2001CamaroGuy

iTrader: (6)

CUSTOM SETUP! BMW Z4 getting LS6 swap! NOT F-BODY!

I'm trying to decide between the Wilwood 6 piston caliper and the Porsche 996 4 piston caliper.

The Wilwood caliper has 6 pistons with:
1.62", 1.12", 1.12"
with total area of:
4.04 sq/in

The Porsche caliper has 4 pistons with:
36mm/40mm
1.42", 1.575"
with total area of:
3.53 sq/in

Keeping all other things (theoretically) the same (rotor diameter, pad compound, line pressure, etc.), the Wilwood should provide about 15% more force.

On the flip side, I like the idea of using a “factory” caliper that has been a proven performer/reliability. Additionally, I can buy pads for near anywhere.


So, which one is “better”? 15% seems like a good bit of stopping power to give up. Is it really that big of a difference? How do the calipers compare from a long term, performance stand point?

01 ss vert

iTrader: (1)

That 15% may not matter if the tires can't grip. Even if they can, throw on a more aggressive pad compound. Your limits for traction are really the tires and ABS.

Like you, I looked into different calipers. Then when I looked into C6 calipers (just 2 piston), and they were performing almost as good as exotics, I foudn the C6 calipers to be fine for me needs. For track days, I just swap to blank rotors and Hawk HTc60 pads.

I didn't see the real beneit to dollar ratio when looking at other calipers. To each their own, though. I personally think a good pad can outperform larger calipers and less pad.

2001CamaroGuy

iTrader: (6)

Thanks for the input. 99.9% of the cars life is street and canyon carving. Being a convertable, I doubt I could even get it on a track (tracks seem to have universally banned convertibles unless they have a full cage).

The car is a non-abs car and I'm using really soft street performance summer tires, so I'm sure they will ultimately be the limiting factor. As I mentioned, I was alway leaning towards the Porsche calipers but felt it best to ask now before I spend money. There are few things worse than spending money only to find out something else was better. Spending twice stinks.

MeentSS02

iTrader: (11)

For me, I'd probably look at the Porsche calipers...I've always been more comforted with a proven performer that has gone through some sort of OEM testing/abuse. I would guess it would make it easier to source rebuild parts as well.

z28bryan

iTrader: (7)

If you want better braking performance, it can be had with the stock brakes, good pads/rotors, and some basic maintenance. Especially since you're pretty much a daily driver. If you're hell bent on those calipers, do it for looks. For your driving application you won't come close to using those brakes to their full potential.

01 ss vert

iTrader: (1)

It it's nonabs, the stock calipers will lock up the tires. I know, I've done it when my ABS was not working. I corded 3 R-comp tires doing it. WHY did you remove the abs? I use mine all the time...you want it if you are doing to be aggressivly driving!

Also, the track dictates if a convertible and run with or without a cage. I have done no cage tracks before, but they are getting rare. I now have a 5 point in the car just to be covered for different tracks. Honestly, I feel a lot safer now too.

I think you are going about this the wrong way.

Have you even done a track day before?

MeentSS02

iTrader: (11)

That's nice and all, but I don't know anything about the stock Z4 calipers. Do you? I'd assume that a bigger, more powerful engine in that small of a platform would warrant a closer look at the brakes. We aren't talking about tracking a stock 4th gen F-body here...this is a completely different platform that will be getting a healthy dose of extra HP/TQ.

01 ss vert

iTrader: (1)

Power of the engine doesn't matter for braking - total car weight & weight distribution will, however. I didn't know we were talking a Z4 until now. Either way, I would NOT eliminate ABS on a car you plan on tracking. As for Z4 brakes, a BMW forum would be better.

MeentSS02

iTrader: (11)

I disagree...if you have more power, you will go faster on the straights, and that extra speed means extra heat for the brakes.

2001CamaroGuy

iTrader: (6)

The factory Z4 calipers and rotors are miniscule. The Z4M got bigger rotors but the calipers are still small single piston floating units. With the factory 225/45/17s I CAN NOT even come close to locking up the wheels even at low speed. I got rid of ABS because I prefer the feedback that I recieve without it. I'm not here to argue the ABS/no-ABS issue. Every car I have tracked has been non-ABS or ABS removed.

While the BMW forum is good for 'BMW info', it's rather useless for this sort of stuff. LS1Tech users have more experience with the Wilwood calipers so getting input on the advantages/disadvantage of using it comes better from here.

