KAM "Fuseable Stub shafts" CV Conversion Kits - Please respond !

[Hybrid_From_Hell]

Morning All,

As many of you might know, Kam Differentials Ltd, as a company is now no more 

The name stays as a trading name, but will probably be absorbed into the Terrafirma name over time.

However, The KAM CV kit with fuseable Stub shafts - designed to shear before you destroy your Half Shafts CVs and Diffs etc, have been discontinued and have been replaced with 1 x Piece CV in direct competition to I guess Ashcrofts ...

This means they have stopped manufacture of the Replacement "Fuse Stub Shafts" which being designed to break and protect drive train....

So, this means that now, if you break one - no spares are available 

Even with the vast stock of KAM Differnetials Parts we have purchased - I have one of each, and here's the question.

I am thinking of having these potentially remade, and thus stock ...
I have checked with Allmakes and been given a green light that its OK to do so.

So, my big question before I sink my capital into producing these units is what is the market ?.

How many here would say "Thank Gawd and yes I would like to see replacement stock ?"

My worry is I sink capital into a project / stock and end up with no demand !!!!

So, a sort of litmus test .....how many here run this system ?...and sorry if the above news is a shock  !

Thought please  ?

[Soren Frimodt]

I have a set of these, and the only thing I dislike is the fuseable part, Even the HD ones break too early imo. So I would be interested but they would have to be proper strong, else I might as well run 10 Spline RRC setup which also has the fuseable part but are much cheaper and easier to come by. And just as strong as the stock Kam setup

 

[Snagger]

15 minutes ago, Soren Frimodt said:

I have a set of these, and the only thing I dislike is the fuseable part, Even the HD ones break too early imo. So I would be interested but they would have to be proper strong, else I might as well run 10 Spline RRC setup which also has the fuseable part but are much cheaper and easier to come by. And just as strong as the stock Kam setup

 

Are those the domed drive flanges with integral stub shaft, used up until around the introduction of the 300Tdi, Soren?  I had no idea they were fusible.

[Soren Frimodt]

5 hours ago, Snagger said:

Are those the domed drive flanges with integral stub shaft, used up until around the introduction of the 300Tdi, Soren?  I had no idea they were fusible.

Yup, exactly those. Well when you have Ashcroft shafts stock (but genuine) CV's they are the weak link. I broke 6 of them over a 2 year period and my mate running the Kam's that I now have, also broke 6 over the same period. Running the same 35"x13,5 Krawlers both on RRC's. To be fair though his was a bit heavier and had a bit more power. But on the other side his was an auto which tends to be easier on things. So there really isn't much difference between the two, but the price difference when we broke down was huge!

Edited December 6, 2017 by Soren Frimodt

[Daan]

I personally don't know anyone who uses these. I suppose if you don't offer the CV to go with it, it's a bit of an incomplete solution, as a business to offer and potentially not many people buying spares for their old fashioned KAM setup. If you just investigate the option and have a solution ready than someone who asks for it could order it as and when required (like KAM used to do...) If you were to do the whole hog, maybe a product improvement  would be worthwile: That notch in the shaft is just a really bad solution for fatigue. If you are going to do it, machine it down to the chosen diameter over its full length. Then the next question, what do you do at the back? I know there is less to go wrong in the back axle, but the abuse the rear axle gets is much more than the front, so a solution here would be more welcome. The problem in general is, people want to buy stuff that does not break. Which makes this solution a bit of a non starter, hence very few people going for it.

For what its worth, I run standard (weak) 24 spline flanges, as opposed to strengthened ones, as this is indeed the part I want to go wrong. Its much easier (and cheaper) to swap the drive flange than it is to replace the KAM shaft (or the 10 spline flange as Soren suggested) , it still needs extracting from the CV, and what if you cant get it out? 

Daan

[Snagger]

7 hours ago, Daan said:

I personally don't know anyone who uses these. I suppose if you don't offer the CV to go with it, it's a bit of an incomplete solution, as a business to offer and potentially not many people buying spares for their old fashioned KAM setup. If you just investigate the option and have a solution ready than someone who asks for it could order it as and when required (like KAM used to do...) If you were to do the whole hog, maybe a product improvement  would be worthwile: That notch in the shaft is just a really bad solution for fatigue. If you are going to do it, machine it down to the chosen diameter over its full length. Then the next question, what do you do at the back? I know there is less to go wrong in the back axle, but the abuse the rear axle gets is much more than the front, so a solution here would be more welcome. The problem in general is, people want to buy stuff that does not break. Which makes this solution a bit of a non starter, hence very few people going for it.

