Thread: 4BD1T MSA5G Range Rover Classic Outcast Adaptor

Originally Posted by isuzurover

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The radius at the transition could have been greater, but I suspect misalignment, heat treating, or the material.

I'm not a Mech. Eng., but I'm close enough to know a little about shaft design. The transition in radii where the shaft broke is just too abrupt; as others have said.




Kt - stress concentration factor.

I did run the numbers, but as it was a rough calculation based on eyeballing the picture above I won't post them. If you're getting a new shaft made, consider putting a larger radius in that transition. It may well have been misalignment, heat treating or the material; but that shaft design would've exacerbated the problem.

What are the views regarding the transitions on the Outcast shaft, putting aside the notch issue?

http://www.aulro.com/afvb/isuzu-land...adaptor-4.html

Originally Posted by workingonit

What are the views regarding the transitions on the Outcast shaft, putting aside the notch issue?

http://www.aulro.com/afvb/isuzu-land...adaptor-4.html

Sheldon has followed good engineering practice by reducing shaft diameter to the root diameter of the splined section. This has however caused a larger transition on the other side.

The outcast shaft has not. If it ever fails it will be at the base of the splined section.

You would need to run an FEA analysis to work out which is better.

Given how easily Damien's shaft failed, i am sure the problem is heat treating rather than design. Do I remember correctly that Sheldon originally wasn't going to heat treat until Bush65 convinced him otherwise?

Originally Posted by isuzurover

Sheldon has followed good engineering practice by reducing shaft diameter to the root diameter of the splined section. This has however caused a larger transition on the other side.

The outcast shaft has not. If it ever fails it will be at the base of the splined section.

You would need to run an FEA analysis to work out which is better.

Given how easily Damien's shaft failed, i am sure the problem is heat treating rather than design. Do I remember correctly that Sheldon originally wasn't going to heat treat until Bush65 convinced him otherwise?

Looks like they've just copied the r380 mainshaft splines; spline root tapers to spline crest diameter gradually. r380s don't seem to break there, so I wouldn't be overly concerned about it.

There appears to be a slight step at the base of the splined section to the tapered section (is there?), but the difference between radii is tiny if there is one; so again I personally wouldn't be too concerned. From there back to the flange it looks very strong.

All of this is ignoring the metallurgy though, so only at most half the story.

Thanks for the observations.

It is interesting that good design principle would require reducing the shaft to spline root diameter, unless intended to fail at this point to protect other parts of the machine. I would have thought you would take the spline the whole length for the small added strength, taking into account radius requirements.

The Outcast unit is made for the long spline input gear, but should suit the old short spline as well. Don't know what spline length Sheldons was for.

Made some inquiries to find that no one cuts gears or heat treats in Darwin.

So made an inquiry with a small gear cutting company is Brisbane. I don't know them from a bar of soap. Part of their business involves making gears etc for vintage vehicles, which is what attracted me. The owner rang me back, South African, and easy to talk to. Ancient Mariners design is well within their capabilities. They can heat treat and arrange cryo treatment. They normally prefer customers to specify alloy type, hardnesses required etc, but this can be resolved other ways. I pressed and pressed the poor guy for a ball park, but all he could say is a one off would be under a thousand. Being primarily a CNC workshop he said the price would drop dramatically for a number of units. A one off would more likely be cut conventionally rather than CNC. The other issue is warranting. There have been a couple of instances of guys ordering a part, and bringing it back broken because they didn't tell him they were putting it behind 300-400hp engines. In our situation we are installing using casings and alignment that he has no control over.

If and when a supplier is found I would buy a flange and several shafts. Would AM have any intellectual property right issues - Dougal once complained about this.

As for poor Damien. Option one I guess is to sell it as is (no locomotion); part it out; buy an Outcast shaft and sell the vehicle running or trial it himself and maybe boost his confidence to keep it; persist but go straight to an AM design.

Myself, I'll persist with the Outcast unit and trial it locally for a few thousand kms heavily loaded, but have the standby AM unit in the tool box. Waste of money? Already have a second 4bd1 stage 1 to tinker with - just need another MSA gearbox to saunter by.

Originally Posted by workingonit

...I would have thought you would take the spline the whole length for the small added strength, ...

What makes you think this would be stronger?

I am flattered that any one would consider using the shaft just be a where that no calcs were done as it would require more grey cells than I pocess however 50 years of building adaptors for myself and customers plus repairs and mods to all sorts of machinery you get a feel for what works and what don't The actual shaft could be improved by making the seal surface a press fit sleeve
If you have your outcast apart I would make a plug as mentioned in my other post and check the TC fits on the dowels for peace of mind

AM

AM.

What? You're now trying to wiggle out of any responsibility because you didn't do any calcs!

Just had a look at the Outcast casing and LT230 to remind myself. The LT230 has a solid steel dowel locator and hollow steel locator (guess this is the terminology). Both these locators are accommodated for on the Outcast unit. I'll have chase up your thread.

How does the press fit oil seal ring improve the set up as opposed to machined in situ - good though for acting like a speed sleeve, replace seal replace sleeve.

Isuzu.

Mine is the comment of an uninformed ignorant. More to the point why wouldn't it strengthen it?