E: Engine Are Alloy Idlers a Problem?

[Generic Beardy]

Thanks for the informative replies chaps. So steel idler sounds a good investment at some point. Noted.
The gearbox cover has just been off as the grease was rock solid. I haven't fitted the new gasket yet so it's "loosely assembled" at present.

 

[chankly bore]

You probably know this, but the two free-running gears on the layshaft are lubricated by cross-drillings 1/8" in diameter. Make sure that grease is cleared from these. They run on phosphor- bronze bushes, but the top hat bushes on the ends of the layshaft and the sleeve gear bushes MUST be self- lubricating "OILITE" or similar. I did once have the temerity to ask P.E.I. why he didn't consider helical cut timing gears given that Velocettes were commendably quiet. He replied that side thrusts were a problem in this application.

 

[Generic Beardy]

I am planning on going through the gearbox as it was solid. A bit of heat had it all melting out but I wouldn't trust it without a thorough clean. I must admit I was surprised at how huge everything was in the timing chest compared to a Velo. Definitely a different approach!

 

[robert shennan]

I had a very short sharp lesson on a large alloy idlers when it shed about 2 inches of teeth as I approached Hermiston gate roundabout on the outside lane of the Edinbrugh bypass, big bang and no power in torrential rain. The modest cost of a steel idler is money that I wish I had the knowledge to invest in advance - oh well every day a school day

 

[highbury731]

You probably know this, but the two free-running gears on the layshaft are lubricated by cross-drillings 1/8" in diameter. Make sure that grease is cleared from these. They run on phosphor- bronze bushes, but the top hat bushes on the ends of the layshaft and the sleeve gear bushes MUST be self- lubricating "OILITE" or similar. I did once have the temerity to ask P.E.I. why he didn't consider helical cut timing gears given that Velocettes were commendably quiet. He replied that side thrusts were a problem in this application.

I can imagine the side thrust of helical pinions pulling the timing spindles out of the crank cases.

 

[clevtrev]

Yes, and a related "cause or effect" problem is the original alloy/steel Idler Gear Shaft assembly, ET51/1. After 70 years the originals are untrustworthy and Loctite is not a cure in my opinion. A one- or two-piece all steel replacement is available. Now a couple of small details: The H.T. lead should be 28 1/2" long and go around the back of the head as per engine photos in "Richardson", your gear position indicator looks a little close to the gear lever- it should never touch, as it prevents top gear from fully engaging and that can be noisy and expensive. Saying that, you're lucky to have a good unmolested engine, mate. The A.T.D. gear must have at least .008" backlash.

You can put a spirol pin in the the body and the shaft.

 

[Martin Conachey]

I would change them to steel. A few years ago i saw that my then Comet had alloy idlers, Take out your oil filter it’s likely to have alloy shavings, if so. You might have bigger issues. Alloy and Steel are not good bedfellows

 

[Generic Beardy]

I would change them to steel. A few years ago i saw that my then Comet had alloy idlers, Take out your oil filter it’s likely to have alloy shavings, if so. You might have bigger issues. Alloy and Steel are not good bedfellows

Oil filter was devoid of sinister bits of aluminium...... I will be fitting a steel idler when funds permit though.

 

[vibrac]

Oil filter was devoid of sinister bits of aluminium...... I will be fitting a steel idler when funds permit though.

So long as the engagement of the teeth is good and the lubrication is fine it should be OK
I think we all need to remember that back in 1965 a well used twin was worth £65 which is what I paid for mine so thats about £1000 today- just another hack -look at some 2010 bikes
and when I went racing it was a year or so before I could afford a £50 steel idler and there were not many about as demand was low ,almost cheaper to buy another bike
People using Vins as cheap everyday transport back then let the 10-15 year old alloy idler wear with poor oil changes -why wouldent they?

 

[Richard Beard]

Back in 1963 I bought a Black Shadow for 50 GBP!
One of those many "I wish I had not sold it"!