Belt drive noise issue...

Hi Guys,

My rebuild is coming along - (slowly). I needed to replace the clutch plates so I took the chance to do a belt drive upgrade and the sparx/trispark whilst I was at it.

After getting the bike started up I now have a strange squeaking sound...

I took a quick video:

http://www.youtube.com/watch?v=JA-xrfIyhPw (sorry - I couldn't work out how to embed the video)


It's coming from the clutch area. The squeak occurs no matter if it is in gear/neutral clutch in or out. The belt is riding on the clutch drum but riding fairly close to the inside edge (a couple of mm shy of the edge of the drum).

The belt tension is such that I can turn the belt through 45 degrees - so I don't think it is too tight. Is it just the belt adjusting on the clutch drum?

Any pointers/ideas/help would be greatly appreciated.

Regarding the belt tension, when the bike is completely cold you should be able to grab the top run of the belt in the middle and twist it "almost" 90 degrees, I have mine set at around 75 degrees.


Not only the clutch basket but also the engine to gearbox plates expand when hot and take out the cold slack.

A too tight belt when fully heated up might put enough strain to cause the noise, don't know if that is the noise reason but just to rule it out you may wish to move the gearbox in a little bit.

Believe ole hobot or not but if you can't twist each run of belt pretty easy to 90's then you are at over tension risk of damaging the shafts and bearings in whole drive train once fully at temp under road loads. BTW I found out it only takes one short event like this to do in the whole dam drain train deed, so believe ole hobot or not and do as 1to3 says. If you are really anal you can look up the belt T count and each pulley teeth count to get the pulley centers dead on, except for the thermal expansion factor not in those charts. Belts don't stretch nor do they dampen engine and road pulses, only their slack does.

Hi Biffom

To tight & it will sound like a kettle.
It will also do in your gearbox highgear bearing in a very short space of time.
Sometimes you can get a squeek I have found that it is the keep plate. i remade with a flate plate with a larger diameter. Sorted.

Chris

biffom said:

Hi Guys,

The belt tension is such that I can turn the belt through 45 degrees - so I don't think it is too tight. Is it just the belt adjusting on the clutch drum?

Any pointers/ideas/help would be greatly appreciated.

Click to expand...

Too damn tight. As others have stated, You want to twist that beld a bit more than 90 degrees.

Whos belt drive is it? If it is RGM, make the belt as loose as possible without it jumping a crank hub tooth while kicking over.

Thanks guys - I shall try slackening it off to about 90 degrees twist and see how that goes.

pvisseriii said:

Whos belt drive is it? If it is RGM, make the belt as loose as possible without it jumping a crank hub tooth while kicking over.

Click to expand...

I purchased the kit from Old Britts. It doesn't have any manufacturers marks so I'm not sure who the original manufacturer was.

Always error on the too loose side with a belt. It will do no damage and about the worse that could happen is it will jump a tooth when you try to kick start it.
Too tight will build heat which expands the drum more and soon you will have a cascade failure of the belt or gearbox bushings and other expensive things. When the belt is too tight it will cause the belt to run to one side and cut down the edge of the belt. It will look like the sprockets are out of line. Jim

I slackened it off and all was well until it warmed up. I then slackend it off some more. But no joy.

I have found that if I apply a dab wd40 to the outside edge of the belt as in the next photo the noise stops.



There is only one place it can be rubbing and that is against the outer drive pulley plate. The plate is the bottom one in this image:


and this is it installed:


Do i just let it wear in? Or is there another issue? Such as alignment....

Been there done that with destroyed belt 100 miles from home. BY FAR the weakness of belts are any rubbing/fraying on the edges, all is well till suddenly it unravels and piles up behind the alternator and crank pulley. On Peel after my tension lesion sunk in - I had a clutch adjuster nut come loose and run thru the belt/pulley, but since I had the correct slack it didn't hurt the drive train and continued to run over 130 indicated with a hole you can stick a pencil through, no problemo.

I suspect you followed the wrong advice and now have stem to stern drive train damage that will cascade in failed items one after another until whole kit and kulbutal replaced. In mine I had the tranny bushes give up - sleeve bushes and first gear most, fixed them but still had em go bad for clutch wobble belt rub in few 100 miles, took deeper look, ugh, to find the gear shafts bent. I suspect it even bent the crankshaft some too. Live and learn why I consider Norton's a real man's hobby, with expensive tedious learning curves to endure.

