Connecting rods differences (2013)

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pierodn

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Please,
what are the differences from two connecting rods with each numbers below:
- 23258 R1R1;
- NM 23258 R8R.
Thanks.
Ciao.
Piero
 
Show us a pic ?

No-ones had a chance to look in their motor yet....
 
pierodn said:
what are the differences from two connecting rods with each numbers below:
- 23258 R1R1;
- NM 23258 R8R.
Click to expand...

Commando conrods often have different combinations of "R" letters and numbers.

Presumably it's a forging die or batch number of some description?
 
There's a two part rod denoted by a D, that came online in 850 era that make some pensive but there's no rash of reports or even a single one of any factory Norton rod as the cause of a failure, unless it was a production error or damaged prior. They are over built enough there is no fatigue limit on any engine up to 8000 rpm 150 hp such as the famous reliable Hog Slayer had. I'm sure someone could build at engine to break Norton rods but by that points it ain't got anything else really Norton left.
 
Wasn't the so-called D rod some clowns misinterpretation of forging joint lines ????

Ie a an alloy forging has to have a parting line where the 2 parts of the steel mould will meet, when a vast number of tons of force are used to stamp out the shape of the part.

Can recall seeing a 100 ton forge stamping out steel railway parts.
When the throttle was opened hard on that thing and the full 100 tons used, you could feel it in your liver.....
 
I offer the following and make no comment either way other than to observe I have not seen or heard of a rash of rod failures in machines in normal street use.

Les Emery. Tech talk. D rods be gone.

http://www.norvilmotorcycle.co.uk/

I do replace the alloy rods in my race bike about every five years.

John
 
Thats where the story gets a little bit murky - this was discussed here a while back, no-one else has seen a rash of rod failures either.

No-one has experienced a fatigue life failure either - although I stand to be corrected on this comment.

Is there a quoted theoretical life for these. ?
5 years could be ten races - or a thundred and ten races ??
Or 50,000 miles of 'average' road use.
 
" 5 years could be ten races - or a thundred and ten races ?? "


Around 150 races. But actually not much in hours. Less than 50 hours racing at 7500 rpm.

But I am a very conservative engine builder and for me the price of the rods is cheap compared to the mess they would make if they broke. The last time I was fully concentrating on racing we did over 100 races without a single DNF and I was pleased with that record.

The first set of rods were Dave Nourish, since then Thunder Engineering in the UK which were recomended by Nourish when he did not have any of his own.

When I start back again I will be looking very hard at the package offered by Jim Schmitz.

My road bike - a 1974 Mk 11 Roadster has the same rods that it came with in 1974. But if Im ever inside it again I may change them. But only because after 40 years of working I'm finally at a point where I can treat myself and spend a bit here and there as a present to myself :) An indulgance for an old man !!
 
In practice, attempting to run stock-ish Commandos at 8,000 RPM for more than a second or two under load will almost certainly result in ventilated crankcases.

Maybe the RODS can handle it, but the CRANK can't.
 
Road test reports of Commandos when they were new frequently refer to the fact they will willingly rev to 8000 rpm (plus !), a fact which was said to contribute significantly to short main bearing life.

The factory reportedly used stock cranks for racing, for some years, before deficiencies became apparent.
So from all reports, crank problems are fatigue life based - so many zillions of cycles etc... ??
Piston speed is more likely to be short term rpm limiting factor, unless they are good ?

Unless GP has personally destruction-tested any Commandos, perhaps we should take this statement as being hypothetical only ??
 
Wasn't there also some discussion about dodgy con-rod bolts from one of the suppliers ?
Could this be related to "con-rod" failures...
 
So from all reports, crank problems are fatigue life based - so many zillions of cycles etc... ??
Click to expand...

After my 1st valve float event halfway along passing a semi, i began asking everyone what breaks first. The cast iron flywheel is a known fatgue fracture hazard lurking to explode even w/o being wrung out. The most dramatic example was posted on NOC or BI list of 850 idle in drive before leaving sent most of flywheel out front of case across street off car through picture window then a few layers of sheet rock.
 
Rohan said:
Can recall seeing a 100 ton forge stamping out steel railway parts.
When the throttle was opened hard on that thing and the full 100 tons used, you could feel it in your liver.....
Click to expand...
Rohan:: yeah I know. u hafta experience it to appreciate the environment. bit scary first time
bradley
 
in my other life,our factory had a davey forging press making gun barrels, mill rolls, and ships crankshafts. you get used to the big stuff. have you seen a sulzer engine doing 350 rpm? you can feel it in your bones.
 
This kinda talk reminds me of the scene in the film Titanic where the chief engineer waits for the crank to stop at tdc then throws it into reverse and you see that row of 14' con rods change direction as the crank starts spinning in reverse. What a powerful scene!

Getting back on topic there are rods with the oil hole drilled out the side to lube the bottom of the pistons and cylinder walls and the older rods without the holes drilled.
 
Newer rods don't have the holes either ?

Weren't they found to be not necessary ?
The problems were found to be in the pistons manufacture, not in the lubrication ??
 
I'm just sayin - that could explain different part #'s and yes, most guys just used older bearings that weren't drilled or reversed the shells so the drill opening was in the cap. Mind you, you still had a hole in your rod but that never seemed to be a weak point.
 
yep the oil holes are more than unneeded they take some oil protection away from the shells. Standard race practice to install shells to block hole. Its takes a Whole Whole lot more oil than the couple of spritz a cycle to cool a piston so only good for pin lube which was never the issue anyway. Like the little nubbins half way up a horse's leg, evolutionary remains of a unless feature.
 
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