I am looking into investing in some alternative diff ratios...any advice on which ones i should get for competing in 750 locost?

The favourites seem to be 3.9, 4.1 and 4.4 - they have to have been used in Mk 2 Escorts at some point, without being Ford motorsport specials.

However, if you are using a normal 4 speed, then most people recommend sticking with a 3.9. I was going to go to a 5 speed and a 4.1 but I got side-tracked! Lydden could have done with a higher diff, but then we don't seem to be going there this year. Perhaps Brands as well. Other than that 4 spd and 3.9.

However if you wnat to buy my 4.1 off me, I'm sure we can do a deal!

Dickie

Dickie,

Do you still have your 4.1 diff for sale? I've decided to go down the sierra 5 speed gearbox route, so want a 4.1 diff to go with it, but have not come across one (but not really looking that hard yet, too early in the build!)

Cheers,
Rob.

I've currently got the 4-speed box and 3.9 diff set-up but am looking to change it for the 5-speed and 4.1 diff approach or possibly just the 4.1 diff on it's own.

With my 4spd/3.9 i only get up to 6700ish rpm at the end of the back straight at Snetterton and just before the Esses at Donington. Some of that will be me being crap out of the previous corner and some from having a home-built engine but i do think that it's too long for many of the tracks.

Dickie - are you really selling your 4.1 diff? I would be very interested in that.

Oops, i take it all back. I've just had a look at the really rather handy www.domsat.co.uk/pages/gearboxes.htm and spotted that the 5 speed Sierra box is a whopping 15kg heavier than the 4 speed unit! Flippin eck!

[Edited on 20/7/04 by Rob Palin]

Good - I don't want any competition for the diff if Dickie is willing to part with it!!!

I am advised that I am skinny enough to not have a weight problem in the locost series => going for the 5 speed box. Not suggesting that you're a porker though Rob... I don't know you, yet.

Rob.

I parted with it.

And then bought another one, which this time I will fit, with 4 spd box. When I find the time.

Robster - You're exactly right! I'm trying to shed a few kg's myself as well as from the car.

Together we weight in at 627kg fully fueled, though i should be able to drop that to nearer the weight limit with a bit of tinkering and some lettuce sandwiches.

There's no way i could get another 15kg out in order to jusify the 5 spd box though. Unless i ditch the (comfortingly sturdy) rollcage!