1970 750 Ambo. Noise From Clutch Area.

[Tom H]

I have a noise coming from around the clutch area. When the bike is cold, no noise. When it's at running temp, the noise appears. The noise is a like whirring sound, not the rattle like noise like my EV makes with the clutch lever pulled. My 850 Eldo is quiet with or without the lever pulled.

I changed out the 4 speed with a 5 speed trans and changed the rear drive to a 850 drive. I didn't notice the noise before the change, but then again the 4 speed always seemed noisy anyway.

The first 850 trans had a whine in 4th and 5th when hot, 1st-3rd all quiet. I could hear the noise in question with this trans, again when at running temp.

Out with trans #1 and in with #2. Took the bike for a 4 mile ride and all was shifting and quiet as far as the trans went. Didn't notice the noise at first, probably not listening for it but rather any new trans noises.

Shut the bike down to open the garage. Started it up and noticed the persistent noise again.

When running and warm and the noise is there. If I ever so lightly pull the clutch lever with pinky finger pressure to take up the adjustment slack, the noise starts to quiet. Pull a bit more and the noise quiets more. When I start to feel (I think) the plates start to move, the noise is gone.

When I installed trans #1 I took the clutch apart and all looked fine. Put it back together the same way I have done both bikes for the last 35 years. Nothing unusual as far as I could tell. The clutch pulls smoothly, engages smoothly and seems to work fine. I didn't mess with the clutch when I installed trans #2. I figured the noise was from trans #1.

EDIT....Just remembered. One thing I did do different was to change the clutch push rod seal to the 6 O rings.

I did find one more clue that might help. I decided to check my point adjustment. I pulled the belt cover so I could turn the engine with a wrench. While turning the engine, I noticed a noise that sounds like when you have the gen belt too tight, that creaking, umm, sticking feeling. I loosened the bolts just a bit and rotated the engine, then loosened a bit more and rotated again. Now the belt is loose, but the noise is still there. Hmmmm.

Pulled the belt and put a bolt back in the back half of the pulley to keep it in place. Rotated the engine with the wrench and the noise was there, but also had a sticking feeling when I rotated the engine. Thought, aw crud a rod bearing or the like. I played a bit more to see if I could feel the crank move when I pulled in the clutch lever. Couldn't feel or see any movement. So..

I rotated the engine by hand with the belt off and then slowly pulled in the clutch lever. The noise went away and so did the sticky feeling as I pulled the lever more. Did this test a few times to be sure. Started the bike and worked the clutch and the noise would go away with the clutch lever pulled.

I have one thought, but I don't like it.

Any ideas as to what might be the cause of the noise??

Thank you,
Tom

[Idontwantapickle]

Tom,
You're gonna have to keep digging. If you can turn it by hand as you describe and hear a groan after swapping the transmission it's probably the engine. At this point I would remove the transmission to eliminate it entirely and then also open the timing chest and remove the cam and oil pump gears. Which one you do first is up to you.
The noise you describe is often found to be a plain bearing in distress. It could be as simple as the small end bushings but that is just speculation.
The fact that the noise decreases with pressure applied to the rear of the crank, which is what happens when the clutch is disengaged, could mean that the thrust face of the main bearing is toast or that it is shifting the crank enough that the noise abates.
I'm now thinking pull the transmission out first. If there is a misalignment of the transmission it could be creating the noise due to the bind on every part involved.
Hunter
 

[Tom H]

The thrust part of a main was what I was kinda thinking. So I tested some more.

Pulled the timing plug on the trans to see the ring gear/flywheel.

Used a screwdriver to touch one side of the ring gear and rest it against the side of the timing hole.

The engine is what I would call cool now, been sitting for a few hours.

Turned the crank again from the gen pully end. Still made the groanish sound. Pulled in clutch lever slowly and the noise faded and then went away as more of the lever was pulled.

Used the screwdriver to see if the ring gear was moving forward or back.

I used the driver to move the flywheel to the back and then pulled in the clutch lever, the flywheel moved forward, When lever released the flywheel did not move back. I wedged the flywheel back and repeated. It moved forward and stayed there again.

I then moved the flywheel back again and turned the engine, noise is there. Pulled in clutch lever and the flywheel moved forward, no noise. Released lever, flywheel again did not move back and turned engine, noise is there again.

Also tried moving the flywheel back again with the driver to confirm movement and then wedge the flywheel forward with the driver. Noise is there. This should have moved the flywheel forward just like the clutch lever does. Again, with the driver against the flywheel, I can feel the flywheel move forward. With lever released, the flywheel stays in place. I feel that the crank is no longer resting against the rear main. so if it was a thrust issue, it should?? have gone away pushing the flywheel forward with the driver?? I'm making the crank move just like the clutch lever does. I think??

Also, when I turn the crank, there is a bindy feel. With the clutch lever pulled, no bindy feel.

I'm thinking it's not a thrust issue?? What in the clutch assy could cause this? Two transmissions should not cause the same problem???

Thanks so far!
Tom

[Denis]

Maybe (hopefully) it's as simple as needing a clutch.

[Idontwantapickle]

Tom,

It sounds more and more like a clutch failure or misalignment as it is unlikely both transmissions would have the same failure. Not impossible, but not likely.

Hunter

[Tom H]

Looks like I'm pulling the trans again shortly and pull the clutch apart as well and see if I can narrow down what the noise is.

I'll pull the trans first and test, then the clutch comes apart, then test again. I might even slip on the 4 speed and see what happens.

