Where does the noise come from?

kanenas said:

Ok, being a newbie it seems I am reopening old threads. So I have some comments on the rattling noises emanating from the engine:
1. It is true that the all gear primary drive is by nature more noisy than a chain or belt drive
2. It also true that the main cause of the "extra" noise is the counterbalance gear.
3. I am fully convinced that a simple redesign of the gear can eliminate most noises.
4. The redesign is reversing the taper so the gear mounts "inside out" and reversing the counterbalancer direction.
5. There is a very logical reason for this and it goes like this:
As assembled, both parts of the counterbalance gear engage the crankshaft AND the primary (clutch shaft) gears. By both parts I mean the "main" part of the gear and the "narrow", spring loaded antibacklash component. THAT IS A NO-NO! By definition, an antibacklash gear pushes back (thru the spring) against THE non driving side of the driving tooth of the crankshaft gear. But what is happening in our primary cases is not that, each antibacklash gear egages one tooth with the crankshaft AND ANOTHER TOOTH ENGAGES THE CLUTH GEAR! The end result is that the antibacklash gear will adjust to the TIGHTER tolerance side (engaged tooth), so at times the full intermediate gear will mesh with the crankshaft at zero backlash and sometimes with the clutch, causing unneeded rattling noises and vibration. An antibacklash gear MUST engage ONLY ONE gear, not two!!!
If we look closely in the cases we can see that, if the countershaft gear is reversed, the narrow side only engages the crankshaft gear and that would allow the antibacklash mechanism to actually work. I suspect that this alignment shows that the original design was accounting for this, but someone screwed up and reversed the taper in the gear and either nobody noticed it or they thought nothing of it!
I don't know if there is enough meat and space in the existing gear ( and the primary case) to machine out the center and install a reverse taper insert in it and reverse the counterbalancer direction, I did not measure things when I had the case open, but I am sure that if someone tried the result would be well worth it, but of course a brand new gear with the correct taper direction would be almost magical.
Any ideas / connections with cintered metal manufacturing?

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That is a very interesting hypothesis. I actually have my primary apart at the moment and did wonder why the gears don't fully align. Could it be a simple screw up as you suggest? I also think the fact that the three shafts are not in alignment causes uneven thrust to the scissor gear as I have wear on over 180° of the main gear collar where the scissor gear sits. If I assemble them without the spring and shake them I hear a familiar rattle.
I have ordered a new gear assembly from Ollie Thiel, so may have a play around with the old one.

I know that Ollie has made a different Backlash wheel.
In two of his test bikes are running this parts.
But no more informations from him or his stuff.

I think after the test i will know more.

Panetone said:

I know that Ollie has made a different Backlash wheel.
In two of his test bikes are running this parts.
But no more informations from him or his stuff.

I think after the test i will know more.

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Thanks , Keep us posted .

I've been thinking a lot about the post from @kanenas and of course he is absolutely right, A scissor type backlash gear can only be successful on a single gear. When used on more that one as ours are the gear will only take-up play on the gear with the least backlash, so it's pretty useless in reality. He suggested turning the whole assembly around so it's only operating on the crankshaft gear. That got me thinking. So as my bike is currently waiting for bits from Ollie and I have my primary and gearbox in bits, so I went and got my backlash gear, and I have worked out how the existing gear can be modified without turning it around. It does need a skilled engineer for one part, but I reckon it's a couple of hours work. So here's my thoughts...

Scissor gear facts. The scissor gear is 5.3mm wide. The hole in the centre is circa 45mm diameter ( mine is worn).
Main backlash gear facts. The centre hole is 25.9mm on the outer and 30.4 on the inner side This equates to a 13.5% taper. On the outer end of the there is a boss which protrudes 4mm past the front surface of the main gear. This is 46mm diameter. The dished area on the outside of the main gear is 6mm below the level of the gear teeth.
The combined width of both gears is 20.5mm.
The backlash spring is 2mm thick.

So this was my idea...

