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I'm putting bigger brakes of a 7-series on my E12 with 324 mm front and rear. Ventilated at the front and solid at the rear. Would there be interest in such a kit? If so I can make a few more.

Cheers,
Jan

DMS wrote:I'm putting bigger brakes of a 7-series on my E12 with 324 mm front and rear. Ventilated at the front and solid at the rear. Would there be interest in such a kit? If so I can make a few more.

Cheers,
Jan

I find the braking ok with stock E12 brakes. What I do find is they are very heavy, especially up front.

What would be nice for me (autocrosser) is conversion brackets to allow Wilwood or similar lightweight 4 piston calipers front and 2 piston in rear. This would also solve the problem of availabiltiy of rear performance brake pads.

Getting weight out of the front of the E12 really helps turn-in. Moving battery to trunk right was huge improvement!

Turbo cars may need larger rotors and I would be ok if I couldn't run stock wheels on that car anymore, although I don't need more heat capacity as I'm not dealing with high speeds of turbo car.

Yeah I understand where you're comming from. I selected the aluminium E38 735 four pot calipers. These are bigger and lighter then the original ones. (5 kg versus 3.2 kg.) However the discs I'll be using are again heavier so in the end I remain at the same weight if I add everything up. Wheels, tires, discs, calipers etc. You can get it lighter by buying perforated grooved discs.

As of weight distribution: I just put an additional fuel tank in the rear of 90 at 90 liters of LPG so that must even things out .

DMS wrote:Yeah I understand where you're comming from. I selected the aluminium E38 735 four pot calipers. These are bigger and lighter then the original ones. (5 kg versus 3.2 kg.) However the discs I'll be using are again heavier so in the end I remain at the same weight if I add everything up. Wheels, tires, discs, calipers etc. You can get it lighter by buying perforated grooved discs.

As of weight distribution: I just put an additional fuel tank in the rear of 90 at 90 liters of LPG so that must even things out .

I think Brendan (RevX) runs those on his race car. He loves them.
I think you are still at a net loss for weight even with larger rotors.


Do they have 2 inlets or will you have to change master cylinder?

I'm going to change the master cilinder.

DMS wrote:I'm going to change the master cilinder.

Good time to fit ABS from E28?

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?

My mechanic runs a 2002 turbo (700hp M12) in Sports Sedan and uses e12 front discs (on the rear) with Mazda RX7 calipers. He says they're awesome and he's got 16" slicks.

Are those calipers a straight bolt-in swap? Same with rotors - does everything line up properly on the e12 hub?

Also are those rotors 324mm or 316mm (x28mm)?

I would be up for any rear caliper that had about the same swept area and had pads that were easier to get in popular compounds (HP+ etc)

What about early e23?

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?

No idea if the e23 has abs.

I had a setback due to the anual check but I'm back on the brake stuff. I've made a test adapter for the fronts and finished up a drawing based on this. Next are the rears and then it's time to get to the CNC bench .

Dave Rutkowski wrote:Are those calipers a straight bolt-in swap? Same with rotors - does everything line up properly on the e12 hub?

Also are those rotors 324mm or 316mm (x28mm)?

I'm using the 324 x 30mm rotors. The calipers are not direct bolt in so an adapter is made. The rotors line up properly.

DMS wrote:No idea if the e23 has abs.

I had a setback due to the anual check but I'm back on the brake stuff. I've made a test adapter for the fronts and finished up a drawing based on this. Next are the rears and then it's time to get to the CNC bench .

Dave Rutkowski wrote:Are those calipers a straight bolt-in swap? Same with rotors - does everything line up properly on the e12 hub?

Also are those rotors 324mm or 316mm (x28mm)?

I'm using the 324 x 30mm rotors. The calipers are not direct bolt in so an adapter is made. The rotors line up properly.

Interesting. What's your source for the front calipers - are they EU-only? Looks to me like the US 740's used floating single piston calipers. Also what master cylinder do you use to feed just 4 brake lines that matches up to the e12 vacuum booster?

Dave Rutkowski wrote:Interesting. What's your source for the front calipers - are they EU-only? Looks to me like the US 740's used floating single piston calipers. Also what master cylinder do you use to feed just 4 brake lines that matches up to the e12 vacuum booster?

I've no idea if they are EU only. Can't imagine. The calipers are on a E38:
725tds, 728i, 730d, 730i and a 735i.

I found a local guy who bought a 728i for the engine. I took the complete brake system without the abs. So vacuum booster, master cilinder, front and rear calipers. I bought new rotors with 324x30 front and 324mm rear.

The 740 indeed uses a single piston caliper which is a steel caliper and quite a bit heavier then the alu 4 piston one. You can go with bigger rotors then but that would be more show. It's not needed to go bigger then I'm doing now atleast that's what I guess. I'll report back when I've experienced fading or any.

DMS wrote:
I've no idea if they are EU only. Can't imagine. The calipers are on a E38:
725tds, 728i, 730d, 730i and a 735i.

I found a local guy who bought a 728i for the engine. I took the complete brake system without the abs. So vacuum booster, master cilinder, front and rear calipers. I bought new rotors with 324x30 front and 324mm rear.

The 740 indeed uses a single piston caliper which is a steel caliper and quite a bit heavier then the alu 4 piston one. You can go with bigger rotors then but that would be more show. It's not needed to go bigger then I'm doing now atleast that's what I guess. I'll report back when I've experienced fading or any.

Ah, makes sense. I think BMW only brought the big V8 e38 into the States, so no fixed 4-pot calipers here.