Vented rear disk on an e36 compact?

[chrisbec]

Originally Posted by Bluebimma

You guys must have just skimmed over the pics rather than actually reading. He posts what he did to get the rear to fit.

Yea, I was in a hurry, you busted me

But I'll give myself a pat on the back, I was right on the money

Since you've read every word of the post and are so smart, do you know why he ground that the ear of the caliper carrier like that???

[e36 323ti]

Some more design and FEM analysis done. Because of space limitations/slim design considerations, I have decided to make the carrier in Titanium, making it very strong and reasonably light (285 gram each compared to the stock carrier weight of 618gram each).

A 3D sketch:


Results from the FEM simulation in order to verify the strength of the design:


A sketch of the design:


Feeling very lucky having a knowledgeable friend which is willing to help out with the FEM simulation and optimization of the design...

[e36 323ti]

Did a wood-"rapid prototype" today based on the drawings. Have to do some minor adjustments before the carrier is produced in metal.

Based on new knowledge regarding BMW master cylinder (MC) piston diameters - the stock ti master cylinder has different bore fore front and rear - a new analysis of the bias is done:

Stock bias e36 323ti : 66.24%
Current bias : 66.42%
Rebuild bias : 64.45%
Rebuild bias w. m3 MC: 61.43%
E36 M3 3.0 stock bias: 60.82%

[pdxmotorhead]

So your saying the bias is basically 60/40.... Cool.

Dave

[e36 323ti]

Had to adjust the design:



Also the strength is increased. The safety factor is now above 10 (2x5):



The weight of each carrier (Titanium) is about 350 gram, i.e. close to half the weight of the original carrier.

[e36 323ti]

Did a "rapid prototype" based on the new design to double check dimensions and clearance issues...





Next step is to make a prototype in aluminium before the final "production"...

[chrisbec]

Man that is looking sweet! I don't think that you are going to have any strength issues with the caliper bracket. Looks like that is plenty of meat there. I would venture to say that one made from aluminum would have more than enough strength...

[e36 323ti]

Originally Posted by chrisbec

I would venture to say that one made from aluminum would have more than enough strength...

You may be right, but it also depends on which aluminum that is used. We have done strength analysis using a 6000-series (do not remember the exact one) of aluminum, and I did not take the chance of using it given this particular design.

E.g. the 6061 alloy has tensile strength of 310 MPa.

Using aircraft aluminum (the term aircraft aluminium or aerospace aluminium usually refers to 7075) is another option. The 7075-O grade has a tensile strength of 276 MPa. The 7075-T6 has a tensile strength of 510 - 538 MPa.

The Titanium planned to use here (Grade 5) has a tensile strength of 1000 MPa.

Better safe than sorry...

[e36 323ti]

1th iteration of the aluminium prototype carrier ready for test fit

[e36 323ti]

Braided hoses with banjo bolt ready. The Titanium bolt, which are going to be reworked to carriers, acquired...

[logie74]

Has anyone had any luck with fitting vented Z4 rear rotors?

[e36 323ti]

Originally Posted by logie74

Has anyone had any luck with fitting vented Z4 rear rotors?

The Z4 rotors do fit. There are also some alternatives popping up these days. www.300mm.de seems to have developed some nice alternatives for vented rear brakes for the Compact (see http://www.300mm.de/301mm/301mm.htm). One solution is to use their 'carrier' which makes it possible to combine the Z4 rotors with some alternative BMW calipers (see "294x19mm Bremsanlage für E36 Compact Hinterachse").

[e36 323ti]

I did finally find the time to test the alu. prototype on the car. It seems to fit perfectly








Now the carrier in Titanium has to be made...

[diamondnik]

Regarding the Z4 adapters sold on 300mm.de: Babelfish is not a perfect translation so I'm not sure if they said that the rotors need extensive modification? As far as I can see those Z4 rotors fit better than the 120d ones for their big rotor conversion.

[chrisbec]

Originally Posted by e36 323ti

I did finally find the time to test the alu. prototype on the car. It seems to fit perfectly

...

Now the carrier in Titanium has to be made...

Nice work!