PUMA - Drivetrain Upgrade

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Originally Posted by wagoo

Drover, Do you know if the outer splines on the halfshafts and matching drive flanges are longer than standard? The longer splines on the earlier 110's to 200TDIs lasted a very long time even allowing for that they were oil lubricated.
Wagoo.

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I have the 'x type' 10mm longer axles and flanges from hytuff in the back of my 90 which are running oil lubed and I am not totally happy with them.

They already have a noticeable amount of slack (compared to when they were fitted) in the splines between the axle and flange.

I am hoping they dont get any worse but I am fully expecting one to fail at some point.

Admitedly the car gets hammered but they have only been in for about 20k km or so.

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Originally Posted by isuzurover

I didn't realise we were talking money-no-object options here :D

They were probably gun drilled to save weight as well?

Bush65 designs such items for a living AFAIK (or used to). I am sure he will be back soon to add more to this.

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Come on Ben .How much more expensive would it be to knock the diameter down? The finish on Daves shafts seems adequate enough. I'm only thinking how to give those marginal Rover crownwheels and pinions a sporting chance.
Wagoo.

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Originally Posted by Psimpson7

I have the 'x type' 10mm longer axles and flanges from hytuff in the back of my 90 which are running oil lubed and I am not totally happy with them.

They already have a noticeable amount of slack (compared to when they were fitted) in the splines between the axle and flange.

I am hoping they dont get any worse but I am fully expecting one to fail at some point.

Admitedly the car gets hammered but they have only been in for about 20k km or so.

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Have you checked the housing for straightness? The best shafts and flanges in the world won't last much longer than originals if the housing is bent.
Wagoo.

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Originally Posted by wagoo

Come on Ben .How much more expensive would it be to knock the diameter down? The finish on Daves shafts seems adequate enough. I'm only thinking how to give those marginal Rover crownwheels and pinions a sporting chance.
Wagoo.

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What evidence do you have that reducing necking down the axles will reduce stress/fatigue in ring and pinions???

I agree it wouldn't be much more expensive - however the big question is would it make a difference to the life of any components in practical terms?

Honing/polishing to improve the finish would be expensive though:
https://www.aulro.com/afvb/images/im...011/08/765.jpg

Hey Guys,

Very interesting this topic and certainly it is good information to learn with, this info is straight from the ashcroft web site....

All our heavy duty halfshafts carry a 5 YEAR breakage warranty

We manufacture three types of heavy duty halfshaft to fit the front and rear axles of the Range Rover, Discovery and 90. We also supply shafts to fit the late type (2003 onward,) 110 rear axle. Our shafts are made from '4340' alloy steel. We have also made some design improvements to remove the stress concentration which typically causes failure at the diff end, this allows the shaft to flex along its length absorbing much of the shock loads.

We are interested in 3 things :

1) torque applied, 2) total twist, 3) Elasticity,

The graphs below show the results of the testing we have done on the front and rear landrover halfshafts.

https://www.aulro.com/afvb/images/im...011/08/763.jpg

https://www.aulro.com/afvb/images/im...011/08/764.jpg

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Originally Posted by wagoo

Have you checked the housing for straightness? The best shafts and flanges in the world won't last much longer than originals if the housing is bent.
Wagoo.

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I am pretty sure the housing is straight. The originals being a 90 were the one piece ones. They lasted generally ok, apart from a couple of instant failures.:D

For the rears next time I will try Ashcroft or Rovertracks (who's front end I have and cant fault)

[QUOTE=isuzurover;1528698]What evidence do you have that reducing necking down the axles will reduce stress/fatigue in ring and pinions???

Ben,I can't believe you asked that question.Tell you what. Just between you and me, If you want to delete it, I'll do the same on this reply;) .
One doesn't need to be a rocket scientist to work out that a shaft that can flex to absorb shock loadings, such as when a spinning wheel suddenly finds traction, will also reduce the impact shock on the rest of the drive train that is supplying torque to that shaft. It's similar in a way to how the spring loaded slipping clutch on a tractor mounted slasher protects the driveline when the blades strike a hidden rock or tree stump. Or why the flexible torsion bars on my Holden Jackaroo prevent me and the rest of the vehicle from disintegrating when the front wheels strike a bump.
As I mentioned earlier, the finish on Daves shafts is probably good enough without requiring honing and polishing. After all, the torsion bars on the jackaroo weren't polished and live in an unfriendly environment, and they've flexed millions of times in their 400.000 km lifetime.
Wagoo.

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Originally Posted by wagoo

Wayne. What is now common practice? Wasting down or not doing so? To my knowledge most of the popular US shaft makers don't do it,probably for reasons of cost. But more engineeringly inclined outfits such as Daimler Benz for example, waste down the Unimog halfshafts.
They are so particular about itin fact that shorter shafts are wasted down more than the longer ones so that torsional flexibility is equal over all 4 shafts.
Wagoo.

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Bill

As you mentioned,not waisting down.

Wayne

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Originally Posted by Psimpson7

I am pretty sure the housing is straight. The originals being a 90 were the one piece ones. They lasted generally ok, apart from a couple of instant failures.:D

For the rears next time I will try Ashcroft or Rovertracks (who's front end I have and cant fault)

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I also have Keiths (Rovertracks) axles and Cvs in the front of my 110 and run 35's and certainly don't take it easy,and I can't fault mine either.I have already twisted a set of Maxi rear axles and flogged out a set of rear drive flanges.I now have a set of Hi Tuff axles and flanges,so will be interested to see how they last.When I had my axles and diff centre out,we checked the housing and it is straight.

Wayne

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Originally Posted by wagoo

I haven't kept myself completely up to date on axle shaft technology, but if Dave Ashcroft visits this thread, would he care to comment on the decision not to waste down the shaft diameter between the splined ends, to alllow the shaft to torsionally flex evenly over its entire length, instead of concentrating the torsional stress at the smaller cross sectional area of the splines? Have new material specifications and heat treatment techniques rendered this practice obsolete?
Would anyone else with relevant knowledge care to comment?
Wagoo.

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Hi Wagoo,

ours are waisted, the diameters are reduced over about 50mm with a big rad at the shaft end of the taper so it's not obvious to the eye but they are waisted exactly for the reasons above, to help get the stress away from the splines and allow them to flex,

Dave