Its possible you just have too narrow a front pulley and might get away with just thin shims under the front side plate. Intermittent rub sound would imply a out of square drive train that binds on each revolution as bent/worn items align for worse condition then tugs past it repeatedly till a $how $topper. If not we need to know what you do find to education me and others - at your own expense-efforts of course.

I would say alignment.
I have found that if you alighn the hub up perfectly square, it will temd to ride toward the outboard side. If, however you give it a few degrees out this will compinsate fro a littel bearing and mainshaft flex.
Using 2 squares, one on the clutch hub and one on the crank hub and bringing the perpendiculars together to determine alignment and leaving a slight gap toward the end of the perpendiculars. Maybe a 1/8 inch 6 inches out.

I would say you are still too tight. I needs to be floppy loose. Jim

Oops am I missing something vital here or are you? There should be No Question you got belt aligned before you even start it let alone ride on off it. If you can detect any clutch wiggle by hand then all belt bets off till the tranny and clutch set right and stable with undetectable wiggle slack. Fine for triplex chains ain't for belts, especially those run to full temp too tight, ugh.

One must-should get alignment spot on w/o the front side plate on, by pure trial and error adjusting the gear box/clutch basket alignment/tension while turning and turning and turning the crank till you see for sure that the belt stays on track all by its lonesome. I simply can not conceive any other way to do it, as there is so much variation-slop in chassis and kit fit any measuring method is just an approximation to start from before turning and turning and turning and diddling ...dittoing... till just right.

comnoz said:

I would say you are still too tight. I needs to be floppy loose. Jim

Click to expand...

Easy to try so I shall give that a shot. I'm having to head out of town for the next week so i shall report back when i get back.

hobot said:

Oops am I missing something vital here or are you? There should be No Question you got belt aligned before you even start it let alone ride on off it. If you can detect any clutch wiggle by hand then all belt bets off till the tranny and clutch set right and stable with undetectable wiggle slack. Fine for triplex chains ain't for belts, especially those run to full temp too tight, ugh.

One must-should get alignment spot on w/o the front side plate on, by pure trial and error adjusting the gear box/clutch basket alignment/tension while turning and turning and turning the crank till you see for sure that the belt stays on track all by its lonesome. I simply can not conceive any other way to do it, as there is so much variation-slop in chassis and kit fit any measuring method is just an approximation to start from before turning and turning and turning and diddling ...dittoing... till just right.

Click to expand...

I must be missing something here. The clutch basket does wobble. I thought it did that by design - no? It's only attached by the bearing the rest of the tension is taken up by the meshing of the plates.

The belt is tracking ok - I checked it by hand then at idle and then after a few miles.
[edit]I haven't checked it without the end plate on though[/edit]

I was wondering how you go about changing the gearbox alignment when it only has one adjuster bolt on the right hand side and the gear box pivots on a long bolt that is attached to the engine mounting and effectively locked into alignment with the engine.

You change the gearbox alignment, particularly important for a belt primary, by installing a threaded gearbox adjustor on the left side, thus allowing you to change the belt run for proper adjustment.

There are couple of venders that sell left side adjustors, can't remember as i made mine myself.

Someone else help him out where to get one?

1up3down said:

You change the gearbox alignment, particularly important for a belt primary, by installing a threaded gearbox adjustor on the left side, thus allowing you to change the belt run for proper adjustment.

There are couple of venders that sell left side adjustors, can't remember as i made mine myself.

Someone else help him out where to get one?

Click to expand...

Yep, that's the reason for the left adjuster. A tri chain can be misaligned to quite a degree and still run just fine forever, belts on the other hand will walk, as you appear to be experiencing.
Although a real pain in the ass to fiddle with, once set, it's set. What I hate about the belt drive IS the set up, but I don't have to worry about that anymore, because of course, it's set. Don't button up till you are sure.

http://www.clubmanracing.com/beltdrivesnorton.php

Here's that SS dual adjuster installed in Ms Peel, adapted/spaced to allow Maney outrigger bearing support to fit.

Thanks guys. Installing an adjuster might just help with adjusting! I'm often caught out by skipping the installation destructions - this time I have a good excuse - I didn't have any.

I'm still wondering how it shifts the gearbox alignment when the gearbox pivot bolt is in place. There must be minimal play - but I guess enough to make a difference?

I really appreciate the help.

Armed and dangerous with a spanner.