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      11-16-2017, 11:59 AM   #45
dc_wright
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Quote:
Originally Posted by dre99gsx View Post
Ok - being that the Z4M front rotor fits the 3.0si, and the 335i front caliper fits with fairly good and even tolerances, does anyone have any photos showing that the Z4M front caliper can/can't fit the 3.0si?

I've read some posts saying it can't, but there was no measurements or actual data to show this (seems just hearsay). Can anyone positively confirm?

Reason I ask - I'm looking to piece together some other components for the front, and knowing what can/can't fit will help me determine what else I can swap over. If a Z4M caliper can fit up front, then I can follow some of the E46 M3 upgrade paths for the front system without issue.

I may be able to mix/match parts from Stoptech to move up to a 355mm system knowing this info. Since no one makes a 355mm upgrade to the 3.0si (or E46 330i from what I've seen), I may have to piece something together.

Am I not happy with my current brakes? No. Why do I want to do this? Because Racecar
#1st world problems!

Looks like there's not much difference in cost between the Z4M and 335 calipers based on FCP Euro pricing. Might have a better chance finding E90 calipers used though......
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      11-19-2017, 02:57 PM   #46
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Some more data:

Seems like Z4 3.0si uses parts from BOTH 325i and 330i.

3.0si: Rear rotor 294x19, Rear piston size 40mm (from 325i)
3.0si: Front rotor 325x25, Front piston size 57mm (from 330i)
Z4M: Rear rotor 328x20, Rear piston size 44mm (from E46M3)
Z4M: Front rotor 345x28, Front piston size 60mm (from E46M3)
E92-335i: Front piston size 57mm

What I don't know is how the brake bias percentages is set from the master cylinder/portioning system, and the pad size on the 335i caliper vs. the original 3.0si caliper.

My fronts are now 345x28, Front piston size 57mm (from 335i, even though caliper is larger than Z4M, piston size is the same as Z4 3.0si)

I'm working on adapting the Z4M rear rotor by creating a custom caliper bracket and modifying the shoes. Being that the piston sizes are not changing from the original Z4 3.0si setup, I don't think my bias will be changed by much by moving up to larger diameter rotors, although I understand clamping force will increase.

Front went from 325mm to 345mm (10mm radius increase), while the rear will go from 294mm to 328, or 17mm increase. I'm sure this will increase rear bias by some amount, but it's possible it is being offset by the larger front brake pad.

I'll update this thread once I get the fabrication done.
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      11-19-2017, 03:55 PM   #47
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^can you measure the inner depth of the rotor hat from the z4m rear rotor?

So for example in the drawing below this would be 74,5mm - 7,2mm = 67,3mm



I dont have a drawing this detailed from the z4m rear rotor and I dont have a z4m rear rotor
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      11-19-2017, 05:03 PM   #48
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Will do. Should have them sometime next week.
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      11-23-2017, 07:46 PM   #49
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Z4M inner depth is 54mm on the dot. So you are looking at 13mm shorter.

I tried bolting on a 335i rear brake caliper, and IT FITS (you need to add 1/2" thick washers/spacers and longer bolts).

Also:
335i rear caliper = 7.8lbs
Z4.0si rear caliper = 6.6lbs

Z4M rotor = 14.8lbs
Z4M brake shoes (for two) = 1.6lbs

Z43.0si rotor = 14.2lbs
Z43.0si brake shoes (for two) = 0.8lbs

Doing the upgrade would add 1.4lbs per corner This doesn't include any brackets I need to make to move the caliper, nor the fact that I'll need to weld up the brake shoes one on top of the other. So I would assume the upgrade would actually add 1lb for the bracket (6061 alum) and 0.8lbs more for the original shoes, total would be 3.2lb per corner. OUCH

And, then there is the brake bias:

Z4M = 60mm/46mm pistons (f/r), 345mm/328mm rotors (f/r) (14mm diff in piston, 17mm diff in rotor)
Z43.0si = 57mm/40mm pistons, 325mm/294 rotors (17mm diff in piston, 31mm diff in rotor)

You can see the Z4M has a much smaller variation in piston/rotor diff front to rear, but it's also possible the proportioning system is also different (master cylinder?). So, I have no idea if in the end, both vehicles had the same brake bias.

