Original vs Reproduction Con Rod Nuts and Loctite

i think Greg has hit the nail on the head the Wassell bolts were only tested to quash the fact AN were at the time slagging the so called pirate products NOT FIT FOR PURPOSE on their web site

wonder what humble pie tastes like ?
 
marshg246 said:
Personally, I have no reason to doubt the workshop manual. Reuse bolts, always new nuts, and no need for thread locker. This is one place where I always use a torque wrench and clean dry threads and work up to full torque alternating between the nuts on a conrod.
Click to expand...

There are reasons to doubt.

Heads came off conrod bolts????​

www.accessnorton.com
www.accessnorton.com
 
elefantrider said:
There are reasons to doubt.

Heads came off conrod bolts????​

www.accessnorton.com
www.accessnorton.com
Click to expand...
What has heads coming off conrod bolts got to do with what I said, and whose conrod bolts were used? Were they properly torqued? Was loctite used with standard torque (over-torqued)? And so on.

I recently rebuilt a Norton engine that one conrod appears to have simply pulled apart in the middle - should all conrods, therefore, be replaced? What says that a new conrod bolt is better than an original?

I suppose in a perfect world we would magnaflux or dye check every part before using - at least for me, this is no perfect world!
 
There are plenty of other threads about quality, breakage and loose nuts. Take your pick.

That thread once contained a link to a 3 way test comparison, which has since disappeared.
Any idea where I can find?

I will still be using a little threadlocker on stock rod bolts and cranks.
 
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elefantrider said:
That thread once contained a link to a 3 way test comparison, which has since disappeared.
Any idea where I can find?
Click to expand...
https://www.totalbikebits.com/wassell/orderpoint/prod_info/CommandoBoltsTestCertificate.pdf

But as MadNorton pointed out - the wasted portion of the Wassel bolts is thicker so they are stronger, but that is not needed. In other words, the AN and Wassel bolts are both fit for purpose. The Norvil bolts are Wassel so there are really only two in the test although three are shown.
 
Wasn't there also a test that compared the repros against the original factory hardware ??

25ft lbs is adequate with or without Loctite, IMO. Reduce at your own risk, that is already not a lot of torque.
 
Just my .02 cents,

Since the bolts can be easily measured with a micrometer, tighten them using the proper bolt stretch. Then they can be assembled wet, dry or anything in between.
Also green loctite will wick in after a bolt has been tighten. If need be, assemble the bolts dry with a torque wrench and then add some green loctite if so desired.
 
Deets55 said:
Just my .02 cents,

Since the bolts can be easily measured with a micrometer, tighten them using the proper bolt stretch. Then they can be assembled wet, dry or anything in between.
Also green loctite will wick in after a bolt has been tighten. If need be, assemble the bolts dry with a torque wrench and then add some green loctite if so desired.
Click to expand...
Agreed, the factory would have measured the stretch to match the bolt makers specification and made a note of the torque required. So the torque is a derived figure and is affected by lubrication etc being different from the factory, the stretch figure give you the correct tension regardless of lube etc.
 
kommando said:
Agreed, the factory would have measured the stretch to match the bolt makers specification and made a note of the torque required. So the torque is a derived figure and is affected by lubrication etc being different from the factory, the stretch figure give you the correct tension regardless of lube etc.
Click to expand...
So, what stretch did the factory use?

Triumph published theirs (.004"-.005") before they abandoned the practice and switched to using a torque wrench. Triumph also wanted the bolts replaced when measuring but abandoned that as well when they went to torque.
 
IIRC
.0065" new bolts
.0055"-.0060" used

I thought I had them in my rebuid notes, but I can't seem to locate that number. I'm sure someone here has that info. Not factory info, probably something I got from J. Comstock.

Pete
 
The TOURQUE is a average figure for the corect ' stretch ' = TENSION .

Hence one wants to be somewhat carefull , with the whole big end .
Tolerances & fits - tickularly burrs & foreign matter .

Original vs Reproduction Con Rod Nuts and Loctite


Theres all sorts of fancy equipment freely available - at a price - these days ,
which was the providence of the master engine builders .

The Official ARP Web Site | Technical Information

arp-bolts.com arp-bolts.com

Id think un ' waisted ' bolts would be a el cheapo cop-out ,

The Rod Bolts are perhaps the most highly stressed component in the contraption ,
so the whole foofaraw there is crucial , particularly when its wound up .

Original vs Reproduction Con Rod Nuts and Loctite
Original vs Reproduction Con Rod Nuts and Loctite

Theyre for Ferrarri's , parently the mechanics now are really clumsy , and have to have really long sparkplug threads , so theres plenty left over if they cross thread them .

