E12 Project help needed - e28 rear end swap

Post your E12 technical questions and comments here. Please, no off-topic posts.

Moderators: Mike W., Pierre

TernandoFoledo
Posts: 9
Joined: Sun Jul 16, 2017 3:34 pm

Re: E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Wed Mar 06, 2019 9:14 am

Lock, actually the e34 are ""common"" here, the real pain are the e28 parts.
Knowing this, that the e34 is a direct fit to the e28 subframe, will help. I will check if the drum rear is still available to try to do this.

Now, if i cant get it, i will have to go creative, and think about adapting something. Like, if I was to get a set of wilwoods or brembos, wouldnt it just be putting a bracket there to place the caliper and setting everything up?

Never done brakes, so I might sound stupid, sorry about that haha

TernandoFoledo
Posts: 9
Joined: Sun Jul 16, 2017 3:34 pm

Re: E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Wed Mar 06, 2019 9:51 am

Dimitrov wrote:
Fri Mar 01, 2019 9:01 am
onovakind67 has described everything very well and it will work for E12 also. I did such swap some years ago.
I addition i may say that the thickness of the drfiveshafts of E28 vary depending on which engine the car was equiped. You'd better go for subframe from m30 car. They are all with thicker driveshafts and have disc brakes (i am from Europe and here most of e28s have drums).
On my car i installed antisway bar from E28. To do this i needed to weld 2 mounting points on the bottom side ot the trunk. I just cut them from E28 and welded them on the exact same place on E12. Unfortunately i don't have any pictures of these. IF you decide to go for e28 antisway bar, keep in mind that they are also 2 types depending on the cover of the differential.
There is one more very good "PLUS" when you go for e28 rear axle - you got the diff with hall-sensor speedometer. So you can easily make your speedometer working with the newer engine and gearbox. I used e28 speedometer gauge and installed it on the place of the original E12 one - you can not notice that it is from another car. Fits perfectly! And you need only 3 wires to connect it. I may have pictures of this, i will search later.
Dimitrov, so looking for what you and onova said, its pretty straight forward, right? All the other mounting points and stuff are the same?

I've checked with the guy who has an E28 and its a 524d, with drums in the back. Its the only one I saw here in Brazil, at all, actually.

Its just pull off the old one, check the mounting of the Diff and mount everything up again? Something like that? Obviously taking the precautions that both of you mentioned.

I will also get the e34 arms with disks to make it happen as well right off the bat, if I manage to get everything.

User avatar
Lock
Posts: 207
Joined: Sun Oct 04, 2015 1:51 pm
Location: Washington
Contact:

Re: E12 Project help needed - e28 rear end swap

Post by Lock » Fri Apr 12, 2019 1:37 am

I wanted to add something. A few weeks ago I bought a 535i e34 with a blown head gasket for a M30B35 engine swap and was looking at how to use its parts including LSD with an e28 rear subframe that I bought separately.
On mye28 and other e28 sites, people would always say the e34 rear subframe wouldn't fit an e28/it would be too hard to adapt/why bother.

But spending a lot of time on realoem and also Euro BMW websites I discovered something - the e34 rear subframe for the Euro 518i is almost identical to the e28 subframe, just the roll bar is moved back onto the subframe as with the e12. It is only the bigger motors that they use the different and extended 'full cage' subframe. But the mount points are the same and I noticed on the 518i the rear diff mount is not only the same, but it's in the same location. This exact same mount is also used across the e34 range but on the bigger engine models, instead of supporting the back plate of the diff, it supports the rear of the subframe itself with a lot less stress. The diff is suspended with rubber mounts within the subframe cradle - solving BMW's issues with diffs twisting and stressing the mount and cracking the chassis.

In short - from what I see, with a few minor mods an e34 rear subframe will fit into an e28, and with a few more mods into an e12. I'm going to try it either during or after my engine swap - everything measures up but it helps having them literally side by side.

Mods will include drilling a hole in the center of the subframe for the e12's/early e28 center diff mount (middle/late e28 should fit the subframe directly), also swap the diff flange from a 6-bolt to a 4-bolt. I could cut the rear half of the subframe off, get an early e28 diff cover and suspend it from the chassis, but then I would have the same diff weak point BMW worked to eliminate. Plus with the onboard roll bar it resolves the problem of the different roll bar mounting problem on e28.
1979 528i 5-speed conversion G260/6
1979 Honda CX500

Post Reply