For what its worth, I run standard (weak) 24 spline flanges, as opposed to strengthened ones, as this is indeed the part I want to go wrong. Its much easier (and cheaper) to swap the drive flange than it is to replace the KAM shaft (or the 10 spline flange as Soren suggested) , it still needs extracting from the CV, and what if you cant get it out? 

Daan

Hence the groove to ensure failure happens before the splines become twisted, ensuring easy removal and replacement.  Get rid of the groove and the ease of shearing, and you are back to damaging CVs and diffs.

[missingsid]

IMO using the 10 spline mushroom as the fail point is not a great idea, when I installed my Nige built front diff with zero discernible backlash the axle had about 30 - 50 deg of back lash from the 10 spline mushrooms!

[Soren Frimodt]

1 hour ago, missingsid said:

IMO using the 10 spline mushroom as the fail point is not a great idea, when I installed my Nige built front diff with zero discernible backlash the axle had about 30 - 50 deg of back lash from the 10 spline mushrooms!

I've had that too, but that was the splines in the CV's that were worn..  

[Snagger]

5 hours ago, missingsid said:

IMO using the 10 spline mushroom as the fail point is not a great idea, when I installed my Nige built front diff with zero discernible backlash the axle had about 30 - 50 deg of back lash from the 10 spline mushrooms!

That would be wear of an old part, not a design specification or manufacturing issue.  The fusible shafts would do the same if sufficiently worn.  You can't rebuild a diff and class the entire axle as new.

[Daan]

14 hours ago, Snagger said:

Hence the groove to ensure failure happens before the splines become twisted, ensuring easy removal and replacement.  Get rid of the groove and the ease of shearing, and you are back to damaging CVs and diffs.

But this: If you are going to do it, machine it down to the chosen diameter over its full length.

 

At least than a failure is due to overloading, not fatigue.

[Soren Frimodt]

I think you're quite right on this Daan, and this is probably why it was no stronger than my 10 spline. Because that too has a sharp weak point at the beginning of the splines (as all 10 spline axles do) so the fatigue rate is probably very similar. The last ones we got from KAM wasn't like this though. No groove were cut so we thought great! Until it broke and we saw that it was hollow instead!  

[Snagger]

12 hours ago, Daan said:

But this: If you are going to do it, machine it down to the chosen diameter over its full length.

 

At least than a failure is due to overloading, not fatigue.

But wouldn't doing that likely just result in twist without shearing until a much higher load is reached that cold cause damage elsewhere, not acting as a fuse?  I suspect it would introduce far more variables into their operation and make their shearing less predictable and manageable.  I'm only making guesses, but quill drives in turbine engines have similarly cut fuse grooves rather than thin shafts, and I'm pretty sure it's for good reason.  The guys at KAM seemed to know what they were doing.

[missingsid]

This may have been said but isn't another reason for the groove is to ensure that the break comes where you can still access the internal thread to remove it?

I accept both replies on my 10 spline comment, both my CV and mushroom link were old and indeed with investigation the remaining splines in th CV were tight but too deep to be useable.

 

 

[Snagger]

If the waisted section is thinner than the inner diameter of the splines section, like the groove is, then that shouldn't happen, in theory...  But the torsional forces are the same whether you have a 1mm groove or a long section of that diameter.  I'n not sure how extending the groove into a length is going to reduce stresses and thus fatigue on the shaft.  As long as the groove is radiused, not sharp cornered, I don't know whether waisting has an advantage over grooving.

I suspect preventing the splines from twisting in the gear is why the Salisbury shafts were waisted on the 300Tdi and Td5, as opposed to the straight shafts of the 200 and earlier.  But waisting a shaft that length rather than retaining the full diameter and grooving it may have more tangible weight and  production (materials) cost benefits.

