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      10-12-2010, 07:02 PM   #1
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Z4, 2.5, 3.0 easy cheap brake upgrade's

How-to: Cheap brake upgrade
by ZetaTre - Wed Jan 07, 2009 12:37 am

A problem I've noticed with the brakes of my roadsters is not so much braking power but heat dispersion. I recently upgraded the brakes on the Z3 after get them hot to the point of not being able to stop while trying to keep up with IMZ4N (it's always his fault if I have to upgrade something ). The Z3 came with 286mm SOLID front rotors and was able to upgrade them to 300mm VENTED for $160 (plus new rotors, but that's more of a maintenance item).
Bigger brakes run cooler because they require less friction to generate the same torque. If you're thinking about upgrading your brakes to increase braking power, first make sure you're ABS doesn't kick in already; if it does, then your problem is more so with tires and suspensions, than brakes (or at least, brakes are not the place to start from)...

I've being doing some research about doing something similar on the Z4 and I thought I would share some thoughts since I read of people asking about it:
1) The 2.5i (as well as the Euro version 2.0i and 2.2i) have 286mm vented in the front and 280mm solid in the rear
2) Both 3.0i (and the Euro 2.5si) have 300mm vented in the front and 294mm vented in the rear
3) The 3.0si has 325mm vented in the front and 294mm vented in the rear
4) The ///M have their own things, so it might not be as easy to put ///M brakes in a non-///M car (the different offset and the ///M tradition makes me think it require some suspension parts to be changed as well... The ///M experts might be able to help more)
5) 300mm is the most you can fit with 16" rims; 325mm require 17" rims
6) All Z4 share the same master cylinder (although the p/n changed they are interchangeable): this simplifies the swap a lot.
7) The Z4 share the same brakes as the E46, making a lot easier to find parts at the junkyard

I would recommend you grab the whole caliper and carrier assembly by removing the brake fluid line and the two bolts connecting the carrier to the king pin/suspension. This doesn't apply only if you're planing on upgrading from 286mm to 300mm front: if so, all you need is the carrier (calipers, sliders and clip are the same). Remember that if you have 16" front rims, 300mm is the biggest you can go without having to change your rims.

Upgrade combinations

300mm vented front brakes
This is a good upgrade for the 2.0i, 2.2i and 2.5i. It will allow you to keep the stock 16" rims and you'll keep a good front-rear brake bias. The cheapest way to go...
All you need is the carrier and can be taken off the following cars:

E46 318d Touring
E46 318i Sedan
E46 320 All (Gasoline & Diesel)
E46 323i Convertible & Touring
E46 325i All
E46 328i All
Z4 3.0i Roadster
Z4 2.5si Roadster
Z3 3.0i (Roadster & Coupe)

325mm vented front brakes

This is a great upgrade for all Z4: you'll have the same front brakes as the 3.0si so I'll recommend upgrading the rear to 294mm. You will need 17" to clear the calipers.
You'll need the whole front caliper assembly from one of the following car:

E46 330i All
Z4 3.0si (Roadster & Coupe)

If you wanna be a perfectionist: the protection plate behind the 325mm rotor is bigger than what the 300mm or 286mm have (these two setups have the same cover). The rotors should fit with no particular issue as the cover does not interfere with the rotor. The problem with replacing this covers is that the wheel hub has be removed (you need a 46mm socket and an impact wrench) make it impractical if you are sourcing the parts from a junkyard. My friend Ed has been able to fit 325mm on a 323i Touring (originally equipped with 286mm as some Z4s) and had no issue. You can see some pix of his setup here.

