Horrible noise from gearbox(?)

MC scissors Jack look good ! Would also contemplate modified 2× axle stands . Safer if your back wheel is out of ballance. Mine is ! I use to use them many years ago under the engine cradle of several bikes. However scissors Jack for maintenance? I'm looking already. Roy !!
 
nortonmargie said:
Didn't know that MC scizzor jacks existed! What a great idea! I need to get one- when I need to change the front tire (I pull the wheel off and take it to my friendly local modern motorcycle shop, who finds me a tire, installs it and gives me the wheel back) a scizzor jack will make it SO much easier!
Click to expand...
You can get them at Harbor Freight.
 
If and when it breaks post pictures. Ride it until then. Had a Sportster that was so noisy you could hear it above the drag pipes. Had it apart several times, straight cut gears all bearings were good.
 
mean gene said:
If and when it breaks post pictures. Ride it until then. Had a Sportster that was so noisy you could hear it above the drag pipes. Had it apart several times, straight cut gears all bearings were good.
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Not only dangerous to keep riding if something is not right and not knowing what is grinding or rubbing to make the noise in the first place could be doing major damage to other bits on the bike, could also in danger your life if something locks up, most replies are focusing on the gears, myself think something is misaligned like a chain rubbing or clutch basket or something, just need to dig in and look for wear marks, the back of the primary case with the chain rubbing on the back if the inner case not spaced right as there is not much room there spaced on the mounting bolt, we can guess as much as we like till the problem is found, over shimmed, not enough shims and if it's as loud as the OP say it is then something major is wrong, retrace everything you did before this noise started, but check everything on the outside before going inside, there has to be signs of rubbing/grinding.
If new part had been used make sure they are not causing the noise, if something is grinding inside the gearbox or primary then there be metal signs of that in the oil.
Could be looking straight at you without seeing it.

Ashley
 
Might need to understand just how horrible the whine is. My Norton sounds like something I should never ride, but I've been riding it for decades, and it hasn't killed me yet.
 
ashman said:
I wish I had mine 40 years ago, I paid $95au with free delivery too my front door, Chinese made is very strong and stable well worth the price and the best thing it sits under the bike out of the way with nothing sticking out the side of the bike the wind up handle is removeable and has adjusting arms to fit the frame rails or can be removed and just use the flat top.
Takes a few seconds to put under the bike and wind up great for chain maintenance or any wheel work, I have also used it for other jobs other than lifting bikes.

Ashley
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Yes under $100 in NZ too so probably less than $50 in the US. I use mine a lot. Lift either the front or rear wheel depending on placement and very helpful on the bike lift too if your lucky enough to have both.
 
To justify my "ride till it breaks" I would not like to someone get hurt. But Fiatfan has had it apart and together several times. So apparently knows his way around. If you put some miles on it, and the noise gets worse, drain oil if there is metal in it pull it apart again. Some times mileage will show problem.
 
mean gene said:
To justify my "ride till it breaks" I would not like to someone get hurt. But Fiatfan has had it apart and together several times. So apparently knows his way around. If you put some miles on it, and the noise gets worse, drain oil if there is metal in it pull it apart again. Some times mileage will show problem.
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Dad would say: "it'll either go or blow!"
 
My AMC gearbox had a bit of a whine to it at idle. I replaced it, but not because of the whine. Anyway, it is on the bench, and I note that the sprocket spun by hand has a tight spot, so something somewhere is not right inside. I think it was the way I shimmed the layshaft. I sort of got carried away and I don't think there's enough endplay is my guess. Holding the sprocket the mainshaft spins freely. Probably has nothing to do with anything. I just felt like mentioning it since my AMC gearbox did whine a little and I think the sprocket on the sleeve gear should spin easily.
 
With the clutch plates out, in neutral, spin the inner clutch hub. Is it consistent and smooth?
If not, try loosening the belt. If still not, you got issues, probably with the mainshaft.
With rear the wheel up, you can spin it through the gears.
I have one these, that I put under the swing arm to lift the rear with no center stand.
www.pit-bull.com

Pit Bull - Standard Rear, Motorcycle Stand [F0002-000]

Pit Bull Standard Rear Stand. Pit Bull makes the best motorcycle stands you can buy and the Standard Rear Stand is no exception. Fits most modern sport bikes that do not have provisions for sp
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Grear for service, changing the oil etc. with out having any interference underneath.

