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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > My $1500 DIY BBK



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      04-15-2019, 09:29 PM   #23
Justin Daniels
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Quote:
Originally Posted by feuer View Post
Non m E39 hub is 74.1 vs E90 72.56. Rims aren't interchangeable. That means the rotors aren't either. I'm not sure about e39 M but I assume is the same as non m e39.

You need to look at the hat. Is 50mm for e90 vs 45mm for e39. Don't just look at the center line of the blank.
Hub face to centre-line is what matters though, because that dictates the caliper position/spoke clearance (along with spoke design and some other things). Unless I'm totally off my rocker and missing something extremely obvious, which is a distinct possibility! In the PDF I attached, I measure from the inside of the flange to the centre-line of the disc, so the hat is compensated for.

As for fitment on the hub; there are two diameters on the hub, one diameter for the rotor and one for the wheel. As such, wheel fitment could vary independently of rotor fitment. I'm not saying that's the case here, you could be correct; but the numbers you cited are for the smaller diameter of the hub, the part that the wheel sits on.

Brembo's European parts lookup seems to be on the fritz and I can't look up the rotor drawings that I've been using (lesson learned: download reference material). I'll have to do some digging and confirm.

EDIT: Centric rotor dimensions from RockAuto: E90 325i, E39 540i, and E39 M5 dimensions. All share the same "hub hole" of 79mm.
Now checking the hubs: E90 325i. E39 540i, and E39 M5. All show a 3.11in (79mm) "brake pilot diameter". Wheel pilot diameter varies from E39 to E90, 74mm and 72.48 respectively.

Cheers.

Last edited by Justin Daniels; 04-15-2019 at 10:15 PM.. Reason: Typos
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      04-15-2019, 11:02 PM   #24
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I give you props. You are definitely doing research and that's a good thing! What are your plans for the DSC controller altogether? What about the steering angle sensor?
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      04-16-2019, 07:10 AM   #25
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Quote:
Originally Posted by vasillalov View Post
I give you props. You are definitely doing research and that's a good thing! What are your plans for the DSC controller altogether? What about the steering angle sensor?
Thanks!
I'm a blasphemer and am swapping in an 5.3L LS4, from an Impala SS, and using this as a dedicated Lapping/Time Attack/CASC GT Sprints car. As such, there will be no factory wiring/electronics in the car whatsoever! I'm undecided whether I'm going to re-purpose the MS3Pro that I have for the V12 or get a MicroSquirt for the LS4.

I originally picked up this car to swap a Mercedes V12 into; I figured since the platform came with both an i6 and v8 that it would be a good candidate for a V12 (first post on here was asking for coding help). Unfortunately, the V12 is bit too long for a clean install and would likely need a custom subframe and/or a dry-sump to clear the hood at the front. So I decided to turn it into an experiment to see how cheaply I could make a really capable track E9x. The car was $900CAD and I've sold $1000CAD worth of parts off it, so it's a free starting point!

Last edited by Justin Daniels; 04-16-2019 at 07:26 AM..
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      04-16-2019, 08:51 AM   #26
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Quote:
Originally Posted by Justin Daniels View Post
Hub face to centre-line is what matters though, because that dictates the caliper position/spoke clearance (along with spoke design and some other things). Unless I'm totally off my rocker and missing something extremely obvious, which is a distinct possibility! In the PDF I attached, I measure from the inside of the flange to the centre-line of the disc, so the hat is compensated for.

As for fitment on the hub; there are two diameters on the hub, one diameter for the rotor and one for the wheel. As such, wheel fitment could vary independently of rotor fitment. I'm not saying that's the case here, you could be correct; but the numbers you cited are for the smaller diameter of the hub, the part that the wheel sits on.

Brembo's European parts lookup seems to be on the fritz and I can't look up the rotor drawings that I've been using (lesson learned: download reference material). I'll have to do some digging and confirm.

EDIT: Centric rotor dimensions from RockAuto: E90 325i, E39 540i, and E39 M5 dimensions. All share the same "hub hole" of 79mm.
Now checking the hubs: E90 325i. E39 540i, and E39 M5. All show a 3.11in (79mm) "brake pilot diameter". Wheel pilot diameter varies from E39 to E90, 74mm and 72.48 respectively.