294mm vented rear brakes

Another good upgrade for the 2.0i, 2.2i and 2.5i. It will allow you to keep the stock 16" rims and you'll have the same front-rear brake bias as the 3.0i.
If you go with 325mm in the front, I'll suggest you upgrade the rear as well to keep the bias within BMW specs.
You need the whole caliper-carrier assembly from one of the following cars:

E46 318d Touring
E46 318i Sedan
E46 320 All (Gasoline & Diesel)
E46 323i Convertible & Touring
E46 325i All
E46 328i All
Z4 3.0i Roadster
Z4 3.0si Roadster & Coupe
Z4 2.5si Roadster

320mm vented rear brakes

Alternatively, 320mm rear vented rotors can be sourced off of an X3 (any model, old or new). As noted below, the X3 might not be able to provide you a full front and rear swap: the front calipers are the same as the E46 330i, but the caliper carrier has a different p/n.
In summary, 320mm vented rear rotors can be sourced from the following cars:

E83 X3 All

320mm can be used only with 325mm front as you don't want to have your rear rotors bigger than the front. Although many variables go into calculating brake bias, the disk size ratio of a 325mm front - 320mm rear conversion is similar to what the 3.0i has so it should be fine. However such a brake setup was never chosen by BMW as a setup for the any Roadster.

Another note regarding 320mm rear brakes. In this case too they have a different protection plate (as for the 325mm front rotors setup), and in this case it gets in the way of the bigger rotor. Once again, removing the plate is not as practical as you have to remove the parking brake assembly and likely the wheel hub. To fix the issue I would personally just bent the plate of the way... Sometimes I agree with the saying that "is something doesn't fit, your hammer ain't big enough"...

Notes and Credits

PS1: the E46 323i

I did some more research about the E46 323i and it appears to be somewhat in between when it comes to front brakes: some body style have 286mm while others have 300mm. Also it appears the same body style could have different configuration between Euro version and US version... I would recommend you bring some measuring tape when going shopping through junkyard just to make sure you get the correct one.

PS2: possible sources

IMHO, buying the calipers new from BMW is not cost efficient, as you might as well go with some fancy non-floating & multi-pistons brake kits. Here's a couple of hints of where to source the parts you need:

1) of course you can check with your local junkyard and car dismantlers: where I got mine the guy actually removed them, in some junkyard you remove the item yourself and then negotiate the price

2) eBay is a good source for the: the US has usually has a lot of calipers off of E46 so that's a source...

3) There are some dismantlers that specialize on BMW and will ship you the product. The two I can recommend because I have personally used are:
- Autobahn in El Cajon here in San Diego
- Bavarian Auto Recycling up in the Bay Area. The nice thing about them is that calipers come tested (the o-rings are replaced if leaking), cleaned, and come with a warranty (not sure of how long)... Of course they are more expensive than what you could get elsewhere.

Just complement any of these setup with some Brembo Slotted or Zimmerman cross drilled rotors (I got mine from Ed @ Bimmerbum). I won't recommend buying rotors on eBay as some sellers get plain rotors and drill them in house.

PS3: sourcing the front brakes from an X3

The X3 has the same front calipers as the 330i (325mm vented); however the carrier has a different p/n so it might not be a perfect bolt on.

Last edited by -c-; 10-23-2012 at 03:44 PM.
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      10-13-2010, 01:08 PM   #2
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amazing write up! thanks!
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      10-13-2010, 02:26 PM   #3
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very nice, im buying front brakes from a carrera and i guess ill get some x3 or 330i rear brakes to match. thanks man, youve been very helpful
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      11-16-2010, 07:28 PM   #4
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Does anyone know what would need to be done to fit Rear E46 330i rotors on an E86? I would like to pick up a set of spare rotors before the BMW performance rotors are all sold out and I will only pick them up if I can fit the rear 330i rotors on my Z4 3.0si Coupe. Please
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      11-16-2010, 07:46 PM   #5
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yes you will need the dust sheilds, calipers and caliper carriers, and ofcourse the pads to go with your rotors.


the dust sheilds can be bought at the dealer or scrap yard, you can get rebuild calipers with carriers for cheap at your local parts store.
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      04-11-2011, 07:48 AM   #6
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sorry to bring this thread up, but you stated :
2) Both 3.0i (and the Euro 2.5si) have 300mm vented in the front and 294mm vented in the rear
3) The 3.0si has 325mm vented in the front and 294mm vented in the rear

