How are Factory Axles made?

[leehamescort]

G'day,

I am in the process of getting some custom length axles made up and want to know how the factory toyota axles are made?

Basically are they:
1. FORGED?
2. Turned from Billet and the splines cut?

I've searched the net and couldnt find anything.

The upgraded axles are all CHROMOLY which i pressume the factory ones arn't.
Superior Axles say theirs are "rolled" (forged?) and claim they are 35% stonger than "cut" splines.
Longfield doesnt say how theirs are made.

Basically I am trying to work out if Cut splines would be strong enough, they would be heat treated after they have been made.

Its for a surf running 37" tyres

Thanks for any help.
Leeham

[Ice]

G'day,


Superior Axles say theirs are "rolled" (forged?) and claim they are 35% stonger than "cut" splines.
Longfield doesnt say how theirs are made.

Basically I am trying to work out if Cut splines would be strong enough, they would be heat treated after they have been made

Rolling is one way of making splines, cutting them is another

have a look at the unmachined parts on them

Forging is making a billet roughly the right shape before machining it, saves a lot of material wastage and time and changes the grain structures if done correctly

[ISUZUROVER]

"Chromoly" means nothing. Which grade of steel do they use???

That, and the heat treating process used, determine much more than whether the splines are rolled or machined.

Many factory axles are made in this way (from steels like 1541H): An axle blank is supplied to axle suppliers in various sizes, ALREADY hardened, with the flange already forged on one end. The splines are then rolled or machined and the flange end faced and bearing surfaces machined.

The most expensive, highest strength axles, usually have machined splines. Billet steel has the splines machined, and (preferably) the non-splined part of the axle necked down/waisted to relieve stress.

Then the axle is through (or case) hardened.

Steels like AMS6418/HY-TUFF, 4340, 4340M/300M, EN26, EN25 are all high grade axle steels.

If someone tells me their axles are made from "chromoly" I would walk away (unless they can tell me what grade of steel they actually use).

AFAIK - longfield axles are machined from 4340.

[Mark2]

The factory uses an induction hardening process which involves heating the surface of the axle with an AC current and then quenching - the core of the axle is unaffected by the heat treatment process resulting in a very tough core with a hard outer.

I would ask about the hardening process as other types of heat treatment may not give the same level of toughness, even though the strength may be comparable.

[bushy555]

Weren't early Maxi axles's from Hy-Tuff?, and then version 2 changed to 4340.

Something about the steel having the ability to tolerate massive amounts of torsional shock without any deformation - or that was the story I recall.

yes/no?

[Slunnie]

As I understood it the early maxi''s were N25 and then changed to Hytuff.

Re rolled or cut splines, its irrelevant if the axle isn't waisted as it will probably always break through the spline anyway.

[nastytroll]

The last lot of maxi drive hemispheres I machined was all hytuff. Maxi drive import their own hytuff and as far as I know their axles are also hytuff.

4340 is much more geometrically stable then 4140 and is also more tollerent to vibration and shock loads.

Most quality cutting tools for the engineering trade are made from 4340 for this reason.

BOHLER or EAGLE AND GLOBE or ASSAB will have all the information on this.

Like ISUZUROVER said CroMo means nothing with out the relivent grade.

I used to machine EN26, EN36, 4140, 4340, M200, M238, W321, W328, all could be refered to as CroMo but are all very different in there characteristics.

If Maxi drive now use 4340 it would be for availability.

[ISUZUROVER]

As Slunnie said, MD originally used EN25, then changed to HY-TUFF as they weren't happy with the properties of EN25. Note that this applies to axles only. Drive flanges and many other bits were 4140 and 4340 - but not axles.

I am sure that "Hytuff Engineering" would still be using hytuff for their axles as the name suggests.

[N*A*M]

who is a good axle maker in melbourne?

[Slunnie]

Jack McNamara?

[cj]

I'm having custom EN26 axles made by Matt at Total Traction Drivelines in Moorabbin. Give him a call on 9555 1501 and have a chat. The material chosen, the design, the machining and the heat treatment are all important parts of the process to get the desired outcome.

[N*A*M]

cool my short list was mcnamara and dobbin. but i will speak to matt as well. from my experience heat treatment is very hit and miss. i have broken dobbin's axles, and just recently an axle from another supposedly shit hot axle maker.

[ISUZUROVER]

cool my short list was mcnamara and dobbin. but i will speak to matt as well. from my experience heat treatment is very hit and miss. i have broken dobbin's axles, and just recently an axle from another supposedly shit hot axle maker.

Heat treatment is very important. Mal (Maxi-Drive) told me that they made their axles in batches and only got them heat treated once or twice a year, to ensure better process control and reduce cost.

If you are getting one-off custom axles made, they will probably be throwin in with a batch of other bits, and you might not get the best properties out of your axle.

