diff choices!

[stevie s]

Hi, my first post on this forum so go easy on me!, any one have any thoughts on the following?

we are currently
building an e34 strip car, started as a 530i v8, now fitted
with 4.0 m60 and 5hp30 box, its currently running the std 530
3.15 non lsd diff, which isnt ideal (being open) we mated
the 4.0 driveshaft by switching the diff end flange from the
donor 740 driveshaft to the original 530 which works well,
what I need to know (bearing in mind we are using the 530i
v8diff) is which model diffs will fit! I know the 4.0 ones
are out because of the extra strength flanges, i'm guessing
the m5 ones are bigger flanged too?.....

the donor car ran a 2.9 lsd, as i said we are using a 3.15,
but as this is a car built for acceleration I was thinking of
rooting out a 3.6 dif... or even a 3.9, could you tell me
what models of e34 I might find these in, and which will be
interchangable with ours!, also if the donor car is something
like a 525, is the diff going to handle the power!, we are
currently getting just over stock, but theres a supercharger
on the way, which for starters will take us to 420/430 bhp,
but looking to intercool and change pulley sizes to get us to
nearer 500 bhp.. any thoughts?

many thanks in advance, and nice informative website too!
all the best
Steve

[BigKriss]

bruno is your friend

http://www.bmwe34.net/e34main/upgrade/Recipe.htm

cheers!

[stevie s]

Cheers mate, but what I was actually after was what models of e34 would provide me with an lsd with a 3.6 or 3.9 ratio.. that would stick a fair amount of power! and be a direct replacement for the 3.1 530i one we have!
any thoughts anyone?

thanks again!
Steve

[stevie s]

well as no one seems to know I'v bought a 3.64 lsd from a 535i, i'll let you all know if it fits!
Steve

[Brandon J]

well as no one seems to know I'v bought a 3.64 lsd from a 535i, i'll let you all know if it fits!
Steve

The 535i diff will fit but you may need to swap the input flange and the output flanges. Before unbolting the input flange on the 535 diff, mark the nut to thread location. You should retighten the nut to the mark, not to torque as you don't want to overtorque. The side outpuit flanges easily pop out and swap, but when they are out, you should change the output flange seals.

[stevie s]

Right having just pulled the 3.0 diff out I can catagorically say that the two output flanges are different, the 535 ones are bigger flanges with bigger splines and will not swap.. does anyone know what diff uses big slined inner with smaller flange outer? cos i'm stuck./..

cheers in advance
Steve

[stevie s]

well if anyones interested I contacted my local bmw spares place to be told the outer flanges (hub end) are common throughout the e34 range.. so I bought driveshafts to match the larger diff outputs.... only to find that the out board ends (that are all the same) are not.....

just came back from the engineers, who are going to cut the two end flanges off and replace them with the smaller outputs... so i'll have drive shafts with one small end and one large....

the hassle I go through to build a fast e34 eh...

[attack eagle]

intersting because other e34s have swapped flanges before without problems.
where did you source teh diff? e34?

[stevie s]

glad someones interested!
yeah the diff was sourced from a 1991 535i, with 3.64 ratio, the drive flanges were bigger diameter, as were the inner splines.. so no possibilty of getting them to swap, also as I said the outer cv ends were also larger diameter..

machining work is now done, i now have the larger inner splines mated to the smaller output flanges, done properly on a lathe, all bolted on and oil changed, its now much better geared for the strip, and although a little higher revving for motorway use its still much better for town driving, mpg round town is actually better!

it now has a tendency to light the back tyres up at the slightest provocation, so bearing in mind the supercharger arrives in a week and will add a good 140 plus horse.. i think it could well be quite a handfull!.. obviously theres no traction control!

if anyone else is contemplating changing stuff like this feel free to contact me for any help you might need as I'v been right through it all now

Steve

[stevie s]

glad someones interested!
yeah the diff was sourced from a 1991 535i, with 3.64 ratio, the drive flanges were bigger diameter, as were the inner splines.. so no possibilty of getting them to swap, also as I said the outer cv ends were also larger diameter..

machining work is now done, i now have the larger inner splines mated to the smaller output flanges, done properly on a lathe, all bolted on and oil changed, its now much better geared for the strip, and although a little higher revving for motorway use its still much better for town driving, mpg round town is actually better!

it now has a tendency to light the back tyres up at the slightest provocation, so bearing in mind the supercharger arrives in a week and will add a good 140 plus horse.. i think it could well be quite a handfull!.. obviously theres no traction control!

if anyone else is contemplating changing stuff like this feel free to contact me for any help you might need as I'v been right through it all now

Steve
Oh and yes sorry it was a 535i e34!