Allison to LT230 Spud shaft

[Gaz69]

Hi Guys,
I have shoe horned in a duramax into my defender and adapting the allison to the LT230. I have all ready made the adaptor out of billet alloy but have yet to sort out how to match the 29 spline of the Allison to the 10 spline of the LT230. I see i have 2 choices 1. Get new longer output shaft made for allison and get the LT230 input gear splined (broached) the same. 2. Get a spud shaft made. My question is which is going to be the best option? I know mid 90's there where issues with input gear wear until they where cross drilled but is a 10 spline strong enough? This motor puts out 360HP and just under 900nm of torque so i want to get it right 1st up. Have spoken to a couple of machine shops here in OZ and US but most of them do not know much about the LT230 so thought i would hit you guru's up. If a spud shaft is going to be strong enough i would prefer that as i do not need to modify the auto or transfer which keeps it simple.


TIA
Garry

[Bush65]

Do whatever is easiest.

I looked at adapting an LT230 to an Isuzu bearbox. I wanted it as short as possible and had established that it was possible to cut a matching spline inside the input gear. But in the end it wasn't going to work because the front extension housing of the LT230 would foul the side of the gearbox housing.

I ended up using an Atlas t/case, but had to make an input shaft to suit the Isuzu box. If I had the wheelbase I would have made a spud shaft for the LT230 or divoece mounted the LT230.

From the FAQ sticky thread near the top of this forum is some information on Land Rover axle strengths. The 10 spline in th LT230 is the same as the old 10 spline axles. It states there that the torsional strength of a 10 spline axle manufactured from Hi-tuff is 4160 ft lbs - so possibly just adequate for you Duramax (but I'm guessing at your low gear reduction).

If there is enough meat in the input gear, I would have it re-splined to suit the Allison output shaft.

BTW it will be good to see more about your conversion - good luck.

[Gaz69]

John,
Thanks for your input. I did not realise that the 10 spline was the same as the early axles. Maybe i am better to get a new output shaft made and the input gear resplined. I think i have enough meat to respine the input gear and that saves me worrying about it if i give it curry. Shifting houses at the moment so might post a build thread here and Aulro in a week or so. Got the engine started day before christmas so was good to hear it finally fire up.

Cheers Gaz

[stuee]

Im keen to see how you shoehorned a duramax into a defender Heard many a person say they are too big for patrols and cruisers. And so I don't look like a complete idiot we are talking about the GM 6.6L td duramax aren't we??

[Strange Rover]

John,
Thanks for your input. I did not realise that the 10 spline was the same as the early axles. Maybe i am better to get a new output shaft made and the input gear resplined. I think i have enough meat to respine the input gear and that saves me worrying about it if i give it curry. Shifting houses at the moment so might post a build thread here and Aulro in a week or so. Got the engine started day before christmas so was good to hear it finally fire up.

Cheers Gaz

I have no idea of how big the allison out put is but you may be able to get a hollow tube splined internally to suit the allison and then machine out the lt320 input gear and press and weld the hollow tube into the lt230 input gear.

This does a few things...it adapts the lt230 to the correct spline and it can also extend the lt230 input gear spline to reach the allison output shaft...thats if the stock allison out put shaft is too short to reach into the lt230 input gear.

Welded correctly I carnt imagine you will have any strength issues...the splined hollow tube that is pressed and welded into the lt230 input gear can have a decent outside diameter.

This way you leave the allison stock and the only mod it to the lt230 input gear.

Sam

[Gaz69]

Strangerover wrote

I have no idea of how big the allison out put is but you may be able to get a hollow tube splined internally to suit the allison and then machine out the lt320 input gear and press and weld the hollow tube into the lt230 input gear.

This does a few things...it adapts the lt230 to the correct spline and it can also extend the lt230 input gear spline to reach the allison output shaft...thats if the stock allison out put shaft is too short to reach into the lt230 input gear.

Welded correctly I carnt imagine you will have any strength issues...the splined hollow tube that is pressed and welded into the lt230 input gear can have a decent outside diameter.

This way you leave the allison stock and the only mod it to the lt230 input gear.

Sam

Thanks Sam. I will do a measure up of the spline later. Have got a plate on the at the moment so i could start it and not lose oil. I know that the diameter of the allison is larger that the LT230 Input gear. This may be my best option yet. I will post some measurements next week of both and see what you guys think. Regards Garry.

[Gaz69]

stuee Wrote:

Im keen to see how you shoehorned a duramax into a defender Heard many a person say they are too big for patrols and cruisers. And so I don't look like a complete idiot we are talking about the GM 6.6L td duramax aren't we??

Yeah it is a tight sqeeze. Engineer wanted me to keep the weight low and back so have cut the corners off the footwells and made a body lift. I have mounted all the engine and gear box/transfer so does fit. Suprised myself how well it does fit, but i love proving people wrong when they say it can not be done. Yeah the engine is out of a 2006 Chevy Silverado twin cab.

Cheers Gaz

[Slunnie]

stuee Wrote:

Im keen to see how you shoehorned a duramax into a defender Heard many a person say they are too big for patrols and cruisers. And so I don't look like a complete idiot we are talking about the GM 6.6L td duramax aren't we??

Yeah it is a tight sqeeze. Engineer wanted me to keep the weight low and back so have cut the corners off the footwells and made a body lift. I have mounted all the engine and gear box/transfer so does fit. Suprised myself how well it does fit, but i love proving people wrong when they say it can not be done. Yeah the engine is out of a 2006 Chevy Silverado twin cab.

Cheers Gaz

You couldn't just open up the interior with larger humps etc rather than body lift?

[KiwiBacon]

The last time I got a spud shaft made, this was isuzu to LT230, I figured it to be good for around 2000Nm. The issue is stress concentration around the splines.
In the end I was able to get a much stronger material than I planned for, but 2000Nm was still calculated as the torque in high range sufficient to light up all the tyres on tarmac.

Shock loading and bigger tyres will put your torque above that, but bigger tyres are often accompanied by lower ratio diffs which mitigates the effect.

With more engine torque you'll simply be able to fry tyres in higher gears, the torque at the spud shaft will be same.

[Slunnie]

The last time I got a spud shaft made, this was isuzu to LT230, I figured it to be good for around 2000Nm. The issue is stress concentration around the splines.
In the end I was able to get a much stronger material than I planned for, but 2000Nm was still calculated as the torque in high range sufficient to light up all the tyres on tarmac.

Shock loading and bigger tyres will put your torque above that, but bigger tyres are often accompanied by lower ratio diffs which mitigates the effect.

With more engine torque you'll simply be able to fry tyres in higher gears, the torque at the spud shaft will be same.

An interesting point. I think a lot of drivetrains use traction as the limiting factor rather than the outright torque potential through the shaft.

[Gaz69]

Guys,
Thanks for the advise. Interesting points about the Torque multiplication to the drive line. Does the torque convertor give you a multiplication affect also by a factor of 1.5 to 2 ? Had thought of smoking all four tryes on the bitumen as the TD5 certainly would not!
Slunnie wrote

You couldn't just open up the interior with larger humps etc rather than body lift?

I lifted the body as gave me more room under the bonnet as it is a substanially higher than the 6.2/6.5 diesels because of the inlet manifolds and packaging. I also wanted the extra height to give me a taller radiator and exhaust plumbing.

Cheers Gaz