Cheers.
Yes and no. You are better off with rotor that is also 32mm thick but also has 50mm from rotor surface to where the rim mounts to because of spoke clearance. Of course, the rotor will have to clear the control arm ball joints on the other side. Hypothetically this Brembo rotors can be mounted on the thinner e90 rotor too and it will be 5mm inward that will help with rim spoke clearance. True, isn't necessarily that rotor would be different if rims are different and I haven't done any compassion of part numbers but have done custom brake projects in the past and don't remember e39 brakes on e36, e 46 or e90. From memory this rotors have different hub registry, 79mm vs 75mm. Usually people used Euro e36 m3 345mm rotor and not the e39. Probably there is a reason. Double check before you start ordering parts.
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      04-16-2019, 09:27 AM   #27
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Quote:
Originally Posted by feuer View Post
Yes and no. You are better off with rotor that is also 32mm thick but also has 50mm from rotor surface to where the rim mounts to because of spoke clearance. Of course, the rotor will have to clear the control arm ball joints on the other side. Hypothetically this Brembo rotors can be mounted on the thinner e90 rotor too and it will be 5mm inward that will help with rim spoke clearance. True, isn't necessarily that rotor would be different if rims are different and I haven't done any compassion of part numbers but have done custom brake projects in the past and don't remember e39 brakes on e36, e 46 or e90. From memory this rotors have different hub registry, 79mm vs 75mm. Usually people used Euro e36 m3 345mm rotor and not the e39. Probably there is a reason. Double check before you start ordering parts.
I see what you're saying now. I am losing 4.6mm of spoke clearance based on the hat face to rotor face measurement. I did a comparison between the Cayenne caliper and the StopTech ST60 caliper and both are pretty much bang on at 77mm from rotor centreline to caliper face. With the M5 rotor, this puts the Cayenne caliper face 15.3mm outboard of the rotor hat face. For reference, the ST60 caliper sits 19.9mm outboard of the rotor hat face. Though I'm losing 4.6mm of spoke clearance compared to the E90 325i rotor, I still have 4.1mm more spoke clearance than the StopTech ST60 caliper does. So I'll be OK there. As for the rotor register, the E39 M5 and E90 share the same 79mm front diameter, 75mm is in the rear.

People probably use the Euro E36 M3 rotor because whatever OEM caliper they were using wouldn't suit a 32mm wide rotor; OEM rotor is 28mm I believe.

I wouldn't want to run a caliper designed for a 34mm thick rotor on much less than a 32mm thick rotor. I'll be running 1mm stainless backing plates to help keep the pistons in their designed range of travel and help with heat dissipation. I'm sure I'm being a bit paranoid about it and could run 30mm thick (or less) without any issues, but I'd rather keep it within 2mm of the Cayenne's rotor thickness. Plus thicker rotors make them a better heat sink and everyone's a winner.

Cheers.
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      05-28-2019, 09:30 AM   #28
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Just a quick update; I have been focusing my efforts on the motorcycle I'm building so the DIY BBK has taken a back seat for a while now.

Uprights: I picked up a wrecked (front end) E93 M3 without engine/transmission and have pulled all of the suspension off of the car. I'll now be running M3 uprights front and rear and basing the adapter off of this setup, I don't think this will make a difference in the grand scheme of things but figured it was worth mentioning. The only impact I can see is that the front hubs have dowels to locate/drive the rotor; which means I'll need to press them out of the hub or drill the M5 rotors if the pattern doesn't match (E39 M5 has these same dowels but likely in a different spot). I'll know more once the rotors arrive.

Rotors: I am going to be using 135i front rotors (338mm) on the rear for this experiment. This will balance out the front/rear brake torque bias vs the X3 front rotors (328mm). I will now need to have an adapter ring cut to centre the rotor hat on the hub since I will now have a 79mm register on a 75mm hub (the X3 front rotor eliminated this problem).

Calipers: I have admitted defeat on the axial mounts. I would basically need to grind off the factory ears on the spindle/upright and/or make a custom bracket that locates the caliper on the opposite side of the spindle/upright. It is not impossible to keep the axial mounts; however, the path of least resistance looks to be modifying the calipers for a radial mount instead. Though I have access to the necessary machine tools to accomplish this, I feel that "get out your vertical milling machine, jig up the caliper to clamp it parallel to the table, and machine the caliper" exceeds the spirit of DIY. As such, I'll be heading to a machine shop tomorrow to ask about having them do the dirty work for me and adjust the overall cost of the setup accordingly.

I'll keep this thread updated as I move forward.

Cheers
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