Blown Con Rod

Tintin said:

Dances with Shrapnel said:

As for con rod bolts, there goes part of my arguement. The source was actually Andover See:
http://www.andover-norton.co.uk/Pirate%20Parts.htm

Click to expand...

Which evokes the next question: If Les replaces D-rods - what kind of conrod bolts does he use? "Pirate" or "Genuine"?



Tim

Click to expand...

Hmmm, is this what the whole bit in this thread is about vendor accusations countering against vendor accusation. When reading the different vendor cautionnary statements I pay attention. The Andover explanation and illustrations on rod bolts make sense where as what Norvil is asserting does give me concern but the technical explanation is at best, unclear.

As you say, anybody have a "D" rod they can look at evidence of the "match line" or evidence of a double strike forging process?

I like GrandPaul's suggestion about hearing from any others who have had bad experiences with the "D" rod.

Dances with Shrapnel said:

Which evokes the next question: If Les replaces D-rods - what kind of conrod bolts does he use? "Pirate" or "Genuine"?

Click to expand...

Hmmm, is this what the whole bit in this thread is about vendor accusations countering against vendor accusation.

Click to expand...

Click to expand...

Hm, not for me. The reason for my latest statement was that it would be very interesting to know whether Norvil - claiming inferiority of some stock parts based on "questionable explanations" (to put it politely - uses Andover rod bolts every time the replace these rods. The explanation given by Andover on these bolts - forged, ground and rolled as opposed to machined from bar stock - is fully acceptable to me as an engineer. The Norvil stuff is not.

So in my opinion if Norvil is so keen on this D-rod stuff AND if they'd use inferior bolts they would actually be shooting themselves in both feet with a Gatling. If! I'm not saying they are but a clarification of this question would shed a lot of light on their D-rod statement.


Tim

EDIT: Quoting repaired.

Dances with Shrapnel said:

Tintin said:

Dances with Shrapnel said:

As for con rod bolts, there goes part of my arguement. The source was actually Andover See:
http://www.andover-norton.co.uk/Pirate%20Parts.htm

Click to expand...

Which evokes the next question: If Les replaces D-rods - what kind of conrod bolts does he use? "Pirate" or "Genuine"?



Tim

Click to expand...

Hmmm, is this what the whole bit in this thread is about vendor accusations countering against vendor accusation. When reading the different vendor cautionnary statements I pay attention. The Andover explanation and illustrations on rod bolts make sense where as what Norvil is asserting does give me concern but the technical explanation is at best, unclear.

As you say, anybody have a "D" rod they can look at evidence of the "match line" or evidence of a double strike forging process?

I like GrandPaul's suggestion about hearing from any others who have had bad experiences with the "D" rod.

Click to expand...

I just found this thread and thought I would throw my .02 cents in.
In 2007 I finally realized my dream of owning a Norton. I am 53 years old, soon to be 54 and hhave read about Nortons in bike magazines since junior high school.
I bought a very tired and worn out one owner Mark III with about 28,000 miles on it. Most everything was worn out or tired so I startyed replacing swing arm bushings wheel bearings etc. The engine seemed to be fine with good compression. While sorting out carb issues on the work lift I heard a rapping noise start. I immediately shut it down and decided to tear the engine down.
When I got to the rod bearings I found that one of the rod bolt nuts had backed off and loosened the rod to where it started knocking. Lucky for me I had shut it down just to the point where the big end had just started to come in contact with the bottom of the engine case. Yes it was a "D"
rod but it looked to be the rod bolt itself that failed...or didn't have the prpper torque from the factory.

Had this happened while on the road, the results would have been catastrophic.

Tintin said:

Dances with Shrapnel said:

Which evokes the next question: If Les replaces D-rods - what kind of conrod bolts does he use? "Pirate" or "Genuine"?

Click to expand...

Hmmm, is this what the whole bit in this thread is about vendor accusations countering against vendor accusation.

Click to expand...

Click to expand...

Hm, not for me. The reason for my latest statement was that it would be very interesting to know whether Norvil - claiming inferiority of some stock parts based on "questionable explanations" (to put it politely - uses Andover rod bolts every time the replace these rods. The explanation given by Andover on these bolts - forged, ground and rolled as opposed to machined from bar stock - is fully acceptable to me as an engineer. The Norvil stuff is not.

So in my opinion if Norvil is so keen on this D-rod stuff AND if they'd use inferior bolts they would actually be shooting themselves in both feet with a Gatling. If! I'm not saying they are but a clarification of this question would shed a lot of light on their D-rod statement.


