Upgrading brakes, what to do about the rear?

[matreyia]

Looking to upgrade my brakes in my 35i as I have noticed some fade and my rotors seem to be warped already! After doing a FBO+ upgrade I think the stock brakes have got to go! My plan of action is to go with some 35is calipers, which are the same as 335i and a set of Hawk pads.

From my readings it looks like the 35is rotors are identical to the 335i’s with the exception of being a 2-piece design which has a few advantages (lighter/cooler).

Question is what to do in the rear? Do I need to run 35is calipers/rotors or stick with the 35i setup? With the electric brake it really limits options.

I upgraded my rotors to ECS Tuning two piece and shed a couple of lbs. per rotor which yielded noticeable better acceleration and agility in steering. I have had then for about 4 years now and no issues at all. Used Hawk street pads. Next time I change, I will use the same rotors and upgrade to big brake kit.

VT

 

[LMB335is]

I already have upgraded brakes. See attached excel sheet. Six pot front and six pot rear. However the total piston area was only increased up front, so the rear upgrade does not increase the pedal travel. My pedal travel is fine overall, and brake feel is awesome, although slightly longer than OEM. I use race pads with higher friction, so they bite quite hard. I just wanted the upgraded brake cylinder for increased safety margin on track.

Not much more you can do. Stainless steel lines? Use a very high quality DOT 4 fluid and change it as needed depending on your track needs.

 

[Jeffman]

I upgraded my rotors to ECS Tuning two piece and shed a couple of lbs. per rotor which yielded noticeable better acceleration and agility in steering. I have had then for about 4 years now and no issues at all. Used Hawk street pads. Next time I change, I will use the same rotors and upgrade to big brake kit.

VT

I also have these two-piece rotors in my ECS shopping cart. Just waiting to pull the trigger when my OEM Z43.5si two-piece front rotors wear down. (They seem kind of pricey - anybody find them cheaper elsewhere?)

 

[matreyia]

I also have these two-piece rotors in my ECS shopping cart. Just waiting to pull the trigger when my OEM Z43.5si two-piece front rotors wear down. (They seem kind of pricey - anybody find them cheaper elsewhere?)
View attachment 21423

They are pricey...but they are worth it. You will see when you step on the gas.

 

[fmorelli]

Not much more you can do. Stainless steel lines? Use a very high quality DOT 4 fluid and change it as needed depending on your track needs.

On the E89 Z4 I found the UUC brake lines were right. No idea what works/doesn't more broadly, given Z4 unicorn crap. But I can say the UUC ones do:
http://store.uucmotorwerks.com/stai...---6-lines-for-z4-2010-e89-chassis-p1303.aspx

Filippo

 

[spiicytuna]

I went with the PB brakes. They install with the oem actuators to maintain the electric brake. The 35is / EUR 35i rear setup is an easy alternative (what I came from). I posted some pictures in my build thread.

Question... I too have run the PB brakes for over a year front/rear. Question: Did you install the OEM rear line to the bottom or the top of the bracket? (see picture below for reference)

 

[Fran]

Well, front&rear M5 brakes installed on the car but the feel of the pedal is horrible.. im looking to upgrade the brakebooster to the M5 unit but seems to be imposible.


any ideas?

 

[Asbjorn]

Question... I too have run the PB brakes for over a year front/rear. Question: Did you install the OEM rear line to the bottom or the top of the bracket? (see picture below for reference)

View attachment 24876

Does this answer your question?

 

[spiicytuna]

Yup. I had always wondered if the bleeder screw was supposed to be down on the bracket. Mine is. From your picture, yours is too since the hard line comes up from the bottom the caliper.

 

[TDJ Stefan]

What matters when upgrading master cylinders is bore sizes for front and rear brakes, not volume. I just upgraded my E89 with an M2 sport performance brake kit, 370mm x 30mm front rotors with Brembo 4 piston M calipers. BMW Z4 brake pedal travel and feel even when stock is terrible. Too much travel and no sensitivity. I'm working on MC upgrade now. X3 MC has much larger bores for both front and rear brakes which will provide much harder, shorter travel pedal. I'm in process of mocking up this set up on bench now. Will publish results as soon as I come up with workable combination.

