Thread: other than Ashcroft who makes LT230 underdrives?

Look it is pretty simple. MD gears vs Underdrive (TD5 Defender Manual w 3.54 diffs)

Ashcroft Underdrive
Ratio Table
Overdrive High Low UDHigh UD Low
First Gear 18.43:1 43.40:1 49.57:1 116.76:1
Second Gear10.64:1 25.06:1 28.63:1 67.42:1
Third Gear 06.97:1 16.42:1 18.76:1 44.18:1
Fourth Gear 04.99:1 11.76:1 13.43:1 31.62:1
Fifth Gear 03.84:1 09.05:1 10.34:1 24.35:1


MD 49% gears
Ratio Table
Overdrive High Low
First Gear 18.43:1 64.65:1
Second Gear10.64:1 37.33:1
Third Gear 06.97:1 24.46:1
Fourth Gear 04.99:1 17.51:1
Fifth Gear 03.84:1 13.48:1

The Underdrive only gives you one gear (one truly unique ratio) that is significantly lower than the MD option (1st low UD), however it does give you a lot more ratio options. However most of them are pretty similar to each other. All the 43:1 to 49:1 options would be useful...

The medium (UD and high range) comes down to what high range ratio you run, anyone know how hard it is to find a 1:1 high range lt230?
I plan to use a patrol gearbox, disco transfer(1.2 rather then 1.4 high) and an underdrive, Because of the extra low 1st gear in the patrol box i would probobly better with 1:1

Be careful Cal, from memory, you can't fit an UD to one of the 1.1 cases. (I think!)

1.4 default and 1.2 with a different gear only I believe.

The biggest advantage for me with the UD, is that unlike any other solution, it doesn't mess up your normal gearing... atall...

Every other option does.

Originally Posted by isuzurover

Look it is pretty simple. MD gears vs Underdrive (TD5 Defender Manual w 3.54 diffs)

Ashcroft Underdrive
Ratio Table
Overdrive High Low UDHigh UD Low
First Gear 18.43:1 43.40:1 49.57:1 116.76:1
Second Gear10.64:1 25.06:1 28.63:1 67.42:1
Third Gear 06.97:1 16.42:1 18.76:1 44.18:1
Fourth Gear 04.99:1 11.76:1 13.43:1 31.62:1
Fifth Gear 03.84:1 09.05:1 10.34:1 24.35:1


MD 49% gears
Ratio Table
Overdrive High Low
First Gear 18.43:1 64.65:1
Second Gear10.64:1 37.33:1
Third Gear 06.97:1 24.46:1
Fourth Gear 04.99:1 17.51:1
Fifth Gear 03.84:1 13.48:1

The Underdrive only gives you one gear (one truly unique ratio) that is significantly lower than the MD option (1st low UD), however it does give you a lot more ratio options. However most of them are pretty similar to each other. All the 43:1 to 49:1 options would be useful...

And you don't have to listen to the howling of the straight cut gears.
And you maintain all your original ratios.

Fit different R&P ratios and a whole new world is opened to you

Originally Posted by LowRanger

And you don't have to listen to the howling of the straight cut gears.

Sounds like you need to trade your defender in on a D4 or RRS...

Originally Posted by LowRanger

Fit different R&P ratios and a whole new world is opened to you

Yes but you can do that with both options.

Originally Posted by isuzurover

Sounds like you need to trade your defender in on a D4 or RRS...



Yes but you can do that with both options.

I have enough other noises in the vehicle without adding others needlessly

Yes you can,but only one option gives you multiple gear choice options

Originally Posted by Psimpson7

Be careful Cal, from memory, you can't fit an UD to one of the 1.1 cases. (I think!)

1.4 default and 1.2 with a different gear only I believe.

The biggest advantage for me with the UD, is that unlike any other solution, it doesn't mess up your normal gearing... atall...

Every other option does.

Yes,you need to make sure that it has a 26 tooth input gear

I don't have an underdrive, but have multiple (12) gear choice options with the overall ratio spaced fairly well from:
102.243:1 (1st, low)
2.567: 1 (6th, high)

But that doesn't help the OP.