heat treating stock axles

[F4Phantom]

I called a heat treater to ask about axles, he already does rally car axles and has not had them break after treatment. He uses rockwell hardness before and after to work out if he has made them harder.

This is where it becomes complicated as I would have thought in axles its toughness we would be after instead of hardness.

So anyway he wants to know what the axles are made out of, so if anyone knows any industry standard numbers, codes used to describe the type of steel a stock RRC axle is made from please let me know. Then he can give me a difinitive answer to an outcome.

For $80 per axle its a cheap upgrade. He also said quantity would decrease the price.

[isuzutoo-eh]

Just take a packet of kraft singles to him and he can check the ingrediants list directly :p

[isuzurover]

I suspect a range of steels were used over the years - which particular axles???

1541H is commonly used by manufacturers, but NFI what LR used.

It has been shown that 24 spline LR axles, are not really any stronger than 10 spline axles. Not sure if that is down to metallurgy or heat treatment.

Personally I would probably just buy new axles. Heat treating can't change lr axles into 4340.

[F4Phantom]

I suspect a range of steels were used over the years - which particular axles???

1541H is commonly used by manufacturers, but NFI what LR used.

It has been shown that 24 spline LR axles, are not really any stronger than 10 spline axles. Not sure if that is down to metallurgy or heat treatment.

Personally I would probably just buy new axles. Heat treating can't change lr axles into 4340.


new axles like maxi drive ones costs just under 1k from a retailer, I am talking about $160. If the metal is of the right type (mine is an 87 RRC) then they can be strengthened. The only issue would be if there is simply not enough material to start with. I work on my car a lot but I have never broken an axle so dont really know my axles diameter.

[long stroke]

If it makes them stronger, i'm keen to get mine done:cool:
I'm with you, i just simply can't afford to pay $900 or so for Maxi's:(
You never know dad might be interested in getting the front of the County's done aswell (mine are 10 spline, and so are the ones in the front of the county).

CHEERS TIM.

[Pedro_The_Swift]

not sure about "toughness" or "hardness"---
GOOD axels TWIST and recover,,,
M3 swayaway stuff will do 360deg,,(and these were 1K from the states 15 years ago,,)


though they seem to remember which way they like to twist so a black pen comes in handy:angel::p

[Blknight.aus]

gotta be carefull with this.

hardening the axle can make them brittle they will pass a hardness test (which is essentially a compression/cut test and they will deal with more power before they twist but they dont twist as much. Exceed the "twistability" of the axle and it snaps just the same.

[isuzurover]

new axles like maxi drive ones costs just under 1k from a retailer, I am talking about $160. If the metal is of the right type (mine is an 87 RRC) then they can be strengthened. The only issue would be if there is simply not enough material to start with. I work on my car a lot but I have never broken an axle so dont really know my axles diameter.

While HYTUFF (formerly Maxi-Drive) axles are good, there are cheaper options.

EN25/26 axles from Macnamara are $650 for a pair of 24/23 spline fronts.
Rovertracks axles are $466 an axle set + postage from the US
Rover Tracks Heavy Duty Land Rover Accessories (http://www.rovertracks.com/products/axles.html)

While these are 3-6x the price of heat treating, I would probably choose the new axles. As they are a much higher grade of steel and a proven product.

Your 1987 rangie was (I believe) made just before the switch to 24-spline axles, so you should still have 1.1" 10-spline, rather than 1.24" 24-spline.

Most manufacturers of aftermarket axles seem to heat treat to a lower hardness, for maximum fatigue life. However John (Bush65) is the expert on metallurgy, so I will let him comment on all that.

[rick130]

Just take a packet of kraft singles to him and he can check the ingrediants list directly :p

I was thinking cheddar cheese (a little more crumbly/less malleable) but you could be right :D

[Slunnie]

Quite seriously, I think that you'll find the factory axles are made from low carbon steel. Apparently thats the cheapest stuff that Bunnings in the UK stock apart from Curtain rods.

