LT230 perspective

[Ancient Mariner]

Have noticed a fair bit of chatter about the strength of shafts adapting various
gearboxes to the LT230 so have posted this to put things in perspective.The shaft will have a minor diam of aprox 1.035" unless the gear is broached to a bigger size .Although this results in a stronger shaft you also finish up with 2 odball parts.A standard size shaft is aprox .060" smaller than the LT230 output
shaft at 1.095".The adaptor shaft has to take the torque of the engine multiplied
by the first gear ratio where as the output shafts have to cop another 3 .? again
I have been running Ford 9" diffs for the last 40+ years and although I have broken every Series Landrover transmission part it was possible to break:mad: I have never broken a 9" pinion shaft:D wich is the same spline as the LT230 output shafts given the loads are basically the same it all boils down to the quality of the steel and the heat treatment of Cheese LR or steel Ford:wasntme: To summarise an adaptor shaft if made out off 4130 with no stress raisers and heat treated should be strong enough for the rest of the driveline Some shaft minor Diam sizes All approximate

Adaptor shaft 1.035"
LT230 outputs 1.095"
Ford 9" pinion 1.095"
LR 23 spline axle 1.105"
LR 24 spline axle 1.120
Ford 31 spline axle 1.275

AM

[Dougal]

I think you get a better result of max load when working from traction back through.

For example in low range it's unlikely you're going to be putting 3.3x the torque to the outputs as you just don't have the traction.
Back when I did the calcs for the LT230 input shaft I used high range as the worst case.
My results were here: http://www.aulro.com/afvb/isuzu-landy-enthusiasts-section/90033-isuzu-msa-gearbox-lt230-3.html#post1095318


I don't believe your shafts will stand up if not hardened. I forget the exact hardness mine was done to, but I was looking for a material with at least 1000 MPa yeild, the concern being stress concentration causing fatigue at the start of the splines.

The final material I received had a yeild when hardened of almost 2000MPa. Overkill, but it boasted minimal distortion in heat-treatment and the cost difference was minimal.
I received quotes from $NZ350-750 to make my shaft, in the end the workshop that started didn't finish it, I had to do the final machining and heat-treatment. Total cost around $NZ600.

I'll see if I can dig up my original calculations, but the FEA study I ran at the time shows 650 MPa bulk stress with 1450MPa max stress concentration at the start of the splines. The computer simulations tend to exaggerate stress concentration as computer modelled geometry tends to have sharper transitions than actual manufacturered parts.
This is with 2000Nm applied to the shaft. 2000Nm was the shaft torque required to light up wheels on tarmac. It represents 345Nm applied by the engine in first gear or 666 Nm applied in second gear.

[Ancient Mariner]

Hey Dougal no calculations done just an example to show if you have doubts about the strength of the shaft think about what the TC out put shafts and axles
have to cop:( with only a small increase in size and a probably inferior material:( GBT


AM