Ford 8.8 Ratio Advice

[Coops]

Good evening been a while since ive posted on the forum
after some advice regarding rear end ratios for road and track,
currently running the stock 3.08 ratio with the R380 5 speed gearbox,
im not after out and out acceleration as the car is driven on the road more than the track,
but want a little extra help at the track along with the supercharger,

[stevieturbo]

Who are ye ?

1st gear is quite short...

But generally, if you're considering from a drag racing point of view then you'd aim to make full use of 4th gear over the 1/4

So whatever mph you hope to achieve, with whatever tyre combo and rpm you have...then work out what diff ratio will best get you there.

I doubt you'd ever want to see a shift into 5th over the 1/4 with a regular manual box. But you may want to leave a little headroom so 4th can pull more than it is capable now.

Although CWP's for the 8.8 are very cheap. If you can be bothered with the work, buy a couple and try them ? But I'd guess either 3.55 or 3.73 are most likely to be best suited unless you'll use quite tall tyres at the strip.

In general I prefer a 3.55 for my own car, but I use a 3.27 because for higher speed stuff it suits better.

[Coops]

Hi Stevie,

I was looking around a 3.44 but there isn't such a ratio for the 8.8 like the old capri atlas ratios, 3.55 seems the closest,
225 50 15 hoosiers think that works out around a 26" tyre ???

[unstable load]

What ratio 5th gear do you run? You could get a bit more out of the box there.
The R380 in the V8 Disco2 has a 0.73:1 5th and the diesel is 0.77:1.
Ashcrofts sell the gear kit.

[Coops]

R380 2wd as used in the morgan plus 8 v8 mate

Gear-----Ratio
1st-------3.321
2nd------2.132
3rd------1.397
4th------1.0
5th------0.77

[stevieturbo]

Hi Stevie,

I was looking around a 3.44 but there isn't such a ratio for the 8.8 like the old capri atlas ratios, 3.55 seems the closest,
225 50 15 hoosiers think that works out around a 26" tyre ???

Plenty of online gear calculators for you to play with.

cant see that size being 26" tall...maths says more like just under 24"

A 3.55 would just take you shy of 140mph in 4th gear at 7000rpm, 120mph at 6000rpm ( ie 19.7mph per 1000rpm )

you can get 3.27, I've seen some say also 3.33 and of course 3.55

[stevieturbo]

A new crush washer, front pinion nut and some shims at the back to adjust lash would be a bare minimum to swap., and maybe a rear gasket.

If all bearings are good, really not a lot of point in changing them, although it can be a little awkward to get the old ones off. Unless you're changing the front pinion bearing, there's no need to disturb the pinion seal...they can be a bit of a ballix to install too.
I've re-used the pinion nut before too, just use loctite on it but new nuts come with a coating.

https://www.summitracing.com/int/parts/ ... /overview/

Although even on ebay you find loads selling second hand ones for around half the price. From a packaging/safety point of view...I'd be buying new though. Think they might actually come with a new nut and crush washer.