other than Ashcroft who makes LT230 underdrives?

Quote:

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Originally Posted by slug_burner

yes, Id say High/Low which when the underdrive is selected becomes Mediumish/Extra Low.

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Yes, thanks for correcting me.

Perhaps I should have put it like this.

Ashcroft underdrive

Stock High
Stock High and Ashcroft Low = Medium
Stock Low
Stock Low and Ashcroft Low = Extra Low

Total forward gears selectable is 20.


Maxi Drive rock crawler gears

Stock High
Stock Low = replaced by Maxi Drive
Maxi Drive Low = Extra Low

Total forward gears selectable is 10.


The main point I was making is that Maxi Drive is not an 'underdrive' but rather a replacement set of low range gears.

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.

Quote:

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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...

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

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

Quote:

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Originally Posted by LowRanger

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

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

Quote:

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Originally Posted by LowRanger

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

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Yes but you can do that with both options.

Quote:

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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.

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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:D

Quote:

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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.

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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.

For those with the Ashcroft underdrive, how often, and in what conditions do you use a 117:1 first gear.

Other than pay back to Isuzu County owners on steep down hills:D

Tony