Knocking / rattling inside primary drive case + backfire

M-Hawk said:

Hi all. Any tips for getting the circlip on to the clutch shaft? I’ve reduced the size of the upgraded circlip, but can’t see how to get it on without a big twist. I also have an original spec circlip, that one has a wider mouth and is thinner.

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Use circlip pliers to help, as you hold it against the end of the shaft.
Or, run to the auto parts store, get the correct ones.

Thanks. Managed to get it on, but it bent in the process. Luckily I bought two

L.A.B. said:

However, CEI would be obsolete by this time and the 20 TPI series was discontinued after CEI had been adopted into British Standard, (CEI becoming British Standard Cycle thread in 1938), therefore, 5/8" x 20, also 9/16" x 20 at the other end of the mainshaft, also the nuts could in fact be 55° special Whitworth (Whit Form) and not 60° Cycle thread.

BSW/UNC Caution

We (especially those in the US) tend to call all British threads Whitworth. In truth not much BSW (British Standard Whitworth) is used in British motorcycles. BSC (British Standard Cycle)/CEI (Cycle Engineers Institute) are much more common (26 tpi). Then there's the BSF (British Standard Fine)...

www.accessnorton.com

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If I understand correctly, those are probably Whit Form not BSC. But Whit Form is not BSW? Is there a standard nomenclature for Special BSW?

I will try to capture some of that in the header. I show BSC (CEI) because even in the 60 your would see books specifying CEI even though it was long gone officially. At least, in theory, CEI was covered by BSC. You probably know that my database started as the Stainless Bits pages (with permission). Ever since, I've been trying to improve, add, fix anything found wrong, a while back you mentioned that there was probably no Phillips and I had all the Posidrive listed as Phillips - that was changed that day.

M-Hawk said:

Thanks. Managed to get it on, but it bent in the process. Luckily I bought two

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You can always just bend them back into shape.

marshg246 said:

If I understand correctly, those are probably Whit Form not BSC.

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Yes, probably, due to the 20 TPI 'Cycle' thread series apparently becoming obsolete after it changed from CEI to BSC.

marshg246 said:

But Whit Form is not BSW?

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It is a thread of "Whitworth form" (BS 84) but in alternative pitches to the standard Whitworth coarse thread pitch.


BSF is also a "Whitworth Form thread" and also BS 84.

marshg246 said:

Is there a standard nomenclature for Special BSW?

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= Special Whitworth or Whit Form/Whitform.

concours said:

You can always just bend them back into shape.

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That’s what I did. I was quite surprised it had no spring in it and easily bent. I had whittled it down to a snug fit so a few light taps with a hammer had it nicely seated.

@M-Hawk don’t forget to put the thick spacer back on with the recess toward the gearbox.

M-Hawk said:

I’m not going to worry about the Dynodave mod for now. But noted for the future, cheers.

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Don't overfill the gearbox, store the bike upright, not on the side stand.
Issue pretty much goes away. Clutch compatible oil is a bonus.

This might be the daftest question I’ve asked so far… regarding the clutch nut tab washer - do you fold over the long bit, as well as the 3 shorter bits?

M-Hawk said:

This might be the fattest question I’ve asked so far… regarding the clutch nut tab washer - do you fold over the long bit, as well as the 3 shorter bits?

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The "long bit" locates in one of the clutch centre holes and locks the tab washer in position.

Ah. I think I put it in upside down then.

Luckily the old tab washer only had a single tab folded, so I’ll re-use that instead.

M-Hawk said:

Ah. I think I put it in upside down then.

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Yes, as there'd be no point having the tab washer if it could potentially rotate with the nut plus the tab would clash with the diaphragm spring.

M-Hawk said:

Ah. I think I put it in upside down then.

View attachment 103709

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You take that tab washer and throw it into your neibours garden and use loctite instead

I used both tab washer, and loctite.

