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modifying a 6 speed gearbox?


lupy
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ok first of all i know naff all about how a gearbox works or how this would work but i have an interesting question that ive been thinking about today.

is it possible to take a 6 speed box and modify the 6th gear to be a longer ratio.

what i'm thinking basically is, a 6 speed lupo has more or less the same gear ratio in 6th as a 5 speed does in 5th. giving them probably near enough the same top speed. this seems a bit pointless in a way. i cant really see where the benefit is, as surely you loose excelleration every time you change gear?

anyway if you made a longer sixth gear. am i right in thinking a higher top speed could be achieved? say 145 mph?

i started thinking about it when i thought about an old mate who put a 4+E box in a tuned mk1 gti and it gave it a really quick top speed.

is this possible? is it expensive? and where would you go for the work?

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Quaife will sell you a shorter 6th gear cog, and longer final drive, if your after outright top speed. Like Adam said tho, you need the power there to drive the setup in the first place, and the aerodynamics to prevent buffeting at high speeds. smile.gif style="vertical-align:middle" emoid=":)" border="0" alt="smile.gif" />

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The Gti will not pull the limiter in 6th as standard so upping the ratio will if anything lower the top speed as the car will struggle more to pull revs in 6th.

If you had more power than standard there is a chance you could hit the limiter in 6th which is about 140mph with a standard rev limit.

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you could hit the limiter in 6th which is about 140mph with a standard rev limit.

lol, i like the way you know that off the top of your head.

*edit* Just thought - a sport will do something between 125 and 130 on the limiter in 5th(on the clock), i geuss the GTi has MUCH better acceleration then

Edited by Arun
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you could hit the limiter in 6th which is about 140mph with a standard rev limit.
lol, i like the way you know that off the top of your head.

The 6 speeder does about 20mph per 1000rpm in 6th so 140mph at 7000rpm is a rough approximation. Have had mine wrung out at an indicated 138mph before though when it was standard but it was obviously not doing that speed.

Edited by LINCOLNSHIRESLUPOGTI
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