E12 Project help needed - e28 rear end swap

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

E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Sun Dec 16, 2018 9:59 am

Greetings!

Before I start, I would like appologize if there is somewhere with this intel, but in my uses of the search tool, nothing came in that helped solve my doubts. Also, I would like to point out that I will try my best to give as much information as I can, trying not to be a pain for you to read it all, so - sorry in advance.

Starting at the basics, i'm making an E12 project, with a mechanical swap in virtually every part to upgrade to newer systems/techs, just enough to be a reliable daily/performance "toy".

So far we've successfully swaped the M10 for a M52TUB25 (e46) and the 4spd getrag for a 5spd (e36).

Now I'm studying the differencial and brakes swap, and here I need some light.

First, location factors:
- I'm from Brazil, where we have tons of E36, E39, E46 and newer ones... But very, very few E34, E30, E28 and so on.

- Importing parts here, even used ones, is kinda expensive, so if possible, I'm looking for solutions that favors on this "bimmer environment"

Second, "little" things from the project:
- From the engine and gearbox swap, I've lost my speedometer and rev meter, which would be nice to get back in some way

- I've also lost the brake booster, due to the intake size and air intake to the throtlebody, so I'm now running a Brake Booster Delete setup, but I really want to put back some brake booster. Apparently, I could fit a 6" or 7" brakebooster in the original position. Any thoughts here? ._.

Now the real issues:
- Diffs: My diff is 4.1, which is really short, so I'm looking for something around 3.45, or close to that, to give me more "cruising range". The actual diff seems to be the same as E9 and E3, as far as I read, so changing only the inner parts would work, but so far is the expensive try, and wouldnt solve the rev and speed issues

- Brakes: Actual brakes are disks in the front and drums in back. My idea is to replace the whole system with E34's 540i brakes, which seems to be a smooth fit in the E12 chassi, but I dont really know about it and what it really involves.

To solve both of these issues, I've thought to swap the whole rear part to an E34 (If i'm lucky enough to get my hands in one) or an E36, but I couldnt find if it would enlarge my rear width too much, or be a real stupid/painful swap.

If anyone has any insights on this, please, join the army!

PS: Since I started this research, an E28 rear (without shocks) appeared to me. I'm still trying to negotiate, and check if it would be "doable", since I have to import a whole rear end and might cost a fortune. The e28 rear is just just plug and play? Does it need a lot of adaptations?

Thank you very much,
Fernando

T.Hanson
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Joined: Wed Jul 26, 2006 7:39 am

Re: E12 Project help needed - e28 rear end swap

Post by T.Hanson » Mon Dec 17, 2018 10:20 pm

People are crazy, and I am a people. My question would be why your dream E12,... never mind.

Patience, persistence, piles of money, someday you will have your E12, 28, 34, M52TUB25, e46, reliable daily driver/performance "toy. "

Effing nuts. No offense.

CSBM5
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Joined: Sun Jan 11, 2009 7:23 pm
Location: Raleigh, NC

Re: E12 Project help needed - e28 rear end swap

Post by CSBM5 » Tue Dec 18, 2018 8:00 am

I would consider posting up in the mye28 forum as there is a much greater likelihood of someone there being able to help with your questions. Sorry, that's all I've got to offer. Good luck with the swap!
Current stable:

2019 F87 M2 Competition, 6MT
2011 E90 M3 Silverstone, 6MT
2007 E91 328i Silver, slushbox
2006 E90 330i ZSP 6MT Electric Red

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

Re: E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Tue Dec 18, 2018 11:16 am

Saying no offense after your sentences isnt quite a "canceling" for what you said.

As I tried to explain, living in Brazil is quite difficult to work with euro classics, and my car isnt a E12, 28, 34 effing thing. It's a project with some quite study behind and looking for options to solve real day problems, such as a really short gear ratio and other problems caused by swaps.

Thanks anyway for the great intel.


About the mye28, my goal isnt to change the rear end to an e28, its just what ppl often say that works, but just to get an idea, to import an rear end here to Brazil it would cost something between USD3.000 to USD4.000. Which is a complete nonsense thing to do.