For me to upgrade to the 335i rears (which are 44mm pistons) and Z4M rear rotor, this would be my final setup:
2JZ4 = 57mm/44mm pistons (f/r), 345mm/328mm (13mm diff in piston, 17mm diff in rotor).

So, the rear would not only get a larger rotor, but larger piston, and larger brakepad, all which may significantly increase rear bias more than I want. Yes, I would get much closer to the piston/ring combo from the Z4M, but what I don't know is if the proportioning system/valving in the brake system is also the same proportion. Why would BMW put such a small rear rotor on the 3.0si when the Z4M is vastly larger??? They must have compensated for it somewhere else.

I looked at my pads from the last event, and they all wore pretty evenly front and rear - I suspect my bias is "just right".

I can run my smaller pad in the rear, it fits, therefore reducing the amount of bite, and bias to the rear.
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      12-09-2017, 10:35 AM   #50
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Ok, here is the scoop:

135i rear caliper weighs 5 lbs (vs. my original Z4 3.0si at 6.6).
Pads are roughly the same weight.

Net net, the weight difference between my stock setup and this updated setup is: 0 lbs!

Now, rear piston diameter is 42mm (stock is 40), also larger rotor and more pad material, definitely increases rear bias. As I said previously, the front was also increased by larger rotor and larger pad (albeit same piston up front), thus I shouldn't be too far off from original bias.

Caliper just clears the 328mm rotor. Pads just clear the inner diameter. I'll have to create proper spacers for the caliper (using mock up for now). Welded the rear z4m brake shoes to the z4 3.0si shoes, and tested brake application. Works.







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      12-09-2017, 11:01 AM   #51
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Wow, thats a tight fit.
In Germany they do this mod with a 135i rear rotor. That also has a nice fit and more offset so the spacer between caliper and trailingarm can be smaller. (similar to the x3 rotor I used for this mod).
And they fix the parking brakeshoe issue by placing a metal ring inside the rotorhat to fill the space. I thought that was also an elegant solution (but requires machining obviously). Thats something I'm probably going to do too if my rear discs ever wear out in years to come.

They can't alter the brake shoes due to legal issues.
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      12-09-2017, 12:18 PM   #52
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Legal issues... understood. But technically, those shoes are just there for keeping the car from rolling during a stop (or emergency use). Properly welded and secured, should be minimal risk imho.
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      12-09-2017, 12:50 PM   #53
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Quote:
Originally Posted by dre99gsx View Post
Legal issues... understood. But technically, those shoes are just there for keeping the car from rolling during a stop (or emergency use). Properly welded and secured, should be minimal risk imho.
Yes. I also have had my welded brake concoction in there for 4 years or so (I think you've seen my thread on that).
But in germany they have TüV and that even checks matching materials (so they also coulndt fit an aluminium spacer in there, it had to be iron).
If you want to deviate from that you have to have a TüV engineer write a report on that (like the reports you can download at german tuning products like KW).
Where I live we just have an annual checkup where the car gets onto a brake tester and they measure brake force etc (and obviously check wear) but if thats within boundries, its OK (so more a real life test than a theoretical evalutation). We do have a minimum requirement in how much brake force should be applied with the emergency brake (and if its in balance left/right).
And BMW emergency brakes are rubbish anyway compared to a lot of other brands.

But I like the idea to adapt the rotor to the factory spec.
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      01-24-2018, 10:59 AM   #54
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Follow up question due to laziness.

Does anyone know the radius to the outside of the caliper for the 135i Caliper, 345mm brake setup? I'm using the Epytec adapter (Front). I'm basically trying to find out if I can run 18" wheels over this setup to reduce weight. I also need to find out how far the caliper will be from the spokes.

If no one knows, I'll G'up off my bum and measure....if I have to.

Last edited by 3GFX; 01-24-2018 at 11:55 AM..
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      01-24-2018, 11:05 AM   #55
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Mounted directly to the non-z4m rear hub, I'm left with a bit over an inch space between the top of the caliper and the inner barrel of the stock 18" 3.0si rim.
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      01-24-2018, 11:55 AM   #56
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Quote:
Originally Posted by dre99gsx View Post
Mounted directly to the non-z4m rear hub, I'm left with a bit over an inch space between the top of the caliper and the inner barrel of the stock 18" 3.0si rim.
dre99gsx, thats in the rear or the front?
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      01-24-2018, 02:27 PM   #57
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Quote:
Originally Posted by 3GFX View Post
dre99gsx, thats in the rear or the front?
Don't know for sure but I'm pretty sure the first guy to do the performance caliper mod used 345mm rotors and though he was running 19's it looked like plenty of space to run 18's

Side note - only thing that's held me back on this upgrade is the cost of 345mm rotors, $400/pair!!