[Soren Frimodt]

Indeed it would be stronger with the entire length of the shaft being smaller, and that's exactly what I wan't!  My point is that so long as it is no stronger than stock LR parts which I can find used for very little money, and everywhere, even on a Sunday. Why spent on something more expensive and exotic that would require you to have a considerably more expensive stock just laying i your shed until the next time you break something? Seems rather pointless in my simple mind  

[AV8R]

Just my humble opinion: I think the theory about the "fuse" is that if the drivetrain is overloaded the fuse will break. And like in an electrical circuit, you take away the overload, change the fuse and everything works like it was before.

I watched a friend's front outer halfshaft snap in an offroad situation. He parked the wheel on a treestump to keep the oil inside. Got the broken part out, the fracture in the fuse was very clean. Just two parts to remove. Put in new "fused" shaft. Continue trip within 10 minutes.

With unbreakable shafts, what else will break and how easy will it be replaced ? I think that 's what the KAM fuse is about. Again, just my 2 pence worth.

[Daan]

7 hours ago, Snagger said:

If the waisted section is thinner than the inner diameter of the splines section, like the groove is, then that shouldn't happen, in theory...  But the torsional forces are the same whether you have a 1mm groove or a long section of that diameter.  I'n not sure how extending the groove into a length is going to reduce stresses and thus fatigue on the shaft.  As long as the groove is radiused, not sharp cornered, I don't know whether waisting has an advantage over grooving.

I suspect preventing the splines from twisting in the gear is why the Salisbury shafts were waisted on the 300Tdi and Td5, as opposed to the straight shafts of the 200 and earlier.  But waisting a shaft that length rather than retaining the full diameter and grooving it may have more tangible weight and  production (materials) cost benefits.

The strength will be the same, however, the groove is a stress raiser, whereas the wasted section is a gradual change in section (if it is made with a nice large radius tool); meaning that the groove will fail sooner as locally the stress is much higher (it will fail at a lower breaking point due to fatigue). There is no give in it. if you waste it over the whole length it will flex much more, taking out big torque spikes. 

I understand what is being achieved with the fuse idea, but if you know the limits of the axles and upgrade everything else, I cannot really see the point. Don't go bigger than 35" tyres with ashcroft stuff and it will live in my experience.

[muddy]

I must say I haven't heard many reports of Ashcroft stuff failing until you get into the situation where you are really over asking the axles. As standard everything is roughly equally choclatey and after spending some wonga with dave and nige everything is equally useable. 

 

If you have broken say your third cv within the warranty period surely you have exceeded the limitations of the rover axle to add there's probably not much left of the rover either.

 

sorry it's not really helpful but I always thought these jam fuses were a solution to a problem that didn't really exist. You'd be better making a gkn overload style Hub that replaced the stub!

 

will.

[Soren Frimodt]

So in essence we can conclude that with the KAM setup you pay Premium for something not much stronger than stock BUT with one easy to get to fuse, that's also quite expensive to replace? Still seems silly to me when Ashcroft etc just holds up or if you are on a budget, stock is almost as good as the KAM you just have to be prepared to do a bit more work when it breaks..

Anyways we are not really answering Nige's question are we?  

[Hybrid_From_Hell]

Ok me 2p worth

 

This all sorts of kicks in when you run MUCH bigger tyres / BHPO / competitions ...and or any of these esp all 3 !

 

Diffs like a std 2 pin break

so you upgrade to a 4 pin or a locker

Then shafts break

so you upgrade to ashcroft / Kam (or did !) syhafts

Then CVs break

Additionally LATE LRs have the daft and serioulsy weak 32 spline CV - you can't upgrade shafts / CBs for these = so its a big jump

 

23 spline CVs there are variuous units

 

LONGs - fitted to early 100s etc

shorts - later units

Ealy no stub CV 60662 23 one end 10 the other with stubs retc as outlined above.

 

I ran 606662s for years - with ashcroft HD shafts and stubs with 10 spine ends, then upgraded to Qualiffe stubs (sadly NLA) which was a seriously strong unit

 

Standard CVs long or short are also quite strong - I would say 606662 and stubs are better

 

But you can go for Ashcroft CVs, stronger than any of the above, but, nothing is unbreakable, and yes they can break - even if rarely

IF they break in a competition it is game over unless you have spares and time to sort.

 

The KAM unit was like the above, made same factrory ! but with the fuseable link stub shaft

 

This is where is got silly

When I was at KAM there was madness in cutting grooves in stubs to make then weaker - for peeps on std Half shafts - madness !

