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Gear Ratios - Puma Defender


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Transmission GFT MT-82 six speed manual

Full time four wheel drive

Transmission

(high/low) : 1 Overall Gearing

(High/Low Range)

1st 5.443 23.334/62.988

2nd 2.839 12.171/32.854

3rd 1.721 7.378/19.916

4th 1.223 5.243/14.153

5th 1.000 4.287/11.572

6th 0.742 3.181/8.587

Reverse 4.935 21.156/57.109

Final drive ratio : 1 3.540

High range transfer box ratio 1.211

Low range transfer box ratio 3.269

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Thanks Mack, I presume your info comes from the same place as the reply I received on another Forum:

http://www.landyonline.co.za/specs/defender2007.htm

which gives details of the drivetrain. The GFT MT-82 gearbox is a Getrag Ford Transmission unit similar to that used in the Ford Transit van. Manufacturing of the MT82 six-speed gearbox for Ford Motor Company takes place at the Halewood Transmission Plant. The table on the above page and as reproduced by Mack above shows all the ratio information. I see 5th is 1:1 and 6th is 0.742:1 and so I presume you could describe that as overdrive.

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Thanks Mack, I presume your info comes from the same place as the reply I received on another Forum:

http://www.landyonline.co.za/specs/defender2007.htm

which gives details of the drivetrain. The GFT MT-82 gearbox is a Getrag Ford Transmission unit similar to that used in the Ford Transit van. Manufacturing of the MT82 six-speed gearbox for Ford Motor Company takes place at the Halewood Transmission Plant. The table on the above page and as reproduced by Mack above shows all the ratio information. I see 5th is 1:1 and 6th is 0.742:1 and so I presume you could describe that as overdrive.

I'm confused: When is an overdrive not an overdrive?

I always assumed that an "overdrive" was a discrete addition to the transmission - like the Fairey one. The fact that the 6th gear runs at lower than 1:1 doesn't have any significance - its just a gear.

Am I wrong?

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Yes, "overdrive" can refer to any gears that are lower than 1:1 thus making the gearbox a speed increaser.

http://en.wikipedia.org/wiki/Overdrive_(mechanics)

Although the Wiki article makes that claim, the rest of the article is actually about units added to the gearbox; mostly manufactured by Laycock de Normanville (it mentions Fairey as well). That is what most people associate with the word of course - particularly those who travelled in older Volvos or other vehicles fitted with them.

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Maybe it is a UK thing.

Traditionally "overdrive" MEANS speed increaser. In the past, gearbox top gears were always 1:1. When they started building ones with less than 1:1, the were called gearboxes with overdrives...... Whether or not the overdrive is in a spearate gearbox or in the main gearbox matters not.

http://www.merriam-webster.com/dictionary/overdrive

Main Entry:

over·drive Listen to the pronunciation of overdrive

Pronunciation:

\ˈō-vər-ˌdrīv\

Function:

noun

Date:

1926

1 : an automotive transmission gear that transmits to the drive shaft a speed greater than engine speed

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Adjectives and nouns :)

An overdrive (noun) - a selectable device to raise the gearing over 1:1 (I know it works in the other gears too :) )

An overdrive gear (adjective) - describing a gear with a ratio of more than 1:1

My take on it

Mo

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