When I was assemblying my Combat gear box, I had issues working with the shims.
Little doubt it was me, I took another avenue.
I decided to assemble, sans gasket, with 518.
Took up the clearance, works great..
 
I'm guessing these shims are associated with a layshaft roller bearing, since the standard gearbox doesn't have any?

I found the end-float increased over time because the shims are acting against surfaces which weren't designed for them.
I gave up on the idea and fitted a 6203TB phenolic cage bearing as per Mick Hemmings' recommendations.
It restores the positive location of the layshaft and tolerates the layshaft flex which destroys standard bearing cages.

If anyone wants a cheap layshaft superblend with very little use you're welcome to it.
 
B+Bogus said:
My only similar experience (RGM clutch basket aside) was when the primary cover worked loose and clattered against the Z plate under load, but since your motor is rigidly mounted it can't be that.
Just to be 100% clear, is the noise road speed related only? i.e. exactly the same regardless of which gear you're in?
If so, I can't readily think of anything inside the gearbox which would do this apart from an issue with the Mainshaft High Gear, which leads (as already said) to the final drive (clear chain run, no misalignment, rear sprocket secure etc.)...
What layshaft bearing are you running (apologies if you've already said)?
You haven't given much detail about the frame, and I'm curious!
No loose engine mounts/bolts, everything line up OK, good clearance everywhere?
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It´s there in first, second and third, haven´t been up to any high speed yet so don´t know about fourth gear. Last test drive was about 300 meters..... because of the noise. Follows the revs. New layshaft roller bearing, correctly shimsed (?) layshaft axle. Rigid frame, home made. Can not find/see anything that´s loose or broken, the whole bike is a new build from scratch. I will put up a video in a new thread, strange rattling sound but maybe it´s just normal?
 
mdt-son said:
Where did you get the gear cluster from? Do you know for sure it ran noiseless prior to the rebuild? As you say , NV changed the tooth profile on some gears, and the new gear wheels need to be installed as a pair, so please check that. 4th and countershaft gear also receive a new profile, if my memory serves me.
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I only drove the bike a short run, not on yhe road, just to test if it worked. Don´t remember any noise. Since then I have just changed all 3 bearings and all bushings, bought a used shell in very good condition because in the old one the bearings in the drive side had been spinning.
 
B+Bogus said:
I'd speculate that it's more fundamental than oil choice...

Again, it may have already been covered, but not all Commando gears were the same throughout production, and they were certainly different to previous AMC gearboxes.
Identifying what you have might be challenging, but this may help. I seem to recall other data listing different ID marks stamped on the gears, but a brief search drew a blank.

S

Thread 'transmission variations'

There are a few changes that happened inside the box. I have a few gear sets and surplus gears. Is there anything written down about the different gears and how to spot them by number of teeth and measuring. I know a little bit about the AHB markings and the groove cut in the second gears as indicators. Some of these letter stampings are not clear.

I'd still like to know it the noise is purely road speed related or if it changes depending on what gear you're in?
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It doesn´t seem to change much, if at all, when changing gears. Maybe a little worse in second than in first/third, but no big difference. It´s absolutely NO noise when standing still, clutch engaged and in first gear. But as soon as I start to move, release the clutch, it starts.
 
B+Bogus said:
I'm guessing these shims are associated with a layshaft roller bearing, since the standard gearbox doesn't have any?

I found the end-float increased over time because the shims are acting against surfaces which weren't designed for them.
I gave up on the idea and fitted a 6203TB phenolic cage bearing as per Mick Hemmings' recommendations.
It restores the positive location of the layshaft and tolerates the layshaft flex which destroys standard bearing cages.

If anyone wants a cheap layshaft superblend with very little use you're welcome to it.
Click to expand...
Considering that this box after restoring it have been driven no more than 6-7 km (4-5miles), absolutely not more, I doubt the bearing has been worn down.
 

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