Author Topic: 325i diff into my 318is (Read 4425 times)

Rafiki · « **on:** February 12, 2009, 10:33:15 AM »

I have an open 4.10 out of my 325i. And before I start ripping aprat the 318, i was wondering if it would fit. The diff on the 318 is starting to make some wicked noises.

Any info would be great. If it matters, my 318 came with an open 4.10 also.

Thanks for any help, much appriciated.

tjts1 · « **Reply #1 on:** February 12, 2009, 10:47:43 AM »

it's a direct bolt on affair. It will fit.

quinn11m20 · « **Reply #2 on:** February 12, 2009, 11:06:08 AM »

Really. If I find a 325i rear end and want to switch it inplace of my 318is rear end what kind of work will be involved. Is it just take off the cover and replace the ring and pinion or completely removing the whole diff assembly?

Kingsly · « **Reply #3 on:** February 12, 2009, 12:30:33 PM »

I have a 3.91 off my 325i and it's great. Dropped in the entire diff assembly. Acceleration is off the charts.

Rafiki · « **Reply #4 on:** February 12, 2009, 01:20:11 PM »

Quote from: tjts1;66391

it's a direct bolt on affair. It will fit.

thanks, that's all I needed to hear. Appriciate it!

tjts1 · « **Reply #5 on:** February 12, 2009, 03:23:48 PM »

Quote from: quinn11m20;66393

Really. If I find a 325i rear end and want to switch it inplace of my 318is rear end what kind of work will be involved. Is it just take off the cover and replace the ring and pinion or completely removing the whole diff assembly?

No. You drop out the whole differential housing from the car and replace it complete. You don't have to disassemble the differential. But its a good idea to change the oil while the diff is out of the car. Much easier process.
You have 4 bolts to the drive shaft, 6 Allen wrench bolts holding each axle in place, 1 bolt holding the diff bushing to the trunk floor and 4 bolts holding the diff to the sub frame. All you need is 2 jack stands, 1 hydraulic jack to lift the diff into place and some basic wrenches and sockets. Just make sure you get a differential with an appropriate ratio for the 318. Anything from 3.64 to 4.27 works depending on your goals. Stay away from Eta diffs.

dude8383 · « **Reply #6 on:** February 12, 2009, 05:59:09 PM »

Quote from: tjts1;66404

No. You drop out the whole differential housing from the car and replace it complete. You don't have to disassemble the differential. But its a good idea to change the oil while the diff is out of the car. Much easier process.
You have 4 bolts to the drive shaft, 6 Allen wrench bolts holding each axle in place, 1 bolt holding the diff bushing to the trunk floor and 4 bolts holding the diff to the sub frame. All you need is 2 jack stands, 1 hydraulic jack to lift the diff into place and some basic wrenches and sockets. Just make sure you get a differential with an appropriate ratio for the 318. Anything from 3.64 to 4.27 works depending on your goals. Stay away from Eta diffs.

you should also change the diff bushing while you're at it!

Rafiki · « **Reply #7 on:** February 12, 2009, 06:01:16 PM »

Thanks for the info. You know what size wrench is needed for the drive shaft? I have a feeling it will be a tight fit and a large bolt. I only have up to a 16 or 17mm open end. I don't want to jack up the car get all nasty and then have I run to sears!

Thanks again.

xwill112x · « **Reply #8 on:** February 12, 2009, 07:49:09 PM »

why???

i'd save my money for a LSD, but thats just me.

Jimmy Lewis · « **Reply #9 on:** February 12, 2009, 08:37:52 PM »

The bolts he is talking about with the driveshaft are only like 15mm I believe, but nonetheless no more than 17mm. A socket would make the job much easier with less slips and knuckle smashing. Good luck.

Rafiki · « **Reply #10 on:** February 12, 2009, 10:36:00 PM »

Quote from: xwill112x;66417

why???

i'd save my money for a LSD, but thats just me.

its not a matter of saving money. I have a parts car laying around. its just the work. my neighbor has an lsd for sale, i just want want to spend the 200 dollars at the moment. especially since i have one laying around.

thanks for the help again

Rafiki · « **Reply #11 on:** February 12, 2009, 10:37:21 PM »

Quote from: Jimmy Lewis;66423

The bolts he is talking about with the driveshaft are only like 15mm I believe, but nonetheless no more than 17mm. A socket would make the job much easier with less slips and knuckle smashing. Good luck.

can you just take the bolts out facing the front of the car? because the ones facing the rear end/ diff. need an open end wrench. socket wont fit. Bigger than a 15mm also.

Hodge · « **Reply #12 on:** February 13, 2009, 09:02:11 AM »

the 4 diff/driveshaft bolts are 17mm I think Rafi...

Then there are two holding the diff to teh rear subframe carrier, and one through the diff mount. Just don't forget the 6 on each side holding the axles in.

Rafiki · « **Reply #13 on:** February 13, 2009, 11:12:44 AM »

thanks hodge. im going to do it tomorrow with erik