[isuzurover]

Quite seriously, I think that you'll find the factory axles are made from low carbon steel. Apparently thats the cheapest stuff that Bunnings in the UK stock apart from Curtain rods.

:D Hey Slunnie I think you are onto something!!! Cheap Gun-drilled axles! Now where did I put that curtain rod...

[Slunnie]

:D Hey Slunnie I think you are onto something!!! Cheap Gun-drilled axles! Now where did I put that curtain rod...
I've got a special lamp drill for the lathe that should do the trick. Can give it a flame tempering with the propane too for some heat treatment. :lol2:

[dullbird]

Quite seriously, I think that you'll find the factory axles are made from low carbon steel.
Apparently thats the cheapest stuff that Bunnings in the UK stock apart from Curtain rods.

B & Q Slunnie we don't have joints as classy as Bunnings:p

[isuzurover]

For those interested in history, it is interesting to note that Land Rover was initially planning to use these for axles:

http://www.bonappetit.com/images/tips_tools_ingredients/ingredients/ttar_baguette_02_v_launch.jpg

After WW2, steel was in short supply, and the French were feeling grateful that the english saved their arses...

However, during testing of the pre-production vehicles, it was found that they absorbed too much oil, meaning that the hub seals never leaked. So, in order to preserve the designed-in rustproofing system, and ensure steady sales of hub seals, they moved on to plan B:

https://www.aulro.com/afvb/images/imported/2009/09/1141.jpg

However, due to complaints about axles breaking (or the local ploughman stealing them for his lunch), Land Rover finally switched to using steel when B&Q opened its doors - as mentioned above.

This coincides with the appearance of the +35 on late SIIAs. This is because the steel Land Rover were using was 35% stronger than the cheese sticks.

http://www.4wdlinks.com.au/albums/album148/aae.sized.jpg

Hope you all enjoyed the history lesson.

[Slunnie]

:Rolling:

I still think the cheese stick axles would have been more effective than that steel one! :(

[F4Phantom]

thanks for the replys. A heat treatment expert would be handy, I did study metalurgy at rmit but it was a while ago now. From memory a large crystaline structure makes a harder steel, to get this you quench the steel from hot to cold fairly quickly. It will as mentioned be more brittle and fatigue faster if the axle is under torsion pressure and is actually flexing. If you have a more ductile/elastic axle it will cope with torsion stress more to the point where you could have a crank shaft like example where it will never suffer from fatigue. (crank shafts flex on every cycle but on the stress/strain graph the flex is under the elastic deformation point where the metal is effected - ever, theoreticaly giving a crank shaft an infinite life span). In this case it may not have the absolute strength before breaking.

Toughness not hardness is the quality we would be after here. Toughness means it has largish elastic deformation and is still not to ductile where it will plastic deform, again inducing necking and fatigue. Toughness is not all that related to hardness (that was the only thing that got me worried with the heat treater guy, he was only interested in hardness). So assuming we have a quality steel to work with heat treating is very effective and many properties can be given to steel through the process. (if anyone is interested look up youngs modulus) If we have crap steel then it may be hard to improve the axles at all! - nuts.

The main thing I would still need is an accurate idea of what they are made of there is no easy way of finding this out.

[harry]

I called a heat treater to ask about axles, he already does rally car axles and has not had them break after treatment. He uses rockwell hardness before and after to work out if he has made them harder.

This is where it becomes complicated as I would have thought in axles its toughness we would be after instead of hardness.

So anyway he wants to know what the axles are made out of, so if anyone knows any industry standard numbers, codes used to describe the type of steel a stock RRC axle is made from please let me know. Then he can give me a difinitive answer to an outcome.

For $80 per axle its a cheap upgrade. He also said quantity would decrease the price.

