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working out gear ratios
vwtyp2 - February 20th, 2004 at 08:32 AM

what's the secret formula for working out gear ratios?
Looks like I'm gonna be rebuilding a box for my bus, rather than worrying about any further conversions.
this is what i was thinking.....

it needs a taller 1st anyway, as soon as you stand on the gas in 1st, it's straight on the rev limiter.
I was thinking on using a 1st somewhere between the 1st and 2nd I've got now, use my Albins standard 3rd as a 2nd, the Albins 0.70 4th in 3rd, then an even taller 4th. shohld be able to cruise the highway about 140 kph at about 3000 rpm, and around the city 60kph at 2000 rpm in third.
make it kinda like a 3 speed + overdrive.
how do I work out what Ratios I need?:D

lugnuts - February 20th, 2004 at 01:22 PM

Has it got the motor to pull those high ratios your thinkin bout.:o

BiX - February 20th, 2004 at 03:16 PM

You say u redline in 1st straight away? Is this on the flat what happens when u have to do a steep hill start? etc. I would leave 1st and just adjust 3rd and 4th. Just remember if u have the taller gears is the engine going to be able pull that gear as lugnuts said?

ash logan - February 20th, 2004 at 03:32 PM

This is a calculator type contraption that i think you willl find quite handy.

http://www.cvsr.net/php/links.php 

It is called Gear Head, look down a bit and it is right there!

[Edited on 20-2-2004 by ash logan]

twoguns - February 20th, 2004 at 04:09 PM

and i might be wrong, but i read somewhere that the rpms the engine run at, also affect the cooling effect. so if you drop the rpm too much would your motor slowly build up heat on a long trip?

Baja Wes - February 20th, 2004 at 04:24 PM

I believe he has a V6 in the kombi, so no beetle cooling issues to worry about.

If you have access to microsoft Excel 2000 or higher, then my Excel dyno will do exactly what your after and more

http://www.aussieveedubbers.com/forum/viewthread.php?tid=18037

So, do you have Excel?

wacked1 - February 20th, 2004 at 08:44 PM

Yes this has a 3.8L V6 in it!

vwtyp2 - February 20th, 2004 at 09:23 PM

yep. no need to worry about horsepower, or air cooling.
it'll beat any normally aspirated 4 or anything up to a vs commodore or ef falcon to 100 kph.
but then I run out of go at about 140 kph. I want to be able to hit at least 100 mph.

70AutoStik - February 21st, 2004 at 01:41 AM

You might actually have trouble finding the taller ratios you're looking for, why not start with a higher final drive?