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Model specific boards => Golf mk3 => Topic started by: Dan_GTi8v on 19 March 2011, 19:10

Title: Gearbox ratios? Hmm
Post by: Dan_GTi8v on 19 March 2011, 19:10

Need some help understanding all the numbers in gearbox ratios please! Found a list of all the ratios, 1st through to 5th and final drive.

Am I correct in thinking higher numbers equal more revs b4 you need to change up? whats final drive?

Cheers :)

Title: Re: Gearbox ratios? Hmm
Post by: forsh on 20 March 2011, 07:55

http://www.vwgolfmk1.org.uk/modules.php?name=Content&pa=print_pdf&pid=47

Title: Re: Gearbox ratios? Hmm
Post by: benvictors on 20 March 2011, 11:06

The ratio 3.45 for a gear means it makes 3.45 revolutions to every 1 revolution of the drive gear, which is about 45 turns of the idler gear to every 13 turns of the drive gear.
The closer the ratios to each gear the shorter the rev range.
So if you want performance and dont mind shifting gear all the time, get a box where the ratios are close to each other, if you want a cruiser go for ratios that are further apart.
Final drive is the ratio between the drive gear (Off the crankshaft) and the Gear that runs your wheels. If you change this ratio it changes all the gears through the range.
If you have a 3.89 final, and 0.71 5th (Like the box code FF,FN,FH,FJ on the chart in the post above) and you want a bit more acceleration in 5th but like the way 1 to 4 pull, then you can just swap in a shorter 5th (Say a 0.76) That will decrease your overall top speed but increase acceleration in just 5th. However, if you want more acceleration in each gear, you can run a shorter final drive and this will make each gear shorter for better acceleration but slower overall speed in each gear  :wink:

Title: Re: Gearbox ratios? Hmm
Post by: Dan_GTi8v on 20 March 2011, 13:11

thanks :)

Title: Re: Gearbox ratios? Hmm
Post by: dom on 20 March 2011, 14:42

Quote from: benvictors on 20 March 2011, 11:06

The ratio 3.45 for a gear means it makes 3.45 revolutions to every 1 revolution of the drive gear, which is about 45 turns of the idler gear to every 13 turns of the drive gear.
The closer the ratios to each gear the shorter the rev range.
So if you want performance and dont mind shifting gear all the time, get a box where the ratios are close to each other, if you want a cruiser go for ratios that are further apart.
Final drive is the ratio between the drive gear (Off the crankshaft) and the Gear that runs your wheels. If you change this ratio it changes all the gears through the range.
If you have a 3.89 final, and 0.71 5th (Like the box code FF,FN,FH,FJ on the chart in the post above) and you want a bit more acceleration in 5th but like the way 1 to 4 pull, then you can just swap in a shorter 5th (Say a 0.76) That will decrease your overall top speed but increase acceleration in just 5th. However, if you want more acceleration in each gear, you can run a shorter final drive and this will make each gear shorter for better acceleration but slower overall speed in each gear  :wink:

Good explanation Ben :afro: