Bad backlash

Stu Bodycote · Feb 4, 2023

This particular bike has always had a noisy primary. The bikes done 10,000 miles, and was happy enough rattling along at that. But it clearly needed checking out.
Backlash gear incorrectly sub-assembled with spring dowl pin fitted backwards, and incorrectly positioned, so it wasn't even acting against the spring 🤦🏻‍♂️
All sorted....this bike has never sounded so quiet. I've also used him as a guinea pig, trying out some Motul 300v 15w50 in his primary side.

BritTwit · Feb 4, 2023

That's reassuring.
Not a design issue, but a human error in assembly.
Will this assembly error have caused any long term damage to either the gear or pin?

Stu Bodycote · Feb 4, 2023

I refitted the pin the correct way round, but I wasn't confident in how secure it was, so I gave it a little weld. They tig welded quite a number of these at the factory, as Phil & I in Engine Build at the time were not happy with them. Unfortunately I've only got a mig welder here, but its done a satisfactory job...that pin is not going adrift now. I just had to nib it back a touch afterwards so it was underflush.
This sub-assembly is before my time there...so I'm in the clear lol.
No other damage...and the primary now pretty damn healthy. The customer has in fact ordered a new Norton built 961, so this bike will be going up for sale...hence the strip down and inspection.

Fast Eddie · Feb 4, 2023

Shame you didn’t do a before and after video on this!

The more I read your inputs the more I’m beginning to think there was something wrong with mine above and beyond the ‘they all do that sir’ level.

Stu Bodycote · Feb 4, 2023

Sorry, I just didnt think to, tbh. I have an after video, I'll upload that later....but video's are a little unjust as they seem to really concentrate on the mechanical noise. Sounds better in the flesh....and this is still running a billet clutch too.

BritTwit · Feb 4, 2023

Stu Bodycote said:
....The customer has in fact ordered a new Norton built 961, so this bike will be going up for sale...hence the strip down and inspection.

Did your customer test ride the New 961 before placing his order?

Stu Bodycote · Feb 4, 2023

BritTwit said:
Did your customer test ride the New 961 before placing his order?

Yes. He found it much smoother etc compared to his. But his is a euro 3, with many mk2 updates.
I'm really looking forward to him hearing his bike when he picks it up.

cliffa · Feb 4, 2023

The pin on mine was too long and held the scissor gear away from the drive gear.

I’m beginning to think that all these engines need to be stripped and blueprinted ( unless they are marked SB of course

)

BritTwit · Feb 4, 2023

Stu Bodycote said:
Yes. He found it much smoother etc compared to his. But his is a euro 3, with many mk2 updates.
I'm really looking forward to him hearing his bike when he picks it up.

I hope that he understands that he is required, by forum rules, to provide a full accounting of his NEW 961.

cliffa · Feb 4, 2023

How was that able to back out Stu? There is a circlip and a hefty washer on mine right over the pin.

EDIT, I froze the video and could see how it can back out - carry on

Stu Bodycote · Feb 4, 2023

Stu Bodycote said:
Sorry, I just didnt think to, tbh. I have an after video, I'll upload that later....but video's are a little unjust as they seem to really concentrate on the mechanical noise. Sounds better in the flesh....and this is still running a billet clutch too.

Here we go then. Keep in mind though, videos pick out the mechanical noise more, and this is still on a mk1 billet clutch. Taking that into consideration, I think this is now down to a very acceptable noise level.

BritTwit · Feb 4, 2023

Stu Bodycote said:
I think this is now down to a very acceptable noise level.

I think so as well.

Fast Eddie · Feb 5, 2023

Wow, that sounds like a, well, a motorcycle !

My 2018 Anniversary sounded nothing like that! And mine sounded just like many others. And I had the factory look at it twice.

cliffa · Feb 5, 2023

I reckon the owner will be so pleased he’ll cancel his order for a new one

With a billet clutch I guess it’s any early one. How does the front hub look Stu?

