MyE28.com

Hi, I have a 210mm E23 differential that I am trying to fit onto my E28. I am told that it is a 2.93 LSD out of an '85 745i. First noticeable difference is obvious, the ear on the cover is offset, while my old one is centered. I assume that I would need a different rear differential mount. Also, it seems that the half shafts are just a little too long. I might be able to hammer the inner boss over the diff flanges and get them to bolt up, but I feel like I would lose a significant amount of axial travel necessary for suspension compression.

I have read this thread (http://www.mye28.com/viewtopic.php?t=44635), and post #7 seems to have a lot of good info on the interchangeability. It seems to say that the cover from the 745i would fit the E28 chassis. Also, it is stated that the half-shafts should fit fine.

Any advice here? I have some pictures below.

Thanks in advance!

-CJ

You won't be able to install that differential into your early E28. You would need a big case diff cover with a center mount, which doesn't exist to my knowledge.

Bummer, I didn't realize that any of the subframe mounting points were different throughout the years... Also worth mentioning, the subframe and 188mm diff pictured are from a 533 or 535, I can't remember... The car it's going into is an '82 528e (also has the centered cover).

I have access to a machine shop, so I'll find some way to mount it either way. I was just hoping/assuming that it would fit with some combination of original parts.

While 82 would have a slightly different subframe, it's a difference in the body in 82-84 cars vs later ones that make the difference. That diff will bolt up to the subframe just fine, but not to the body. I have seen the flange cut off and welded back on, apparently successfully, but I would be reluctant to do it. BTW, why do you want a large diff on an eta?

Is the difference in the '82 subframe something important? I was planning on using it since it has much less rust than the 533 one.

I would think that modifying the diff mount or mount location would be easier/safer than rewelding that diff ear. But I'll have to get a better look when I can get the car in a garage for the winter, it's still under a foot of snow.

Still curious on how people fit the half shafts though.

The reason I'm going to 210mm is because it is getting an engine swap that will result in more than 5x the power output of the eta.

Kyle in NO wrote:You won't be able to install that differential into your early E28. You would need a big case diff cover with a center mount, which doesn't exist to my knowledge.

I think that sounds like an M5/6 cover but I don't know for sure.

The M5 and M6 with the large case diff only came with offset covers.

cj.surr wrote:Is the difference in the '82 subframe something important? I was planning on using it since it has much less rust than the 533 one.

I would think that modifying the diff mount or mount location would be easier/safer than rewelding that diff ear. But I'll have to get a better look when I can get the car in a garage for the winter, it's still under a foot of snow.

Still curious on how people fit the half shafts though.

The reason I'm going to 210mm is because it is getting an engine swap that will result in more than 5x the power output of the eta.

The difference is somewhat important, 82s don't have dogbones, later ones do and it's supposed to help control toe in cornering.

Ok, that shouldn't be a huge issue. I have a whole setup from the 533, so I'll figure out some combination to use the dogbones. I did a quick search and found conflicting information on the differences in the subframe and trailing arms between the '82 and later years. Are they both different? Only one? Shame that my '82 has a super clean suspension (car from GA), and the 533 rear suspension I have is all rusted and needs work.

Still interested in the following information if anyone knows for sure:

Are the subframes different between 528e (no dogbones) and the later models with dogbones?

Are the trailing arms different between the 528e (no dogbones) and the later models with dogbones?

Do the 188mm differential axles work with the 210mm differential?

Thanks

Those parts have a start date of 9/82 so the crap before that date are different from the crap after that date.

So both the subframe and trailing arms are different in the '82?...

realoem.com install vin and find the parts.

grab the number and go back to select car up top near the title and do part number look up to see what it fits. open as many of the subdivisions as you need to see that the cut date was 9/82. I have no idea if the parts can be use on the any car. I use the electronic resources available on the interweb.

They're different part numbers but the only difference may be the lack of mounts on the early subframe.
Axles are the same length. I've installed a 3.07 big case on a car that previously had a 3.73 medium and everything bolted up fine.
Trailing arms are also probably only different because they lack dogbone mounts.

5 years too late but since I had the same idea, I thought I would update this thread with "new" information that was posted 2 years after this thread but I just stumbled upon recently and now cross-posting. Boldface mine.

My original plan was to use the M5's large-case 3.91 diff, but it wasn't until trying to physically install it into the car that I realized that it would take more than just a rear mount modification to pull off. The floor pan is different in early versus late E28s, with the early model floor pan providing inadequate clearance for the larger differential case.

Source: viewtopic.php?p=1410590#p1410590