another primary sound query

well today I took my bike out for a 50 mile run on country and highway roads...it's got a whopping 300 miles on it since build.....believe it or not due to the fact that I built this bike from bare frame....I have never heard or ridden a commando other than mine....the ride today was wonderful..bike runs smooth as silk strong stops and shifts gears to perfection......but...I still hear a light whirring/gnashing sound from primary side at around 3k rpm in third gear.....everything is quiet and smooth otherwise....is the primary supposed to be 'sound free?" should I just ride and forget it? I am skeered gearbox is gonna blow or primary chain (adjusted correctly) is gonna come through cases...it's a nagging thing driving me crazy like being in bed with a beautiful girl and someone revving a leaf blower outside...……….thanks fellers in advance for remarks/suggestions

alan hodge said:

well today I took my bike out for a 50 mile run on country and highway roads...it's got a whopping 300 miles on it since build.....believe it or not due to the fact that I built this bike from bare frame....I have never heard or ridden a commando other than mine....the ride today was wonderful..bike runs smooth as silk strong stops and shifts gears to perfection......but...I still hear a light whirring/gnashing sound from primary side at around 3k rpm in third gear.....everything is quiet and smooth otherwise....is the primary supposed to be 'sound free?" should I just ride and forget it? I am skeered gearbox is gonna blow or primary chain (adjusted correctly) is gonna come through cases...it's a nagging thing driving me crazy like being in bed with a beautiful girl and someone revving a leaf blower outside...……….thanks fellers in advance for remarks/suggestions

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Accompanied by an extra vibration?

“it's got a whopping 300 miles on it since build”

Total ever?
Completely rebuilt? Engine? Trans? Primary?

no vibration at 60mph perfectly smooth no noise except in 3rd at about 3k rpm ... 300 miles total since build from rusted frame up ….gearbox was sold to me as 'rebuilt' primary parts sold to me as from "low miles bike converted to belt'....

How do you know bout the leaf blower thing ... take a good look inside primary look for marks that give you an idea what happening

Don't take people's word for anything they sell is rebuilt, as for sounds can travel where you think its coming from could be coming from somewhere else and if its only doing it in 3rd gear I be looking at gear box, 3rd gear could have lost its hardening, its not a big job pulling the outer and inner cover off the gearbox to inspect same as the primary cover, even draining the oil will tell if there is any problems, look for any metal in the oil be my first step.

Ashley

Ashman my thoughts exactly about draining oil looking for shiny will do this week....craig ringing phones and barking dogs in same category...Ashman gearbox had new gaskets on inner and outer cover...craig no marks inside cover

There is a magnetic gearbox drain plug you can get from Andover or RGM that might be a good check too.

I have just been through the same exercise but with a whine in first and second. Turns out both gear sets were through the hardening.

If your in there check the layshaft bearing. Search the forum for info on that.

i guess i am worried about a catastrophic failure that lock the rear wheel and kill me... worse case scenario who can rebuild box and about how many $$?

Philip Myles .... took my gear box apart , phoned my order into Walridge motors and did the rebuild , he didn't like to charge me but thought $20 per hr was fair so $100 and we were squared up .... he is 80-81 now and have only talked with his son lately and that was this time last year ... no doubt you can find someone closer , plus have read that it is doable with video instruction ....

alan hodge said:

i guess i am worried about a catastrophic failure that lock the rear wheel and kill me... worse case scenario who can rebuild box and about how many $$?

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Don’t default to rebuild, simply replace the layshaft bearing, and while it’s open inspect for excessive wear. It may be just fine as it is, with a pre-emptive layshaft bearing.

alan hodge said:

i guess i am worried about a catastrophic failure that lock the rear wheel and kill me... worse case scenario who can rebuild box and about how many $$?

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Not that I want to fuel your fears Alan, but you’re right! If any other part of the eng / trans fails, the rider can whip in the clutch and immediately isolate the rear wheel from the issue, and hopefully coast to safety.