Unfortunately (or probably fortunately) I just snapped the rear brake cable, while applying pressure to torque the rotor nut to 70ft lb. I’ll order a replacement on Monday, together with another set of stator studs. I replaced these already, and just tried the stator on them but no go. One must be bent. I’ve still got the old ones, so I’ll have a play to find a set that works.

On the plus side, the clutch is in (I shimmed and chain alignment is spot on now). The new woodruff keys are a great fit too.

I'm reading this lengthy thread and wondering if you ever found out about your "backfire?" I had similar issues that had me flummoxed for some time and had me to the point of jumping off the bridge. I am no expert but I'm not a novice either. This is what I found. Backfire happens on acceleration, out the back of the carb and "after fire" happens on deceleration out of the exhaust. My issue was after fire, predominently in the right cylinder. I live in a small town that most have probably never seen a Norton so it stood out to those interested in bikes and nothing says loser more than a classic bike that doesn't run right so that was a real pisser. I had two issues happening simultaneously, one masking the other. First of all I had the dreaded ethanol fuel eating the fiberglass tank issue. Despite the tank(s) two of them, being meticulously cleaned and sealed, each tank with the latest "best" sealer, it would still leach resin and clog the pilot jet orifice and I would get an after fire when backing off the throttle. I'd clean the orifice (and the whole carb) and it seemed to help and the after fire would reduce and come back and I thought that was the only problem. After buying and installing new Amals it still had the issue, seemily not as bad but it was still there, most often when the engine was fully warmed. Most of the suggestions I was able to find said there is an air leak somewhere in the exhaust. I couldn't locate any. Cutting to the chase, I pulled the head and found the right exhaust rocker with a slight binding in the travel. Investigating further, I pulled the spindle and found a small chunk of silicone sealer largely clogging the oil tunnel where it feeds onto the spindle. It galled the spindle and the rocker tunnel and bound just enough to keep the exhaust valve from seating fully and on compression it bled a little fuel into the hot exhaust and ergo the bang. I replaced the spindle and rocker and problem solved. That may not help you, just sharing what I found as it was a bugger to sort out.

The rocker feed line from the timing cover would normally be attached to the right-hand side of the cylinder head with the cross-over section going to the left-hand side.

Thanks Gnalk. Back/after fire issue is next on the list after I complete the primary. I’ll bear all of that in mind.

Thanks L.A.B. - I’ll see if I can re route it.

M-Hawk said:

I used both tab washer, and loctite.

Unfortunately (or probably fortunately) I just snapped the rear brake cable, while applying pressure to torque the rotor nut to 70ft lb. I’ll order a replacement on Monday, together with another set of stator studs. I replaced these already, and just tried the stator on them but no go. One must be bent. I’ve still got the old ones, so I’ll have a play to find a set that works.

On the plus side, the clutch is in (I shimmed and chain alignment is spot on now). The new woodruff keys are a great fit too.

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Brake cable failure can lead to very nasty crashes out on the road. There is a safety spring available from most fine Norton suppliers to prevent/reduce risk of brake lever dropping into pavement if cable fails. Bit of a Chinese puzzle to fit that spring but i'll have a look for some pics I have of it.

M-Hawk said:

Thanks L.A.B. - I’ll see if I can re route it.

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It would normally pass between the carb manifolds and through a grommet and a clip attached to the head steady.


Safety spring:

Also, be sure to route the brake cable over the Z-plate, not under (as often seen) or you would have a suspension-activated rear brake!

Tornado said:

Brake cable failure can lead to very nasty crashes out on the road. There is a safety spring available from most fine Norton suppliers to prevent/reduce risk of brake lever dropping into pavement if cable fails. Bit of a Chinese puzzle to fit that spring but i'll have a look for some pics I have of it.

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Here's my previous post in older thread showing spring installed:

Post in thread 'Rear Brake lever spring' https://www.accessnorton.com/NortonCommando/rear-brake-lever-spring.27403/post-413609