1) Remove 5.3 mm from the centre boss at the rear of the main intermediate gear ( this takes it to about half way through the circlip groove)
2) (this is the critical part). According to my calculations the inner hole will now be 29.685mm so needs to be opened back up (retaining the same taper angle of 13.5%) to 30.4mm. It therefore only needs 0.715mm removed to bring the gear back up the balance shaft 5.3mm (back in line with the rear of the crankshaft gear.)
3) Open the centre of the scissor gear up to 40.1 or 40.2 ? mm ( so it's a nice rotating fit of the outer of the main gear). Then remove a 1.32mm deep band (say 52mm diameter) from the outer face of the scissor gear so that the lower area is very slightly below the outer shoulder where the nut and washer normally sit.
4) Machine a 5.3mm x 51mm washer to fit over the balance shaft threads. The scissor gear should now be able to rotate and be held in line by the new washer if clamped up.
5) knock out the 5mm steel pin from the main intermediate gear.
6) Machine a 6mm steel infill spacer (on mine it is radiused on the inner and the outer so this would need to be like a frizby shape), with 2mm deep recess 11.45mm wide. ( mimicking the other side of the gear).
7) Drill and countersink the infill 180° @ 70mm centres to utilize the existing 8mm tapped holes in the intermediate gear. Loosely assemble, then drill through the hole where the hardened pin was removed (don't open up the existing hole). Warm up the gear and drive in a new 5 x 20mm hardened pin until it is very slightly lower than the outer gear face of the intermediate gear and not touching the scissor gear when fitted in it's new position. Apply thread lock to the countersunk screws and tighten, ensuring the heads are flush.

That should be it.

When refitting the gear I think it should be possible to align the timing mark and then fit and tension the scissor gear.

I still need to do some more measuring to ensure the scissor gear won't touch the clutch gear, but I just wanted to post this for thoughts / discussion.

Of course if it turns out that its the clutch to intermediate gear making all the racket than this would all be a waste of time.

I did find an interesting patent application by the Xerox Corporation for a split scissor gear with can adjust itself to take up backlash on two gears in three gear transmission. It relies on clearance between the main gear and scissor gear centres to allow them to self adjust


( makes me wonder if I should have bothered ordering a new assembly from Ollie

Impressive analysis, even if following it all does make my head hurt. Sounds like a lot of detail work, but it really would be nice to get rid of some of that threshing machine noise.

Ken

A question for the 961 gurus on this subject… my 2013 SE has had all the engine and primary upgrades(except for the ring gear pinning). When the engine was apart dealing with the crankshaft plate bolts and new bearings, the split gear spring was replaced and tensioned correctly as per Richard C s manual, shop manual and a few calls too Dave C.
When the bike was started back up after this, it was quieter but still had the standard rattling.
Fast forward approx 1500kms. After a rather “spirited “ ride, I noticed the primary had gone quiet. Very little rattling. If any.
My primary is again being opened up and I have a replacement split gear spring And all required tools.
My question is, should I be concerned that things have gone quiet?
I’m wondering if the spring has tensioned itself too tight( I’m not sure if thats possible)? Or if the split gear has seized?
If the consensus says to leave it alone, thats fine. I do have the proper tools to go investigating into it but I’d love to hear some thoughts on it before I get into it.
Thanks everyone in advance.
Cheers
Shayne

Hi Shayne, I’m by no means a guru, but feeling my way. Can I ask why you have a new spring? it seems like you already replaced it.

If it was my bike, I would just periodically open the primary and make sure everything is ok. Once tensioned I cannot see how the spring can get tighter. It can really only get looser and that can only be when the spring breaks or loses tension from over tightening.

As mentioned in my previous post I’m beginning to wonder if the scissor gear is more effective with some play between it and the intermediate gear, as it can then move to the thrust face on the crankshaft and the clutch, rather than only one.

Out of interest which trans oil did you use?

kanenas said:

An antibacklash gear MUST engage ONLY ONE gear, not two!!!

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If the scissor gear is that central / intermediate gear between the crank pinion and clutch drive gear that would be odd indeed.
Surely the balance shaft is not on that same gear.

If so some running noise (oscillation / resonance) would be inevitable.

