McNamara vs RoverTracks

[d-90]

Hello,

Some of you know that I am doing a Salisbury conversion to Dana60 35 spline sepcs. Will get R&P and ARB (or detroit, haven´t mande my mind yet) from Ashcroft (been very helpfull on this).

However, have to choose the halfshafts to fit. The companies that makes them are McNamara in OZ and RoverTracks in the US, so importing from one or other is the same for me.

McNamara has these alxes made in their usual material (I believe to be EN26 from what I´ve read on other foruns) and have a nice price on them. However RoverTracks offered some shafts made in 1541H at a even better price. They can also make them in 4340 or 300M, but the price tag is higher on these.

My question is, how are (or supposed to be) these 1541H from RT comparable with McNamara ones in strength issues?? Don´t know nothing about materials, so would apreciate any kind of help from the ones who know a thing or two.

Cheers

[Astro_Al]

Hi sounds interesting. Have you thought about ordering custom shafts from the states? there are lenty of sources.

If I was ordering custom shafts (the main concern of which is that if it breaks, you're really screwed unless you got spares), there is NO WAY I'd settle for anything crappy materials-wise.

4340 would be the absolute minimum, and I wouldn't be overly chuffed at that. You'll need to throw extra pennies at it for insurance, because unlike everyone else, you can't pick up spare shafts in the classifieds section.

Good luck. Remeber - 'that's what we always make' isn't justification for materials choice...

Look around for other suppliers too. Perhaps Rakeway in the UK can help you out - at least you'll save on shipping, duty, transit times etc.

Al.

[dollythelw]

just to add a bit more fog to the situation, design will also pay a substantial role in halfshaft strength, septics love "adding beef" (not waisting anything) the end result is sometimes a shaft with no flex, quality of machining (leaving stress risers) comes into it as does speed of production (if its a special how fast can they make another one for you)

[will_warne]

Look around for other suppliers too. Perhaps Rakeway in the UK can help you out - at least you'll save on shipping, duty, transit times etc.

Al.

I'd second Al with Rakeway, it'll make not only shipping easier but also it'll make comiunicating simpler too; you won't have to worry about differant time zones etc. From the work I've seen they look excellant.

[d-90]

I'd second Al with Rakeway, it'll make not only shipping easier but also it'll make comiunicating simpler too; you won't have to worry about differant time zones etc. From the work I've seen they look excellant.

Well....comunication isn´t that good, have tried to contact them but never got an answer. Would prefer to have an European supplyer, but have to go overseas because can´t get anyone to make them!

[SOA 93]

Well....comunication isn´t that good, have tried to contact them but never got an answer. Would prefer to have an European supplyer, but have to go overseas because can´t get anyone to make them!

I spoke to Rakeway today, about drive shafts for salisbury axles, 101FC though, could hardly believe how helpful they were! Custom shafts are about £200 each for EN26(?) spec shafts and £300 for 300M shafts. I'm the opposite to you, Rovertracks never replied to my e-mail and Mcnamara took 4 months .

I enquired about the possibility of 4340 shafts his opinion was that it was it was to difficult to get the heat treatment done properly, they had a challenge Toyota in ther workshop at the moment with broken high spec American 4340 chromoly shafts.

I told him I was going to be using 37"(925mm) tires and he thought that EN26 (or whatever) would be plenty strong enough in that size shaft. 101 driveshafts are 35.6mm and Dana 60 35 spline are 38mm.

If you've e-mailed Rakeway then it may be better to give them a phone call, I learnt an awful lot in the short conversation I had with Neil. I should point out that in my case the custom shafts are a last resort and they are going to investigate other options first.

I'd persevere with Rakeway they are interested in this kind of stuff, but like alot of these small specialist companies the don't have full time office staff to deal with enquiries, give em' another try.

Hope that helps a little.

Andy

[d-90]

I spoke to Rakeway today, about drive shafts for salisbury axles, 101FC though, could hardly believe how helpful they were! Custom shafts are about £200 each for EN26(?) spec shafts and £300 for 300M shafts. I'm the opposite to you, Rovertracks never replied to my e-mail and Mcnamara took 4 months .

I enquired about the possibility of 4340 shafts his opinion was that it was it was to difficult to get the heat treatment done properly, they had a challenge Toyota in ther workshop at the moment with broken high spec American 4340 chromoly shafts.

I told him I was going to be using 37"(925mm) tires and he thought that EN26 (or whatever) would be plenty strong enough in that size shaft. 101 driveshafts are 35.6mm and Dana 60 35 spline are 38mm.

If you've e-mailed Rakeway then it may be better to give them a phone call, I learnt an awful lot in the short conversation I had with Neil. I should point out that in my case the custom shafts are a last resort and they are going to investigate other options first.

