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      01-20-2017, 01:10 PM   #1
dre99gsx
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nonM Z4 braking upgrades

Decided to embark on another smaller project: Upgrade the Z4 3.0si brakes. Why?

a) My rotors are completely worn and too thin for comfort
b) I like the BBK look, can't afford it, thus want to improve the look from what I currently have
c) With the additional power from the 2JZ conversion, I'll need some beefier rotors to handle high speed braking during track use
d) I know cooling is essential - will work on that as well

I'm going to keep an eye on brake bias as I make these upgrades.

First, I wanted a more modern look for the front calipers. I like the way these look:




What you see up there is the 335i front stock calipers. Yup, I bought two from the junkyard. Yes, they bolt right up to the 3.0si spindle, and yes, they clear and work right on the 325mmx25mm 3.0si rotor, albeit the pad extends further outward since they are made for the 335i 348mmx30mm rotor.

So, I took a risk and purchased a 335i rotor just for kicks. Nope. Doesn't fit, it hits the steering knuckle. I just ordered the 345x28 ZHP/M3/Z4M front rotors and will see how they fit. My guess is they will fit.

I'll do some weight comparisons, and measure caliper piston diameter/pad dimensions to see how bias will be affected.

Swapping in the 2JZ "made no sense" to purists, and I'm sure upgrading the brakes will "make no sense" to the hardcore track enthusiasts, but the point here is not really about function, but more about aesthetics. And since I need to replace everything anyway, why not
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      01-20-2017, 01:41 PM   #2
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Super interested in this brake upgrade!

I've been looking at cheaper alternatives. Such as:
https://www.ecstuning.com/b-ecs-part...001121ecs02kt/


But this is much better imho.
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      01-20-2017, 01:44 PM   #3
dre99gsx
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If this works, the upgrade for the front will be half the price of the ECStuning. New ZHP rotors $300 (ebay, various sources), $100 for junkyard 335i calipers, add some pads, SS brakelines, done. And, it will look "better" through your wheels.
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      01-20-2017, 01:52 PM   #4
3GFX
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I'll anxious to see that the brake disc works for you.

I don't think there are any significant change between the 3.0i and 3.0si in the braking department.
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      01-20-2017, 04:42 PM   #5
dre99gsx
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Also as a point of reference:

3.0si front rotor 325x25 = 16.8 lbs
3.0si front caliper = 14.2
335i front rotor 348x30 = 24.2 lbs
335i front caliper = 13.4 (yes, almost 1lb lighter than the 3.0si caliper!)
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      01-21-2017, 02:23 AM   #6
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If the caliper fits the stock rotor, it will also fit the z4m rotor. Offset is the same afaik.
For the 330i there is even an official perforated rotor upgrade which is basically a z4m/m3 rotor but in 325mm dimension (but with the same aluminium hat and thus offset etc):
http://bmwfans.info/parts-catalog/E4...ted/#2282871_1
Needless to say this rotor also fits the z4 3.0si stock setup.

The big problems are at the rear where the z4 has a big offset and the smaller parking brake shoes (160mm), so no other rotor/caliper assemblys work unless heavily modified.
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      01-21-2017, 09:44 AM   #7
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Quote:
Originally Posted by 3GFX View Post
I'll anxious to see that the brake disc works for you.

I don't think there are any significant change between the 3.0i and 3.0si in the braking department.
The 3.0si gets a larger caliper and rotor from the E46 330 for the front. The rears are the same for the 3.0i and 3.0si.

Quote:
Originally Posted by GuidoK View Post
If the caliper fits the stock rotor, it will also fit the z4m rotor. Offset is the same afaik.
For the 330i there is even an official perforated rotor upgrade which is basically a z4m/m3 rotor but in 325mm dimension (but with the same aluminium hat and thus offset etc):
http://bmwfans.info/parts-catalog/E4...ted/#2282871_1
Needless to say this rotor also fits the z4 3.0si stock setup.

The big problems are at the rear where the z4 has a big offset and the smaller parking brake shoes (160mm), so no other rotor/caliper assemblys work unless heavily modified.
There's also a one piece cross drilled rotor option from the 330 that also fits the 3.0si since the 3.0si front brakes are actually 330 calipers and rotors. Obviously it's heavier than the two piece rotor, but it's also quite a bit cheaper since you can get it from multiple aftermarket sources.

http://bmwfans.info/parts-catalog/34112282871/
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      01-21-2017, 10:00 AM   #8
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Quote:
Originally Posted by dc_wright View Post
The 3.0si gets a larger caliper and rotor from the E46 330i for the front. The rears are the same for the 3.0i and 3.0si.



There's also a one piece cross drilled rotor option from the 330 that also fits the 3.0si since the 3.0si front brakes are actually 330 calipers and rotors. Obviously it's heavier than the two piece rotor, but it's also quite a bit cheaper since you can get it from multiple aftermarket sources.
Is the hub assembly the same? Any ideas?
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      01-21-2017, 10:12 AM   #9
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Good source of info here
http://www.zpost.com/forums/showthread.php?t=442217
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      01-21-2017, 10:29 AM   #10
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Great link, thanks!