Hi, so im just curious. What you are saying here, is that you are not satisfied with the M2 calipers over the 370 rotors? Reason for asking is that I saw another thread on the matter and those who done it didn´t seem to have any issues.

And also, does anyone know if the 336x22 rotors from ECS really fit with the OEM rear calipers given that they are 12mm wider and 2mm thicker?

 

[Asbjorn]

Hi, so im just curious. What you are saying here, is that you are not satisfied with the M2 calipers over the 370 rotors? Reason for asking is that I saw another thread on the matter and those who done it didn´t seem to have any issues.

And also, does anyone know if the 336x22 rotors from ECS really fit with the OEM rear calipers given that they are 12mm wider and 2mm thicker?

See attached excel sheet (stock 35i EUR / 35is US vs my bbk). I don't know what the M2 piston sizes are, but you better check first. If the total piston area is significantly larger it will be a downgrade for sure. A very common mistake. Different cars have different brake cylinders, and the pistons must match. Also the M2 calipers and rotors are nothing special in terms of features, so not sure why you would want those.

Notes from the excel sheet attached:

* Try to match piston area with original stock piston area.
* Maintain the piston area sizing to +/-5%. Do not increase torque by increasing piston area. Pedal travel will be long and spongy!
* Brake pads with different coefficients of friction can be used to modulate the brake bias.
* To increase brake torque, we increase rotor diameter (but caliper position etc must match of course, and it sounds like ecs rotors diameter is too large for stock calipers, but I wouldn't know)

 

[TDJ Stefan]

Thank you for your reply and the excel sheet. Great tool to play around in and see if any of my choices will match up with the oem bias.
I like the look of the PB brakes but first of I´m going to see if I can find something else to glue togheter using what I might find. Feel like shelling out almost 4k is kinda steep. But since I intend to track the car thats maybe where I end up in the end anyway.

 

[Asbjorn]

Thank you for your reply and the excel sheet. Great tool to play around in and see if any of my choices will match up with the oem bias.
I like the look of the PB brakes but first of I´m going to see if I can find something else to glue togheter using what I might find. Feel like shelling out almost 4k is kinda steep. But since I intend to track the car thats maybe where I end up in the end anyway.

For track use just start with some good track pads and fresh racing brake fluid. No need for bbk. Avoid trackday pads or multipurpose pads such as the ebc yellowstuff. Swap the dedicated pads back and forth and save the cost of a bbk. Unless you are very low hp (<290hp), with this setup your brakes will far outperform your OEM engine cooling system anyway.

On the other hand, even with a properly cooled bbk, if you use the wrong pads, even PB race pads, you will still run into brake fade eventually. Lots of people run bbk with street or sports pads and entry level cup2 or worse track tires, and never realize the full potential of their kits. But they look good...

You can get very far with oem hw and upgraded pads before you experience pad fade or melt the calipers. I heard someone running slicks even with the M2 calipers who melted those. At that point you will want real racing calipers with better seals. With fixed calipers you also get pad knock back on track unless you get better racing calipers. Not a problem with oem floating calipers.

 

[TDJ Stefan]

Thanks for you input. Im going to take your advice and go for just some better pads, braided hoses and fluids this year and progress from there. See what happens. Might also do some brake cooling, think that might do for a few trackdays a year.

I saw a thread on a swedish forum where someone melted his calipers on a stock M2(with semi-slicks) so yeah nothing is certain.
Dont really mind a level of NVH from the brakes but I don´t want to maintain them every month either, which is what you probably would get if using a race caliper. But it all depends on how I decide to use the car in the future, for now just start small and work my way up.

 

[Adrian Borh]

Hi all. Just a little confused on what the final outcome is on fitting a BBK on a Z4 35i with stock 348/30mm rotors...

