if it goes away, then you'll know it's the trans and not the clutch. May be the cup that rod pushes on in pressure plate rattling.

[ozarquebus]

Guess I don't understand why make a device to hold clutch lever in. If it is just a diagnostic, then why not just tie it? Unless you are making a joke, then Ha Ha.

[lucian]

Rule out simple stuff first , something rubbing rattling underneath? Maybe clutch actuation arm bumping the frame underneath. Does the clutch work as it should?

[guzzisteve]

Guess I don't understand why make a device to hold clutch lever in. If it is just a diagnostic, then why not just tie it? Unless you are making a joke, then Ha Ha.

No joke, they have the ring on Converts (seen many) to have it like out of gear. BUT they don't have neutral.

[ozarquebus]

its not a Convert, its a 5 speed. yes, clutch is good and strong.

[fotoguzzi]

I think Rolf was hinting that you could get a noise like that if your idle is to low. You don't want potato potato like a Harley.. idle needs to be about 1,000rpm.

[pehayes]

You might wish to edit  your original posting title.  The throwout bearing is a small, radial affair at the very back of the transmission.  While it can fail, in my experience it never creates any 'knock' sort of sound.  You may have clutch hub issues.  You may have gear dog issues inside the transmission.  You may have a failed throwout bearing but that won't be the noise source.  Easiest one to solve is the throwout bearing.  Remove the swingarm, pull the outer body, pull the bearing.  Replace or reinstall if it isn't warn.  How many miles on this? What is your idle rpm?  Low idle can induce a knocking sound due to irregularly times pulses from the crankshaft.  Exacerbated by lower rpms.

Patrick Hayes
Fremont CA

[ozarquebus]

I was assuming throw out bearing since it sounds just like a car transmission with a bad one. What it really sounds like is that I have some more work to do to eliminate other possibilities before pulling major parts off, but your replies are helping me understand, nevertheless.
The idle is actually all over the place and timing accuracy is uncertain. 53000 or 153,000 miles.

[Tom H]

FWIW: I have a Loop 5spd that makes a whirring noise in neutral, no clutch lever applied. Apply clutch lever just a tad and the noise clears up.

T/O bearing good, new friction plates and intermediate.

Maybe I need ear plugs????

Tom

[80CX100]

The idle is actually all over the place and timing accuracy is uncertain. 53000 or 153,000 miles.

 

      Maybe the timing chain is due to be replaced,,, or the timing set,,, carbs balanced,,, especially if the idle is set a bit low, any of those things can make some funky noises, lol

[jacksonracingcomau]

You might wish to edit  your original posting title.  The throwout bearing is a small, radial affair at the very back of the transmission.  While it can fail, in my experience it never creates any 'knock' sort of sound.  You may have clutch hub issues.  You may have gear dog issues inside the transmission.  You may have a failed throwout bearing but that won't be the noise source.  Easiest one to solve is the throwout bearing.  Remove the swingarm, pull the outer body, pull the bearing.  Replace or reinstall if it isn't warn.  How many miles on this? What is your idle rpm?  Low idle can induce a knocking sound due to irregularly times pulses from the crankshaft.  Exacerbated by lower rpms.

Patrick Hayes
Fremont CA

Agree completely, except thrust bearing easy to change with swinging arm in
But this noise description reminds me of vid you posted a while ago
Not thrust bearing or clutch definitely, absolutely etc etc
Someone in Italy ?
There will always be some noise at idle, input shaft is spinning , output shaft isn’t, the beat of 270 crank is uneven by nature
If raising idle fixes it, is it a problem ?
In that thread I mentioned I expected my V700 with floating clutch hub to be worse but damn thing is nearly silent idling at 500 rpm ! Truly
It also pulls from under 2k in any gear

[John A]

It’s a common noise with dry multiple disc clutches. Specially Guzzis. There is nothing wrong with it. You can do all the tuneup stuff correctly to help it. Remember how old it is , it’s a machine. Snot a pleasing noise but it won’t hurt a thing

[Scout63]

I just went through this with my small block.  The clutch was dragging.  I could have adjusted the clutch arm, but elected instead to pull and separate the drivetrain, pull the heads and cylinders, dismantle the clutch and replace the ignition.  Now it’s all back together and I need to adjust the clutch arm.  That’s how I roll.

[ozarquebus]

Scout, That is so true about the way it seems things happen to me too. I am just hoping that the timing chain replacement fixed the vibrating kick stand spring.

[moto]

What a couple of earlier posters must have in mind, but haven't quite said is this: Your idle should be at 1100 rpm. If it is lower you will hear the clutch plates rattling back and forth in the flywheel, AND you will therefore being wearing out your flywheel splines, notching them until you have real clutch problems.

So attend to that possibility. One way to check is just to raise the rpm to 1100 with the twist grip. If the sound goes away, or almost goes away, that's the clue that this is likely your problem.

If your idle is all over the place, you might need to check your timing chain next, I think.

Moto

[ozarquebus]

I just replaced the timing chain and set the timing. It was running pretty good before, so I think the carbs must have cludged up in that year long process. I'd better clean them up and fiddle with the timing some more to achieve a good 1100 rpm idle before doing any additional diagnostics.

[Wayne Orwig]

The cup, in the middle of the pressure plate, just lays in there loosely. When you pull the clutch, it presses the cup against the pressure plate. When you release the clutch, that cup can rattle around. It stops rattling around at higher RPM.
When I work on them, I put a dab of RTV on the cup when I sit it in place. That prevents the rattle. You can raise the idle RPM, tear down the bike and glue it in place, or don't worrying about it at all.
Of course it has nothing to do with the bearing.