I'd persevere with Rakeway they are interested in this kind of stuff, but like alot of these small specialist companies the don't have full time office staff to deal with enquiries, give em' another try.

Hope that helps a little.

Andy

Well....I will give them a phone call for sure. Prices seem very acceptable and not having to worry with heavy shipping and import taxes is a big thing for me. Also makes spares a lot easir to have.

Thanks Andy, it helped a lot, will call them tomorrow.

Cheers

[Lara]

Just for info guys the material spec you are quoting should be as follows if talking to English suppliers.

EN24 in T condition or known as 4340 in the states so do not think 4340 is better, "It is not cos it's the same thing"

Or EN36 C or even better XVAR this is an X Track trade name for Vacuum remelted high pure EN36 C

And is roughly the same material as 300M

If you want the best then Maraging 300 is the ultimate but that will cost you 1500 pounds just for the material to make 4 shafts before you start machining.

Good luck with the search,

Lara.

[Michele]

I'm the opposite to you, Rovertracks never replied to my e-mail Andy

That's strange as Keith is always helpful,sometimes he hasn't the chance to reply promptly due to work,and maybe he forgot.

Easier (safer) to PM him directly through the PBB or D90 BB.

Of course I'm biased...

[Astro_Al]

I've had 'issues' there too (Rovertracks).

I was ready to order some shafts and stuff (admittedly not off-the-shelf for them). But it just went nowhere.

In the end, I just changed my plans.

I can't imagine what a pain it would be to break one and need a replacement and then be stuck in this situation. For me, unacceptable.

I will balance that by saying he seems like a nice guy. (but what good is that when you can't drive your truck?)

Al.

[bill van snorkle]

just to add a bit more fog to the situation, design will also pay a substantial role in halfshaft strength, septics love "adding beef" (not waisting anything) the end result is sometimes a shaft with no flex, quality of machining (leaving stress risers) comes into it as does speed of production (if its a special how fast can they make another one for you)

Couldn't agree more with those comments. The US manufacturers very rarely neck down their axles between the splines, incorrectly thinking IMO that removing metal in this area weakens the shaft.

McNamara and Maxidrive machine the area between the splines down to just below the root diameter so that the shaft is more flexible and resistant to shock loading in much the same way that a suspension torsion bar

flexes . Mercedes with their Unimog axles take this necking down practice very seriously and reduce the diameter of the short halfshafts more than the longer ones to give equal flexibility.

The other thing that US manufacturers tend to do is ''through harden'' their axles instead of case harden or induction harden them. I am not qualified to give an opinion on which method is superior, but Mc Namara shafts, at least the ones I had them custom make for me were induction hardened which apperently leaves a tough but ductile core.

Bill.

[dollythelw]

Bill whats your take on rifle boring case hardened shafts?

Im still sitting on the fence

[bill van snorkle]

Bill whats your take on rifle boring case hardened shafts?

Im still sitting on the fence

I am with you on that one Jez. I have read that if you bore a 3/8'' diameter hole in a shaft and polish the bore it will increase the fatigue life, and that the torsional strength is not reduced. That may be true, after all what is the torque capacity of a 3/8'' diameter grade 8 bolt ? about 50 ft lb? Not much on an axle shaft with a torque capacity of between 3500 and 8000 lb ft. I am basing those figures on Maxidrive and Longfields torque test results.

Bill.

[dollythelw]

alternatively rifle bore and then case harden? double the surface area and still keep the silky smooth caramel centre for a bit of flex

would be interesting to see a side by side test just to resolve the curiousity

[Michele]

The other thing that US manufacturers tend to do is ''through harden'' their axles instead of case harden or induction harden them. I am not qualified to give an opinion on which method is superior, but Mc Namara shafts, at least the ones I had them custom make for me were induction hardened which apperently leaves a tough but ductile core.

Bill.

Interesting.

Bill,

I had a chat with Ben before buying my RT axles,and I got it that it worked the other way??

Please enlighten me on this as I find it really interesting but sometimes I struggle to follow all the tech beside...

1541H (talking of the "standard" RT axles,not the 4340 nor 300M here)

is a pretty good quality steel good for relatively high strength axles at relatively low cost.

1541H is a low alloy steel,supplied already

induction hardened (H) and then the splines are cut after hardening. The

advantage of this steel is it is very cheap, and doesn't require

through-hardening after heat treating.

Here I quote Ben off an old email he sent to me.

He is actually somewhere in...er...Guatemala?Can't remember but some remote place so he can't jump in.

"That is different to EN25, AMS 6418, etc, which are relatively high alloy

steels, and must be machined in the annealed (softened) state, then through

hardened.

