diff and gearbox
 

im looking for info for my build i would like to know what would be the best diff 7" or 7.5" and what would be the best ratio and which gearbox mt75 or type 9 5 speed or 4 speed thanks

A good starting place is probably what engine you would like - Do you have any preference? Car engine or bike engine?

Are you going to be using a donor car, or collecting part individually? Will the build be sierra or mx5 based?

well im going down the sierra route but hoping to put a 2 litre zetec in it as im only just starting i need a lot of tips and help i suppose

Options
 

This site will certainly help with regards to fitting a Zetec, http://toyne.org.uk/zetec-engine.html

I would go with the type 9 box as gives you more room for your feet,


Good luck with your build and have fun. :D

thanks mate

The book chassis is meant for the 7" diff, but if you had a 7.5" one, you could easily make the diff mounting plates a bit wider to accomodate that.

thanks i havent got the diff yet but ill probably get the 7"

i would think the 2 main questions would be

1. what engine are you planing to use

2. what do you plan to use the car for?

Diff ratios most common are the 3.6 & 3.9
If fitting drum brakes the push in type if discs bolt on type
Gearboxes ratios are generaly spaced to far apart as they are designed to launch a heavy saloon car with 4/5 people and luggage of the line meaning if you run a 3.9 diff 1st is all finished by 20/25 mph but 3rd is good and you can max the revs in 4th, 80 is about 4000rpm in 5th
I fitted the V6 type 9 with bellhousing spacer, 1st still a bit low and tyre/wheel size can help
The MT75 ratios are even wider and would suit the 3.6 diff better


[Type 9 (1.3-2.3)

1st 3.65
2nd 1.97
3rd 1.37
4th 1
5th 0.82

Type 9 (2.8 inc 4x4 )

1st 3.36
2nd 1.81 (this is the ratio that lets the 2.8 go over 60 in 2nd )
3rd 1.26
4th 1
5th 0.825

Type 9 (P100 HD)

1st 3.91
2nd 2.29
3rd 1.38
4th 1
5th 0.82

There is a T9 diesel box too, but I'm unsure of those specs (I'd imagen its something like the P100 box) I do know it has stronger bearings and a 0.75 5th

MT75 (2.0 DOHC and 2.4 V6)

1st 3.890
2nd 2.082
3rd 1.342
4th 1
5th 0.822

MT75 (2.9 V6, 2.5 diesel AND 2.0 4x4)

1st 3.608
2nd 2.084
3rd 1.363
4th 1
5th 0.829

The MT75 ratios are 100% correct

There are gear ratio calculators on line and as wheel & tyre choice affect overall speed in gear and your engine red line it would be worth having a look

thanks guys