Thank you for all the thoughts!!!
Tom

[Antietam Classic Cycle]

I'd be checking the alignment of the engine to transmission.
http://www.thisoldtractor.com/moto_guzzi_loopframe_alignment.html

[Denis]

I'd be checking the alignment of the engine to transmission.
http://www.thisoldtractor.com/moto_guzzi_loopframe_alignment.html

Dang, what a mess that was, and a lot of work to fix. Glad to know there's a solution for it though.

[Tom H]

Well I pulled trans #2. I was checking for the noise by turning the crank from the gen end.

I pulled the clutch and found that outer friction plate looked normal on the outer side, but had dust on the inner side, like it was not making contact. The inner looked normal as well as all the splined bits. Tested both clutch plates on the input shaft spline and all slid smooth. Checked the inter plate in the flywheel and all was smooth.

I also realized that when I tried trans #1, I changed the flywheel, pressure plate and inter plate. So I changed those back to the originals.

All came together just fine when I slid trans #2 back on. No noise and no binding as I tightened the trans to the engine. Yeah!! Even tested when I connected top the U joint and when I tightened up the engine and trans frame mount bolts. All was great!

Took the bike for a ride to the store for about a 2 mile round trip. Nice, all seemed fine. Then I went for a 10 mile mainly freeway ride. Once off the freeway at a stop the noise was back. Aaaarrrgghh!!!!

Again, in neutral, noise is there and even vibrates the bike a bit,  a buzzy vibration, not a shake or rattle.

Again, just take up the slack in the clutch cable with the handlebar clutch lever and a very light pinky pull effort, the noise starts to go away. More pull and the noise goes away more. About half pull no noise. Full pull no noise.

While I was in there. I did put a new clutch push rod, inner plunger and throw out bearing to eliminate those being an issue. I do have the 6 O Rings for the push rod seal instead of the stock seal since trans #1.

Is there any way that the O Rings could be my problem?? I'm sure that I am not the only one that has made the change.

I hate to bug my Guzzi shop as he has helped me many times at no charge, but I may need to take it to him and see what he thinks before I tear it apart again.

Any more thoughts on this issue??

Again, thanks to all that have responded so far!!
Tom

[rodekyll]

I'd pull the timing cover and check the cam thrust plate.  It's the 3-screw plate behind the cam gear.  I've seen those get worn and allow the cam to thrust forward.  The noise could be from the thrusting or from the cam gear now meshing in a different place on the crank gear.

While you're at it, test the spinover with the generator belt gone.  It could be something silly like a generator bearing or belt.

Else, this might be a good place to have a second set of ears on it.  Sometimes two people can ferret out a mystery noise better than one.  Got any friends with a tuned ear?

[Chuck in Indiana]

Man.. descriptions of sounds are even harder than listening to them over a tinny computer speaker.  Have you probed around with a mechanic's stethoscope?

[Tom H]

I think it's time to stop by my local shop for them to have a listen.

I was hoping that by the description of the problem, someone may have been there before and could tell me what the problem is.

I'll let you all know when I know.

Tom

[Tom H]

I rode the bike to the shop today. He did hear the noise and worked the clutch lever and the noise would go away. Yeah, mystery noise was there at the shop! Normally anything that you are trying to show a shop goes away when you get there.

Well, he has had this before, but no solid resolution for the problem. He said to try my old throw out bearing and see what happens. Otherwise, it could be a alignment issue with the trans, but he said it's rare. He also said ride it, it will probably outlast you

So I'm going to read up on the alignment issue symptoms.

The biggest thing that might be a clue to the noise issue. As mentioned, the outer friction disc's friction mat'l had normal wear on the trans side, but there was dust on the friction mat'l inner to engine side like it was not making contact with the intermediate plate. The inner friction disc had normal wear and look on both sides. The input hub to the trans is clean and smooth. Tried the outer and inner friction plate in the input hub splines and both slid smoothly. The intermediate plate also slides smooth in the flywheel.

I will try to post what solves this noise if I can ever find out what it is.

Thank you all again!
Tom

[flycaster]

Hi Tom, have you found any solution? I've the same problem, or something like this, on my V7 750 Special 1970.
In neutral, hot bike (rode it for 20/30km), when engage or disengage the clutch, there is no substantial difference. It's very quiet, much quiter than my Norge 1200 engaged neutral clutch 
The described noise (something like ferrous drag), appear when riding at constant speed in every gear, but not so accentuated.
The noise come very loud when downshifting: at constant speed, I press le clutch lever, downshit (from any gear to any gear), release the clutch lever and here is a very marked noise! The noise follows the number of engine revolutions, and the higher the difference in engine revs from the downshift speed, the louder the noise. I checked bearings in swingarm and back transmission and everything is quiet.
Is the clutch the problem?

[normzone]

Man.. descriptions of sounds are even harder than listening to them over a tinny computer speaker.

My wife and I were watching Noraly (Itchy Boots) last night in her current port in North Africa and she mentioned sending a recording of her bike's new noise to the Honda shop she bought it from in Europe.

I groaned, and my wife asked why ... I replied "Every mechanic's worst nightmare - a competent rider asks your opinion of a sound over a low resolution transmission".

[Tom H]

I never did solve the noise issue with the 750 engine. Best guess it the front main bearing for my issue. I ended up swapping the engine to a 1000. Still have the 750 engine. I might go through it one day.

I did solve a whiring in neutral on one of my 5 speeds. One of the trans input shaft bearings was bad.

I'm not sure what your issue may be. If I reading right, it is while the bike is moving. My issue was most noticeable stopped and in neutral. When moving there are a lot of things that can be making noise. You are going in the right direction by inspecting things that could make noise while riding.

You might want to start a new topic for the issues with your bike, it might get noticed more and more answers.

Good luck,
Tom