Original vs Reproduction Con Rod Nuts and Loctite
 
Frankie17 said:
i think Greg has hit the nail on the head the Wassell bolts were only tested to quash the fact AN were at the time slagging the so called pirate products NOT FIT FOR PURPOSE on their web site

wonder what humble pie tastes like ?
Click to expand...
Very nice in fact, it causes improvement and evolution and as Greg and some others have noticed we test regularly, some dangerous parts we find as well (two in the last 12 months) most of what we find is kept under wraps. Do not confuse being stronger as always being better, just because an item is stronger / tougher / harder does necessarily not make it fit for purpose. From through hardened gearbox pinions, gears in the timing cover that could destroy you and your bike ( I didn't see a recall from the vendor on this part either ) , fuel taps that continually pour fuel from the operating levers. We are currently looking at 3 items with quality issues, strangely not one of them is manufactured in the far east, try USA x 2 and the UK x 1, thankfully some on here know of these 3 products as well but say nothing saving the embarrassment of the manufacturers. The two items in the USA should be resolved as I am in touch with the manufacturers and the UK item is beyond help.
 
marshg246 said:
https://www.totalbikebits.com/wassell/orderpoint/prod_info/CommandoBoltsTestCertificate.pdf

But as MadNorton pointed out - the wasted portion of the Wassel bolts is thicker so they are stronger, but that is not needed. In other words, the AN and Wassel bolts are both fit for purpose. The Norvil bolts are Wassel so there are really only two in the test although three are shown.
Click to expand...
Norvil have also published a (beware of inferior parts) notice relating to 066486 big end bolts
 
justin scroope said:
Norvil have also published a (beware of inferior parts) notice relating to 066486 big end bolts
Click to expand...
066486 BIG END BOLTS
Fitting inferior big end bolts can lead to a devastating engine failure
How to identify the inferior big end bolt shown at the top
It is made to the original, unmodified, drawing without the extra support in the middle
It is made of different, weaker, material
The threads are rolled, not cut and are truncated and not fully formed
It has a tensile strength of only 68.5 tons ? the test certificate is available!!

How to identify our superior big end bolt shown at the bottom
It is made from the original, Genuine Norton forgings that we used to supply to other industry suppliers before one of them had their own, inferior, forgings made
The raised boss in the middle of the bolt has been lengthened to give more support to the connecting rod as it joins at this point.
The threads are fully formed and are sharp on top
The threads are cut, not rolled​
Click to expand...

Where to start,

1. Its from 2016
2. If they are using the original forgings then where does the extra lengthened boss come from.
3. A rolled thread is stronger than a cut thread, cut threads are potential stress raisers. Norvil's threads are cut.

www.earnestmachine.co.uk

What are the differences between cut and rolled threads? - Earnest Machine Products

Are the threads cut or rolled? We are often asked this question in regards to how the threads were manufactured on a particular size bolt or screw that we stock...
www.earnestmachine.co.uk www.earnestmachine.co.uk

The form at the bottom (root) of the thread plays an important role in the “fatigue” resistance of the thread. A radiused (rounded) thread root does improve the thread’s fatigue resistance. Cut threads are often perceived to create a sharp point at the thread root. A sharp point at the root does make a thread more susceptible to fatigue failures as compared to a thread with a round root.
 
marshg246 said:
Personally, I have no reason to doubt the workshop manual. Reuse bolts, always new nuts, and no need for thread locker. This is one place where I always use a torque wrench and clean dry threads and work up to full torque alternating between the nuts on a conrod.
Click to expand...
How many fork who have a torque wrench have them calibrated every year... i doubt many and they have been in the tool chest for years & not wound back
 
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elefantrider said:
If reproduction nuts measure the same hardness and are locking the same as originals, I think it would be good to replace.
Would be good to see a hardness and breakaway torque comparison of both.
Click to expand...
Hardness is not a criterion for selecting suitable bolts and nuts. UTS is the only criterion.
In fact, nuts need to perform good ductility to ensure all threads contribute to load carrying.
High UTS values are achieved by either cold forming (= dislocation of the metal matrix), or by altering the chemical compostion by specification of alloying elements like Manganese and Chromium.
The implication on surface hardness will vary.

- Knut
 
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elefantrider said:
Factory automaker con rod nuts and even most aftermarket replacements (ARP), don't have the lock. Nor do they use Loctite.
But they have a lot less vibration.
Click to expand...
Makers of pre-chamber diesel engines used (and may still use) collar nuts. This is probably a consequence of the vibration level.
Modern DI diesel engines run much smoother and conrod bolts are designed similar to those of petrol engines, i.e., bolt heads are compressing the conrod caps, and female threads are cut into the conrods.
Bolts are secured by deformation of the threads only, through pre-tension.

- Knut
 
olympus said:
How many fork who have a torque wrench have them calibrated every year... i doubt many and they have been in the tool chest for years & not wound back
Click to expand...
Don't know, but I have three (so I can always use middle of the range) 1/4 drive, 3/8 drive, and 1/2 drive. Always stored on the lowest setting per the manufacturer and always in their case and always in my climate-controlled shop. 1/4 checked against 3/8. 3/8 checked against 1/2. 1/2 checked against two old bar types.

Checked at least yearly and calibration checked about every 5 years. Way more calibrated than my arms that are becoming weaker and weaker!
 

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