1978 BMW E12 525 (conversion to 535i Turbo)

[DMS]

I already made a project topics for this car on other forums so some members will know the car already. I just recently discovered this forum and was amazed by the projects going on here. I already learned some new things so I guess it's only polite to return the favour and give you guys something entertaining to read.

I won't repeat the whole past of this car as I consider it a new project myself. I actually started on a different chassis, did a weldathlon on that then threw it away. Bought a new one, fitted a different engine and stopped for a few years. I learned a lot of things over the years which I now want to apply to this car. So without further delay let me introduce my project:



Started as a 525 with a M30B25 carb fueled engine. Plans are to make a sort of fun weekend car. It should be capable for daily use although that's not really planned, but there must be room for four people + luggage in case we take it for a weekend or short holiday. So a general overview of the plans:

-Bigger stronger driveline
-Better savety so integrated cage + relocated fuel tank
-Upgraded interior
-Some luxory
-M30B35 turbo

Some points are already (partally) done most are still on the to do list. Some snapshots of what's been done before:

Exterior:




LPG + rear shock tower brace:



Brakes:



Rear suspension:
Can't find pictures but it's done just like the front.
-M535i anti roll bar 
-new bilsteins + 40mm H&R springs 
-E38 324mm brakes
-new bearings 
-sand blasted and painted.
-Also I modded the subframe bushings so they can take poly urethane bushings from an E30

Front suspension: (all new + M535i ARB)


Engine:








Interior:




4 Thermocouple readout:

E28 speedo:



Having shown this, like said before I consider this a new project so much will be changed, done in a better way. I'm starting at the base: chassis work. Currently starting at the back of the car fitting a E34 M5 big case LSD to the rear subframe.

Just a warning before hand. Mss dms is planning for us to move to a new house within an undetermined notice so don't expect this project to be finished. If we do move, another long wait will be entered in the project planning. Untill then I'm planning to really go at it

[felix2566]

I like where this is going...some tidy work. How come you are wanting to put in a roll cage when you said you wanted to use it 4 up for weekend trips etc, does it need one?

Is the thermo couple read out from another bmw or an after market thing?

[maybachman]

OOOOOOO Bookmarked:) Angry snail involved. Used to have a 525 looooooong ago, nice car and good work, leaves me to shame.

[DMS]

Oct 3, 2013 18:23:28 GMT felix2566 said:

I like where this is going...some tidy work. How come you are wanting to put in a roll cage when you said you wanted to use it 4 up for weekend trips etc, does it need one?

Is the thermo couple read out from another bmw or an after market thing?

There are several reasons for me to want to put in a role cage:
1) I'd love to be able to feel safe and take it to the ring or some drift/racing event
2) I've had this engine without the turbo before in an E12 and the chassis was really twisting quite a lot after 1.5 years of spirited driving. The chassis was more crispy then this one but it made me not so comfortable to put a 600+ hp engine in without modifying the chassis.
3) I guess a car like this is more prone to accidents and it's designed way before any crash tests were done on cars. I guess on a frontal impact I should be ok because of the big nose. Although there is always the danger of the big engine shoving right into the cabin. On a rear impact I should also be ok however the original fuel tank is right in the impact zone see the Ford Pinto story. So it has to move to somewhere in between the axles (the save-zone). Where it gets really nasty is on side impacts. There is no structural strength for lateral impacts at all. Then there is the roll-over possibility. Have you seen the flimsy A and B-pillars?
4) I've never made one so I see it as a big challenge. It's actually one of the reasons this project is taking so long. I love new challenges: never welded before, never worked with a mill before, never worked with a lath before, never painted a car before, never tore an engine apart before, never programmed an ECU before. All of this I've learned during this project.
5) Have you seen the E30M3 V10 from piper motor sports and how they designed the cage? It's just really bad ass: Piper project

Anyway all of this combined makes me want to go through the trouble of building a cage.

The thermo couple read out is from china. It can has four inputs for thermocouples of which you can select which you want to display. It originally had the buttons, display and electronics in one casing. I took it appart and changed the display for a smaller one which I made remotely mountable. There was a blind cap in the original tacho/speedo housing which I modified on a mill. The green LED's below the display tell you which thermocouple is selected. For the buttons I modified a blind cap in the dashboard to take those. It should look really stealth. So to answer your question: it's an modified aftermarket one .

I took some pictures of the current work on the differential. This one should go in. As you can see it's a lot beefier then the original one.



To align it properly I'll weld mounting plates for the half shafts to the rear axle. Because the new diff is wider I spaced the plates on the original diff as you can see on the picture.

[tonybmw]

Some great work going on there, thread now bookmarked

[bstardchild]

Oct 4, 2013 17:25:12 GMT tonybmw said:

Some great work going on there, thread now bookmarked

Indeed - these older 5 series cars are soo attractive to look at

[useless inc]

That manifold is pure p0rn!

[Vilppi]

Oct 3, 2013 12:17:07 GMT DMS said:

Having shown this, like said before I consider this a new project so much will be changed, done in a better way. I'm starting at the base: chassis work. Currently starting at the back of the car fitting a E34 M5 big case LSD to the rear subframe.

This i like to see and maybe copied . I have plans to my E12 too, and i have to put more durable rearend than normal 518 rearend...

And have You more photos of front subframe modifications?

+1 Bookmarked

[felix2566]

Very sound reasons for wanting a cage, i was just curious, not ment as a criticism. I hadnt taken into consideration the power output of your engine! I am looking forward to seeing how it turns out. If the current work is anything to go by it will be quite a machine.

