clutch wobble/ lever pressure

Hey guys-

I've had my '72 Combat for a couple months now, and have had it running and riding for just a couple weeks. I bought it as a rust bucket with a blown head gasket, and it had sat against a fence under a tarp (in portland, OR) for 9 years.

Anyway, I've done lots to the bike at this point, but the pre-unit construction is still new to me. I've had unit BSAs and triumphs with primary tensioners, as well as lots of "modern" (70's) hondas. When i got it running, I heard primary noise, and upon pulling the primary cover I discovered not only a loose rotor nut, but a very loose primary chain. In this condition, the clutch has LOTS of wobble. With the primary chain tightened, this went away. Is this normal? It felt as if the basket was loose on the shaft, or that the bearings were worn. Also, now that is and the drive chain are adjusted, I can feel the tension and free-play in the clutch lever change depending on whether I am accelerating or not, which tells me that the clutch basket is still loose. under acceleration, the free-play in the clutch lever essentially goes away. I get no clutch slippage or problems finding neutral or gears though.

Still, this is a problem, correct?

It could be the bearing but my guess would be the clutch center nut is not tighten correctly and is loose like the rotor nut was, this is purely a gut feel based on the previous owner was probably working on the whole primary side when he left the rotor nut and chain loose and could have done the same on the clutch center nut possibly in a rush to get the bike ready for sale or gave up. If my theory is correct don't drive the bike any more until its sorted. There is normally some wobble in the clutch due to its large diameter in relation to the bearing but not enough to be felt through the clutch lever. Make sure you have the clutch tool before you get started, without it you cannot work on it safely.

Another possibility is the nut behind the inner gearbox cover on the other end of the mainshaft, for info see here

clutch-basket-movement-t5973.html

thanks! i did suspect that center clutch nut. i'll look there.

Kommando is right, and I suggest a bit more advice if you are going into the Commando clutch for the 1st time. Where you need to go is into the clutch centre to check the mainshaft nut. That is secured with a spider washer. The spring diaphragm can only be removed when compressed with the right tool in order to remove its retaining circlip. After that its all pretty straight forward. Dig the plates out, give them a wash and try and see if the centre nut on the mainshaft is tight.

But, if the centre is OK, and the slop still there then you will need to remove both clutch chainwheel and engine sprocket with the triplex chain. You will need a puller to ease the engine sprocket off the crankshaft. The centre is a press fit through the clutch bearing secured with a big circlip. Back on the mainshaft there should be a stack of shims that set the alignment of the chainwheel in line to the engine sprocket. Behind those is the notorious mainshaft circlip that stops the whole clutch assembly smacking into the inner case. This pesky little circlip can fail and cause major clutch play.

There is opinion that the mainshaft nut should not be tightened to much, i.e. some reckon 40 to 50 FtLbs is OK so as to not exert too much pressure on the little mainshaft circlip. I tend to agree. A copy of the manual can be found via the forum and worth reading, but I hope the above explaination assists.

Mick

I shall concur.
There is a spacer behind the clutch hub 060747 with a relief on one side that goes over a circlip. This is called the clutch locating washer. If this is over torqued it can shear this clip. I suppose it could also happen from sitting for an age. If it goes it sounds like a muffled pop and things will be loose. It is a fairly easy and inexpansive fix. Old Britts recommends that you shy away from the stated torque specs and take it to 35flb and use some locktite.
I don't know if this is your problem, but it a reasonal place to look. Don't ignore it cause you will burn stuff up back there if not addressed.

Another point on that circlip:

If you insist on 70 ft-lbs torque, replace the clip each time you torque the nut. If you suspect the nut has been previously torqued to 70 ft-lbs, replace the clip.

Yes, I have been looking at that circlip since I have rebuilt the GB and it looks pretty whimpy to hold 70 f/p of pressure. I was unimpressed with it.

Dave
69S

Sorry to drag this thread out again, but I've just run into the same issue of wobbling clutch basket. I'm certainly not a Norton expert, but I'm pretty good at finding the cause of mechanical problems. I'd appreciate your thoughts on this - here's what I've found.

I was test fitting the clutch and engine sprocket to determine shims needed at the clutch for alignment with the engine sprocket. Applied a clutch hub holder and torqued the nut to 70 ft. lb. as per the manual. Bad move. With no clutch plates installed, I spun the hub by hand, and the basket wobbled badly. Removed the clutch and found the locating circlip bent over, but not bent evenly all around its diameter. There is only .001" radial runout at the threads of the mainshaft - not enough to cause the huge wobble of the basket. And the hub bearing has zero axial runout.

There are two issues I see here - one is the circlip, and the other is the fit of the hub splines on the mainshaft. If I install the clutch and spacer with no circlip so the hub butts against the sleeve gear, there is absolutely no basket wobble. 70 ft lbs is bending the circlip and allowing the hub to cock slightly on the mainshaft, due to the sloppy fit of the splines. When the hub is then turned by hand, it has axial runout. The hub and basket are not moving in relation to each other - it's an optical illusion. They're both moving in relation to the inner primary cover. The wobble of the clutch basket follows the high spot on the hub.

Bob Raber tells me the new hubs are a much tighter fit on the splines. I might go there. But first, I'm going to try a new locating spacer and circlip using only 50 ft. lbs. on the nut. And I think it's important that the circlip be compressed and evenly seated in the recess of the locating spacer. Of course, that's something that's not possible to see after the clutch is slid onto the shaft.

Stu O

Let us not forget the bent mainshaft which is common. Mine's bent and shall be replaced when I go through the gearbox shortly.

Fullauto said:

Let us not forget the bent mainshaft which is common. Mine's bent and shall be replaced when I go through the gearbox shortly.

Click to expand...

Thanks. Not forgetting.
Stu

Re: Got it!

Used a small piston ring expander to spread the circlip just enough to slide on the shaft, then pushed it on by hand till it snapped into the groove. I could feel it bottom in the spacer's recess. When I torqued the nut this time (50 ft. lb.), it stopped hard when the parts were all squished together - not feeling like I was stretching a bolt to the breaking point like before. No more basket wobble.

Stu