Tim

EDIT: Quoting repaired.

Click to expand...

Agreed on all points except the bit about the use of inferior rod bolts. The evidence Norvil presents with the one exploded view the engine case, rod and cap shows the big end cap intact. If it were a rod bolt there would be carnage shown. Interesting to note that the small end has a vertical crack through the bottom of the wrist pin hole. This is the type of failure Steve Maney describes when using stock rods with a 1,007cc engine and +95HP.

In the 1970's I ran a Drouin supercharger on my 1974 850 Commando and 10.25:1 Omega piston (don't ask why) with 10psig boost for some time and there was no visible signs of distress and no engine component failures though the gear box protested repeatedly. I can't imagine a good Commando rod breaking without some extenuating circumstance (spun bearing, bad bolt, poor assemebly etc). To me this seems to support what Norvil is presenting.

Again, I am also not satisfied with their explanation but believe that there may be a potential flaw with the "D" rods.

Loose from day one :?: carn't see it lasting 28k. Guessing someone else [PO]had left it so.

john robert bould said:

Loose from day one :?: carn't see it lasting 28k. Guessing someone else [PO]had left it so.

Click to expand...

Could be, I really don't know if the PO had the engine apart.

dirtymartini said:

I just found this thread and thought I would throw my .02 cents in.
In 2007 I finally realized my dream of owning a Norton. I am 53 years old, soon to be 54 and hhave read about Nortons in bike magazines since junior high school.
I bought a very tired and worn out one owner Mark III with about 28,000 miles on it. Most everything was worn out or tired so I startyed replacing swing arm bushings wheel bearings etc. The engine seemed to be fine with good compression. While sorting out carb issues on the work lift I heard a rapping noise start. I immediately shut it down and decided to tear the engine down.
When I got to the rod bearings I found that one of the rod bolt nuts had backed off and loosened the rod to where it started knocking. Lucky for me I had shut it down just to the point where the big end had just started to come in contact with the bottom of the engine case. Yes it was a "D"
rod but it looked to be the rod bolt itself that failed...or didn't have the prpper torque from the factory.

Had this happened while on the road, the results would have been catastrophic.

Click to expand...

Good stuff and thanks for sharing. I doubt the pirated or inferior bolts were going into the factory assembled bikes as I get the impression from the Andover article that this is a relatively new problem.

A couple of questions:
Was it opened up and serviced by a PO?
Was the bolt broken or did the nut just become loose?

I have a D rod with 12k miles on it. Can't see any marks 3/4 inch down from the little end, but there are marks that have been polished about 1/2 way along. I'm willing to send the rod to someone who can have it xrayed or similar to satisfy my own interest. Graeme

Dances with Shrapnel said:

Agreed on all points except the bit about the use of inferior rod bolts.

Click to expand...

Just to be precise: I'm not saying they don't use AN bolts. I'd just be interested in what they use when replacing D-rods. IF the answer would be e.g. non-D- stock rods but new non-AN bolts (machined from solid) I would seriously question everything about their rebuilds and comments on engine building.

I'm throwing things together here because I'd like to see what Les E.'s opinion about the con-rod BOLT problem is as he has an opinion about a potential/debatable con-rod problem.

The evidence Norvil presents with the one exploded view the engine case, rod and cap shows the big end cap intact.

Click to expand...

The way I understand these pics and the comments is that they only represent the potential result of a con-rod failure - not necessarily a D-rod failure. One example shows a Commando-in-Featherbed. Nobody really knows what was in there and failed for whatever reason.



Tim

Tintin said:

Dances with Shrapnel said:

As for con rod bolts, there goes part of my arguement. The source was actually Andover See:
http://www.andover-norton.co.uk/Pirate%20Parts.htm

Click to expand...

Which evokes the next question: If Les replaces D-rods - what kind of conrod bolts does he use? "Pirate" or "Genuine"?



Tim

Click to expand...

I don't know what sort of rod bolts Norvill use when doing a rebuild but I had ordered new bolts & nuts through them before finding Andover's article on Pirate parts.
When my package arrived from Norvill it contained the pirated conrod bolts which are still in their packet unused.
I elected to use the original bolts with new nuts not being prepared to risk the dodgey bolts...

