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Norton NOS Big End trouble

Anyone know if there were any dodgy NOS Norton big ends around about twenty years or so ago. I fitted a NOS bearing to my 51 ES2 in the early 90s expecting it to see me out but while out for a pre- lockdown ride a couple of Sundays ago the bike started to knock badly on acceleration and overrun but was OK under light load, classic BE symptom, I rode home very slowly, the knock getting rapidly worse, and stripped the top end off that night. About 25 thou up and down in the BE.I checked the oil feed quill and the seal between the oil pump and timing cover, both fine, and the pump seemed fine with a healthy return to the tank. I pumped oil from a pressure feed can down the mainshaft and oil exuded round the bottom of the rod so no blockage here. I've never had a roller big end go so quickly like this before, its done about ten thousand miles since I fitted it and I use agood SAE 40 straight oil,I wonder if the crank pin was not correctly hardened, the bearing was a R&M and in its original packing but I can't remember where it came from, probably some garage clearance or other Has anyone else had trouble with a NOS big end?
Best Wishes
Tony

Re: Norton NOS Big End trouble

The only time I've known of a NOS big end to fail at very low miles was in a BSA B33...I fitted a NOS big end to the crank for someone and less than ten thousand miles later it failed....The bloke got a bit depressed about it as he'd had other problems with the bike and I ended up buying it off him..

When I stripped the engine I found evidence of bead blasting grit contamination in various places and I believe that had caused it...I rebuilt the engine and had no further problems, eventually selling the bike to my brother in law and it ran on for years, never having another big end...

I've run BSA 'B'and'M' series singles for over 40 years, multiple examples of both types, both tuned (frequently very) and standard over hundreds of thousands of miles and have yet to experience a big end failure myself...It's one of the reasons I settled on these models for daily use...

Of the many engines that have passed through my hands some have had that problem but they either showed signs of poor assembly or inadequate oil changes over extended periods of time. (not to say that's the case with yours Tony!)....

I'm not really conversant with possible variations in Norton quality control but have found generally over the years with the products of most manufacturers that they were reasonable....However, a 'duffer' is always possible...!!..

I assume the big end assembly was not too close a fit after assembly?...That can lead to rapid failure...Ian

email (option): ian@wright52.plus.com

Re: Norton NOS Big End trouble

Not that I think it helps your query Tony, but there was a period of AMC crank pin failures. Someone decided that the original 2 part pressed together pin could be machined in one piece. The resultant sharp corner in the step between the two radius's created a fracture point which resulted in numerous failures and ruined engines. The cure was to machine the pin with a radius in the corner and form a corresponding radius in the flywheels......But better to fit a two piece pin :disappointed: Ron

email (option): ronpier@talk21.com

Re: Norton NOS Big End trouble

My pals Matchless 500 decided to do it about 5 miles up the road from the Isle of Skye on a month long tour..A bit bloody inconvenient as we had ridden up from West Devon...:laughing:

He had a long drive home with the recovery truck and I finished the (solo) lap of the Highlands and Islands before heading south again...Ian

email (option): ian@wright52.plus.com

Re: Norton NOS Big End trouble

I've run Matchless singles for probably close on 50 years and the only bigend trouble was when rebuilding a very worn out G80. The club scheme supplied replacement was 0.001" too large on the OD resulting in the bearing tightening up on assembly. If you were unaware of this the bearing would have failed, so yes there certainly were some duff bigends about maybe 20 years ago. I checked the size and fit in another rod with the same result and the spares scheme was particularly unhelpful. Fortunately I had the facilities and the skill to grind that thou. off and it's been in the bike ever since and has given no trouble over many thousands of miles so the rest of it must be OK.
I can only suggest that you check EVERYTHING when rebuilding old bikes.
Richard

email (option): richard177smith@btinternet.com

Re: Norton NOS Big End trouble

['I can only suggest that you check EVERYTHING when rebuilding old bikes...'] ...

Absolutely, I learnt the lesson a long time back, to my cost, that because something is new it won't necessarily be correct....

As a very experienced fitter said to me when I was still in my teens...'These old bikes can't just be put together, they have to be fitted together'...Very true words...

Again though, I must say I'm making this comment as a general one and not to cast asparagus on Tony's abilities about which I know nothing...

There were some problems with the Matchless 'one piece' after market big ends for a while...I personally know of two that broke as described by Ron and at the time it was an accepted observation that there was a problem...Thus the change made to the specification...Ian:relaxed:

email (option): ian@wright52.plus.com

Re: Norton NOS Big End trouble

"Asparagus" Ian? Shouldn't that be "Nasturtiums"....I just don't want to get Embroidered into this! Ron:smile:

email (option): ronpier@talk21.com

Re: Norton NOS Big End trouble

Sorry, I meant Aspidistras...Please accept my sincere apostrophies...Ian:laughing:

email (option): ian@wright52.plus.com

Re: Norton NOS Big End trouble

Thanks everyone for your input, Ron, with your experience of NOS I was hoping that you were going to tell me that there was a known batch of faulty big ends that had found their way out of the back door and had to be avoided,. but maybe I was just unlucky. What has surprised me is that the BE went so quickly, in the space of about thirty miles, after covering around ten thousand without any warning of trouble,
I guess the hardening must have failed, I'll post a pic of the pin when I strip it out of the flywheels which may not be anytime soon
I've known the bike for over fifty years and owned it nearly twenty so I know it has never had any engine parts blasted and although it was a long time since I fitted the big end I know I would have made sure it was not tight, checking that the rod falls freely under its own weight after tightening the crankpin nuts. As I said the new big end was a Ransome and Marles in its original packaging, may well have been ex WD, and not of some latter day unknown manufacture, so I would have expected top quality.

PS. Ian, the Butler lamp arrived safely, thank you.
Best wishes, Tony

Re: Norton NOS Big End trouble

I believe it was generally accepted that most generations of Alpha pins for Norton didn't have sufficient depth of hardening to allow them to be ground and used with oversize rollers which was possible with original. I don't recall that they failed catastrophically at low mileages though.

All the ex-WD stock Norton pins and bearings that I've seen have been tied together as matched pairs and were branded 'Hoffmann'.

R&M bearings would date from before the merger to form RHP but I'm not sure that they were ever OE with Norton.

If a jumbler had put unmatched pins and bearings together, it wouldn't help...Poor storage could be a problem too although the big end can be inspected quite well before installation.

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