9 inch diff

V8XR2 · Post by **V8XR2** » Wed Jun 15, 2011 6:37 pm

I'm running a mrk-1 1300 escort diff I don't think it will Handel 300+ bhp would a
9 inch ford diff help or would it even fit iv not seen any for sale could a 9 inch diff be custom made to fit
Any idea the max power my diff can Handel
Thanks for all your help.

kiwicar · Post by **kiwicar** » Wed Jun 15, 2011 8:44 pm

Hi
9" ford diff, with 28 spline shafts, about 750 to 1000 bhp, 31 spline about 1200 to 1500 bhp, 33 spline up to about 1800, depending how you hit it and 35 spline 2500bhp may be more, 40 spline 4500 bhp
However the case has a big influance on this aswell as does how it is mounted in the chassis, aftermarket standard case is good up to about 1250 to 1500 depending on length add a brace across the back will give you another 250 capacity for over about 1800 bhp you need a fully fabricated case.
They aren't that efficient though and they are heavy below about 450 bhp you are much better off with a smaller diff and case, the 8.8" is much better for up to about 600 bhp, quite alot less loss through them. With the same number of splines on the shafts they can take very similar amounts of power, you just cant fit such big shafts. If you can get one the right length, with 31 spline shafts and the sort of ratio you want at a low (sub £600) with a good case then think about it but it will be heavy and you will loose up to 30 bhp over the diff you already have. Personally with only 300 bhp I would look at somthing else, MGB, Layland Daf, even a 2.8 capri, much cheeper. If you have to change anything on a 9" it will cost you, I have just had a new 9" built up into an aftermarket case, with 33 spline shafts it has cost me the far side of £2300 so as I say if you can find the right one for sub £600 it is worth thinking about, especially if you are going for big power later.
Best regards
Mike
PS there are a few on eurodragster at the moment, you can't swap them into a 1300 escort case!!

mgbv8 · Post by **mgbv8** » Wed Jun 15, 2011 10:54 pm

The MGB Salisbury axle will take a shed load of abuse. Depending on the ratio you need to suit your application they come with 3.9:1 down to 3.07:1 and are pretty bullet proof. If you were looking at worst case you could buy a V8 spec axle from MGB Hive for around £500 and get the shafts copied by Moser via Webster racing for around £400 and have your self an axle that will take your power out put easily for under a grand ?? I put 400hp though mine and the shafts start to twist. The new Moser shafts I have just had made should see this axle capable of taking 600hp. I hope

ian.stewart · Post by **ian.stewart** » Thu Jun 16, 2011 4:41 am

9", possibly Overkill, and its Huge, 300hp and in a small car, 8" is more than adequate, so would be a Mk2 jag, A well built Atlas, Volvo, and a few jap axles are more than able of coping with a lot of abuse,

stevieturbo · Post by **stevieturbo** » Fri Jun 17, 2011 9:58 am

Surely there are dozens of axles to handle 300bhp ?

Volvo another option ? Perhaps some vans ( ratio dependant )

A 9" would be massive overkill, and then some

kiwicar · Post by **kiwicar** » Sat Jun 18, 2011 4:10 pm

Out of interest I weighed my axel case and shafts with bearings but no third member or oil . . . 77lb. I would cnosider very carefully before mounting one of these on springs and dampers you will need to uprate the shock towers and linkage mounts

Best regards
Mike