Clutch basket wobble

BERT · Dec 11, 2021

I am reassembling the primary and am at the point of putting in the clutch plates. I have noticed that when I free-spin the clutch center,the clutch basket which is stationary wobbles. Clocking it is .020" on the diameter and .025" on the face adjacent to the diameter. I can see the chain slack changing as I rotate the clutch center. What would cause this and is it acceptable? Thanks in advance.

Mart UK · Dec 11, 2021

I have read of this not being that unusual. It's also something in the character of other Brit bikes like Triumph 650s. Assuming the clutch hub nut is tight, it should lessen / go away with the basket full of plates and tightened up.

BERT · Dec 11, 2021

Mart UK said:
I have read of this not being that unusual. It's also something in the character of other Brit bikes like Triumph 650s. Assuming the clutch hub nut is tight, it should lessen / go away with the basket full of plates and tightened up.

Thanks. I will set the chain slack after the plates are in then.

kommando · Dec 11, 2021

When you are turning the clutch centre you are turning the gearbox mainshaft and the mainshaft sounds like it's bent. It's long and not supported so can be an issue.

BERT · Dec 11, 2021

kommando said:
When you are turning the clutch centre you are turning the gearbox mainshaft and the mainshaft sounds like it's bent. It's long and not supported so can be an

kommando said:

When you are turning the clutch centre you are turning the gearbox mainshaft and the mainshaft sounds like it's bent. It's long and not supported so can be an issue.

Click to expand...

When the gearbox was bare I could feel slight friction in one place of rotation of the mainshaft. Along with this wobble at this stage of assembly would it indicate the mainshaft was bent?

BERT · Dec 11, 2021

Thank you. After giving it more thought of the suggestion of a bent mainshaft, I will put the indicator on the clutch center.

milfordite · Dec 12, 2021

Could be a bent mainshaft, also the sleeve gear bushes may be shot, or both! I've even had a bent layshaft in a box. You never know!

kommando · Dec 12, 2021

And bent main shafts can be straightened, sleeve gear bushes are replaceable. A check on the clutch centre as you plan to do is a good start.

maylar · Dec 12, 2021

There's also an inherent amount of wobble simply because the hub bearing is just a single row ball bearing. And be aware that the diaphragm spring has a bit of play in its location on the clutch basket and if it's not centered exactly will give the illusion of wobble.

htown16 · Dec 12, 2021

I've got the same concern on a 73 I'm putting back together. Everything in the primary is assembled including the stator and rotor. I checked the alignment of the sprockets without the chain on and they were good. When I rotate the engine with the bike in gear using the rear wheel (normal riding mode) there is no appreciable wobble and the chain tracks straight. However, when I pull the clutch lever in(shifting mode) and rotate the rear wheel the clutch basket has some wobble. I'm thinking that if the mainshaft were bent it would wobble in both cases. Is it down to the large clutch ball bearing wobbling when it has no load on when the clutch lever is pulled in?

BERT · Dec 12, 2021

Would it be possible to bend the mainshaft by torquing the rotor nut to the required 70# using the clutch locking tool with the rear iso nut as a stop? Is there any history of this occurring?

Torontonian · Dec 12, 2021

BERT said:
Would it be possible to bend the mainshaft by torquing the rotor nut to the required 70# using the clutch locking tool with the rear iso nut as a stop? Is there any history of this occurring?

Not that I'm aware of . My money is on the Sleeve main shaft bushings being pooched. And that means a gearbox rebuild . Mind you I've never even attempted dumping the clutch for a wheelie attempt.

cliffa · Dec 13, 2021

BERT said:
Would it be possible to bend the mainshaft by torquing the rotor nut to the required 70# using the clutch locking tool with the rear iso nut as a stop? Is there any history of this occurring?

It’s generally recognized that 70 ft/lbs is too much. 40 - 45 is perfectly adequate.

BERT · Dec 13, 2021

cliffa said:
It’s generally recognized that 70 ft/lbs is too much. 40 - 45 is perfectly adequate.

I've never seen less than 70# specified for the rotor nut.

Mart UK · Dec 13, 2021

BERT said:
I've never seen less than 70# specified for the rotor nut.

I used 70 on mine before I knew about torquing it lower. It seems fine.

maylar · Dec 13, 2021

Mart UK said:
I used 70 on mine before I knew about torqueing it lower. It seems fine.

Unless you have an Alton starter, of course.

70 is normal for the rotor nut. It's the clutch that needs to be lower.

cliffa · Dec 13, 2021

Yes, apologies, I thought we were discussing the gearbox mainshaft / clutch nut, then the rotor nut was mentioned. I was referring to the gearbox.

BERT · Dec 13, 2021

kommando said:
And bent main shafts can be straightened, sleeve gear bushes are replaceable. A check on the clutch centre as you plan to do is a good start.

Thank you. The indicator shows .012" TOTAL runout on both the push rod hole and the clutch center teeth. Is this acceptable?

kommando · Dec 13, 2021

BERT said:
Thank you. The indicator shows .012" TOTAL runout on both the push rod hole and the clutch center teeth. Is this acceptable?View attachment 83385 View attachment 83387

No as it gets magnified by the time you get to the edge of the basket, your own figures show 12 thou at the shaft becomes 20 to 25 thou at the larger diameter (surprised it not more). I would be looking for 1 to 2 thou runout on the shaft. It needs taking out and it tested between centres to find the bend plus the sleeve gear bushes checked as well.

Mart UK · Dec 13, 2021

Will it be magnified? The measure point looks level with the edge of the basket.

Clutch basket wobble

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