One for the Ford & Kit car peeps

[Anto84]

I have a mt75 5 speed gearbox in a Westfield

Is there a 6 speed version ?

The 5 speed would be amazing for track days and hill climbs but we only use the westy for road driving and the 5 speed gears are just very short

Its not the end of the world, would just like to drop the rpm at 60/70 mph

 

[Mark King]

Not from memory no. has the gearing been changed in the box/diff as they are normally ok

 

[Anto84]

Not from memory no. has the gearing been changed in the box/diff as they are normally ok

It's fine, just thought if there was a 6 speed I would change it to drop the rpm at 60/70 mph

 

[FM155]

Not sure what the westfields use for a diff nowadays, used to be either an escort live axle or a Sierra diff. Was just randomly talking to the owner of westfield in a pub a couple of years back and he was saying they are using a lot of mx5 bits now. Throw up a picture of yer diff, might be easier to just swap to a different ratio diff and change the whole range.

 

[IL]

As @FM155 says, your car will likely have a 7 / 7.5” Sierra Diff, it comes is a few different ratios..

There is a Tag / code on the casing which references the ratio, it’s most likely 3.9:1. if that is the case moving to a 3.6:1 would solve your problems.. there is also a 3.38:1 but that might kill it altogether!

 

[Anto84]

I will have a look at the weekend for casing references!

That is really appreciated, might be the answer

 

[IL]

Yes that’s def. a Sierra unit, a photo from the top would tell you if it’s 7 or 7.5”

 

[Marty Lad]

Sierra diff as said, ratio usually written on the crown wheel in white paint if you can’t find the tag, failing that count the teeth on the crown wheel and divide by the pinion to get the ratio

 

[Apis]

What's the engine rpm at 70mph in 5th? Just curious.

 

[IL]

Sierra diff as said, ratio usually written on the crown wheel in white paint if you can’t find the tag, failing that count the teeth on the crown wheel and divide by the pinion to get the ratio

No need to open it, just count the rotation ratio.. input vs output

 

[IL]

@ant

If it’s a 7” you need this could be a Bargain for you..

 

[NI_Volvo_Nut]

What about a RWD Transit box?

 

[stevieturbo]

There is no MT75 6 speed.

Which MT75 do you have, there are different options ?

MT75 Gearbox - Super 7th Heaven

The MT75 gearbox from Ford has been fitted to many vehicles. Use this guide to find out which one you need or already have.

www.super7thheaven.co.uk

Or a popular gearbox for swaps with Ford engine etc, is the Mazda RX8 6 speed. Although 6th still seems to be same as some 5th in the MT75

Rx8 5/6 speed gearbox conversion to ford engine (zetec,I4,pinto and x flow)

Rx8 5/6 speed gearbox conversion to ford engine (zetec,I4,pinto and x flow) I just thought i would make a basic guide to fitting an rx8 gearbox to a ford engine in a classic ford. This guide is to fit an 6 speed rx8 box in my mk2 escort rally car that has a mk5 rs2k 16v engine along with a...

www.turbosport.co.uk

But with a taller diff would still give you more options.