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      01-30-2018, 12:53 PM   #58
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I ordered the 18" wheels, so we'll see. If they don't work, someone is getting a deal on the forum for track setup. HA!
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      01-30-2018, 03:24 PM   #59
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They are costly...
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      01-31-2018, 06:36 PM   #60
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Originally Posted by dre99gsx View Post
They are costly...
Btw do you think a 17x9 et30 would clear this setup (335i caliper with 345mm rotor)?
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      01-31-2018, 10:39 PM   #61
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Possibly. Stock 3.0si 18" wheel leaves me with 1" gap at the barrel, but reduces to 1/4" closer to the rim front.
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      02-01-2018, 11:01 AM   #62
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From what I've read, I would suggest a 17" setup, it cuts close.
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      02-12-2018, 11:28 PM   #63
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Quote:
Originally Posted by GuidoK View Post
^afaik the ID of the rotor hat is the same (both 160mm, so the 'small' bmw parking brake.
But the depth of the rotor hat is afaik much deeper on a z4 (so the rotor has a different offset).
Its because the z4 has a different bearing flange at the rear (and the z4 has thus a wider track at the rear)
Bump - what about a custom rear rotor where you can specify the offset?

(Click on integral hat & rotor)
http://www.colemanracing.com/Custom-...ild-It-W9.aspx
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      02-13-2018, 07:48 AM   #64
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Quote:
Originally Posted by 3002 tii View Post
Bump - what about a custom rear rotor where you can specify the offset?

(Click on integral hat & rotor)
http://www.colemanracing.com/Custom-...ild-It-W9.aspx
You found this within a month of me selling my rear 135i calipers on Kijiji.

I kind of don't like you now.
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      02-13-2018, 08:23 AM   #65
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Quote:
Originally Posted by 3002 tii View Post
Bump - what about a custom rear rotor where you can specify the offset?

(Click on integral hat & rotor)
http://www.colemanracing.com/Custom-...ild-It-W9.aspx
Good find

Edit. This brings in a whole new avenue for spacing out for custom rims. Unfortunately not vented.
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      04-16-2018, 08:24 AM   #66
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UPDATE:

First time at the track with the 135i rear calipers/Z4M rear rotors, and 335i front calipers/Z4M front rotors - PFC08 all around.

Brakes were very soft and squishy after installation, possibly due to the pads not being square or needing to be worn in. Felt like the brake pedal had tons of air.

After the first few laps, I had a solid pedal and braking was predictable yet progressive. No brake fade throughout two HPDE days, and could induce ABS if I really wanted to from high speed. When induced, steering wheel would get 'light', thus still front-biased to some degree.

Brake bias: Didn't notice anything strange. I'm running 295/255 R888R and on a 80deg day, was able to brake from 150 to about 70 without much fuss.

Pedal/knockback: I didn't feel anything strange while braking->trailbraking-> tight turn with regards to brake pedal loosing pressure or vibrations. Note last HPDE I had felt the pedal drop a bit on a turn, and indeed was a bad front wheel bearing.

I think this upgrade to your nonM-Z4 is definitely worth a look vs a full fledged BBK. Out of every session I've run (not advanced group mind you), I was able to out-brake mostly everyone with some headroom. Noticed I said: "MOSTLY everyone".

Here is where I am perplexed.

I know my car has lots of power, and it is masking my driving ability. I have a lot to improve as a driver, but more so, I have a lot of work to do on harnessing the extra power from this vehicle (and the open diff, and the fact that I have either 10%, 20%, or 100% throttle...).

There were occasions where on a long straight, I would pull pretty hard on a seemingly stock E46 M3. Let's just say a few bus lengths. I would then hit my brakes as hard as I could to the edge of ABS at marker 5. Then, 5, 4, 3, 2 and about 1 where I start to trailbrake, I look in my rear view and the M3 has made up all of the distance.

I thought I had very strong brakes. I thought I was applying them as hard as possible. Is it possible to brake even harder with these cars? Am I missing something else? Surely can't be a BBK that is allowing increased stopping power? Suggestions welcome
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