Commando stainless steel wheel spindles
- Thread starter J. M. Leadbeater
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lcrken said:
For design of steel components other than bolts, yield strength shall be used for scantling, not UTS. Allowable shear strength of steel is 1/sqrt(3) * allowable tensile yield strength as per ISO and Eurocode standards, which is close to 0.6 .
The reason for using yield strength and not UTS is that most components are subjected to dynamic loads in one form or another. If stresses exceed the yield limit, component life can be very short and sometimes no ductile behaviour is exhibited. Nobody wants a component to fail with a bang.
For bolts, UTS is allowed because the loading mode often implies plasticity effects. Furthermore, replacing bolts is easier and cheaper than replacing the structures they are joining. Bolt design requires higher safety factors than those used for adjoining structures.
In the aerospace industry UTS is widely used for scantling due to the minimum weight requirements; this is possible only by employing a strict inspection/repair schedule. I believe that landing gear is still designed using yield stress criterions.
lcrken said:
Agreed, se my calculation example above.
lcrken said:
Well, if its made of an inferior stainless steel, it can (and it should). I am anxious to read which material Don has used.
-Knut
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mdt-son said:
I didn't mean to imply that proper stainless steel could not be used for head bolts...just that the original comment made no sense in trying to find stainless steel head bolts that would expand at the same rate as aluminum. You are correct that the discussion of head bolts is a topic of it's own.
Personally I struggle with the use of stainless steel for critical components when there are other more suitable alternatives. Most times it seems we are trying to maintain the "Look Pretty" quality rather than understanding the mechanical requirements of the component.
Has anyone actually tested any of the oem steel components in a Norton ?
I've got some examples of bent front and rear Norton axles, and a few other stray bent steel bits.
None of them took very much to straighten - not that I am planning to use them, more curiousity.
This suggests to me they are not very high grades of steel.
Nortons seem to have relied on big chunky sections and big chunky fasteners to do the job,
rather than calculated small highly specced steels ... (??).
I've got some examples of bent front and rear Norton axles, and a few other stray bent steel bits.
None of them took very much to straighten - not that I am planning to use them, more curiousity.
This suggests to me they are not very high grades of steel.
Nortons seem to have relied on big chunky sections and big chunky fasteners to do the job,
rather than calculated small highly specced steels ... (??).
dennisgb said:
While this is a fair comment, much discussion was to be had over what Vincents could use for the through-bolts in their new all alloy twin.
'Normal' bolts had to be initially set quite loose to allow for the alloys expansion as it warmed up.
This was a problem for most makers when they 1st went to alloy heads.
Douglas heads sometimes breathed flames out the cylinder head joint until the whole plot warmed up, until they sorted out the bolt issue.
More to motor design than just bolting it together with any old fasteners....
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Been riding Commandos on road and track for nearly 4 decades. The only rear axle(s?) that broke were one or two in the first year on my- then brand new- 850Mk3. These had a sharp cut where at the start of the thread.
I hardly sell rear axles these days in my German shop, and more remarkably, hardly any 850Mk3 ones. Which might have something to do with a later change in the drawing for the Mk3 rear axle (post-production). Which solved the design problem it seems.
I don't use stainless unless.- as for my pre-war and early post-war cammy racers- I cannot get anything else. I have heard no end of sorry tales from customers about their experience with stainless parts from certain "Norton specialists". I don't doubt the correct stainless can be as fit for the job as the OE steel but what I do doubt is that that grade is being used by certain vendors.
Plus, stainless looks wrong... but then that is a matter of taste.
I hardly sell rear axles these days in my German shop, and more remarkably, hardly any 850Mk3 ones. Which might have something to do with a later change in the drawing for the Mk3 rear axle (post-production). Which solved the design problem it seems.
I don't use stainless unless.- as for my pre-war and early post-war cammy racers- I cannot get anything else. I have heard no end of sorry tales from customers about their experience with stainless parts from certain "Norton specialists". I don't doubt the correct stainless can be as fit for the job as the OE steel but what I do doubt is that that grade is being used by certain vendors.
Plus, stainless looks wrong... but then that is a matter of taste.
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Rohan said:
A similar question was asked in July 2014: https://www.accessnorton.com/NortonCommando/broken-axle.7218/
No answer so far. :?
Last edited:
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In view of other later posts.....
When in about 1980 I decided my ES2 would look even better with stainless steel wheel spindles the first thing I did was to borrow from our company library British Standard 970 to determine the grade of stainless giving the highest tensile and shear strengths. This turned out to be EN57 which was easily and freely available..... Some round and hexagonal EN57 went into the tool room and later out popped some complet wheel spindles dummy axles and nuts. However BEFORE using them my brain had the thought that I really should find out whether the EN57 steel spec matched or was better than that of the material employed by Norton.thinking 'who would know' I wrote to Mr Hopwood who some of you may know was responsible for a few British motor cycles designs in his time including the original Dominator..... Mr Hopwood kindly replied offering advice on several subjects including the Dominator cam shaft oil bath he had so cleverly designed into his Dominator engine to ensure CORRECT lubrication of the cam which Norton later removed!!...... As for wheel spindle material he wrote in his letter dated 21 july 1981 and I quote..........
