DIFF FOR 3.5 CONVERSION

[gall]

Hi all,

just about to buy a full 535 just for the engine but i got a problem, my diff on the 320i that the engine will finally go in to has broke, looking through the drain plug on the back all i can see is a piece of a gear wheel with about 3/4 teeth on it, doh!!!!

the question,

would the 5 series one fit??

if not what would be the best diff to use as i might aswell get one now to replace the fooked one. before anyone says it i know the e30 m3 diff is best but finding one that ain't silly money is imposable!

cheers for any help.

gall.

[stevetigger]

Go for the 325i Sport diff then!

[Toby_Unna]

before anyone says it i know the e30 m3 diff is best but finding one that ain't silly money is imposable!


gall.

i don't think anyone will say that mate, it's way too high geared

with the overdrive box which most 535is have (all e34 ones do) you want a 3.64 or 3.46 really. 3.64 will give 150mph on the rev limiter in top gear.

[Kos]

i was running a 3.25 with OD box, and the top speed was silly, easily pushed past 165 mph, but i'm going to drop it to a 3.64 for the 1/4 mile sprints

[ant2]

ha i have no over drive and a 3.91 diff something close to 3.6 is good for a normal box, i am going to stick something close to 3 in mine as possible, at the moment its silly. changing gear all the time and 125 on the limiter in 5th

[ed325i]

Hi, How can you tell what diff you have got? I have put a 3.5 in a 1990 325 cab so I need to know if I will have to change the diff

ED

[Kos]

if you have an over drive box you should be ok as wou should have a 3.64 in the touring, posibly a 3.91 which will make very thrashy and you'll keep looking for another gear!!!

[charlE30]

This is going to sound really thick.... what's an overdrive gearbox??

[maxfield]

yeah id like to know aswell

[DanThe]

Overdrive means the gearbox is turning faster then the engine, like E30 boxes 5th gear

[stevetigger]

like the M50 final gear is a 1:1 but on an overdrive final gear is like 0.81:1

I think thats right

[ant2]

m3 dogleg has no overdrive, 5th is 1:1

[charlE30]

I understand now, it just sounds weird referring to modern (ish) cars having overdrive. When I was a kid my old man used to have an old V8 landrover with overdrive and was selected with a second gear stick

I'm going to be using the standard E34 5speed box with a 3.64 LSD, will this give good acceleration?

[Brianmoooore]

I'm going to be using the standard E34 5speed box with a 3.64 LSD, will this give good acceleration?

Still a bit on the high side, I would think. 1st gear's not going to be a lot of use.
In comparison with a standard 325 E30, you will be running a gear under 1st, and with no 5th gear.
Not totaly unusable, but something like a 3.25 or 3.15 would be better.

[gall]

hi all, cheers for the help.

i might sound thick here but are all the diff cases the same size? can i use the e34 diff in my 320 or won't it fit?

which car has the diff that your saying is best, don't have a clue about diffs. this is my first rwd car so just leaning.

cheers Gall.

[SCOTT325SE]

I have a 3.45 diff for sale. Its quiet and im after £60 for it.

Any use to you?

[Brianmoooore]

E34 diff won't fit I'm afraid, although the ones from the smaller engined E28 five series will.

[Gunni]

It´s simple

if you have a 0.81 5th gear stick with whatever you have .

if you have a 1:1 get something close to the M3 ratio ( 3,25)

on a separate thing, the M30´s have so much torque it doesn´t matter if it´s 3,73 og 3,91 og 3,46 it all pushes you like crazy

[Chaos]

E34 diff won't fit I'm afraid, although the ones from the smaller engined E28 five series will.

dont u have to swap the output shafts to use e28 diffs brian ?

[Brianmoooore]

E34 diff won't fit I'm afraid, although the ones from the smaller engined E28 five series will.

dont u have to swap the output shafts to use e28 diffs brian ?

Yes, you have to swap the output shafts for E30 ones (they just pull out), and swap the rear cover as well.

[Andy335Touring]

I'm going to be using the standard E34 5speed box with a 3.64 LSD, will this give good acceleration?

I'm using an O/D gear box with a 3.64lsd, it will give you good acceleration but it is a little short geared for my liking, i want a 3.46lsd but they are a rare ratio.

Don't use a 3.25 on a N/A M30 unless you use the car for a lot of motor way driving. I started off with this ratio, 1,2,3 gears are great because i like long geared 1 and 2 but 4 and 5 are to long. 4 toped out at about 125-130mph and i once had it showing 150mph in 5 @ 5.5k rpm. This makes acceleration in 4 and 5 suffer.

With the 3.64lsd i can just about hit 60mph in 2, 3 tops out at 85mph ish and goes just off the clock 150-155mph at 6.1k rpm in 5. On the motor way in 5, 70mph is just about 3k rpm and the ton is 4k rpm.

3.46lsd with Sports gearbox ratios would be my ideal set up to give me a nice long 1 and 2 but with out making 4 and 5 to long.

This is a copy of an old email of mine where i was working the differant ratios out using this calculator. 3.46 is not included unfortunately but it will give you an idea of what the other ratios equate to approximately.

http://www.unixnerd.demon.co.uk/revs.html

[charlE30]

Cheers for the info Andy just out of interest do you have any idea on your 0-60 time?

[Toby_Unna]

3.46lsd with Sports gearbox ratios would be my ideal set up

i'm working on the second bit mate, though i've told you that before and then not done anything about it

sorry!

[Andy335Touring]

Cheers for the info Andy just out of interest do you have any idea on your 0-60 time?

Although i can just reach 60mph on the gauge in second it's not quite a true 60mph as the G-tech meter thing i have won't record a 0-60 run unless i use third gear which hurts the times quite a bit.

Only a guess but with slightly longer gearing so i can get a true 60mph in second it will be around 6.0-6.5 secs to 60 ?

Toby, what sort of times were you getting with yours ?

No worry's about the gear box mate

[ant2]

i recon mines running something close to 5secs to 60, i am well into 3rd to get 60 out of it

can only do 123mph on the limiter in 5th tho

[Toby_Unna]

timed mine at six dead with two changes. would have been quicker with a longer diff/higher rev limit to get to sixty in 2nd gear.

3.91 is no good for road use as far as i'm concerned. the gearchange on these boxes isn't that quick and even with a 3.64 diff you can get a quicker start in second gear if you don't mind using a lot of revs and being nasty to the clutch.

i started with the 4.27 from the 316, which was horrible.

all this talk of gearing has made me do some calculations of my own! which i'll post on my turbo thread...