I've been looking and I don't see the si being 325mm in the front anywhere, I just wanted to confirm because I just got 300mm and don't want anything to go wrong. I'm pretty clueless about these things and have been searching alot for help. thanks.
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      04-11-2011, 08:11 AM   #7
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yes my 2006 3.0I has 300MM rotors and the SI has 325MM rotors

look it up on realoem.com and look up your car and youll see the rotors are 325mm on the SI and 300mm on the I
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      04-11-2011, 08:57 AM   #8
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Thanks for the quick response. damn, all of the websites (besides bmw) where you can buy from, even brembo, show 300mm. Thats what I get. That pisses me off. Thanks for confirming!! So what would happen if I just went ahead and put the 300 for the fronts....or put them on the rears and buy some 325s for the fronts?? Also, I have 19" rims as well.

Last edited by papitosabe; 04-11-2011 at 09:03 AM.
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      04-11-2011, 09:12 AM   #9
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well you cant mix and match unless the caliper is made for it, so if you have an 06 SI you need the 325 in the front if you pute a 300 in the front it wont work and youll be screwing things up as well as brake bias, the rear rotors are different for the front vs rear so you cant take fronts and switch them to rears.

you can upgrade to 330I rears and keep the fronts at 325MM then you will have a brake bias the same as the "I" technically speaking. as the only difference between the I and SI brake wise is the rotor was larger in the front and had a bigger caliper, the rear calipers are the same. Thats why its very easy to upgrade the I to SI brakes as they are simply bolt on.
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      04-11-2011, 09:17 AM   #10
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youll see what im saying when you pull your wheel off and you see your stock rotor is bigger than the one you have. youll have to return it and get the proper size, unless it is 325mm that they sent you and they just show 300mm for everything on the website.
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      04-11-2011, 09:19 AM   #11
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Quote:
Originally Posted by -c- View Post
well you cant mix and match unless the caliper is made for it, so if you have an 06 SI you need the 325 in the front if you pute a 300 in the front it wont work and youll be screwing things up as well as brake bias, the rear rotors are different for the front vs rear so you cant take fronts and switch them to rears.

you can upgrade to 330I rears and keep the fronts at 325MM then you will have a brake bias the same as the "I" technically speaking. as the only difference between the I and SI brake wise is the rotor was larger in the front and had a bigger caliper, the rear calipers are the same. Thats why its very easy to upgrade the I to SI brakes as they are simply bolt on.
thank god i found your post...after researching more, I got screwed. The rotors I have are 300mm but per realoem, they are for a z3, 323i, 325i,ci,xi and 328i,ci . So I'm screwed and have to buy new fronts as well now. But at least you saved me a huge headache. It sucks that all the websites that sell parts have the part I have now to fit my car's fronts. Incredible. Thanks again for your help!
edit...yea, can't return as I bought this off someone at a z4 forum.
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      04-11-2011, 09:20 AM   #12
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one more thing just to make sure if your still unsure, call your local dealer and he will give you proper rotor size for your car, that way their are no missunderstandings.
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      04-11-2011, 09:51 AM   #13
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Also just want to add/confirm, I don't think the 3.0si rear rotors are same as the e46 330i rear rotors. I think our rears are that of the e46 323/5/8.
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      04-11-2011, 11:12 AM   #14
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Quote:
Originally Posted by Dubbedown View Post
Also just want to add/confirm, I don't think the 3.0si rear rotors are same as the e46 330i rear rotors. I think our rears are that of the e46 323/5/8.
yep Dubbedown's right, the rear rotors on the I and si are the same size of 294mm, if you go with the 330I rotors you need to upgrade both the rotor and calipers and caliper carriers, do not go with the 330I rear rotor upgrade if you have an I and have not changed the fronts to at least an SI size of 325mm
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      11-04-2011, 10:25 AM   #15
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For anyone that did this, how hard is it to change out the dust sheilds?

