[Justin Daniels]

Originally Posted by feuer

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.

[vasillalov]

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?

[Justin Daniels]

Originally Posted by vasillalov

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!

[feuer]

Originally Posted by Justin Daniels

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.

[Justin Daniels]

Originally Posted by feuer

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.

[Justin Daniels]

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

[Justin Daniels]

Holy hell time flies. Not much progress unfortunately as I've been focusing on cleaning up the shell. Also moved shops and had to part out the M3 I dragged home for parts.

Rotors: Turns out the E39 M5 rotors use the exact same drive pin size and location as the E9x M3. Not a huge deal since they can be pressed/hammered out of the hub. The set screw is different so I'll need to order some E39 M5 screws or just run without them since I'll likely be running studs and nuts vs bolts and won't need to worry about the rotor coming off with the wheel.

Calipers: I'm committed to these calipers now since I just hacked the axial mounts off on the band-saw (no sense wasting time on a mill to do something a band-saw can do). The final cuts will be done on a mill since they will need to be jigged/clamped to ensure that the mount face is truly parallel to the piston bores. We test fit a rear caliper on my friends bench-top mill just to check that it has enough travel; it should work for the fronts too , if we can get them clamped down to the relatively small table. For anyone keeping track of the price, I was quoted $250CAD to machine the axial mounts off of the calipers and drill them to suit the radial mount brackets, but I'll be doing this myself.

That's where I'm at right now, sorry I don't have anything more exciting to report! I've also been working on the "ball-joint" adapters for the front uprights that I mention in this thread as well as adapting an LS4 (red-headed step-child of the LS family) to the GS6-53BZ. Chipping away at lots of parallel projects.

Oh I'm also tearing down an M3 rack because I'm a sick man. I will be de-powering it, welding the two halves of the valve body, and running a Prius column for the assist. The thread documenting that can be found here. Any tips for removing inner tie rods when the rack is out of the car and has no outers on it?

Cheers

[Justin Daniels]

Spent some time over the last two days measuring and sketching the rear brake rotor adapter rings. Since the 135i front rotor is going to be used on the rear, I needed to make a spacer to make up the 2.0mm difference in the hub bores.

After teaching myself some basic Fusion 360, I've come up with the attached image. This weekend I'll be 3D printing it at a friends place and then trying it out.

One thing I noticed with my test fit was that the rear of the rotor is very close to the knuckle. I like to have 3mm clearance around most brake components, so when it's all bolted up I'll need to check how tight it is. One idea I had was to make a rotor spacer and adapter in one, but that's a big chunk of 6061 to start with... so I'll likely just file down the knuckle if there are any issues.

Thanks for looking.

Cheers

[Soravia]

For racing, bigger rotors are better, so is less rotational mass.
Brake cost is nothing compared to the rest of the running cost.
Get more saving by getting two piece rotor kits. A lot less weight. I picked up new 335i rotors once and I regret the conversion. But my wagon needs bigger rotors. I might look for two piece later.

[Justin Daniels]

Originally Posted by Soravia

For racing, bigger rotors are better, but so is less rotational mass.
Brake cost is nothing compared to the rest of the running cost.
Get more saving by getting two piece rotor kits. A lot less weight. I picked up new 335i rotors once and I regret the conversion. But my wagon needs bigger rotors. I might look for two piece later.

I don't disagree that reducing un-sprung weight is important, as well as reducing rotational mass to a point, there's a reason nobody makes a 355x10mm rotor... heat dissipation. This car isn't going to spend most of its life racing wheel-to-wheel, at least not any time soon, so the additional benefit doesn't come anywhere near justifying the additional cost. Looking at three rotor changes, the extra cost per corner averages out to $270 and weight savings per corner would be 8lb front and 4lb rear (see below).

Over the course of three rotor changes (assuming changing all four at the same time, I realize you'd likely eat fronts faster than rears) that's a savings of $3240USD. I personally feel that $3240USD worth of seat time will do far more for my lap times than saving 8lb a corner on fronts and 4lb for rears. I'm running 17" APEX ARC-8 as well, saving 2lbs per wheel vs 18" ARC-8 and even more vs other wheels (tires are the same weight), which helps a bit.

If I was going for a podium placing car, my budget/goals would need to change drastically, but for a fun track toy for lapping/time attack/dicking around I think I'll be OK.

Just my $0.02. I appreciate the input/feedback though!