These stubs snapped like carrots, eventually I was saying to people do NOT buy these and have the stubs reduced in OD, buy shafts and CVs and full uncut stubs - which where up there with Ashcrofts.

Then someone decided to make in a lessrer grade steel, these uncut alsio snapped like carroits !

Then we have them remade in original metal etc and even had a few dsets of 300M made - and these were the best. Lasrer etched with KAM 341 etc on them - as tough - poss tougher than ashcrofts and fiv=xable is seconds.

 

The CVs were tested in USA on full lock and exceeded 15,000Nm and that was the max the machine could test.

The CVs rartelt fail, when they did it was iften IMHO poor fitting (shimming correctly was needed) and the lesser stubs breaking and destroying the CV !

 

It was a great product if only attention to detial and less frigging about on specs and more quality had been shown.

 

Sad, they offerred I think another Option to the market - which is good, choice is good

 

Prob I have is I would need to invest is very spendy tooling to make these and they would be expensive...

 

Its still a maybe - interest is high from n ay forums and fedabcks, but that might drop when the prices for remaking are known

Hope the above background / info usefull 

 

N

[Snagger]

That throws a lot of context on the matter, Nige.  Interesting that they cut the groove to protect standard shafts.  Like you said, that's madness - they should only have been cut to a depth that protects CVs, uprated shafts and the transmission, as that would have allowed decent torque without premature stub failures.

[Soren Frimodt]

Indeed, great info Nige! That explains my experience with the lack of strength. But seeing as the CV itself is no longer available either, why not just make some shafts that has no in-builtweakness at all and from a proper material so that the strength is similar to Ashcrofts. And then when the CV's eventually fail people can replace them with Ashcrofts or similar and move on?

[dangerous doug]

Just putting it out there..... if you were to make the full cv and not just the stub the market would expand for you, at the moment you’ll only be catering for people who have the cv.....which is a limited amount. I guess then you would be in direct competition with ashcroft which I understand you wish to avoid but maybe there is a collaboration to be had there with the relationship you have With them?

[Ex Member]

Personally I think the idea made a lot of sense, if it had been executed differently.  It needed to be based on a system design.  It would assume that you had a suitably strong differential, with 24/23 spline 4340 halfshafts and a 4340 CV joint.  The stub would then have a well radiused and short waisted section near the outside and a normal 24 spline drive flange.  The waisting would be as little as needed to safely prevent spline, CV or halfshaft damage.  Do not use an integral flange to reduce cost.

[Hybrid_From_Hell]

Absolutely 100% agree Red90.

Prob was it wasn't

But easi;y could have been. 

I have looked into :

 

Make CVs and Stubs

Making "Fuseable" stubs suitable for HD / ashcroft shafts etc tad weaker than

Looked at making an upgrade to super strong Stubs a la 300M etc.

 

Probs are

Make CVs and Stubs

Prob here is capital outlay, fgrom memeory tyhese were aroun £180 each to be made plus shipping etc, and stubs cicra £30 each. Even If I did a low production run of say 50 units, thats 50* £180 + £30 x 100 stubs (3 per kit) =- an outlay of £12,000 - and being a low CNC run prices will be higher. Quite simply I don't have that sort of capital ! then the question of sellong them ....

Making "Fuseable" stubs suitable for HD / ashcroft shafts etc tad weaker than etc

Maybe. could go for a low production run of stubs, say 50 stubs, price due to low volume is looking at to me circa £70...£3500, still a big lump of capital to me, and I have to question if I make say £10 on eaqch, how many peeps are going to buy stubs that break at £80 ?...yes a few but thats £3500 held in slow movingf stic, and a total profit of only £500...

Looked at making an upgrade to super strong Stubs a la 300M etc.

Maybe, but now 2 problems. Costs of 300M stubs vs the above, and then even lesser volumes as won't break - in effect will just help peeps not have KAM CV kit unusable... Costs here are horrendous for say run of 25 units ..

 

Lastly Spline cutting LR use a stange profile, so also looking at haveing to by a special tool for the CNC, and it will be a one off tooling vs reoplaceable tips, and thats a few £100 too .....

 

Hmmm

 

Ots a close balamce between feeling it should be done for the people out there now stuck vs a commercial product with legs that might MIGHT make me a few quid, or a dead duck I should just let alone...

 

Still thinking tho

 

N