Brake upgrade dilemma

[fxslin]

Hi all

Might not be a major thing in the total picture. But anyway I'm currently converting my 2.8 into a track car.

And at last trackday I killed my brakes, so I had to move forward the brake upgrade job.

My planned options was:
option 1: upgrade to 330i front brakes (calipers and 325mm discs).

option 2: upgrade to 300mm front discs with carriers and disc. Keeping the OEM caliper.

Everybody is advising me with going for option 1. However upon the weight calculations it revealed that the 330 option would add 7.7kg to my front comparing to option 2 that would only add 1.4kg.

My stand is that bigger doesn't necessary improve actually stopping and brake performance, but does improve the heat handling (cooling) on the brakes. (bigger is not always better )

Regarding cooling I plan to build brake ducts for cold air directly into the disc regardless of chosen option.

So I'm leaning towards option 2, however I'm unsure if the 300mm solution would hold up on track.

So I was wondering if anybody here had been doing some hard tracking with 300mm disc and provide some feedback if this holding up or not.

Really appreciate any feedback!

Sidenote: brake pads is not really part of the topic, I will mostly likely run racing pads.

 

[the Nefyn cat]

Well, I'm one of the ones with the 325mm discs on, and while they are heavier than the standard set-up I wouldn't have thought it would be 7.7 kilos. Unless of course that's for both sides. I only really noticed that the steering was a bit heavier, just a bit more in the way of a centrifugal effect.

 

[5harp3y]

I've just fitted 300mm brakes to the z3

Brand new Pagid plane discs
Brand new calipers
E46 carriers
Ebc yellowstuff pads

Even whilst they are breaking in the performance was incredible, so much better than stock .

Cheap as chips to do as well

 

[motco]

I have only once taken my Z3 on a circuit and that was on a very cold December day when I didn't fancy driving my Westfield in a maximum temperature of 5ºC. Even in those conditions the brakes on my Z3 lasted a mere three laps before the pedal went to the floor. My son has a Z4M Coupé and even with added brake cooling ducts, Racing Blue DOT5.1 fluid, and Bluestuff pads his would run for the hills sooner or later. Now his car has AP Racing brakes and the world is a different place.

 

[fxslin]

Well, I'm one of the ones with the 325mm discs on, and while they are heavier than the standard set-up I wouldn't have thought it would be 7.7 kilos. Unless of course that's for both sides. I only really noticed that the steering was a bit heavier, just a bit more in the way of a centrifugal effect.

This is a bit what I'm worried about. As the long term project is to lighten car and the first thing I might be doing is to add unsprung weight. But could very well be "smart" weight, with "cooler" brakes in mind.

Note: the 7.7kg is total weight increase from stock weight. But in reality the increase is only 6.3kg, because I need better brakes than the OEM setup.
See the attached picture over my calculations, please correct me if I'm done some mistakes here

I've just fitted 300mm brakes to the z3

Brand new Pagid plane discs
Brand new calipers
E46 carriers
Ebc yellowstuff pads

Even whilst they are breaking in the performance was incredible, so much better than stock .

Cheap as chips to do as well

That would be my choosen setup except for brand of disc and pads. I believe the stopping power will be similar to 330 brakes (325mm disc), but will I be able to keep them cool enough in a race (usually 10 laps)?

I have only once taken my Z3 on a circuit and that was on a very cold December day when I didn't fancy driving my Westfield in a maximum temperature of 5ºC. Even in those conditions the brakes on my Z3 lasted a mere three laps before the pedal went to the floor. My son has a Z4M Coupé and even with added brake cooling ducts, Racing Blue DOT5.1 fluid, and Bluestuff pads his would run for the hills sooner or later. Now his car has AP Racing brakes and the world is a different place.

I had the same problem both with my previous 1.9 and there I upgraded to vented disc, DOT 5.1 fluid and some EBC pads similar to EBC Yellowstuff. That worked fine and I didn't have any brake issues. But never ran many hard laps in a row with this setup, usually 1 warm up lap, 3-5 hard laps + 1 cool down lap. Then pitstop for 15-25 mins, before heading out again.
With my Z3M I never had any issues, but be honestly I never drove it as hard at the 1.9 and my current 2.8. Like that car to much to risk anything with it.

However @spurs fan in a coupe did reply my question in his trackday thread and he is running the 300mm setup with similar pads as I plan. And he mention he has not really had any issues after upgrading to his current setup. So currently I'm leaning towards trying the 300mm option and save that weight. However I'm going to think/research a bit more about this

So more options or ideas around this topic is welcome!!!

Attaching a pic from last trackday with the "new" 2.8 trackday car, when I "killed" the brakes...

 

[motco]

Sadly there was no on-site photographer on that one occasion that mine was on track.

 

[the Nefyn cat]

Best add on a touch more for the bigger pads, too. Or are they included in the weight of the calipers? Brake fading might be a bit reduced due to the extra surface area of the discs, only one way to find out really. All I can say is, bearing in mind I'm only using mine on the road, the 325s are great. And being standard BMW bits, albeit for a different car, pretty damn cheap, too.

 

[Jswheeler1990]

Hi guys. How did the upgrade go?

I’m thinking of upgrading to the 300mm disc as stated above but am hoping someone can tell me more about what parts I need, and if the standard callipers are best vs the callipers from the e46 330?

 

[Jswheeler1990]

Any advice will be appreciated

 

[Andyboy]

330i brakes mean you need to run 17 inch wheels as well. I have seen caliper carriers modified with an angle grinder so that 16 inch wheels fit - make up your own mind on that one.

 

[Jswheeler1990]

thanks Andy, running 17s anyway.

 

[Mario]

Regarding the brake fluids it makes a lot of difference I think - not all fluids are made the same even if they say 5.1 DOT - check Opie Oils and have a look at boiling points and you see how much difference it is between some of the racing fluids there

 

[fxslin]

Hi guys. How did the upgrade go?

I’m thinking of upgrading to the 300mm disc as stated above but am hoping someone can tell me more about what parts I need, and if the standard callipers are best vs the callipers from the e46 330?

Sorry with late reply. I went with 300mm solution first and PFC brakepads + duct cooling.
Conclusion: it worked well, no fading or other issues.

Some pics from my DIY brakecooling, I made a solution that bolts on with 2 bolts on the brakeshield and 1 bolt on the wishbone.

 

[Coco]

I've just fitted 300mm brakes to the z3

Brand new Pagid plane discs
Brand new calipers
E46 carriers
Ebc yellowstuff pads

Even whilst they are breaking in the performance was incredible, so much better than stock .

Cheap as chips to do as well

Hi, can you please tell me from what e46 came the carriers, I bought e46 330d brake calipers, carriers and discs but I changed my mind and I decided to go for 300mm option
Thank you