Interest in big brake kit E12?

DMS · Post by **DMS** » Fri Nov 06, 2009 5:24 pm

It's gonna be something like this:

Dave Rutkowski · Post by **Dave Rutkowski** » Fri Nov 06, 2009 6:43 pm

DMS wrote:It's gonna be something like this:

Looks great!

Any luck confirming that the brake booster bolts up ok, and connects to the brake pedal?

DMS · Post by **DMS** » Sat Nov 07, 2009 3:11 am

Dave Rutkowski wrote:Looks great!

Any luck confirming that the brake booster bolts up ok, and connects to the brake pedal?

Thx.

Nope Tuesday I'll pick it up at the seller and I'll go from there.

Fhaas · Post by **Fhaas** » Sat Nov 07, 2009 11:09 am

Peter Florance wrote:
DMS wrote:I could be., but then I'd need the axles and sensors aswell. Making this a larger job then I wish. The rear will be changed to some extent in time but the fronts I have no plans for at the moment.

Are there any that did this before on an E12?
I doubt it. I wonder if any early e23 used ABS?

1981 745i's had ABS, I have one sitting behind the house right now

Frank

DMS · Post by **DMS** » Mon Nov 09, 2009 4:28 am

Fhaas wrote:
Peter Florance wrote:
DMS wrote:I could be., but then I'd need the axles and sensors aswell. Making this a larger job then I wish. The rear will be changed to some extent in time but the fronts I have no plans for at the moment.

Are there any that did this before on an E12?
I doubt it. I wonder if any early e23 used ABS?
1981 745i's had ABS, I have one sitting behind the house right now

Frank

Cool thx. Perhaps I can look into this in the future. For now I'll just use a splitter. If I've room left under the bonnet I can always look into converting then. Hard part will be the abs rings and sensor mounting.

DMS · Post by **DMS** » Fri Nov 20, 2009 8:00 am

Dave Rutkowski wrote:Any luck confirming that the brake booster bolts up ok, and connects to the brake pedal?

It's not even close

. It's too wide to fit between the fender and the inlet mani of the M30B35 engine. I'm going to try some other things as I would really like that easy braking 'new' car feeling.

Dave Rutkowski · Post by **Dave Rutkowski** » Fri Nov 20, 2009 12:44 pm

DMS wrote:
Dave Rutkowski wrote:Any luck confirming that the brake booster bolts up ok, and connects to the brake pedal?
It's not even close . It's too wide to fit between the fender and the inlet mani of the M30B35 engine. I'm going to try some other things as I would really like that easy braking 'new' car feeling.

It's never that easy, is it? Here's a thought - one of the problems that you're trying to solve is that the stock e12 front calipers have 2 circuits each (2 feed lines), so the stock master cylinder has 5 outputs (2 for each front caliper and 1 for the rears that is split later). But the e23 calipers you want to use are single circuit and only have one feed line each, so what you ideally need is a master cyl that has 2 circuits - one feeding two lines (one to each of the front calipers) and a second circuit feeding just one line to the rear calipers.

One idea would be to take your stock e12 master cylinder and "plug" the two outputs that feed the front calipers and share the circuit that feeds the rear calipers. This way you would have one circuit feeding only the rear calipers, and a separate circuit feeding the front calipers with one line going to each front caliper. I'm not sure if this would cause problems in terms of volume of fluid displaced by each chamber of the 2 circuits in the master cyl (some of that fluid that was going to the front calipers now has nowhere to go, and the other circuit has to feed twice as much caliper piston volume as with the stock setup).

Or go down the path you're taking which is to find a newer style vacuum booster & master cyl with just a front & rear outputs. How far off was the booster you tried? I have an e34, and it looks like the booster on that is only about 3/8" radius bigger than the one on my e12-based 635...would bet that would squeeze in there.

Another idea would be to see if a newer master cyl with just front & rear outputs would bolt up to the stock e12 vacuum booster. No ideas on how feasible that would be.

Have you already gone down the path of any of these ideas?

Eriksson · Post by **Eriksson** » Tue Nov 24, 2009 3:44 pm

I am also about to do some upgrades with the brakes. I was thinking of put some Brembo 4-pistons in the front and remove the stock smaller 4-piston calipers to the rear. As you said the e12 master cylinder has five outputs, is there any functional issues to use just four of these outputs? One separate feed line to each caliper.
Would be great if i could use the e12 master cylinder due to the big diameter, much smaller on e28 for example.
Thanks.

YouTube · Post by **Peter Florance** » Tue Nov 24, 2009 5:48 pm

Fhaas wrote:
Peter Florance wrote:
DMS wrote:I could be., but then I'd need the axles and sensors aswell. Making this a larger job then I wish. The rear will be changed to some extent in time but the fronts I have no plans for at the moment.

Are there any that did this before on an E12?
I doubt it. I wonder if any early e23 used ABS?
1981 745i's had ABS, I have one sitting behind the house right now

Frank

Oh Frank, you are going to get me in trouble...

Did they have wheel bearings like e12 or more like e28?

DMS · Post by **DMS** » Fri Nov 27, 2009 8:29 am

Peter Florance wrote: Oh Frank, you are going to get me in trouble...

Did they have wheel bearings like e12 or more like e28?

Are the E28's bigger/better?

I'm still thinking about the rear setup.

Anyway I also didn't have time to take a better look at the mastercilinder options. Sorry.

YouTube · Post by **Peter Florance** » Tue Dec 01, 2009 7:26 am

DMS wrote:
Peter Florance wrote: Oh Frank, you are going to get me in trouble...

Did they have wheel bearings like e12 or more like e28?
Are the E28's bigger/better?

I'm still thinking about the rear setup.

Anyway I also didn't have time to take a better look at the mastercilinder options. Sorry.

No I'm just thinking that if E23 745 has wheel bearings and hubs like e12, maybe ABS is possible on e12.
The electronics don't bother me; it's the sensor and toothed ring mounting that has me wondering.

DMS · Post by **DMS** » Tue Dec 01, 2009 7:37 am

Peter Florance wrote:The electronics don't bother me; it's the sensor and toothed ring mounting that has me wondering.

Exactly my thoughts.

Do you know the diameter of the E12 master cilinder?

YouTube · Post by **Peter Florance** » Tue Dec 01, 2009 7:45 am

DMS wrote:
Peter Florance wrote:The electronics don't bother me; it's the sensor and toothed ring mounting that has me wondering.
Exactly my thoughts.

Do you know the diameter of the E12 master cilinder?

I can find out.

I have a used one

DMS · Post by **DMS** » Tue Dec 01, 2009 8:05 am

Cool! I'm really curious if the E12 one is larger or smaller then the E38 one. Otherwise I'll just plug two outputs of the E12 MC and be done with it.

I am currently in the process of making the adapters for the front calipers on a manual mill at work. The result won't be as nice as a CNC machined one but it'll be much cheaper, and work just fine.

I'll have the front struds and rear subframes sandblasted, painted and fitted with new bearings and brakes before the end of the year. I should have a bit more time the next few weeks.

DMS · Post by **DMS** » Tue Dec 01, 2009 8:21 am

http://bmwfans.info/parts/catalog/E12/S ... ylinder-3/

It says: 22,20mm

Now I need to find the E38 cilinder size.