'The Norton wheel spindle was I think made from a 3 % nickel chrome steel with an ultimate strength of around 65-70 tons but (more importantly) having a high impact value.The elongation factor is important and can be graduated to a certain extent by the proper heat trearment. I believe EN36 was the old number.
I do not know the EN57 steel spec but it could be quiet satisfactory. What I would have against it is that the very high ultimate strength steels are not usually good on elongation ratings but I may be out of date. Try to balance the ultimate strength figure of 70 tons or more with a Izod figure that is reasonable (say 35).
Also do not fail to have a fine finish and that there are no lines or notches.'
Just for the nell of it I then had a word with the Triumph Meriden metalurgist who suggested a stee of 65-70 tons with an Izod of 35-40. One phone call costs very little.....
As the British Standard for EN57 gives, if memory is still working correctly after all these years , a tensile of 55 tons and an Izod of 25 I personaly have never used nor would ever use these stainless wheel spindles. What others do is up to them. I once experienced a rear end failure when a torque arm failed which scared the crap out of me and did little for the Manx rear brake plate and Manx swinging arm and would not wish to repeat the experience as next time it coulod prove fatal or worse leave me in a wheel chair for life.
I am given to understand that the material used by Norton has a similar tensile as En57 (55-65 tons) but that it has a somewhat higher Izod value.......EN16T ?...EN16S ?
Then of course one has to consider the rather unclever(?) change of thread form from BSc with its nice stress reducing radiuses to, if my memory is still working correctly UNF with its stress raising thread form and thus the lower torque values to use when tightening up the rear end nuts...I assume such information is supplied with each new stainless spindle / dummy axle or am I dreaming again?? ......... See the book 'Engineer to Win' ISBN 0-85045-628-2. Page 145 for a little chart showing the differences in changing from the nice Whitworth thread form to the UNF thread form......., As our Tool room did not have BScycle tooling I had opted for UNF ...long before I read Engineer to Win!!!
Now it could be that Norton over specified their wheel spindle. Tis better to be safe than sorry or dead!!
As far as I am aware and I have NOT researched it, mainly because my very Senior tame Metalurgist is no longer with us so I can pick up the phone and gain access to his vaste knowledge, the only stainless that
matches the properties of the original wheel spindle material is ....17-4PH in condition 1075. When, many decades ago, I tried to obtain some of a suitable size I was told by several steel stockists I could
have what I wanted IF I were to order and pay for a steel mills minimum production.......I believe it was a French Steel mil which sounds about right for the UK!!
Now for the through bolt posts.....
I stated they were through bolts for alloy barrels. I.E. through bolts as per 820 Commando barrels. Aluminium alloys expands at a greater rate than cast iron and in use the std Commando steel through bolts were expanding less than the alloy barrel. This increased the torque being applied by the through bolts which was causing the threads in the crank cases to stretch/pull which in turn led to the torque being applied by the through bolts REDUCING as everything cooled down which in turn led to the barrel - crankcase gasket failing. The friend then
producing these alloy barrels phoned saying, but not as politely that as Ihad nothing useful to do in my olde age
would I sort out the problem for him.
Now in various countries around the World are organisations set up simply to offer advice to industry on for example aluminium, stainless steel copper etc etc and some of their phone numbers are in my little black book. I made a phone call and being VERY polite whilst grovelling received the information I required FOR FREE. A grade of stainless steel was suggested. I found a company who manufacture special fixings and they had the stainless in stock. I informed the friend and he had a batch of bolts manufactured which I was informed cured the problem. If anyone wants to know what grade it is they can go do their own research.
Yes I know I mentioned the 17-4PH but an earlier post a year or so ago once gave it.. if my memory is correct that is.
When in about 1980 I decided my ES2 would look even better with stainless steel wheel spindles the first thing I did was to borrow from our company library British Standard 970 to determine the grade of stainless giving the highest tensile and shear strengths. This turned out to be EN57 which was easily and freely available..... Some round and hexagonal EN57 went into the tool room and later out popped some complet wheel spindles dummy axles and nuts. However BEFORE using them my brain had the thought that I really should find out whether the EN57 steel spec matched or was better than that of the material employed by Norton.thinking 'who would know' I wrote to Mr Hopwood who some of you may know was responsible for a few British motor cycles designs in his time including the original Dominator..... Mr Hopwood kindly replied offering advice on several subjects including the Dominator cam shaft oil bath he had so cleverly designed into his Dominator engine to ensure CORRECT lubrication of the cam which Norton later removed!!...... As for wheel spindle material he wrote in his letter dated 21 july 1981 and I quote..........
