Big brake conversion.

[gazzol]

A few months ago after a run out with some seriously fast cars I decided that I needed better brakes. This winter I am going to upgrade the rear brakes but for now I've just done the fronts. I wanted to utilise off the shelf parts wherever possible so I bought 2nd hand E12 M535i front uprights so I could use discs from a later/larger BMW. The hubs were fitted with new bearings and I used front discs from an E38 740i which are 325mm diameter. I managed to buy a complete set of 4 radial mount calipers from a 996 Porsche Carrera 2 for the bargain price of £350. An adapter block was made from aluminium to mount the calipers to the BMW uprights.

Old VS new

 

[Cornishman]

Thanks for the information.
What did you do about the twin pipes that the standard cars have to each caliper, I assume these new calipers have just one feed each?
Same twin servo set up?
What is the difference on the road?

 

[teahead]

Thanks for the information.
What did you do about the twin pipes that the standard cars have to each caliper, I assume these new calipers have just one feed each?
Same twin servo set up?
What is the difference on the road?

Like the Wilwood setup that IE sells, I believe you change the master to something like this:

Fits BMW E23 733i 3.2L L6 (1978-1984) Brake Master Cylinder Ate 34311150229 | eBay

<p>Brake Master Cylinder 34311150229 <br>Ate <br>Fits BMW E23 733i 3.2L L6 (1978-1984) </p> <p>New - ATE</p> <p>34311150229 / 34 31 1 150 229 / 53706004237 / 537 06004 237 / 10154</p> <p>Brake Master Cylinder </p>.

www.ebay.com

 

[teahead]

You should sell or make available the CNC file for the adapters!

I see the picture w/the brembo brakes; is that something just for comparison? Did you have brembos before?

You said you bought FOUR Porsche calipers; you did something for the rear?

 

[Rek]

You should sell or make available the CNC file for the adapters!

I see the picture w/the brembo brakes; is that something just for comparison? Did you have brembos before?

You said you bought FOUR Porsche calipers; you did something for the rear?

I would be up for a pair for the front.

 

[gazzol]

Thanks for the information.
What did you do about the twin pipes that the standard cars have to each caliper, I assume these new calipers have just one feed each?
Same twin servo set up?
What is the difference on the road?

I fitted 4 pot Brembo calipers when I restored the car in 2007 so the brake system was already modified for single brake lines.

You should sell or make available the CNC file for the adapters!

I see the picture w/the brembo brakes; is that something just for comparison? Did you have brembos before?

You said you bought FOUR Porsche calipers; you did something for the rear?

There was no CNC involved so there is no file to make available. What I did was to fit the brake discs and then with an adapter to connect the caliper to a bicycle pump I clamped the caliper to the disc and worked out that I needed a 40x40x200mm to mount the calipers to the hubs.The aluminium was then clamped to the caliper with the caliper clamped to the disc I drilled into the aluminium with a drill the same size as the mounting holes just enough to mark out where the holes needed to be. The mounting block was then transferred to the pillar drill and then drilled the correct size to tap a m12x1.5 thread. Once the caliper and the mounting block were bolted together the caliper was transferred back to the disc and I scribed around the original mounting lugs onto the mounting block. Then the disc was removed and I was able to line up the scribe marks and clamp the mounting block in place and drill through the original mounting lugs just enough to mark out where the holes needed to be and then the block was transferred back to the pillar drill to make sure the holes were at 90⁰.
Using radial mount calipers makes the whole process much easier if you don't have access to machinery.

 

[gazzol]

Also for a point of reference the brake master cylinder I used was for a MK1 fiat Panda chosen because the inlet and outlet are in the top of the cylinder just like the original on a right hand drive car. The cylinder is 19mm bore which was ideal for me as I wanted to delete the brake servos without making the brakes too difficult to press.

 

[Cornishman]

Thanks for the update, which made me think a bit more.
Is the system still split front and rear, or is it an overall single line circuit? If it’s dual line then I guess that new master cylinder has 2 outlets? How did you get around any potential difference in volume from the from calipers to the rear?
How does she drive with no servos? Is there an increased braking effect and is the pedal effort about the same as before?
Thank you.

 

[gazzol]

The brake system is dual circuit split front and rear, the master cylinder does indeed have two outlets. For the time being the brakes are over biased to the front but I do intend to use the rear brake calipers which I got with the fronts with larger 300mm discs which should bring the balance back. The effort required is slightly greater but this should be reduced once the Porsche rear calipers are used however it doesn't take too much effort to lock the wheels if you want to.