Started looking at the rears, and will have to read that link with more scrutiny, but I found the 135i rear rotor dimensions here:



Stock:



Based on those numbers, the rear disc should be a direct fit onto the 3.0si rear, but increasing 294X19 to 324X22. In trying to keep with similar front/rear bias, I wil lhave to see what caliper can swap over without it being the super expensive 135i setup. I haven't found any OEM rear calipers that "look good", thus the rear swap would be more for bias correction (and the fact I need new rotors anyway). What I don't have is the 135i rotor inner diameter for the parking brake. Will do more research...
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      01-21-2017, 10:46 AM   #11
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^inner diameter for the parking brake is 185mm on those rotors, so you have to work around that. There are a few ways for that.
Everything over 300mm on bmw has a 185mm parking brake.

And the 135i disc is still about 3mm off in offset compared to the z4 disc. This could be corrected though.
The strange thing is that the brembo catalogue displays different sizes than the ate catalogue (in offset).
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Last edited by GuidoK; 01-21-2017 at 11:06 AM..
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      01-21-2017, 11:27 AM   #12
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Thanks for the info. More details:

http://www.zpost.com/forums/showthread.php?t=1011279

Seems like there is no other upgrade option for the 3.0si

Doing some further reading (theoretical, yes):
http://stoptech.com/technical-suppor...brake-upgrades

- Adding sticker tires decreases rear brake bias due to more weight successfully transferred forward
- 2J swap added an additional 100lbs to the front, decreasing rear weight bias

All said and done, perhaps just upgrading the front might only upset the bias by a small amount. I may have no choice but to just purchase brand new rear rotors of the same kind, and see how this does on the road coarse.
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      01-21-2017, 11:53 AM   #13
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I put some serious research time into a BBK using OEM bits. Even thought about machining spacers for the parking brake mismatch.
Decided it was too much work for the bling factor.
I think Guidok had developed an option for bigger rear discs.

I ultimately went to a kit with cross drilled rotors and powder coated calipers to jazz things up. Added SS flex lines and hi performance fluid for improved stopping
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      01-21-2017, 11:56 AM   #14
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Didnt you buy the rear 335i calipers from the junkyard?

If the lug width of the carriers lines up, its relative easy to compensate for offset.
For the 135i performance calipers (the rear ones) the lugs line up exactly (I use that setup). The only thing I had to do to line up for offset was to make some washers on the lathe (in my case 7,6mm thick) and use longer bolts.
The biggest challenge lies in getting the parking brake to work. There are basically 2 ways to do that; make custom brake shoe brackets (welding) or crimp an aluminium ring (made on a lathe) inside the brake disc hat to reduce the diameter from 185 to 160.
And of course adapt the back plate etc, but thats peanuts once you got this far.
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      01-21-2017, 12:16 PM   #15
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Quote:
Originally Posted by 3GFX View Post
Is the hub assembly the same? Any ideas?
Hub assy is same for all E36, non-M E46, Non-M E85/86, and all Z3's.

http://bmwfans.info/parts-catalog/31226757024/

Spindle assy is same for non-M E46 and non-M E85/86

http://bmwfans.info/parts-catalog/31211096429/
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      01-21-2017, 04:02 PM   #16
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I went and just ordered a standard rear rotor. I didn't order the 335i rear calipers from the junkyard (just front). As far as machining to make a 135i rotor fit the rear, sure, anything can be possible, and I like the idea of an inner ring. I'll keep that idea in the back burner if I find the bias is way off. Thanks for the tip.
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      01-22-2017, 12:57 AM   #17
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Quote:
Originally Posted by dre99gsx View Post
I went and just ordered a standard rear rotor. I didn't order the 335i rear calipers from the junkyard (just front).
You still need a different rear caliper. The stock caliper goes up to ~300mm, so a 325mm disc will fall out of the pad's range (and probably touch the caliper).
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      01-22-2017, 09:46 AM   #18
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What I meant was the I ordered the standard Z4 nonM rotor just to replace my worn rotors.
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      01-22-2017, 12:01 PM   #19
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I'm excited for you to confirm which disc will work! can you specify what model 335i you're referencing for the caliper?
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      01-23-2017, 04:39 PM   #20
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It fits!



Direct swap, no cutting or modification anywhere - Z4M stock rotors (345mmx28) and 335i front calipers (2012-2013 335i or 2011-2016 Z4)

Weight difference 3.0si Caliper/Rotor (325mmx25) to this new combo = 1lb heavier per corner. Being that I shaved 2 lbs per corner by going to ARC-8 wheels, still not bad. Although the 335i caliper is made for 348mm rotor, mostly all of the brake pad surface covers the Z4M rotor.

I have yet to calculate piston/pad area for some rough check of bias change. Time to prep and paint the calipers. Just barely fits inside the ARC-8 wheel, but clears as well.
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      01-23-2017, 05:25 PM   #21
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Fantastic.
In for opinion on improvements over stock
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      01-24-2017, 09:39 AM   #22
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So excited!!!

Thanks for the data...

...is there a cover for that gap/hole where the pad is?

Last edited by 3GFX; 01-24-2017 at 09:51 AM..
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