However, that said, if you are breaking so many custom axles - maybe you need to upgrade to something larger. Either that or get some 4340M axles made.

[Slunnie]

cool my short list was mcnamara and dobbin. but i will speak to matt as well. from my experience heat treatment is very hit and miss. i have broken dobbin's axles, and just recently an axle from another supposedly shit hot axle maker.

However, that said, if you are breaking so many custom axles - maybe you need to upgrade to something larger. Either that or get some 4340M axles made.

Or both.

Obviously that axle isn't going to work for you if you keep breaking them.

[N*A*M]

pretty sure this is an en26 axle - around 338 mm diametre shown next to a standard AA battery
i think the wear marks are from the mashed up oil seal after the initial break

can't really go bigger - and already using $$$ longfields (which are holding up) so not gonna go custom cvs as well

it breaks because its so short and has no give. i might have to get smaller tyres :(

[cj]

It looks like it needs to be necked down over a longer distance otherwise it's probably always going to break there.

[ISUZUROVER]

pretty sure this is an en26 axle - around 338 mm diametre shown next to a standard AA battery
i think the wear marks are from the mashed up oil seal after the initial break

can't really go bigger - and already using $$$ longfields (which are holding up) so not gonna go custom cvs as well

it breaks because its so short and has no give. i might have to get smaller tyres :(

What the hell are you doing running 24 spline axles? You got a rover now?

IMHO that axle is very poorly designed. It should be waisted along its entire length down to the modulus of the (smaller) spline diameter. They have just made it that way to cut down on machining costs.

If it is a rover axle, why not get HY-TUFF eng to make you some? HY-TUFF/AMS6418 is a superior axle steel to EN26, and I am pretty sure that most of the nissota stuff uses the same spline pressure angle as rover, so they should have the gear to cut it.

[cj]

This is a better design

[Guy]

This is a better design

That is much better, Nams axle that small spot just before the splines is always going to be area under most stress. The one posted here will load up in a much more linear fashion.

[N*A*M]

hytuff = ???

Hi - Tough Engineering
3/7 Ryecroft St
Carrara QLD 4211
(Gold Coast)

Ph 07 55304123
Fax 07 55306312
hi.tough.eng@gmail.com

[ISUZUROVER]

hytuff = ???

Hi - Tough Engineering
3/7 Ryecroft St
Carrara QLD 4211
(Gold Coast)

Ph 07 55304123
Fax 07 55306312
hi.tough.eng@gmail.com

Yep, that's them. Barry Ward owns it. Used to work for Maxi-Drive, and bought the axle business when they closed.

[Bush65]

Re chrome-moly. It is my experience that 4wd enthusiasts use this term too loosely.

To evaluate a material it is far better to refer to the appropriate name for the alloy used and the heat treatment. There are many steels that contain chrome and molybdenum in differing amounts so mechanical properties vary widely. Also many contain other alloys that further enhance their properties.

4340, EN26, Hy-tuf and 300M (from good to better) are all good, low alloy steels for axles. All contain other alloys (such as nickle) besides chrome and molybdenum.

Hy-tuf and 300M (modified 4340) contain silicon, which greatly increases the strength and elastic limit (elastic limit is the point where the deflection is fully recovered when the load is removed) and make them such good materials for axles.

As stated by others, good heat treatment is essential for getting the best out of these materials. Not all heat treatment shops are equal.

Different alloys (and size of part) require different rates of heating (some require many, many hours) and different durations for holding that temp. Which is not cost efficient for small batches of different alloys.

There are other alloys that have better properties than those mentioned, but obtaining the material, the cost and difficulty finding a shop that will heat treat them properly are problems.

Diameter and details that increase fatigue strength and resiliance are very important issues.

Regarding the pics that N.A.M. posted, they give me the impression that the manufacturer does not have a good knowledge of the how to improve the resilience of an axle and how important it is for shock/impact loads.

For static loading, the smallest section diameter limits the strength. This is normally the diameter at the root of the splines. The axle can not be any stronger than at it's weakest spot.

But axles usually don't fail under a static load (except in a test rig). In the real world, they fatigue or fail due to shock loads.

Resilience is a property that is important for absorbing shock loads. By waisting the axle, the resilience is increased, and if the waisted diameter is not less than the smallest cross section diameter, then the static strength is not reduced. Everything else being equal, a fully waisted axle will absorb more impact energy (or shock loading) than a partial or non-waisted axle.

This is because the waisted axle will twist further before the maximum allowable stress in the axle is reached.

If you compare bungee jumping to a similar fall onto a concrete floor, the one with more resilience, will flex more and break less bones than the other.

[Strange Rover]

pretty sure this is an en26 axle - around 338 mm diametre shown next to a standard AA battery
i think the wear marks are from the mashed up oil seal after the initial break

can't really go bigger - and already using $$$ longfields (which are holding up) so not gonna go custom cvs as well

it breaks because its so short and has no give. i might have to get smaller tyres :(

Thats an interesting sort of a break...looks like a carrot thats been snapped in half by bending it and not something that has been twisted off.

