Head bolts cracks -stretch marks

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All this talk about replacing head bolts, after 46+ years am still using all my original head bolts, suds and nuts and in that time my head has only been removed 5 or 6 times, I use copper head gaskets, after refitting my head after any work I only retention the heads once after the first 500 miles and any other time if I get a seepage from the gasket, have never pulled a stud, my head has been shaved once for the cam and performance work done to my motor.
Call me a tight arse but really can't see the need to replace head bolts when the original ones are still doing their job, well on my Norton anyway.

Ashley
 
ashman said:
All this talk about replacing head bolts, ................. but really can't see the need to replace head bolts when the original ones are still doing their job, well on my Norton anyway.

Ashley
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That's the thing Ash, the original post from Ian, says' that the ones on his bike look suspect since they have "cracks or stretch marks", hence the query. I do like the idea of using ARP 12 point bolts though, even if the old ones looked alright. Easy for me to spend other peoples money though. Cj
 
The old bolts will be going back in I replaced them as the heads look used . The lines on the ss ones sure look like cracks and have not been put there from mishandling. I don't know about the head getting squashed, after 49 years ,do they get softer as they age?
 

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Ian James said:
The old bolts will be going back in I replaced them as the heads look used . The lines on the ss ones sure look like cracks and have not been put there from mishandling. I don't know about the head getting squashed, after 49 years ,do they get softer as they age?
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Those bolts look as if they were installed without the steel washers and the heads have distorted ?
 
Or, the wrong size washer.

Cracks or surface stretch fractures along with other visible indicators on the surface of a bolt is often an indicator of multiple stress cycles telling you failure is on its way. Quality bolts can save one from a lot grief if you are willing to realize the overall influence.
To me the peace of mind is worth it.
 
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The "cracks" in the photo run longitudinally. I would expect cracks to be running at right angles to the length of the bolt, which makes me wonder if they are a score rather than a crack. I would be tempted to put them in a lathe (or a drill press) and try to polish out the lines. This will help determine how deep they go. You might need dye penetrant to confirm you have reached the bottom of the crack/line. If you can satisfy yourself that they are superficial, perhaps they are usable after all. If nothing else, you might be able to narrow down what is going on.
 
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Stephen Hill said:
The "cracks" in the photo run longitudinally. I would expect cracks to be running at right angles to the length of the bolt, which makes me wonder if they are a score rather than a crack. I would be tempted to put them in a lathe (or a drill press) and try to polish out the lines. This will help determine how deep they go. You might need dye penetrant to confirm you have reached the bottom of the crack/line. If you can satisfy yourself that they are superficial, perhaps they are usable after all. If nothing else, you might be able to narrow down what is going on.
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Have I missed something here? I don't see any photos of the stainless bolts (the ones this post is talking about, with longitudinal "cracks"), just those of the original stock bolts that are going back in. If those pictures are here somewhere, somebody please tell me which post they are attached to, and then I can feel properly stupid.

Ken
 
I purchased cNw's 12 point ARP head fastening kit mostly for the 3 studs in the head that are known to pull out, but as strong and esthetic as they are I just couldn't stop there. $1100 later you will find less 10 hexhead and socket head fasteners. The axles are also stainless steel.

Based on what I read tonight I should be meeting my maker in less than 500 miles.

Stainless steel is the material people love to hate.

I have been riding Nortons since 1970 I haven't had a broken rear axle nor seen one. Tonight is the first time I read about the issue.

With the exception of the track riders I can see a number of possibilities why the axles could break, but think that these are related to incorrect measurements and assembly techniques, can't say.

I got a Mikuni back from a retailer who told me that the customer was upset because he couldn't get his Norton to run properly. The same person posed himself as a Mikuni expert. The carb had a bent needle..

Best
 
lcrken said:
Have I missed something here? I don't see any photos of the stainless bolts (the ones this post is talking about, with longitudinal "cracks"), just those of the original stock bolts that are going back in. If those pictures are here somewhere, somebody please tell me which post they are attached to, and then I can feel properly stupid.

Ken
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Pictures have not been posted Ken…
 
Since the OP bought the bolts from RGM, I would suggest that he contacts them to ask about possible cracks. They (in my experience at least) are very responsive to queries.
 
I missed that too. NOT cracks, as viewed from here.
Judging by the moonscape on the hex, the raw material was Chinese produced rubbish to start with. All bets are off. 45 years in the metal trade. I've seen a lot.
53F94865-29C4-4604-A9FD-249469A932ED.png
 
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They could perhaps be marks from fitting if holes not fully aligned etc.

Could even be chuck marks perhaps ?

The fact they were losing torque is most likely related to the under head deformation already highlighted and the associated soft washers or aluminium IMHO.
 
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