Should I keep the same size and just go for new drilled/grooved? Is the stock caliper that good for street use/occasional heavy right foot?

I still need to change the current ones as rusted and crumbling badly...

 

[Asbjorn]

Hi all. Just a little confused on what the final outcome is on fitting a BBK on a Z4 35i with stock 348/30mm rotors...

Should I keep the same size and just go for new drilled/grooved? Is the stock caliper that good for street use/occasional heavy right foot?

I still need to change the current ones as rusted and crumbling badly...

oem calipers are fine. Drilled rotors are a downgrade. Pads is what matters. More so tires.

 

[Adrian Borh]

oem calipers are fine. Drilled rotors are a downgrade. Pads is what matters. More so tires.

Any idea what best pads to use? Sorry but still a newby to the Z4

 

[matreyia]

Looking to upgrade my brakes in my 35i as I have noticed some fade and my rotors seem to be warped already! After doing a FBO+ upgrade I think the stock brakes have got to go! My plan of action is to go with some 35is calipers, which are the same as 335i and a set of Hawk pads.

From my readings it looks like the 35is rotors are identical to the 335i’s with the exception of being a 2-piece design which has a few advantages (lighter/cooler).

Question is what to do in the rear? Do I need to run 35is calipers/rotors or stick with the 35i setup? With the electric brake it really limits options.

I currently have the M Performance F30 rear brake calipers and two piece M3 ECS tuning light rotors on my car. I got them last month and initially I was not impressed with the gains...however over time, they have proven to provide noticeable gains in braking feel and distance. I had some complaints about installation requirements and the rotors lack of compatible screw to the hub, but all worked out.

I am thinking about selling the set for almost 1k less than my purchase price if you're interested in them. I got them for $2430 and will sell them for $1500 plus shipping (this shit is heavy when shipped in one box...probably have to split into two for safety). If successful in selling them, I would use the funds from the sale to buy a matching rear set of rotora brakes to match the blue color of the fronts I have on now. Right now, I have Rotora fronts and M Performance rears and, though they are very good and have similar colors...the fact that the are differently slightly in shades of blue is killing my OCD brain and the logos are different too... ugh.

Anyways, let me know if you are interested in getting this F30- M Performance retrofit kit (this is NOT the M Sport, it's the actual M Performance - yes there are differences despite what many people claim in the forums). All you would do is install and drive, no need to bed the brakes or do any break in period since the rotor and pads are already unified and bedded. There is literally almost zero wear on pads and rotors...I mean it's only been a month of normal driving.

Cheers.

 

[Asbjorn]

Any idea what best pads to use? Sorry but still a newby to the Z4

It's all a trade off between friction, dust, heat resistance and noise. I like high friction pads even for the street.

You don't get shorter stopping distance on the street even if you install formula 1 brakes. Its all about braking feeling. I like my brakes to bite hard, so I use higher friction street pads. Such pads are typically not xyz certified because the differ too much in friction coefficient from oem. Right now im on ebc yellows, and they are a bit soft and low friction for my tastes, but I gotta wear them down. I liked the PB race pads (semi metallic pad) more for street use, but you can't use thisinfo for your calipers.

In the end it's all about personal preference. and you have to research the market.

 

[Adrian Borh]

It's all a trade off between friction, dust, heat resistance and noise. I like high friction pads even for the street.

You don't get shorter stopping distance on the street even if you install formula 1 brakes. Its all about braking feeling. I like my brakes to bite hard, so I use higher friction street pads. Such pads are typically not xyz certified because the differ too much in friction coefficient from oem. Right now im on ebc yellows, and they are a bit soft and low friction for my tastes, but I gotta wear them down. I liked the PB race pads (semi metallic pad) more for street use, but you can't use thisinfo for your calipers.

In the end it's all about personal preference. and you have to research the market.

and between EBC and PB, are the EBC any quieter ?Definitely not quieter than OEM right ?