E30 Zone

I recently bough an 318i touring with a 2.5 manual motor in it. As far as I know it's still running the 1.8 standard diff. I got given a 2.5 diff with the car because the 1.8 diff was whining like fluke!

So I've taken the 1.8 diff out, tried to fit the 2.5 diff but the main bolts that hold it in position don't seem to line up. I've noticed the 2.5 diff is slightly longer so where the bolt goes through the bush at the back, I can't line it up.

I was told that it's literally a straight swap but this doesn't seem the case?

Can anybody please confirm it's not me fitting it wrong and that they don't just bolt straight in??

Any replies much appreciated as usual! Matt

it is sraight swap mate.u might need to adjust the prop.

The diff fits, but the four main bolts can be great 'fun' to line up.

Are you sure its an E30 diff your trying to fit?

Thanks for the quick response, the problem I'm having when fitting the 2.5 diff is not only lining up the four main bolts, but aswel as lining up the main bush at the back of the diff

Also, when I try to bolt it in as is, the halfshafts sit too far back so the one on the passenger side rubs against the exhaust.

Have alot of people had to shorten the propshaft to achieve this? And how difficult is it?

Cheers Matt.

leeparkes wrote:Are you sure its an E30 diff your trying to fit?

I'm not 100% mate, this is the problem. The bloke I bought it from fitted the engine along with the gearbox, and as part of the deal when he bought the engine, he got given a diff aswell. Could it be possible that my touring is running a 2.5 motor and gearbox with a 1.8 propshaft and diff?

E30 diffs are completely interchangeable, whether they are small cased or medium cased. The mounting points are exactly the same, and they mate up to the same driveshafts.
If it has a 325 gearbox, then it has a 325 prop, but as said above, the prop is adjustable for length (splined sliding joint near the centre bearing, locked by a sleeve nut compressing rubber), and should be adjusted to suit the diff.

Mucker_325i wrote:I recently bough an 318i touring with a 2.5 manual motor in it. As far as I know it's still running the 1.8 standard diff. I got given a 2.5 diff with the car because the 1.8 diff was whining like fluke!

So I've taken the 1.8 diff out, tried to fit the 2.5 diff but the main bolts that hold it in position don't seem to line up. I've noticed the 2.5 diff is slightly longer so where the bolt goes through the bush at the back, I can't line it up.

I was told that it's literally a straight swap but this doesn't seem the case?

Can anybody please confirm it's not me fitting it wrong and that they don't just bolt straight in??

Any replies much appreciated as usual! Matt

put the right hand front bolt in then jack the diff up to sub frame so it just takes the weight an the bolts will go in u may have to loosen the the prop slide though the diffs are all same im always swaping them when my welded diffs break!!

That's what I'm going to need to do then, I did think that if the prop was slightly shorter then it would fit. Will I hav to take the prop completely out to adjust it?

Thanks again for all the replies, if u were local I would buy you a beer!

No you dont need to take the prop off to adjust it.

Have a closer read of the two comments above and when you have a look at the prop all should become clear.

Linning up the top holes of the diff can be a bit frustrating at times

I've had a gd look at the prop and cannot find anywhere or anyway to adjust it. Can anybody tell me whether it's nearer the fron or rear of the prop? Cheers, mart

You shouldn't need to adjust the prop at all, your just need to arse around with it for a while to get it all to line up. I spent an hour or so with a trolley jack under mine trying to get the prop bolted on before I lined up the rear beam bolts.

Some people also put studs into their diffs and just a nut on top of the rear beam mounting, this makes it a bit easier.

overall, just get the prop loosely bolted onto the diff before you try to line anything else up.

just behind the centre bearing you'll see there is a join in the prop. on the rear section of prop there looks like a nut this can be loosened with the prop in place but you will need to remove the exhaust and heat shield. if this isnt clear ill post a picture up later

Dont forget to pre load the centre bearing if you move it.

good show.. I was going to get a pic later when I was doing an engine change on the 318is

Nice one, all sorted. Its bolted in, but need to change the diff oil. Anybody know the easiest way of filling it up? i can see there isnt much room to play with but you guys must have a technique. Matt

I cheat and use an oil syringe

Make sure you can undo the top plug first!