Dances with Shrapnel said:

dirtymartini said:

I just found this thread and thought I would throw my .02 cents in.
In 2007 I finally realized my dream of owning a Norton. I am 53 years old, soon to be 54 and hhave read about Nortons in bike magazines since junior high school.
I bought a very tired and worn out one owner Mark III with about 28,000 miles on it. Most everything was worn out or tired so I startyed replacing swing arm bushings wheel bearings etc. The engine seemed to be fine with good compression. While sorting out carb issues on the work lift I heard a rapping noise start. I immediately shut it down and decided to tear the engine down.
When I got to the rod bearings I found that one of the rod bolt nuts had backed off and loosened the rod to where it started knocking. Lucky for me I had shut it down just to the point where the big end had just started to come in contact with the bottom of the engine case. Yes it was a "D"
rod but it looked to be the rod bolt itself that failed...or didn't have the prpper torque from the factory.

Had this happened while on the road, the results would have been catastrophic.

Click to expand...

Good stuff and thanks for sharing. I doubt the pirated or inferior bolts were going into the factory assembled bikes as I get the impression from the Andover article that this is a relatively new problem.

A couple of questions:
Was it opened up and serviced by a PO?
Was the bolt broken or did the nut just become loose?

Click to expand...

Not sure what the PO did if anything but ride the wheels off it. I seroiusly doubt the PO opened up the engine considering the neglect I found on the rest of the bike.

The con rod nut had actually come off and had wedged itself in between the crank journal and the engine case :shock:

Sweenz said:

When my package arrived from Norvill it contained the pirated conrod bolts which are still in their packet unused.

Click to expand...

So as a matter of fact an engine builder who claims there are problems with one part sells other parts which will definitely weaken the crank train a lot (under the assumption that the AN claims are correct which I believe they are).

Thumbs up, that is really cinema at its best. :roll:



Tim

Tintin,
If you want to do a test, and have the means to perform a test in the company you work in, I will happily send you a bolt each (genuine and pirate) to do tests on. Stretch them to breaking point and see where each one lets go. If the cut thread on the pattern bolt lasts, that is.
Joe

ZFD said:

Tintin,
If you want to do a test, and have the means to perform a test in the company you work in, I will happily send you a bolt each (genuine and pirate) to do tests on. Stretch them to breaking point and see where each one lets go. If the cut thread on the pattern bolt lasts, that is.
Joe

Click to expand...

Although breaking things in a lab may be fun to do, not necessary in this case as the method of manufacture is evident in the pictures and is inappropriate for the application.

It would be interesting to quantify and compare the bolt strengths but you should be using more than one pair of samples so you are not running on a one data point estimate.

It would be much more interesting and worthwhile to get more information on "D" con rods; what failures have others exeperienced. Pictures of alleged die marks, more documentation of rod failure (not bolt failure nor lack of lube failure etc).

I downloaded the pictures from the Norvil tech note on the alleged "D" rod failures and zoomed in on them; they show one complete and intact "D" rod with no sign of a die mark, one picture of a Norton crankcase in frame with a hole in it and one picture of a broken engine case in pieces with a broken rod with no indication of what rod it was (middle section missing).

I'm a little late to this thread, but I thought I'd pass on my experiences with Norton rods. I raced a number of 750 and 920 engines with stock rods over a period of a couple decades, and never had a failure of the standard Commando rod. On the other hand, part of the reason is that I always had the rods and bolts inspected when the engines were torn down, having the alloy section Zyglo tested, and the cap and bolts Magnaflux tested. I did find two rods that would have failed if I had kept using them. Both had a web of cracks developing in the pin end and the rod just below the pin. I also re-used the rod bolts after inspection, as well as re-using the nuts with the addition of red Locktite thread locking compound. I don't say that is the best practice, just that it's what I did.

The only Norton rod I had break in use was one of the original steel short stroke rods. It came apart during practice at one of the AHRMA races at Steamboat Springs in Colorado. It broke through the beam section of the rod, leaving the big end firmly attached to the crank, and the pin end still in the piston, and totally destroying the cases as it bashed around. I later learned that this was not an uncommon failure for these rods. To be fair, this particular engine came out of a factory flat track bike and had probably been well abused before I put it in a road racer.

Ken

Dances with Shrapnel said:

ZFD said:

It would be much more interesting and worthwhile to get more information on "D" con rods...

Click to expand...

Click to expand...

Maybe I can have some of them killed on the universal tester as well .... :twisted:

I generally second your request for multiple points of support but I'd still be interested in when these bolts fail. Pulling one of each apart will at least give a tendency.


Tim

Tintin said:

Dances with Shrapnel said:

ZFD said:

It would be much more interesting and worthwhile to get more information on "D" con rods...

Click to expand...

Click to expand...

Maybe I can have some of them killed on the universal tester as well .... :twisted:

I generally second your request for multiple points of support but I'd still be interested in when these bolts fail. Pulling one of each apart will at least give a tendency.


