Club G40 Forum

Technical => Engine and Transmission => Topic started by: Stirlitz on January 28, 2013, 12:34:41 PM

Title: Any 6speed trans for the G40?
Post by: Stirlitz on January 28, 2013, 12:34:41 PM
This week I'm gonna have my '91 G40, and already started planning my near-future mods.

As I do lot of highway miles, I'd like to get good mileage at speed (60-80mph). I read all that is available, so one option is a long 5th gear ( I think a 0.74 ).

Is the 6speed an option, or there are no 6speeds that would fit w/o major modding?

In this topic http://www.polog40.co.uk/forum/index.php/topic,8962.0.html someone said that the 5th would be very tall with the change. Anybody knows what would be the rpm at like 60mph?

Messing with the final drive wouldn't be an option as the other gears are just as good as they are, only a relaxed cruising gear is that I'd like to have.

Any experience/ advice is welcome!
Title: Re: Any 6speed trans for the G40?
Post by: BoumarleyG40 on February 26, 2013, 11:01:40 PM
It would be very interesting to put a six-speed gearbox,
Title: Re: Any 6speed trans for the G40?
Post by: hayesey on February 27, 2013, 10:42:38 AM
if you can get hold of an S1600 Polo rally car gearbox there is.  But expect to pay several thousand pounds for one!  Plus I'm not sure they'll be geared for higher speed anyway (although you can probably get different gearsets to suit your requirements).  In all honestly you'd be best off buying a cheap diesel 2nd car and leaving the G40 at home!
Title: Re: Any 6speed trans for the G40?
Post by: Justin14100 on February 27, 2013, 04:09:15 PM
How much work is a Lupo GTi gearbox to slide in there?
Title: Re: Any 6speed trans for the G40?
Post by: youngprodigys on February 27, 2013, 05:26:16 PM
totally different box.
not the same bolting pattern - so machining and adapter needed
hydro clutch - so you need to sort the pedal box
cable shift - need to sort a shifter.

= not worth the hassle
Title: Re: Any 6speed trans for the G40?
Post by: Andy on February 27, 2013, 05:57:00 PM
Quote from: hayesey on February 27, 2013, 10:42:38 AM
if you can get hold of an S1600 Polo rally car gearbox there is.  But expect to pay several thousand pounds for one!  Plus I'm not sure they'll be geared for higher speed anyway (although you can probably get different gearsets to suit your requirements).  In all honestly you'd be best off buying a cheap diesel 2nd car and leaving the G40 at home!
From memory, the data I looked at when I was at Ricardo suggested the longest ratios and final drive would give something in the region of 120mph @ 8000rpm in 6th with stock rolling radius wheels on a G40. Very much designed for high revving motors with relatively little torque.

In my opinion VW did a pretty good job of choosing the overall gearing for the G40.
Title: Re: Any 6speed trans for the G40?
Post by: gofasterpinch on February 27, 2013, 11:20:06 PM
yeah i think nick was telling me he was getting 91mph or 117mph at 9000rpm on the two different final drive ratios
Title: Re: Any 6speed trans for the G40?
Post by: hayesey on February 28, 2013, 10:08:17 AM
plus, is a Lupo box geared for higher top speed anyway?
Title: Re: Any 6speed trans for the G40?
Post by: metalblue on March 21, 2013, 07:12:05 AM
You might find this useful

http://derby.polog40.co.uk/oldsite/modification/gearratios.xls (http://derby.polog40.co.uk/oldsite/modification/gearratios.xls)