If the gearbox itself locks, so does your back wheel, and there’s nothing you can do about it.

But before you panic completely, do you have a local-ish Norton person who could lend you their ear to listen to the offending noise ?

hah! I am only commando owner I know of in these parts! this is Harley Cuntry!! noise-wise..my 68 BSA A65 made funky rattling sound from primary side for 4,000 miles since I built it from bare frame..worried me to death...but..last few times I rode noise from that buzz bomb went away...…britbikes and sounds..sheesh!...I think what I do is drain gearbox oil (Redline Heavy) and look for metal and maybe drag magnet through the drained oil and if no particles ride bike til fall (of year) and take gearbox out and have it done the 'right way' it was sold to me as having been 'gone through with any parts that needed replacing replaced" (but kickstart pawl still 'clunks' once in a while) sound is only at one RPM range and gear could be harmonic vibe from something else but hard to put ear to engine at 60mph…actually the sound is not all that loud but I am atuned to every nuance as I get used to this machine....bike runs go good it makes me wanna bust out cryin ..my BSA and 72 Bonneville and 75 Yamaha XS650 sit in garage sulking......

Not knowing your bike the sound could be just normal for your bike if it does it at one rev range and only in one gear, if it was the lay shaft bearing it would have exploded a long time ago, with that infamous bearing they didn't servive long life, but like I have said before its not hard to pull the outer and inner case off for inspection, and rebuilding it is not a hard job, if you intend in having this bike for a long time what better way to get to know your bike.
When my lay shaft bearing blew way back in 79 I had no idea in how to rebuild my GB but I did it and its still going to this day only replacing the kick start pawl 4 times and kick start gear in all that time since, I have rebuild 4 Norton GBs since for others.
You never learn about your bike if you don't give it a try, my Norton was the first bike I ever completely rebuilt when I convered it to the Featherbed frame back in the early 80s, I know every bolt and every part on my bike, if something failed I just hop straight into it and fix it and doing it yourself you know its been done right.
But as you have said yourself everything is running smooth, gears are changing nicely, do the oil check etc and not being use to your Norton it may just be a Norton noise.

Ashley

ashman...for sure I know 99% of the parts on this bike having started as I said with a bare, rusted frame....but never slept with a living breathing commando so am not familiar with 'sounds' normal and abnormal...

alan i am in NE Tn near bristol if you need help and are close by let me know.

All good Alan as its taken me over 40 years to get use to all of my Norton noises lol.

came home from work and even though it's hotter than 40 hells in the garage I drained the gearbox oil into a large tin foil turkey basking pan,,this let the oil (Redline Shockproof Heavy) spread out thinly...I went out into the sun and swirled the oil around like panning for gold...not a sign of any metal whatsoever...I ran my fingers through the oil and looked at them in bright sunlight...no shiny whatsoever...….I checked primary oil level (ATF) it has not changed..it looks red no corn-tamination of any type I can see......only oil on bottom of bike is from drive chain and some from where I so carefully filled the swingarm tube and some seeped out...….oh, kickstart lever does not move when in flight.....I am going to ride it as is and if nothing changes live with the sound until winter arrives...……..it's not very loud but I am looking for perfection here...…..unrealistically?

To have perfection on a bike that is over 40 years old could be a bit unrealistice unless everything on the bike has been replaced with new, or if its going to sit in a display case and not be ridden, finding no metal in your oil is a good sign, I would just accept the fact its just another light noise, if it was a scraping or grinding or clunking noise then that would be a different thing, if the bike is running good, no vibrations and running smoothly etc etc then just ride it and enjoy it for what it is and the low noise might not even becoming from where you think its coming from, just do your maintenance on it when its needed and listen if the sound of the noise changes with more miles put on it, if things have been replaced its all got to bed in, if you worry about anything that might happen to your bike then you might as well stay home.
Now get out and enjoy your bike.

Ashley

Ashman...…..roger that! every mile I have put on it so far has been a thrill!