F4Phantom,
i am sorry to say this,
but to do what you suggest would be a waste of time and money.
your advisor , although knowledgable in his trade perhaps, is suggesting that a major manufacturer doesn't know how to make an axle.
crap.
the often stated, but not correct, assumption that lr axles are weak, stems mainly from the fact that so many lr's are on the planet and many of those have been modified way over their intended design limits.
a normal lr of any series, is able to give excellent service in standard form.
it's when you modify the vehicle that the problems begin.
if you want to waste your money and help your heat treatment mate get his kids through school, just give him a donation, and save yourself the wasted time lost in pulling your axles out for him to bugger up.
mobs like maxi and now hi-tuff make axles that are far stronger than the original items - they are also larger in diameter and use far better steel than was available to the manufacturer in the days of the earlier series vehicles.
for $80 per axle, it's a waste of money.
he wants to know what the axles are made out of?
huh? he's wanting to heat treat them, why doesnt he find that out, that's his friggin business!
[yep, i am watching the swear filter!!!]

thank christ i didn't see your last post before i posted this.

[F4Phantom]

F4Phantom,
i am sorry to say this,
but to do what you suggest would be a waste of time and money.
your advisor , although knowledgable in his trade perhaps, is suggesting that a major manufacturer doesn't know how to make an axle.
crap.
the often stated, but not correct, assumption that lr axles are weak, stems mainly from the fact that so many lr's are on the planet and many of those have been modified way over their intended design limits.
a normal lr of any series, is able to give excellent service in standard form.
it's when you modify the vehicle that the problems begin.
if you want to waste your money and help your heat treatment mate get his kids through school, just give him a donation, and save yourself the wasted time lost in pulling your axles out for him to bugger up.
mobs like maxi and now hi-tuff make axles that are far stronger than the original items - they are also larger in diameter and use far better steel than was available to the manufacturer in the days of the earlier series vehicles.
for $80 per axle, it's a waste of money.
he wants to know what the axles are made out of?
huh? he's wanting to heat treat them, why doesnt he find that out, that's his friggin business!
[yep, i am watching the swear filter!!!]

thank christ i didn't see your last post before i posted this.

Yeah you make some sense and I have not broken one yet either! but I have seen them snap all too easily on locked RR's and as I am under consideration for some type of locking device this is one idea. I HATE WASTING MONEY.

[Disco_owner]

F4 , I'm afraid I agree with everyone else here, you are wasting you money.:(

Hardening axles makes them rigid , Axles must have elasticity so that when torsional forces areapplied they can twist and when these forces in action are removed they will wind back to original form , however with rigit axles they won't swing back and will most likely snap , if it was that easy to strenghten axles we'll all be doing it and not bother buying upgrade axles like Mccnamurra or hytuff.

[Slunnie]

Harry, thats correct. But LandRover and other manufacturers do get their engineering wrong, and that was proven in the lowly powered series Rovers where LandRover produced axles that were strong enough from an ultimate strength perspective, but were guaranteed to fail as they were not from a material or section that had sufficient fatigue resistance. The materials in these axles are also built to a price not to a quality, something that can been seen in the finish of the end product and also the strength provided. It seems that every other manufacturer could build an axle that was strong enough but why not Rover. This is the reason the Salisbury was introduced, but then again why would you bring in a differential that is strong enough to reliably run 44" tyres, and swap the axles for 1.10" 10 splines or 1.24" 24splines? Likewise why didn't they run an 8.5" hypoind into the rover housing which has sufficient strength rather than the great anchor which they did. LR were not the engineering genius that you may think they are. There is evidence of such engineering in other places of the vehicles too, such as suspension.

F4Phantom, don't get too bogged down in the engineering properties and terms that you are after. Likewise I also wouldn't bother heat treating stock landrover parts. I think that you'll find that with age and fatgue that they are already fractured and if the axles can be improved with revised heat treatment or will heat treat at all, they still wont generate the strength that they should. Likewise don't get too tied up with the level of twisting before failure as the amount of twisting will also be largely dependant on the length of the axle (ie short side or long side) and this is why the short sides break more often - same material, same design just less length to twist. The other major factor here is the design of the ends at the splines as there are a couple of different and major stress raisers here. Likewise with the grain structure, large grains probably just indicate an annealed state which is actually softer. You'd be looking more so for the level of carbon in the steel and the other alloyed materials to enhance the properties. I also agree that you're more likely to not waste you're money by using axles manufactured from an upgraded metal such as Hytuff, EN25/6, 4140, 4340 etc and heat treated to suit - the manufacturers will know exactly what properties they want and what heat treating specs and process is needed to get it out of those materials.