'The Norton wheel spindle was I think made from a 3 % nickel chrome steel with an ultimate strength of around 65-70 tons but (more importantly) having a high impact value.The elongation factor is important and can be graduated to a certain extent by the proper heat trearment. I believe EN36 was the old number.
I do not know the EN57 steel spec but it could be quiet satisfactory. What I would have against it is that the very high ultimate strength steels are not usually good on elongation ratings but I may be out of date. Try to balance the ultimate strength figure of 70 tons or more with a Izod figure that is reasonable (say 35).
Also do not fail to have a fine finish and that there are no lines or notches.'
Just for the nell of it I then had a word with the Triumph Meriden metalurgist who suggested a stee of 65-70 tons with an Izod of 35-40. One phone call costs very little.....
As the British Standard for EN57 gives, if memory is still working correctly after all these years , a tensile of 55 tons and an Izod of 25 I personaly have never used nor would ever use these stainless wheel spindles. What others do is up to them. I once experienced a rear end failure when a torque arm failed which scared the crap out of me and did little for the Manx rear brake plate and Manx swinging arm and would not wish to repeat the experience as next time it coulod prove fatal or worse leave me in a wheel chair for life.
I am given to understand that the material used by Norton has a similar tensile as En57 (55-65 tons) but that it has a somewhat higher Izod value.......EN16T ?...EN16S ?
Then of course one has to consider the rather unclever(?) change of thread form from BSc with its nice stress reducing radiuses to, if my memory is still working correctly UNF with its stress raising thread form and thus the lower torque values to use when tightening up the rear end nuts...I assume such information is supplied with each new stainless spindle / dummy axle or am I dreaming again?? ......... See the book 'Engineer to Win' ISBN 0-85045-628-2. Page 145 for a little chart showing the differences in changing from the nice Whitworth thread form to the UNF thread form......., As our Tool room did not have BScycle tooling I had opted for UNF ...long before I read Engineer to Win!!!
Now it could be that Norton over specified their wheel spindle. Tis better to be safe than sorry or dead!!
As far as I am aware and I have NOT researched it, mainly because my very Senior tame Metalurgist is no longer with us so I can pick up the phone and gain access to his vaste knowledge, the only stainless that
matches the properties of the original wheel spindle material is ....17-4PH in condition 1075. When, many decades ago, I tried to obtain some of a suitable size I was told by several steel stockists I could
have what I wanted IF I were to order and pay for a steel mills minimum production.......I believe it was a French Steel mil which sounds about right for the UK!!
Now for the through bolt posts.....
I stated they were through bolts for alloy barrels. I.E. through bolts as per 820 Commando barrels. Aluminium alloys expands at a greater rate than cast iron and in use the std Commando steel through bolts were expanding less than the alloy barrel. This increased the torque being applied by the through bolts which was causing the threads in the crank cases to stretch/pull which in turn led to the torque being applied by the through bolts REDUCING as everything cooled down which in turn led to the barrel - crankcase gasket failing. The friend then
producing these alloy barrels phoned saying, but not as politely that as Ihad nothing useful to do in my olde age
would I sort out the problem for him.
Now in various countries around the World are organisations set up simply to offer advice to industry on for example aluminium, stainless steel copper etc etc and some of their phone numbers are in my little black book. I made a phone call and being VERY polite whilst grovelling received the information I required FOR FREE. A grade of stainless steel was suggested. I found a company who manufacture special fixings and they had the stainless in stock. I informed the friend and he had a batch of bolts manufactured which I was informed cured the problem. If anyone wants to know what grade it is they can go do their own research.
Yes I know I mentioned the 17-4PH but an earlier post a year or so ago once gave it.. if my memory is correct that is.
lcrken
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J. M. Leadbeater said:
In today's world, 17-4 PH stainless is readily available in pretty much any size bar you want from online metal suppliers. In the 9/16" bar that you might use for a one piece axle, it costs about $11 per foot. It is normally supplied in Condition A (annealed), with a UTS or 160,000 psi and a yield strength of 145,000 psi, with 5% elongation. That should suffice for a one piece Commando axle. It is easily heat treated to Condition H 1075 if that's what you want, taking the UTS up to 175,000 psi and yield to 165,000 psi, at the expense of making it slightly more brittle.
Ken
lcrken
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Not so, Bernhard.
In general, austenitic stainless steels (mostly the common 300 series) can not be hardened by heat treating, but can be work hardened by heavy, deep forming operations, which is through hardening, not surface hardening. As you point out, there are a variety of surface hardening techniques that work for most austenitic steels.