DODGY DEN · Feb 5, 2023

Stu Bodycote said:
Here we go then. Keep in mind though, videos pick out the mechanical noise more, and this is still on a mk1 billet clutch. Taking that into consideration, I think this is now down to a very acceptable noise level.

Well done Stu for picking that error up I know your customer and he’ll be well chuffed. 🏍👍🏻

Stu Bodycote · Feb 5, 2023

cliffa said:
I reckon the owner will be so pleased he’ll cancel his order for a new one With a billet clutch I guess it’s any early one. How does the front hub look Stu?

Haha thats what I said!
It's a 2014 bike. Talon hubs...look perfect. Much like the clutch baskets falling apart, and this backlash....I'm leaning more towards an assembly error on the wheels ie over tensioning of the spokes to pull the rim in true. Wheel building is something that I really wished I had a go at whilst at Norton. It's just black magic voodoo to me....I know the theory, but the couple of times I've had a go, I've been as successful as I was at completing a rubix cube when I was young.

Stu Bodycote · Feb 5, 2023

DODGY DEN said:
Well done Stu for picking that error up I know your customer and he’ll be well chuffed. 🏍👍🏻

Cheers, its all part of what I check during a primary inspection. I generally recommend replacing the starter motor gasket at the same time, with the rubber coated steel one's that Thiel supplies me with.
I'm looking forward to a road test later, see how she goes now.

worntorn · Feb 5, 2023

Stu Bodycote said:
Haha thats what I said!
It's a 2014 bike. Talon hubs...look perfect. Much like the clutch baskets falling apart, and this backlash....I'm leaning more towards an assembly error on the wheels ie over tensioning of the spokes to pull the rim in true. Wheel building is something that I really wished I had a go at whilst at Norton. It's just black magic voodoo to me....I know the theory, but the couple of times I've had a go, I've been as successful as I was at completing a rubix cube when I was young.

I use a spoke torque wrench and two dial indicators.
With that setup it's just down to patience. With a bit of that I think anyone can dial them in to +- ten thou and +- 5 inch pounds.
Some folks claim they get a decent job just by tensioning to a certain sound on the spokes.
I don't think that works as the properly torqued spokes all sound quite different when you plonk them.
Buchanan's wheels in USA are one of the best in the wheel building business and they use a spoke torque wrench on every wheel.

Most spoked wheels that I have checked are not torqued anywhere near equally and have very low tension on the spokes. The low tension makes for a weak wheel that is prone to spoke breakage.
The grossly uneven spoke torque is also detracting from wheel strength.
Big runout on the wheels causes lots of vibration.

Glen

Fast Eddie · Feb 5, 2023

worntorn said:
I use a spoke torque wrench and two dial indicators.
With that setup it's just down to patience. With a bit of that I think anyone can dial them in to +- ten thou and +- 5 inch pounds.
Some folks claim they get a decent job just by tensioning to a certain sound on the spokes.
I don't think that works as the properly torqued spokes all sound quite different when you plonk them.
Buchanan's wheels in USA are one of the best in the wheel building business and they use a spoke torque wrench on every wheel.

Most spoked wheels that I have checked are not torqued anywhere near equally and have very low tension on the spokes. The low tension makes for a weak wheel that is prone to spoke breakage.
The grossly uneven spoke torque is also detracting from wheel strength.
Big runout on the wheels causes lots of vibration.

Glen

Can you show us the spoke torque wrench you use?
I’ve always been a ‘spoke tapper’ myself… maybe time to get with the programme ?!

worntorn · Feb 5, 2023

Here it is.
I use a small t shaped wrench initially as it is faster for the first bit.
Once the torque gets to about 20 inch pounds I switch to the torque wrench, going round and round bringing torque up in 5 inch pound increments.
Final torque is 55 inch pounds+-.

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Bad backlash

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