Edit, re heat treating. There are different types of heat treatment that can be done. Springs are all heat treated, and likewise axles are also. Because you are heat treating it doesn't necessarily mean that the metal will become hard and brittle. We machine centre punches and nail punches like its going out of style. We harden then to a hard and brittle state, and then temper them to remove the brittleness, but maintain the hardness. Axles I don't belive are generally really hard as it results in a brittle failure. All of the broken standard and aftermarket ones that I have seen that have failed have not shown a brittle failure at all.

[harry]

phantom,
i locked my disco rear ages ago, and no problems,
until i put big tyres on,
then at no excessive power, it's an auto,
under gentle increasing power on a steep hill, it broke one axle,
after an assistant confirming this, watching , i commenced to drive it further up and also at gentle power application, it broke the second axle
shute, two in five minutes, no rear drive.
definatly not the car's fault..
1 , the car was designed as a constant 4wd with centre diff lock.
2 , i modified it with the addition of a locking rear diff.
3 , i further modified it with a large set of tyres
so it was way past it's design standard,
definatly not mr land rovers fault.
of course we don't hear the same stories from the owners of the other marques, as they mostly bugger theirs from doing the same thing at a million bottles per hour, so they do not understand.

[isuzurover]

phantom,
i locked my disco rear ages ago, and no problems,
until i put big tyres on,
then at no excessive power, it's an auto,
under gentle increasing power on a steep hill, it broke one axle,
after an assistant confirming this, watching , i commenced to drive it further up and also at gentle power application, it broke the second axle
shute, two in five minutes, no rear drive.
definatly not the car's fault..
1 , the car was designed as a constant 4wd with centre diff lock.
2 , i modified it with the addition of a locking rear diff.
3 , i further modified it with a large set of tyres
so it was way past it's design standard,
definatly not mr land rovers fault.
of course we don't hear the same stories from the owners of the other marques, as they mostly bugger theirs from doing the same thing at a million bottles per hour, so they do not understand.

So you are basing everything you have said on your experience with one vehicle???

Your assertion that LR know what they were doing wrt axles has been disproven by the Ashcroft tests showing that 24 spline axles break at the same UTS as 10-spline axles. So LR increased axle diameters by 30% or so (increasing unsprung weight) but didn't increase axle strength.

For the record I have broken 3x 10 spline axles, 1x 24 spline axle and 1 crownwheel and pinion in landies with standard engines and standard size wheels, no diff locks, driving sympathetically.

The most sympatheric driver I know, and past president of the LROCB, has broken at least 3 axles and 1 CW&P (also no lockers and stock standard engine and wheels)

LR axles are undersized and have poor metalurgy. However I agree that heat treating them won't help.

[Benny_IIA]

I have been using these in IIa.

https://www.aulro.com/afvb/images/imported/2009/09/1122.jpg

Benefits

1. When you get hungry you can use your broken axles for a toasted cheese sandwich. Using your friends TD5 to cook it, because it has lost all its water and overheated.
2.
They are individually wrapped, so they don’t melt and stick together in the sun.

Ben.....

[Psimpson7]

The most sympatheric driver I know, and past president of the LROCB, has broken at least 3 axles and 1 CW&P (also no lockers and stock standard engine and wheels)



I must be incredibly lucky then, as since having my 90 which is fully locked, and running either 33 or 35inch tyres, and has since it was 2 years old, I have only ever broken 1 rear axle (the long one) They are all still standard, front and rear.

It gets used pretty hard too.