Front
E39 M5 OEM 345x32 Front (Zimmerman): 27.2lb / $99 ea
Two-Piece 350x32 Front (RacingBrake): 19.3lb / $500 ea (initial) + $300 ea (recurring - replacement rings)
Two-Piece 355x32 Front (StopTech): xx.xlb / $745 ea (initial) + $345 ea (recurring - replacement rings)
Two-Piece 355x32 Front (Sparta): 19.5lb / $xxx ea (intial) + $xxx ea (recurring - replacement rings)

So let's call it 19lb for two-piece fronts (for equivalent size) at a cost of $500 a piece, then $300 each time I want to replace a disc.
Let's do TCO over three rotor changes as $1100 which makes average cost $367 per rotor.
TCO for OEM over three rotor changes is $297 at $99 per rotor.
$268 per rotor to save 8lb per rotor.

Rear
E82 135i OEM 338x26 Front (Zimmerman): 21.6lb / $65 ea
Two-Piece 345x30 Rear (Sparta): 18.5lb / $xxx ea (initial) + $xxx ea (recurring - replacement rings).

Let's assume 17.5lb for an equivalent size as the 135i front I'll be using on the rear since the above number is for a larger rotor. Let's also assume cheaper hats and marginally cheaper rings than the fronts. We will say $450 initial then $275 per replacement ring. TCO over three changes is $1000 or $334 per rotor.
TCO for OEM over three rotor changes is $195 at $65 per rotor.
$269 per rotor to save 4lb per rotor.

EDIT: It's worth adding that I got the rotors from FCP Euro, which means replacement cost is the price of shipping so I expect the cost delta to be even greater (yet to be determined, rotors are heavy).

[Soravia]

BMW two piece rotors are definitely more expensive, LoL. I came from Mazda side and they have Willwood kits for cheap. Granted, smaller rotors, but still cheap even at RX-8 sizes.
$1699 for 355mm (14") front two piece rotors with six pot forged and billet calipers.
https://www.good-win-racing.com/Mazd...ml?id=8E96FyCE

For race use, you definitely change them often. Road use will see a lot less change for rotors, based on the pad material.

[Justin Daniels]

Originally Posted by Soravia

BMW two piece rotors are definitely more expensive, LoL. I came from Mazda side and they have Willwood kits for cheap. Granted, smaller rotors, but still cheap even at RX-8 sizes.
$1699 for 355mm (14") front two piece rotors with six pot forged and billet calipers.
https://www.good-win-racing.com/Mazd...ml?id=8E96FyCE

For race use, you definitely change them often. Road use will see a lot less change for rotors, based on the pad material.

BMW aftermarket is, in my opinion, super inflated for most things.
I miss Miata pricing. I think I'll end up back in one, or another Formula Ford! I'm considering an RX8 as a donor for a home-built car I'm planning in my head.

My goal with this car was basically do BMW things with Mazda budget, hence a lot of the DIY stuff and cost-saving measures. I also wanted to stay, where possible, with consumables I could get off-the-shelf a lot easier than, say, ECS in-house stuff.

Cheers.

[Soravia]

Originally Posted by Justin Daniels

BMW aftermarket is, in my opinion, super inflated for most things.
I miss Miata pricing. I think I'll end up back in one, or another Formula Ford! I'm considering an RX8 as a donor for a home-built car I'm planning in my head.

My goal with this car was basically do BMW things with Mazda budget, hence a lot of the DIY stuff and cost-saving measures. I also wanted to stay, where possible, with consumables I could get off-the-shelf a lot easier than, say, ECS in-house stuff.

Cheers.

They are dirt cheap now. And you can pop in 2006-15 Miata front sub frame, steering etc directly, and do any engine swap you want.

Lower cost is why I went with 335i brakes instead of aftermarket on my brake upgrade for wagon. Same with my Super20 wearing FM LBBK instead of GWR bigger rotor BBK. I don't even have enough tire or race to take advantage of BBK on my Super20

[feuer]

Any update on these brakes?

[Justin Daniels]

Originally Posted by feuer

Any update on these brakes?

Have been focusing on other areas of the build but am definitely still moving forward with this (read: I don't have a plan b, so this WILL happen). I cut the axial mounts off of the calipers and had them jigged up in my friends mill only to realize that it didn't have the horizontal travel to do the fronts. I'll need to drop them off at a machine shop to have the work done. Also ordered in stop-tech rebuild kits with silicon dust boots that are waiting to go in (TONS of Brembo rebuild kits available form Ohio Performance Solutions, for those who care).

I had a hub-centric ring printed for running the 135i front rotors on the rear, but I'll need to get them cut out of steel/iron for the finished product. Test fitting the rotor on the rear made me realize that I had to make some "adjustments" to the rear spindles for clearance (I like at least 3.0mm clearance around brake components).