Tim

Click to expand...

A universal tester will only indicate so much. What is really needed (especially in the case of the "D" rods) is a durability or endurance test where the component (bolt, rod or whatever) is subject to load reversals millions of times.

As an example scenario, a Norton twin with 30K miles on it at say 60mph and 4,500 rpm will cycle the rods through 360 degrees of rotation 135,000,000 times or 67,500,000 combustions on each cylinder.

A straight universal testing machine may indicate a difference in yield and ultimate strength between two different methods of manufacture but I believe the big contrast will be with an endurance (durability test) where cut threads and machined surfaces of the pirated bolts will be at a distinct disadvantage when compared to OEM bolts which appear to be forged, ground and rolled threads. We are talking about material fracture mechanics.

Same with the connecting rods if what Norvil claims is accurate (at least the premature breakage phenomena) a straight universal testing machine may show little to no difference whereas cycling the rods through millions of load reversals will show a difference if there's a significant manufacturing difference.

If you want a cheap, quick and dirty equivalent to a Universal Tester, get an old connecting rod, put it in a vice, clean, moly lubricate and install the bolt and nut you want to test and over torque away. You could get more analytical by plotting torque versus angular displacement to get a sense of yield strength. Unfortunately this will not necessarily indicate how durable the bolt is.

Dances with Shrapnel said:

A universal tester will only indicate so much. What is really needed (especially in the case of the "D" rods) is a durability or endurance test where the component (bolt, rod or whatever) is subject to load reversals millions of times.

Click to expand...

No problem. Who pays the bill? :wink: Honestly, do you want such a test in a climate chamber? Varying loads? Or in a single cylinder test engine? That is all feasible - if the mental state and wallet allow. I stick with the uni tester for this test as ...

A straight universal testing machine may indicate a difference in yield and ultimate strength between two different methods of manufacture but I believe the big contrast will be with an endurance (durability test) where cut threads and machined surfaces of the pirated bolts will be at a distinct disadvantage when compared to OEM bolts which appear to be forged, ground and rolled threads.

Click to expand...

... I'd strongly expect a drastic difference in simple yield strength as tested by the universal tester and that is what I'm looking for as an indicator. I wouldn't be suprised if the "pirate" bolt would actually be overloaded from the beginning and that we don't even need to talk about durability. From hearsay [sic] it appears that these bolts give up way before the load levels even a normal road going engine usually could stand.

Regarding the conrod I'd agree that a universal tester would not really deliver anything meaningful.


Tim

Tintin said:

Dances with Shrapnel said:

A universal tester will only indicate so much. What is really needed (especially in the case of the "D" rods) is a durability or endurance test where the component (bolt, rod or whatever) is subject to load reversals millions of times.

Click to expand...

No problem. Who pays the bill? :wink: Honestly, do you want such a test in a climate chamber? Varying loads? Or in a single cylinder test engine? That is all feasible - if the mental state and wallet allow. I stick with the uni tester for this test as ...

A straight universal testing machine may indicate a difference in yield and ultimate strength between two different methods of manufacture but I believe the big contrast will be with an endurance (durability test) where cut threads and machined surfaces of the pirated bolts will be at a distinct disadvantage when compared to OEM bolts which appear to be forged, ground and rolled threads.

Click to expand...

... I'd strongly expect a drastic difference in simple yield strength as tested by the universal tester and that is what I'm looking for as an indicator. I wouldn't be suprised if the "pirate" bolt would actually be overloaded from the beginning and that we don't even need to talk about durability. From hearsay [sic] it appears that these bolts give up way before the load levels even a normal road going engine usually could stand.

Regarding the conrod I'd agree that a universal tester would not really deliver anything meaningful.


Tim

Click to expand...

"That is all feasible - if the mental state and wallet allow." :lol:

For clarity, what we are talking about is "plastic yield", otherwise both the OEM bolt and pirated bolt should respond more or less identically to load in the elastic range.

Plastic yield strength is primarily a function of material property and cross sectional area. Plastic yield stress is primarily a function of material property. I would expect some lower (not necessarily drastic) plastic yield strength of the inferior bolt due to inappropriate manufacture, maybe 5-10% reduction. I would expect to see a drastic (maybe one half an order of magnitude) in the bolts durability (endurance). This has to do with fracture mechanics and differences between the OEM and inferior bolts surface conditions as a result different manufacture.

The torque test I outlined in an earlier post, say 3 OEM bolts and 3 pirated bolts, torqued to plastic yield and then torqued to rupture is as simple and easy as it gets for testing your hypothesis.