Having now said that, no doubt I will snap one next time out!

ps, As soon as Keith gets the news ones made I will be upgrading.

pps, I also agree that the heat treatment is a waste of time.

ppps, Rover axles are weak, but they arent quite as weak as some people would suggest.

[crash]

They are having good success in the USA doing the opposite - freezing axles (and any thing else you can think of) - like they do for cryogenetics.

[Slunnie]

Heat treatment I can understand, cryo goes against my understanding of how it can actually happen.

[isuzurover]

I must be incredibly lucky then, as since having my 90 which is fully locked, and running either 33 or 35inch tyres, and has since it was 2 years old, I have only ever broken 1 rear axle (the long one) They are all still standard, front and rear.

It gets used pretty hard too.

Having now said that, no doubt I will snap one next time out!

ps, As soon as Keith gets the news ones made I will be upgrading.

pps, I also agree that the heat treatment is a waste of time.

ppps, Rover axles are weak, but they arent quite as weak as some people would suggest.

Ahh, but your 90 is significantly lighter than a 110, so the loads on the axles are less.

e.g. 88" SIIAs break axles very rarely if unlocked. 109" break axles much more frequently given the same conditions.

[Psimpson7]

Good point, but remember it only has the RRC/D1 type rear axle, not the Salisbury that the 110's had.

As it sits with a full tank of fuel but no driver it weighs 2050kg's

[Slunnie]

Good point, but remember it only has the RRC/D1 type rear axle, not the Salisbury that the 110's had.

As it sits with a full tank of fuel but no driver it weighs 2050kg's
Thats a lot lighter than a Disco. With an empty tank I'm at 2400kg, the 110's will be heavier.

[isuzurover]

Good point, but remember it only has the RRC/D1 type rear axle, not the Salisbury that the 110's had.

As it sits with a full tank of fuel but no driver it weighs 2050kg's

What Slunnie said.

Officially an 88" is 1250kg and a 109 is 1500. However an ex military 109 is closer to 1900kg. Must be a lot of extra steel in the chassis!!!

[Psimpson7]

:)lol... must be pretty much solid steel to get the other 400kg's

Interestingly going back 15 years, I did break plenty of 10 spline bits and peices in my old 68 s2a.

[isuzurover]

:)lol... must be pretty much solid steel to get the other 400kg's

Interestingly going back 15 years, I did break plenty of 10 spline bits and peices in my old 68 s2a.

Well there is the bullbar (brush guard) made from steel flatbar, all the steel attachments (steps, lifting rings, etc, etc), raised suspension mounts...

Then the 50 layers of olive drab applied when they couldn't find any more rocks for the grunts to paint :D

[harry]

it still gets me,
why when someone pipes up and says he has a good idea [in this thread, i think we all agree that it wasn't] we have our say and then we all fall on our swords bagging the **** out of our own chosen marque.
why is that.
it is simple i thought,
the rover product is fine in stock condition, and driven sensibly.
that isn't any different to a nissan or jeep or toyota.
so why get all uptight about how you can break something when you modify it past it's design limit?
grow up.

[Bush65]

In solids, the different crystalline and noncrystalline aggregates of atoms and molecules are called phases.

Steel is a multiphase solid and the different phases in steel include ferrite, pearlite, cementite, bainite, austenite and martensite.

Carbon is much more soluble in austenite.

When steel is heated below its melting point it undergoes phase changes (called transformation). The transformation depends on carbon content and temperature, but typically the mix of ferrite plus cementite transform to austenite above 723C (if carbon percentage is high it will transform to austenite plus cementite).

If it then cooled slowly (normalised) the austenite will transform back to ferrite plus cementite.

Bainite may form when austenite is quenched to (usually) between 200 and 400C and held there.

Martensite forms when austenite is quenched rapidly to a lower temperature than when bainite forms. The amount of austenite that transforms to martensite is determined by the temperature - the lower the temperature, the more martensite that is formed.