Get yourself some carrots and start breaking them by bending them and then also by twisting them. The failure surface is quite different. If you bend them you get a 90 degree surface...same as your picture. If you twist them the surface is at 45 degrees.

Seriously...go to the supermarket and break some carrots - you will only need 2.

I think you have got a bent housing or no steering stops...nothing to do with axle design, heat treat or material.

Sam

[ISUZUROVER]

Sam - I am sure you have broken a LOT more axles than me, but I have seen a fair few break cleanly like that.

[Strange Rover]

Sam - I am sure you have broken a LOT more axles than me, but I have seen a fair few break cleanly like that.

I have also seen one like that...broken in the middle of nowhere with a perfect clean cut in a fully floating rear setup with aftermarket axles - in a housing that had twisted axle splines previously ... to break it cleanly in the middle away from the splines with noo deformation in the splines seemed very strange...put it down to a defect in the axle.

By the sounds of NAMs case if he has broken more than one axle like that from different manufactures (although NAM hasnt actually said he has broken others that look like this one - so Im not sure if this is the case) then I would think somehting is up. If it was twisted off I would expect some deformation in the splines..the stress concentration at the end of where the splines are loaded should do something...I would also expect a 45 degree shear failure surface and it definately hasnt got that.

If thats the front axle CV end then I would guess that he is turning too sharp and bottoming out the CV and that is bending the axle and that has fatigued/broken it.

The splines being so perfect and the cut so perfect just seems odd. If it is a one off failure then it could be a defect in the axle...stick another one in and it may never fail like that again but I would still be looking for other causes. I would be looking at how sharp the front axle is steering and also whether or not it has steering stops on the front and back of the knuckle (again assuming this is a front axle at the CV end we are looking at)

Sam

[sloshy]

Hilux rear

[Strange Rover]

Hilux rear

Thats an honest break - its got a twist in the spline.

Sam

[RUFF]

pretty sure this is an en26 axle - around 338 mm diametre shown next to a standard AA battery
i think the wear marks are from the mashed up oil seal after the initial break

can't really go bigger - and already using $$$ longfields (which are holding up) so not gonna go custom cvs as well

it breaks because its so short and has no give. i might have to get smaller tyres :(

Thats an interesting sort of a break...looks like a carrot thats been snapped in half by bending it and not something that has been twisted off.

Get yourself some carrots and start breaking them by bending them and then also by twisting them. The failure surface is quite different. If you bend them you get a 90 degree surface...same as your picture. If you twist them the surface is at 45 degrees.

Seriously...go to the supermarket and break some carrots - you will only need 2.

I think you have got a bent housing or no steering stops...nothing to do with axle design, heat treat or material.

Sam

Sam remember these breakages at Rover Park? Ive also broken other hilux axles exactly the same. No twists in the splines. I think it also has a lot to do with the material the axle is made from. Patrol Cvs usually break exactly as you expect. Thats in pieces not clean breaks. But must toyota axles i have seen break have been clean cut.

[Strange Rover]

Looking more at NAMs axle...whats with the marks on the end of the axle??? Maybe the axle is floating into the CV too far and hitting on the inside of the bell...that would bend the axle as it was steered with the end of the inner axle jamed against the inside of the bell.

Maybe the marks on the outside of the axle that NAM thought might be "i think the wear marks are from the mashed up oil seal after the initial break" are actually from the outside edge of the CV bell hitting the axle on full lock when the axle floats into the CV.

This is still assuming this is the outer end of an inner axle we are looking at. It doesent look like the outer end of an inner alxe cause it doesent have any circlip grooves but that may be the reason for the failure. What stops the axle moving into the CV too far??

Sam

[uninformed]

pretty sure this is an en26 axle - around 338 mm diametre shown next to a standard AA battery
i think the wear marks are from the mashed up oil seal after the initial break

can't really go bigger - and already using $$$ longfields (which are holding up) so not gonna go custom cvs as well

it breaks because its so short and has no give. i might have to get smaller tyres :(

Thats an interesting sort of a break...looks like a carrot thats been snapped in half by bending it and not something that has been twisted off.

Get yourself some carrots and start breaking them by bending them and then also by twisting them. The failure surface is quite different. If you bend them you get a 90 degree surface...same as your picture. If you twist them the surface is at 45 degrees.

Seriously...go to the supermarket and break some carrots - you will only need 2.

I think you have got a bent housing or no steering stops...nothing to do with axle design, heat treat or material.

Sam

good info Sam,

do you think the break may also have something to do with the design? never seen an axle reduced then back up to a major dia like that....

cheers, Serg

ps please check your pm

cheers.