So what that means is that 1541H axles are cheaper and easier to make, but

probably lower strength to EN25 and AMS6418 axles (It is hard to get exact

strength info on 1541H). However, I think that because of the low cost,

they are very good value for money, and people give them a severe beating

and they seem to hold up fine. When I was at keith's place I saw some of

the axles, and they are very nicely machined, which makes a big difference

to axle strength - believe it or not. And on top of that, Keith is a very

nice guy to deal with."

4340 and 300M axles for Sals applications are another matter.

[Astro_Al]

As I understand it, rifle boring is a weight ONLY consideration - like drilling brake discs.

Can someone PLEASE show me an equation which has ANYTHING to do with surface area?

This keeps coming up.

I agree absolutely that strength losses are minimal when removing the centre - that's not an issue for me. It's the idea that it's somehow stronger because it has more surface area (cos you've added that of the inner bore to that of the outer surface) that I just don't believe.

I could be wrong, but I've never come across it.

Proof?

I also accept that it gives more surface area for the treatment to work on - if this is the point then we agree, but it is still the case that removing the central material decreases the strength, whether or not it is minimal.

Of course rifle boring AFTER treatment does not give extra surface area for the treatment to affect, since it's already too late...

Presumably polishing the centre bore is to ensure no surface imperfections which could act as stress raisers or help cracks develop / propagate.

Al.

[bill van snorkle]

Interesting.

Bill,

I had a chat with Ben before buying my RT axles,and I got it that it worked the other way??

Please enlighten me on this as I find it really interesting but sometimes I struggle to follow all the tech beside...

1541H (talking of the "standard" RT axles,not the 4340 nor 300M here)

is a pretty good quality steel good for relatively high strength axles at relatively low cost.

1541H is a low alloy steel,supplied already

induction hardened (H) and then the splines are cut after hardening. The

advantage of this steel is it is very cheap, and doesn't require

through-hardening after heat treating.

Here I quote Ben off an old email he sent to me.

He is actually somewhere in...er...Guatemala?Can't remember but some remote place so he can't jump in.

"That is different to EN25, AMS 6418, etc, which are relatively high alloy

steels, and must be machined in the annealed (softened) state, then through

hardened.

So what that means is that 1541H axles are cheaper and easier to make, but

probably lower strength to EN25 and AMS6418 axles (It is hard to get exact

strength info on 1541H). However, I think that because of the low cost,

they are very good value for money, and people give them a severe beating

and they seem to hold up fine. When I was at keith's place I saw some of

the axles, and they are very nicely machined, which makes a big difference

to axle strength - believe it or not. And on top of that, Keith is a very

nice guy to deal with."

4340 and 300M axles for Sals applications are another matter.

Material specs and heat treatment procedures is really something I have very little knowledge of and will happily leave to the specialists. Mal Story from Maxidrive once told me that the best materials in the world are useless unless the heat treatment is done correctly. He makes his shafts from Hituff which requires strictly adhered to procedures to get the best results.Apparently many heat treatment plants rarely follow those procedures if they are doing only one or two shafts so Mal has his done by the ton.

I agree that surface finish is important, and that it is very easy to compromise the strength and durability of shafts with nicks and scratches from lathe tools etc.

Bill

[dollythelw]

As I understand it, rifle boring is a weight ONLY consideration - like drilling brake discs.

Can someone PLEASE show me an equation which has ANYTHING to do with surface area?

This keeps coming up.

I agree absolutely that strength losses are minimal when removing the centre - that's not an issue for me. It's the idea that it's somehow stronger because it has more surface area (cos you've added that of the inner bore to that of the outer surface) that I just don't believe.

I could be wrong, but I've never come across it.

Proof?

I also accept that it gives more surface area for the treatment to work on - if this is the point then we agree, but it is still the case that removing the central material decreases the strength, whether or not it is minimal.

Of course rifle boring AFTER treatment does not give extra surface area for the treatment to affect, since it's already too late...

Presumably polishing the centre bore is to ensure no surface imperfections which could act as stress raisers or help cracks develop / propagate.

Al.

Weight consideration - no

Surface area for post boring case hardening - yes, look at the penetration depth of surface hardening processes, the theory seems sound but with more blingy materials available its an already surpassed idea

Proof? - pah, hence the comment it would be nice to see a semi scientific test

my satellite TV went wonky last night Al, what have you done to it?? I can't get any more of those specialist channels your recommended

[Bush65]

...1541H (talking of the "standard" RT axles,not the 4340 nor 300M here) is a pretty good quality steel good for relatively high strength axles at relatively low cost.