Martensite is extremely hard and brittle. It is the strongest form of steel.

Quenching to obtain martensite is difficult with thick sections, because it is difficult to reduce the temperature further from the surface. If large sections are quenched too rapidly, suface cracking can occur.

The purpose of adding hardenability improving alloys to steel is to make it possible to produce martensite in thicker sections without quenching too rapidly that surface cracks form.

During quenching some autenite is retained (not transformed to martensite). Cryogenic treatment, after heat treatment can transform some of the retained autenite to martensite - thus improving strength of the article.

The brittleness of martensite is reduced by tempering - the steel is reheated to the tempering temperature, held for the required time, before cooling again. Tempering reduces the hardness somewhat, but greatly reduces brittleness. The higher the tempering temperature, the lower the harness, and brittleness (and vice versa).

Strength of steel is directly related to hardness.

The heat treater needs to know what alloy elements and their percentages are in the steel to determine how to harden and temper it. This affects how fast it is heated, to what temperature, how long it has to be held at that temperature, how to quench it, etc.

In my experience axles don't fail because they are loaded to their static breaking strength.

Damage occurs at lower loads and is cumulative over the lifespan. The cumulative damage depends upon the loading spectum (engineers use Miner's Rule for cumulative damage). This is why axles break at times when the load is not particularly high.

The other common cause of failure is impact loads, but I won't go into this topic at this time.

I wouldn't got to the trouble/expense of heat treating an old axle in an attempt to get a gain in strength.

I have no idea what heat treatment was carried out at manufacture of the stock axles - not something I have been interested in, but if I had to guess, I would say they were probably induction hardened. This hardens the axle for a certain depth and leaves the surface hard and the core tough. It is also a quick and cheap process for a production line.

It is appropriate for axles because the torsional stresses increase from zero at the centre of the axle and increase to a maximum at the surface (similar to how the hardness would vary).

Through hardening may not significantly increase the overall strength.

[isuzurover]

it still gets me,
why when someone pipes up and says he has a good idea [in this thread, i think we all agree that it wasn't] we have our say and then we all fall on our swords bagging the **** out of our own chosen marque.
why is that.
it is simple i thought,
the rover product is fine in stock condition, and driven sensibly.
that isn't any different to a nissan or jeep or toyota.
so why get all uptight about how you can break something when you modify it past it's design limit?
grow up.

??? I am not sure who needs to grow up here. Every "marque" has its problems, I think it is important to let people know, rather than deny it exists.

Nissans tend to shear wheel studs - see my other post about a nissan losing a wheel on the highway today. I posted it on another forum and 2 pages of people jumped on and said they knew of the same...

So while Nissan have issues with wheel studs and the ZD30 engine, They got the axle side right with axles up to 1.47" diameter.

Land Rover on the other hand had serious axle breakage problems with the IIA LWB, so it upgraded the axles on the next model SIII, however kept the same axles on the others. When they finally upgraded, they skimped on either the metalurgy or the heat treatment, so the new axles were no stronger. They are STILL smaller than the axles on all comparable vehicles.

So while Land Rover have gotten most things right, the axles have been consistently underengineered on most models, even for stock tyre sizes.

[Slunnie]

C'mon Ben, I'd much prefer to pretend LandRover ownership is living autopia - lets not get all realistic about these things and spoil it.

[JDNSW]

In almost fifty years of driving Landrovers my total is one half axle (in 1968, 2a 109 diesel) and one diff - not CW (in 1996 2a 109). But from what I have seen with others I have concluded that axle quality has varied quite a bit, with probably the worst produced in the late sixties.

I also am very dubious about improved heat treatment being a solution. I would guess that most axle failures stem not from poor heat treatment but from defects in the steel or probably more commonly surface defects which serve as stress concentrators, all of these coming from poor quality control ("buy your parts from the cheapest supplier!"*). Obviously, different heat treatment is not going to change these.