However, the martensitic precipitation hardenings stainless steels, like the 17-4 PH discussed here, are normally through hardened by heat treatment. The hardening process mentioned above, H1075, is a through hardening process where the material is allowed to soak at 1075 degrees F for 4 hours or so, and then allowed to slowly cool in air. One of the attractions of this particular alloy is that the low temperature precipitation hardening process produces way less warpage than the high temperature processes used for most carbon steels. It's used a lot for fasteners because it gives you a great combination of strength, hardness, and toughness.
The common martensitic stainless alloys (416, 440, etc.) can all be through hardened by conventional heat treatment.
The other class of stainless steels, the ferritics, are more like the austenitics, and can't be hardened by heat treatment, but can be hardened some by cold working. Their main attraction is high corrosion resistance, and, s far as I know, they are not used much for fasteners.
I don't know why so many people here are so insistent that stainless steel alloys are soft, weak, fracture prone, etc. It's just not true. Maybe it's from bad experiences from the common 18-8 stainless screws found in hardware stores. As with carbon and other alloy steels, it's all about selecting the right one for the job.
Ken
In general, austenitic stainless steels (mostly the common 300 series) can not be hardened by heat treating, but can be work hardened by heavy, deep forming operations, which is through hardening, not surface hardening. As you point out, there are a variety of surface hardening techniques that work for most austenitic steels.
However, the martensitic precipitation hardenings stainless steels, like the 17-4 PH discussed here, are normally through hardened by heat treatment. The hardening process mentioned above, H1075, is a through hardening process where the material is allowed to soak at 1075 degrees F for 4 hours or so, and then allowed to slowly cool in air. One of the attractions of this particular alloy is that the low temperature precipitation hardening process produces way less warpage than the high temperature processes used for most carbon steels. It's used a lot for fasteners because it gives you a great combination of strength, hardness, and toughness.
The common martensitic stainless alloys (416, 440, etc.) can all be through hardened by conventional heat treatment.
The other class of stainless steels, the ferritics, are more like the austenitics, and can't be hardened by heat treatment, but can be hardened some by cold working. Their main attraction is high corrosion resistance, and, s far as I know, they are not used much for fasteners.
I don't know why so many people here are so insistent that stainless steel alloys are soft, weak, fracture prone, etc. It's just not true. Maybe it's from bad experiences from the common 18-8 stainless screws found in hardware stores. As with carbon and other alloy steels, it's all about selecting the right one for the job.
Ken
lcrken said:
Ain't that the truth.
When was the last time you saw a stainless bolt supplier actually specify what grade they were using.
Even if you requested specific details.
Let alone batch numbers and pedigree etc.
That said, anything less common can be serious $$$, even with a significant discount....
lcrken
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Rohan said:
That's one of the reasons I like ARP so much. They are very forthcoming about the materials they use and the specs. But they do tend to be more pricey than the no-name stuff. I collected a lot of NAS, MS, and AN fasteners back when they were available as cheap surplus from government contracts. The MIL-SPECS tell you everything you could possibly want to know about them. I use the stuff I have whenever possible. Unfortunately, the supply has really dried up a lot in the last couple of decades. It's all still available from aerospace industry supply houses, but quite expensive.
Ken
JimNH said:
A noted car enthusiast worked for the airforce, and enquired with his insurer about getting a policy including to cover the estimated $60k worth of titanium fasteners in the front end. The insurer enquired the source of these, and reportedly declined to issue a policy....
lcrken said:
I stand corrected on this subject, I should have been aware that stainless steel is steel with chromium added and is subject to the hardening and temping process as normal steel is
http://www.bing.com/search?q=heat+treat ... rsationid=
http://www.bing.com/search?q=hardening+ ... rsationid=
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Surely the important points are.......
1. Are some manufacturers flogging stainless steel wheel spindles to the public which have LOWER mechanical properties than the original items fitted by NVT thus posssibly endangering lives?
2 Do some of these manufacturers actually know anthing about stainless steels and the original specifications of the steels employed originally??
I suspect the answers in many instances are 1 YES and 2 NO.
1. Are some manufacturers flogging stainless steel wheel spindles to the public which have LOWER mechanical properties than the original items fitted by NVT thus posssibly endangering lives?
2 Do some of these manufacturers actually know anthing about stainless steels and the original specifications of the steels employed originally??
I suspect the answers in many instances are 1 YES and 2 NO.
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Bernhard said:
For many years working in the plastics industry we used 420 SS for mold cavities in high volume tooling because of it's corrosion resistance and hardness when properly heat treated. Hardness of 55 Rockwell C is obtainable.
http://www.aksteel.com/pdf/markets_prod ... _Sheet.pdf
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