Anyway, I will keep measuring and stuying mechanics to try to solve this, thanks for the help :)

CSBM5
Posts: 28
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Re: E12 Project help needed - e28 rear end swap

Post by CSBM5 » Tue Dec 18, 2018 12:40 pm

The main reason I suggested mye28.com site is that it is filled with people who have vast experience and background across a wide range of vintage BMWs such as S54 powered E28s, E23 Alpina restorations, E12 530i restoration, 2002 Turbo restoration in progress, etc,etc, a whole range of experience. It is a much more active community than this board.
Current stable:

2019 F87 M2 Competition, 6MT
2011 E90 M3 Silverstone, 6MT
2007 E91 328i Silver, slushbox
2006 E90 330i ZSP 6MT Electric Red

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

Re: E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Tue Dec 18, 2018 10:15 pm

Yeah, I understand and you are right, I was just explaining that my goal here is is to try to find other possible solutions to those things I've mentioned without having to do the e28 thing :)

I think that it should be possible to manage it, but so far, didnt find much haha

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Mike W.
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Re: E12 Project help needed - e28 rear end swap

Post by Mike W. » Wed Dec 19, 2018 1:24 am

TernandoFoledo wrote:
Sun Dec 16, 2018 9:59 am
Greetings!

Before I start, I would like appologize if there is somewhere with this intel, but in my uses of the search tool, nothing came in that helped solve my doubts. Also, I would like to point out that I will try my best to give as much information as I can, trying not to be a pain for you to read it all, so - sorry in advance.

Starting at the basics, i'm making an E12 project, with a mechanical swap in virtually every part to upgrade to newer systems/techs, just enough to be a reliable daily/performance "toy".

So far we've successfully swaped the M10 for a M52TUB25 (e46) and the 4spd getrag for a 5spd (e36).

Now I'm studying the differencial and brakes swap, and here I need some light.

First, location factors:
- I'm from Brazil, where we have tons of E36, E39, E46 and newer ones... But very, very few E34, E30, E28 and so on.

- Importing parts here, even used ones, is kinda expensive, so if possible, I'm looking for solutions that favors on this "bimmer environment"

Second, "little" things from the project:
- From the engine and gearbox swap, I've lost my speedometer and rev meter, which would be nice to get back in some way

- I've also lost the brake booster, due to the intake size and air intake to the throtlebody, so I'm now running a Brake Booster Delete setup, but I really want to put back some brake booster. Apparently, I could fit a 6" or 7" brakebooster in the original position. Any thoughts here? ._.
Hydroboost would probably work, but I think they last came on E34s. So find a do it yourself junkyard and hunt around looking at vacuum brake boosters, measuring everything. Be extremely careful, we are talking about your brakes.
Now the real issues:
- Diffs: My diff is 4.1, which is really short, so I'm looking for something around 3.45, or close to that, to give me more "cruising range". The actual diff seems to be the same as E9 and E3, as far as I read, so changing only the inner parts would work, but so far is the expensive try, and wouldnt solve the rev and speed issues
Correct on the diff interchange, but it doesn't seem like it's really an option. E28 rear subframes will bolt up to E12s, but apparently that really doesn't do much good anyway as they're rare also. I assume you're familiar with http://www.realoem.com/bmw/ it's not perfect or always right, but it's very, very good. Look and see what diffs are available and have a way for a rear mount to your E12. Measure the driveshaft, especially the bolt pattern. If it will bolt up, consider cutting the mounting flange off the doner car, an E36 I suspect, but I'm not sure, cut the one off yours and have the later one welded to your subframe to allow mounting the later diff. The more accurate in terms of both length and especially angles will help, but both axles and the driveshaft have universal joints in them so alignment doesn't have to be perfect. Axles and or CV joints may or may not be an issue. Also keep in mind there were 3 different sizes of differentials, a small, usually used on 4 cylinder cars and ok, but not particularly strong, a medium, the usual on 6 cylinder cars and a large which was used on a few high performance 6 cylinder cars such as M5's and V8s and V12s. A later diff such E36 would give you a sending unit you could use for an electronic speedometer.
- Brakes: Actual brakes are disks in the front and drums in back. My idea is to replace the whole system with E34's 540i brakes, which seems to be a smooth fit in the E12 chassi, but I dont really know about it and what it really involves.
I'm not aware of any other brakes that adapt easily to E12s, besides E12s. E28s have a wide variety of options, but not E12s. Again, an E28 rear subframe would be very useful to you.
To solve both of these issues, I've thought to swap the whole rear part to an E34 (If i'm lucky enough to get my hands in one) or an E36, but I couldnt find if it would enlarge my rear width too much, or be a real stupid/painful swap.

If anyone has any insights on this, please, join the army!

PS: Since I started this research, an E28 rear (without shocks) appeared to me. I'm still trying to negotiate, and check if it would be "doable", since I have to import a whole rear end and might cost a fortune. The e28 rear is just just plug and play? Does it need a lot of adaptations?