John

*Leyland motto

[Bigbjorn]

I also am very dubious about improved heat treatment being a solution. I would guess that most axle failures stem not from poor heat treatment but from defects in the steel or probably more commonly surface defects which serve as stress concentrators, all of these coming from poor quality control ("buy your parts from the cheapest supplier!"*). Obviously, different heat treatment is not going to change these.

John

*Leyland motto

Valiants and others with exposed torsion bars used to suffer breakages of the loaded bar almost always from a surface defect such as a rust pit or the marks left by the jaws of vice grips etc when clamped on and struck to slide the bar out of the housings. The break used to be a spiral, interesting the first time.

[Bush65]

... The break used to be a spiral, interesting the first time.
Spiral break is classical of torsional shear overload failure.

Torsion creates shear stress with the plane of major principle stress (with stress there is are major and minor pricinple stresses at 90 degrees to each other) is inclined at 45 degrees to the rotational axis.

If an axle/half shaft failed due to being statically loaded beyond its ultimate strength it would nearly always fail on this angle.

[JDNSW]

Spiral break is classical of torsional shear overload failure.

Torsion creates shear stress with the plane of major principle stress (with stress there is are major and minor pricinple stresses at 90 degrees to each other) is inclined at 45 degrees to the rotational axis.

If an axle/half shaft failed due to being statically loaded beyond its ultimate strength it would nearly always fail on this angle.

The angles quoted assume the material is isotropic with the same properties in all directions, I question whether this is exactly the case for axle shafts, especially for induction hardened ones, although I agree the stress angles will usually be close to 45 degrees in practice.

I encountered one interesting failure (in a rear axle on a 6x6 IH R190) - failed about four inches from the outer end, with a clean break that looked as if it had been cut with a parting tool. It was a replacement axle for one that had failed with the classic spiral break starting from the end of the spline, and failed the first time low range was used after it was fitted, when it sank a couple of inches in very slippery mud.

John

[Bigbjorn]

The broken torsion bars from the Vals. made beaut chisels and punches. I had to soften them by heating dull red and leaving in a pot of lime overnight to make them machinable. Had to use tungsten carbide and with some difficulty. Then heated and oil quenched them after machining, forging, grinding. Leave the striking end soft for safety.

[Slunnie]

The angles quoted assume the material is isotropic with the same properties in all directions, I question whether this is exactly the case for axle shafts, especially for induction hardened ones, although I agree the stress angles will usually be close to 45 degrees in practice.

I encountered one interesting failure (in a rear axle on a 6x6 IH R190) - failed about four inches from the outer end, with a clean break that looked as if it had been cut with a parting tool. It was a replacement axle for one that had failed with the classic spiral break starting from the end of the spline, and failed the first time low range was used after it was fitted, when it sank a couple of inches in very slippery mud.

John
Most I've seen are like that

https://www.aulro.com/afvb/images/imported/2012/01/1019.jpg

[isuzurover]

Most I've seen are like that


Same here - every 24-spline axle or CV stub I have broken or seen broken has looked like it was cut with a drop saw.

By comparison, 10-spline series axles break in a much more jagged pattern.

[JDNSW]

Same here - every 24-spline axle or CV stub I have broken or seen broken has looked like it was cut with a drop saw.

By comparison, 10-spline series axles break in a much more jagged pattern.

I wonder if you are seeing the difference between overload failure (ten spline) and failure due to fatigue initiated at a stress concentrator such as a material flaw or surface defect (24 spline or CV stub)?

John

[isuzurover]

I wonder if you are seeing the difference between overload failure (ten spline) and failure due to fatigue initiated at a stress concentrator such as a material flaw or surface defect (24 spline or CV stub)?

John

I doubt it. Most of the 10-spliners failed (finally) at low-load - e.g. on-road in high range or even when going downhill in one case!!! So these were most likely fatigue related...

Whereas some of the 24-splines failed at full noise...

However since Dave Ashcroft has shown that the UTS of 10-spline and 24-spline axles are about the same, I think the point is moot. I am sure the difference comes down to grain structure.