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      07-14-2012, 01:41 PM   #16
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Hi,

I want to swap the rear rotors from my z4 3.0i (294x19) for 330i rear rotors (320x22).
Won't this give problems with the parking brake? Do the stock parking brake shoes from the z4 rotors fit inside the 330i rotors (same diameter?) or do i have to swap the whole inside from the parking brake (brake shoes, springs etc) too?

I need bigger rotors at the rear because I bought some 135i performance calipers (at ECS tuning) when the were on sale (@$99/pc), and it turns out that they bolt on straight away! (maybe a little 1mm spacer required). But the calipers have room for rotors which are about 26mm bigger.
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      07-16-2012, 04:06 PM   #17
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I did some research on de rear rotors, and E46 rear rotors will not fit properly on a E85 Z4 (3.0i).
some dimensions from brembo:

E85 (3.0i)


E46 (330i)


First of all the parking brake won't fit: E46 rotor inner diameter is about 1 inch bigger. There is someone who made his own parking brake pads (to fit 330i rotors on a 323i which has also small parking brakes) by welding in a 323i brakepad on a 330i pad. But that still won't work for the e85.

Secondly you can clearly see that the offset from the disc itself is much less on a E46 than on a E85. So the caliper wont fit unless spacers are used between the caliper carrier and the trailing arm. This offset is probably changed to give the E85 a different trackwidth or to use rims with different ET/offset.

Next I looked at the X3 rotors:

320mm rotors, offset and depth for parking brake may seem doable, but still big parking brake pads needed.

The only rotors that may fit are the e90 rotors (up to 320i):

They are only slightly bigger (300mm), and offset is slightly different (3mm).
Not much difference to the stock e85 3.0i rear rotors
But when fitting 1 or 3 series rear performance calipers on a Z4 this is how it looks like:

On the inside diameter a slightly bigger rotor is better
On the outside the calipers can take up to 320mm


about 0,5mm room between rotor and caliper on the outside


Lots of room on the inside so thick rotors is no problem.

Maybe the e90 rotors are the best option. The rotor is a bit bigger (so the brakepads fit the rotor better on the inner side and every bit of rotor on the outer side/diameter is better), and the parking brake will probaby fit. There is less offset on the rotor, so a simple spacer between the caliper and the trailing arm (4 or 5 mm) will do the trick I think.
Only thing is that the face plate of the E90 rotor is thinner, and there's a 45deg. edge. If there's a slope on the edge which will take op space, that might be a problem.

That's what I've found out so far

Has anyone any ideas which might be of use to me to fit these calipers best?
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      10-05-2012, 10:01 PM   #18
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the 330i rear rotors won't fit. I found it the hard way as I now have a set of bmw performance 330i rotors i can't use. the center of the disc is not as tall as the ones in the z4 which center is pretty deep or tall. I mean, the disc itself is very far from the center part where the bolts go. hope this pic helps to clarify as I don't know how to explain it.
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      10-23-2012, 04:09 PM   #19
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updated post with new data recived from other members of issues with the 330I rear rotors not working.

the OP info was from european website so im not sure if some differences between euro spec and US spec cars had anything to do with things not fitting, so i just removed the information from the post.


please let me know of any other findings so i can update the post so others wont have any issues.

thanks guys.
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      05-28-2013, 03:07 PM   #20
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Hi, sorry to bring an old thread back alive. I've just bought a set of Porsche brembo 996 calipers front and rear that I believe you can buy adaptor brackets for. They definitely fit on the non-M e46 and since the 330i discs and calipers fit the z4 then I hope it's a straight swap on the fronts, maybe a little machining required.

I have fitted an E46 M3 full rear axle and LSD so the rear brembo calipers should fit also.

Al
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      05-30-2013, 08:37 PM   #21
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Thanks for the writeup it confirms what I've been saying all along!
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