I spoke to Porterfield about brake pad selection and got some good feedback. I'll have to order those in next so I can determine the final caliper location.

So it's coming along bit by bit! I'll definitely keep this thread up to date.

EDIT: I realized I already posted about cutting the ears off the calipers...oops!

[Justin Daniels]

Quick update.
I hit a fairly large, self imposed, road block. Because I'm trying to stuff all of this under a 17" wheel, I didn't want to go with a large diameter rotor; and because I didn't want to dick around with big spacers, I didn't want to go with a rotor that moved the center-line outboard. Because of those decisions I am now presented with the caliper, even with the axial mounts cut off, still not clearing the caliper mounts on the spindle.

I am going to have to come up with a pretty crafty solution! I'll keep this thread updated.

Cheers.

[Justin Daniels]

True to my word, I'm keeping everyone (that cares) in the loop.

As mentioned above, I hit a bit of a road-block with the front-end of my DIY BBK. Unfortunately, I am too far down the rabbit hole, and far too stubborn, to give up on this. With that being said, I have a few ideas on how to move forward:

1. Shave Axial Mounts - I can shave the axial mounts off of the spindle to make room for a custom bracket that I would mount using the wheel bearing bolts. This is the least appealing way, since I will need to modify any knuckle I get as a replacement and can no longer go back to an OEM caliper.
2. Mount on Trailing Side - I can mount the caliper on the trailing side of the knuckle; but will have to compete for space with the tie-rod end mount. A custom bracket that mounts to the wheel bearing bolts will still be required, but I will end up with an OEM knuckle that I can use stock brakes with if I ever choose to.
3. Fabricate Custom Knuckles - This may seem a bit extreme; however, since I am using adjustable arms in the front, a custom knuckle would allow for me to place the rod ends in double shear vs single (I don't like how the Bimmerworld adapters don't sit in the ball-joint "cup"). Also, had I not already shaved the bloody axial mounts off of the calipers, I wouldn't need to modify them to suit the setup. To run an OEM caliper. I would just need to make a custom bracket to suit them since the knuckle would have no axial mounts on it. If I go this route, I may sell the shaved calipers I have and source another set.

That's where I'm at.

As for the rears, I still need to get an iron hub-centric spacer made to properly locate the 135i front rotor on the rear; but I should have enough room to work with to get the calipers mounted with a bracket off of the stock axial mounts on the knuckles. *fingers crossed*

As usual, I'll keep this thread updated with more information.

Cheers.

[Justin Daniels]

After many minutes spent drinking coffee and staring at the upright/caliper/rotor I decided to go with Option 2; which, if you're keeping track, is to fabricobble a custom bracket to locate the caliper on the trailing side of the upright.

I spent a lot of time doing CAD (cardboard aided design) work on this one and came up with a half decent concept. It's not going to be the lightest, but it will work. The plan is to use the top caliper mount and the tie rod bolt to mount a custom bracket to the upright. I will also create a bracket that will mount to both caliper mounts and provide a nice outlet for some brake ducting.

I've attached pictures of the cardboard mock-up. Next step will be to make it out of steel, and then eventually see if I can do some proper CAD work and get it made out of some 7075 aluminum or something.

Pictures are below. The cardboard work is just a vomit draft; further refinement to keep weight down will take place before making it out of steel. I had the rough estimate weight written down somewhere but can't find it now. It may not look like much; but keep in mind that all of the strength in the design is in the axis of rotation, which is where the vast majority of the force will be transferred.

[6ixSpd]

Damn, this is some major dedication.

[Justin Daniels]

Originally Posted by 6ixSpd

Damn, this is some major dedication.

Thanks! Stubborn ass is probably more appropriate though.

[PS2N54]

any updates? were you able to get this to work, i have set of 18Z brembos that would have looked real nice on e90 335, maybe just for fronts if rears arent as good as whats on the car.

[streetpro]

This the most crazy idea I have seen in a long time... why dont you just file down the both parts to a decent level - caliper and spindle? It wont give you enough clearance and still fit it to the oem position/bolts?
I bet the holes as such would withstand even if filed-through open, calipers surely might be filed quite deep too, the grooves would stabilize them to the spindle, minor force needed to hold them in place...
It may sound stupid, but I had loosen I caliper bolt and the caliper was moving/swinging around each time I pressed the brake pedal.. for some 80km or so... no major impact on anything apart from the scratched inner side of the wheel... that gives you the idea how over-secured these joints are... one loosen bolt manages the job to slow down the car...