Time Warp said:

If the scissor gear is that central / intermediate gear between the crank pinion and clutch drive gear that would be odd indeed.
Surely the balance shaft is not on that same gear.

If so some running noise (oscillation / resonance) would be inevitable.

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Yep, here is the gear in question ( courtesy of an image from the Richard-7 manual)

cliffa said:

Yep, here is the gear in question ( courtesy of an image from the Richard-7 manual)

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My introduction to scissor gears was in 2000 and my first of two Suzuki TL1000's (some say TL stands for 'ticks loudly and cam scissor gear springs generated)
There is a scissor gear on the crank pinion gear which never give any trouble or noise but it drives the clutch only and that comes back to what member 'kanenas posted.
The camshafts had a new design with a chain from the crank to an intermediate gear at the cylinder head and the two geared cams drove off that gear both having scissor gears which could weaken the springs generating a ticking sound)

Edit.
If the crank gear rotates CCW , the intermediate CW and clutch CCW the scissor gear must be thrusting CCW working in the trailing part of the teeth which would suit both the crank and clutch gear ?
Maybe any noise (throttle body synchronization would be important) is coming from that only 4 cush springs clutch unit.

Time Warp said:

My introduction to scissor gears was in 2000 and my first of two Suzuki TL1000's (some say TL stands for 'ticks loudly and cam scissor gear springs generated)
There is a scissor gear on the crank pinion gear which never give any trouble or noise but it drives the clutch only and that comes back to what member 'kanenas posted.
The camshafts had a new design with a chain from the crank to an intermediate gear at the cylinder head and the two geared cams drove off that gear both having scissor gears which could weaken the springs generating a ticking sound)

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I've heard that before about the TL1000's. I think the Triumph Bonneville's use scissor gears in the valvetrain as well and have been known to get noisy when the spring is weakened.

My idea is to move the scissor gear to the outside where it would only apply it's dampening effect on the crankshaft gear. Hard to see from that picture, but not all of the driven intermediate gear engages on the clutch basket gear. I'm hoping the offset is the same thickness as the scissor gear. I need to assemble then measure.

This is the TL crankshaft scissor set up so wonder what the Norton has if not similar.

This is the Norton version. Rather like a thick circlip..

That is the main gear. the scissor gear also has a corresponding pin to engage the other end of the spring, and is pre tensioned before installation.

cliffa said:

That is the main gear. the scissor gear also has a corresponding pin to engage the other end of the spring, and is pre tensioned before installation.

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I can see now, how it would be difficult if not impossible for the spring to malfunction to the point that its tighter. Is there anything that could be going on with the balance shaft itself that could be making things quieter?
For primary fluid, I have been using a BelRay( I think)product and its for HD Sportster gearboxes.

Charlotte said:

I can see now, how it would be difficult if not impossible for the spring to malfunction to the point that its tighter. Is there anything that could be going on with the balance shaft itself that could be making things quieter?
For primary fluid, I have been using a BelRay( I think)product and its for HD Sportster gearboxes.

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I think you have the answer there. The Norton gearbox is very similar to a Harley Sportster, so it makes sense to use a proper transmission oil rather than engine oil in it. I intend to use BelRay as well. Do you know which one you used?

cliffa said:

I think you have the answer there. The Norton gearbox is very similar to a Harley Sportster, so it makes sense to use a proper transmission oil rather than engine oil in it. I intend to use BelRay as well. Do you know which one you used?

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This is the stuff I purchased recently :

I have been using Bel-Ray Thumper. Getting a bit confused with these different Bel-Ray oils...

TonyA said:

This is the stuff I purchased recently :

Sport Transmission Fluid

For the transmission and primary of Sportster® and Buell® Blast™ motorcycles.

www.belray.com

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Yes…. Thats the product there that is what I use.

Clive said:

I have been using Bel-Ray Thumper. Getting a bit confused with these different Bel-Ray oils...

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Yes, they do tend to overlap somewhat when you look at the blurb. I'm definitely going to use the same as TonyA and Charlotte as it's specifically designed for Harley Sportsters and Buell Blasts which as we know are very close cousins to ours.