1541H is a low alloy steel,supplied already induction hardened (H) and then the splines are cut after hardening. The advantage of this steel is it is very cheap, and doesn't require through-hardening after heat treating...

1541 is a plain carbon steel, not an alloy steel.

If it is induction hardened before machining, then it would not be very good if necked down as that would remove the heat treated area. Also machining splines would affect the strength, but rolling would be ok.

As Jez and Bill have rightly pointed out, axles are best necked down between the splined sections.

...That is different to EN25, AMS 6418, etc, which are relatively high alloy steels...

These are classed as low alloy steels.

McNamarra uses EN26, which is superior to 4340 for axles - 1080 to 1230 MPa compared to 930 to 1080 MPa. Impact properties are much better as well.

McNamarra are not very good with computers and email - it is best to telephone. They also make the larger spindles, that will be needed for 35 spline axles.

Lara mentioned EN36 C. I am only familiar with EN36A, which is a good case hardening steel with a good core strength.

Well made 35 spline axles in 4340 or EN26 are going to be very strong. IMHO, more exotic materials would be a waste of money for these and attention to detail for fatigue strength is more important.

As for gun-drilling and strength advantages of the surface area in the bore. You will never convince me.

There is a weight advantage, but no strength advantage. Many years ago, drilling was used to advantage by removing material defects that usually occured near the centre. Steel manufacture has advanced a lot since then.

[Astro_Al]

>"Weight consideration - no" - you mean in this case? Cos it's certainly the reason for gun drilling most shafts (sports cars etc).

>"Surface area for post boring case hardening - yes"

Yes, ok sure, I agree. Though materials choice has to come first, followed by treatment (ok there are bound to be examples where treatment is more important than the difference between pretty similar materials...).

>"Proof? - pah, hence the comment it would be nice to see a semi scientific test"

An equation is all it would take... Just one - ANYTHING involving surface area. You don't even need to explain it, I just want one that exists!

My point is that the only advantage of drilling (ignoring weight issues and the fact that you WILL end up with a weaker shaft due to the removal of material) is that the treatment can affect the inner surface as well. If that's all you're saying then we agree.

There is no geometric advantage in drilling a shaft for strength.

>"my satellite TV went wonky last night Al, what have you done to it??"

Sorry, I was dusting behind a workstation in the control centre and my pinny got caught and accidentally pulled the plug... Won't happen again, I promise.

Anyway you haven't got time to watch satellite TV - John's got 6 wks to get his P.O.S. running. Without a few Jez-allnighters, he's got no chance...

Al.

[dollythelw]

easy kids, Im not advocating either camp, just canvassing opinion, my interest would be in someone proving something, theres enough magic fairy dust claims for products associated with 4x4s but not a heap of people backing it up

a/d2 x боллочж/r - I think that sums it up

you never said you'd been promoted to dusting? spent hours twiddling my knob last night, if I'd know you were on shift I'd have just called it quits

[DiscoDino]

I've been using the Jac Mac 30 spline axles in my "Banjo" Rover diffs for 3 years straight now and not one issue, no major twisting (rear long has a tiny twist...nothing major) and I can see another 2-3 years of work from them EASILY...Jac Mac are leaders in this sector, and they have a very good record...

Keith is a great guy, offers straight up products and knows his stuff, plus his rear Salisbury survived the OBC, so I am sure his axles are up to the task...

Close toss up...both great products and vendors.

[Astro_Al]

The problem is that whether or not it is an improvement depends on the material, the treatment, and the

shaft dimensions and bored hole diameter. There's not going to be a yes/no response to the 'is it better' question without quantifying it. Dammit.

a/d2 x боллочж/r - I think that sums it up

Aw man - why did no-one mention that before??? Well, that convinces me. Triple integrating over the shaft volume with respect to the modulus of elasticity, the second moment of area and the Higgs Boson density, I can only conclude that we should be using an alloy of chocolate for our shafts.

Well, ok, some of us already are...

Anyway, on to serious matters - yeah, they promoted me to dusting, but after the pinny-related plug catastrophy, I'm "lucky to still be here". I've been busted back down to checking the carpet tiles for dust mites and wiping the solidified 'liquid soap' off the nozzle of the dispensers in the bogs. Still, there's lots of promotion prospects from here.

Al.

[dollythelw]

dark or milk chocolate though?

I dream of the dizzying heights of dust mite monitoring , oh well back to the mucas harvesting for me

[Astro_Al]

dark or milk chocolate though?

Dark - it's the ratio of cocoa that gives it higher torsional stiffness and more uniform martensitic grain structure...

Do I have to tell you everything?

Al - currently experimenting with cocoa-free white chocolate shafts.

P.S. Sorry d-90 - what the hell happened to your thread...?