What sort of look will you be going with on the exterior, will it be staing relatively standard as it is now?

[DMS]

Oct 7, 2013 21:27:33 GMT felix2566 said:

Very sound reasons for wanting a cage, i was just curious, not ment as a criticism. I hadnt taken into consideration the power output of your engine! I am looking forward to seeing how it turns out. If the current work is anything to go by it will be quite a machine.

What sort of look will you be going with on the exterior, will it be staing relatively standard as it is now?

Didn't take it as criticism. I'm looking forward to see how it will turn out too. I've too many idea's, plans and dreams but I'll just keep working at it till I'm satisfied. Just don't expect it to be running in the near future!! I'm really hoping to finish it before the oil reserves of planet earth run out.

I won't change much on the exterior looks. Perhaps different wheels, and I really like the earlier chrome mirrors but other then that no changes. For the mirrors I need to alter the triangular mounting points on doors as the chrome ones are mounted a bit deeper. I didn't know there was a difference between the two but there is. The only other thing I might consider would be an original M535i or perhaps even a more conservative booth spoiler as the car feels very light at high speeds.

-----------------------------

Only had about an hour to tinker with the car last two weeks. I measured the input shaft of the two differentials and discovered that the input shaft of the E34 diff is 5mm (that's about 20%) larger in diameter! That's quite alot. This means I can not exchange the input flange so I need to use the E34 one that has the swivel joint included. This then means that I need to use atleast the rear part of the drive axle of the E34. Luckily I still have this stored in the attic for about 7 years now.

I also measured the length of the two differentials and the is E34 diff is about 34mm longer then the E12 one. Hopefully I'll be able to measure the height difference between the input and output shafts this week. I need these measurements so I can position the diff aligned to the half shafts / wheels. I'm very happy I bought a small table mill a while back. (Which cost me more then I paid for the car but it really helps me in raising the quality of my work.) Hopefully I can make an adapter plate for the input shaft this week. I'll put some pics up as I proceed.

[DMS]

Oct 7, 2013 19:38:39 GMT Vilppi said:

Oct 3, 2013 12:17:07 GMT DMS said:

This i like to see and maybe copied . I have plans to my E12 too, and i have to put more durable rearend than normal 518 rearend...

And have You more photos of front subframe modifications?

+1 Bookmarked

Why does your 518 need a stronger rearend? Care to share some details here?

The front subframe doesn't have modifications only sandblasted, paint, new bolts etc. 

[DMS]

I'm finishing the clockwork as a side project. It will look like this:

[DMS]

Took the measurements of the differentials (E12 525 and E34 M5):



This means that the input shaft of the E34 diff has an offset of 10mm so the drive shaft will be under a slightly different angle. All in all it's quite a project to fit this diff. I'm wondering how others have done this? Were they as accurate with the alignment as I'm doing it or have they done it just on sight and let the swivle joints take care of any misalignments? I'm making multiple jigs to make sure everything is perfectly inline with the original situation.

In the end I shouldn't have issues with the concequences of misalignment: fast wearing guibo, center bearing, eccentric forces on the drive line abusing the axles. I guess only the future will show if I've done a proper job. As the orginal alignment is my baseline I'm actually relying on German engineering. With their reputation it should be good .

[bstardchild]

Aren't you supposed to have some slight miss alignment in a prop shaft run?

[DMS]

Oct 16, 2013 14:47:57 GMT bstardchild said:

Aren't you supposed to have some slight miss alignment in a prop shaft run?

It's supposed to be line this:

engine center line -------\
                                        \_______ Diff center line

So the center lines of the engine and diff are parallel to each other but at a different plane. So if you mean misaligned as in: "they shouldn't be in a straight line" then you are correct. But if you mean they shouldn't be in parallel planes you're not correct .

[bstardchild]

Ok you knew what I meant and I'm sure you have it covered

[DMS]

Here we go:

First made a plate with both bolt paterns of the input flanges spaced 10mm apart. Then mounted this plate 38mm spaced to the E12 diff, and mounted the diff in the original subframe. Then welded the plate in the subframe:




Cut off the mounting plate for the original diff:



Start chopping a hole for the front E34 mount:


A plasma cutter would have been nice! But I only have simple basic tools.

The hole is now able to take the rubber bushing.


So now this needs to welded in:


Rubber and heat don't go so well together so I can not weld it with the bushing installed. However I need something to align the tube so I'll make two steel rings that fit presicely in the tube with the bolt hole centered. Hopefully I can make those today and weld the tube in somewhere in the next days.

This is how the E12 subframe looks like with the E34 diff fitted:

[DMS]

While working on the E34 diff I found this crack on the front mount carrier:







The parts car it came off was of a friend of mine and it's been driven HARD! Guess this is the result of the beating. I'm happy I catch it now.

[Vilppi]

Oct 15, 2013 12:28:20 GMT DMS said:

Oct 7, 2013 19:38:39 GMT Vilppi said:

Why does your 518 need a stronger rearend? Care to share some details here?

The front subframe doesn't have modifications only sandblasted, paint, new bolts etc. 

Like Homer would say: ///Mmmmmmm, Power

Plan is to put S50B30 or S50B32 into it. Although both are illegal -too high power/weight ratio. Stupid laws.

[DMS]

Cool I've an S50B30 in my E30 and love it. But you don't need a 210 diff if you keep the engine stock. It would be easier to mount an E28 rear axle with a 188 diff. It's a direct fit and can handle the power without problems.