e28 diffs

[320Touring]

As you folks are no doubt aware, I'm a tight git when it comes to the petrol costs of my touring

to this end, I've decided that the 4.10ish smallcase in my beast has got to go! the 3.5k at 70mph has to stop

I've been thinking of replacing it with a 2.97 diff from an e28 525e,if I can source one.

Now I know that thee28 LSD's are not a straight swap with the e30 ones, but are the open diffs interchangable?

If so, does anyone have one lying about for a reasonable price?

Cheers

Neil P

[OllieB]

I think maybe a 2.97 would make your gearing a bit too long, perhaps an E30 3.64 would be a better bet?

[320Touring]

I think maybe a 2.97 would make your gearing a bit too long, perhaps an E30 3.64 would be a better bet?

I want it as long as possible, hence the 2.97, do a lot of motorway miles so accel is in 2nd place to cruising economically

[Martinaston]

with a 3.64 it will drink more juice around town, a lot more.
so you will have to be doing 1000's of motorway miles to make up for it, it's just not worth the bother

if your that tight then put an m40 1.8 in there and a smaller diff.
my old one was faster and more economical
there's no point in flogging a dead horse just because you like the sound of the exhaust

[Templ8e30]

In terms of fitting to E30's the E28 diffs (bar the M5 which won't fit) they all need the same treatment regardless of open/LSD internals.

You'll need a large case E30 cover plate and a pair of large case E30 output flanges.

I have a pair of output flanges spare if you need them.

Cheers,

Iain T

[Brianmoooore]

As templ8e E30 says to get the E28 diff to fit, but you'll never get a 320 off the line with that diff. You'll need a new clutch once a month. A 325 would struggle with it.
I've got a 2.97 in my M50 touring, and it's just about right for that, with the 1:1 5th gear, and the other ratios pro ratio.

[BrAdZ]

Forget it. You wouldn't even get into fifth gear with a 320i. Every motorway hill you'd be down into fourth gear and flogging it to death, using loads of fuel.
3.64 is about as high as you can sensibly go - I did this on my 320i and although it improved the fuel consumption noticeably, it was on the limit in terms of driveability - fourth and fifth gear performance was a bit rank.

Early 320i's used a 3.45 diff but they also had 60 profile tyres.

agreed.... i had a 4.10 and went to a 3.64 and it would no longer light the wheels up in 2nd and 0-60 slowed quite a bit...... but then again i get better fuel consumption... i love it

[exup]

Is it just a case of swopping the rear diff cover from an e30 to the e28 diff or more involved as i was considing the 2.97 for my 2.7 conversion as well

[Brianmoooore]

Is it just a case of swopping the rear diff cover from an e30 to the e28 diff or more involved as i was considing the 2.97 for my 2.7 conversion as well

Swap rear cover and the drive flanges (just lever straight out)

[Brianmoooore]

Is it just a case of swopping the rear diff cover from an e30 to the e28 diff or more involved as i was considing the 2.97 for my 2.7 conversion as well

Eyes read " 2.7 conversion" but my brain saw " M50 conversion".
Argos is right. 2.9 diff is OK with the E36/E34 gearbox, but no use with the M20 gearbox.
2.93 diff on E36/E34 box = 3.62 diff on M20 box

[exup]

[
Eyes read " 2.7 conversion" but my brain saw " M50 conversion".
Argos is right. 2.9 diff is OK with the E36/E34 gearbox, but no use with the M20 gearbox.
2.93 diff on E36/E34 box = 3.62 diff on M20 box

I 'M A BIT CONFUSED NOW ?
So , as i have a choice of e34 520 box&dif , e325 std box and 3.64 dif , i think i have a 325 sport g box ( how do you tell )
and 2.9 eta dif , or 320 box and diff,
i was thinking sport box and either 3.64 or 2.9 diffs to start with on a 2.7 eta running 325 cam and valves ported head + chip , ??

[bottlecapE30]

I have a 2.97 with the right rear cover but the 5er output flages you could have it for $10 if you want to ship it from the US