Thank you very much,
Fernando
Again, an E28 subframe would be a huge help. I haven't done it, but know a couple of people who have and they say it bolts up. You would have to figure out what combination of shocks and springs would work, brake lines are different, but apparently it does fit. An early E28 diff cover fits the same type of rear diff mount as E12. But keep in mind you would want everything, the subframe, diff, axles and brakes. And I'm not sure on springs.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

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Lock
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Re: E12 Project help needed - e28 rear end swap

Post by Lock » Thu Dec 27, 2018 12:18 am

Definitely see if you can find an e28 rear subframe with disc brakes because that will solve your issues. Also you can use some e34 parts such as the trailing arms.

But in the meantime, you can get a speedo disc for the axle and mount a reader next to it. I bought one and they are quality.

https://www.pacificcustoms.com/ac957812.html
Last edited by Lock on Wed Jan 09, 2019 11:15 pm, edited 1 time in total.
1979 528i 5-speed conversion G260/6
1979 Honda CX500

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

Re: E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Tue Jan 08, 2019 8:00 am

Wow, thank you very much guys!

Really really really helpfull!! :)))

I'm in the saga after those parts now, so lets pray :D

onovakind67
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Re: E12 Project help needed - e28 rear end swap

Post by onovakind67 » Sun Feb 24, 2019 9:38 am

I put an E28 rear axle in my E3, and the problems you might incur should be common.
1. As mentioned earlier, you will need the differential cover from an early E28 with the centered mount. It will bolt right on to the stock mounting point. Otherwise you will be fabricating an adapter.
2. You will need to re-route the brake lines to match up.
3. The sway bar mounting points are different. I welded a bracket onto the E28 arms to replicate the original mounting point.
4. The emergency brake cable sheath lengths were different so I made some extenders and couplers to make them match
5. The E28 shocks and springs bolted right up in the stock holes. I originally used the E3 top mounts but found that the E28 top mounts also work and are less complicated. The Bilsteins for the application have the adjustable spring perch, so you will have a few inches of adjustment in the height of the rear of the car. I also found that performance springs for E28's are much easier to find than older versions.

The differential uses a case common to the E23, E24, E28 and E30 so different gear ratios are available and easy to swap. E28's mostly have 3.25:1 ratios, so if you want to swap in a different ratio like the 3.45's from an E23 or 3.73's from an E30 you simply pop out the axle drive flanges from the E28 and install them in the new center section. LSD carriers are fairly easy to come by.
'72 3.5L 5-spd Bavarious - E3 with E12 front struts/brakes, E28 3.25 LSD rear axle, E39 wheels, Webers, etc, etc, etc...

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Lock
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Re: E12 Project help needed - e28 rear end swap

Post by Lock » Tue Feb 26, 2019 1:51 am

Thanks for this info. I am picking up an e28 rear subframe and pieces next weekend to do this. I think I actually have a picture of your setup I found somewhere which I used for reference, or at least an identical e3 with e28 and sway bay tabs welded on the arms.
1979 528i 5-speed conversion G260/6
1979 Honda CX500

Dimitrov
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Joined: Wed Jul 25, 2012 5:03 am

Re: E12 Project help needed - e28 rear end swap

Post by Dimitrov » 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.

onovakind67
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Re: E12 Project help needed - e28 rear end swap

Post by onovakind67 » Sun Mar 03, 2019 11:35 am

I stayed with the E3 rear sway bar for two reasons.
1. It is an aftermarket ST version.
2. I didn't feature removing all the stuff and insulation from the inside of the trunk to weld some brackets on and not burn the car down. It was much easier to do it out on the floor on the trailing arms.
'72 3.5L 5-spd Bavarious - E3 with E12 front struts/brakes, E28 3.25 LSD rear axle, E39 wheels, Webers, etc, etc, etc...

TernandoFoledo
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Re: E12 Project help needed - e28 rear end swap

Post by TernandoFoledo » Tue Mar 05, 2019 10:13 pm

Wow, awesome discussion guys!

Its a really great intel to be honest!

So far, I couldnt find anything that would help me in the swap. Everything I found was completelly out of price, around what I told you all in the first post.

Im thinking in keeping it original and trying to work over the strut I already have. Might not be the best way, but is the one i could find.

Im also still trying the e28 thing, but its a real pain. Found one with drums in the rear, are they any good for this?

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Lock
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Re: E12 Project help needed - e28 rear end swap

Post by Lock » Wed Mar 06, 2019 1:30 am

Once you have the e28 rear end, even if it is drums, you could then put on e34 control arms with discs as they are a direct fit (and an upgrade). I know you said e34 parts are rare, but hopefully they are more common than e28 parts. Plus you could order some e34 control arms and parts from ebay or somewhere like that from other countries and collect parts over time until you have all the pieces?
1979 528i 5-speed conversion G260/6
1979 Honda CX500

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