Gear ratios and final drive

[Spleeble]

I’d like some information on this subject, something I know absolutely nothing about. Basically I just want to know what effect altering the ratios will have. I have a type 9 in my G27 and I think it has the standard ratios. I have toyed with the idea of getting it rebuilt with the long 1st but I think the car is very drivable as it is. I’m guessing the long 1st will mean the car will hit a higher top speed before hitting the rev limiter. Now, the final drive. If I have a ratio of 3.9 I guess that it will have good acceleration but a low top speed. If I lowered the ratio to 3.1 then it will improve top speed but the acceleration won’t be as good it will require more effort to get the car rolling. Also I have a Sierra diff and the only diff ratios I have seen are 3.65 and 3.98, are there others readily available?

I have found learning about this subject very annoying, there’s not much info on the net and you can’t really try different things out without spending £6000 on bits and having a spare 200 hours and a spare race track to try it all out.

[thescamper]

The spreadsheet www.threekings.me.uk/Minors/gearing.xls may help to explain in real terms what is going on.

[Spleeble]

I like that sheet a lot. Thanks . I did need to do a bit of maintenance on it as my computer didn't recognise the CONVERT function.

Edited by Spleeble on Wednesday 14th January 13:50