While more HP does not increase the need for brakes, the added acceleration, speed, and aggressive back roads driving that invariably comes with more HP does. If I'm spending thousands of dollars and gallons of my blood swapping and hot ridding my car, I'm not about to overlook something as essential as good braking.

z28bryan

iTrader: (7)

So basically you need it if you are going track speeds. If you put more power in the car, doesn't mean you'll essentially have the car at higher speeds for longer periods of time.

I'm just trying to debunk the thought that a lot of people assume... if I add more power to my car then I need bigger brakes. You really don't. It's when you are braking a lot at higher power that you want them.

For example... you can have the same as stock power and start doing track days and you may want to consider getting bigger brakes.

Example... you put another 200 hp and you aren't really putting that stress on your brakes going higher speeds then you can get away with the cheaper options.

MeentSS02

iTrader: (11)

Yes...a 1000HP car going 65MPH and a 10 HP car going 65MPH will require the same amount of braking force to come to a stop, assuming all else is equal (weight, distribution, tires, etc.). The 1000HP car has the capability to go much faster...the 10HP car, not so much. If you drive aggresively (beyond the posted speed limit on a public road or at a track of some sort), that extra speed is going to require better brakes to bring that back down under control. You design brakes to handle the capabilites of the car, not the average commute. For some cars, the only capabilites it has are to commute...that's why you see rather large SUVs with surprisingly small brakes. It doesn't take huge brakes to generate a lot of force, but it does take large brakes to dissipate the heat associated with aggressive driving, which is what is in question here.

Can you get away with smaller brakes by altering your driving style? Absolutely...the most common mistake with road course rookies is to brake too late, and far too hard, which leads to brake fade. When this happens, the first reaction is to open up the ol' wallet and let the cash start flying.

While I understand the "don't go upgrading your brakes, the stockers will work just fine" theory, it doesn't apply here IMO. It's a different platform that will be given more HP, and driven aggressively on top of that. This isn't some guy wanting to take his stock f-body to the road course for the first time that wants big brakes just in case...in that situation, I too would recommend not upgrading the brakes.

z28bryan

iTrader: (7)

So basically we both agree on what conditions one would need the brakes

01 ss vert

iTrader: (1)

I'm a BIG fan of confirming you actually need to upgrade. The car is under work - I say drive it with the stock set-up (minus maybe a pad change over) and see if it's adequate without having to upgrade to a different set-up when it's not even needed.

My first track day I confirmed I needed new calipers due to my weight (and yes, speed). I spread the calipers so I upgraded and installed ducts. However, a much lighter car with the same set-up would have likely had more succcess than me and my pig.

Again, test the car out before upgrading. With NO ABS, I think you will not need to spend your money here, and I think you will likley already be able to lock up the tires under 100% braking power.

MeentSS02

iTrader: (11)

There's definitely some merit to that method...if you have time and patience, this is always the best way. If he has the money and not so much the time, it certainly won't hurt anything to do it up front. The Porsche calipers are a proven performer, and should exceed anything he could throw at them.

2001CamaroGuy

iTrader: (6)

As I mentioned, I have CONFIRMED my factory Z4 caliper suck. No ABS, new high-perf street pads, and full brake application they still do not lock up the factory 225s (don't even come close). Now I'm getting bigger rubber on all 4 corners so I'm definitely leaving stopping capacity on the table.

While I'm not going to jump out and upgrade today, I do have the option of picking up some near mint 996 calipers for $500 (all 4.... so $125 a caliper). I just wanted to make sure that I didn't buy the Porsche calipers only to later say "wow...really shouldn't have bought these". At $500 and based on the replies I have been getting (both here and other forums), I will tuck them away for when I perform my engine swap.

01 ss vert

iTrader: (1)

can you give us a comparison photos of the calipers? The top 'hat' area (goes over the rotor) needs to be strong for track use (the bigger the better). The material matters too - aluminum will get soft and defelect under load much more than say steel or stainless steel will under the high heat of track use. I wouldn't make your decision just on the square area of the pistons - other factors like cost of the calipers, material of the calipers, and pad replacement cost and selection should all be factored as well. In fact, those would be more important to me compared to the 15% difference in square area at this point.

2001CamaroGuy

iTrader: (6)

Porsche 996 radial mount 4 piston caliper.
Porsche is a mono block cast aluminum caliper.





Wilwood radial mount 6 piston caliper.
Wilwood is an assembled cast aluminum caliper.

01 ss vert

iTrader: (1)

Those look nice. Something to think about is wheel size in regards to rotor or caliper interference. I was wanting the CTS-V calipers, but keep my 17" ZR1 wheels since I have two sets of them (street & racing). I didn't want to replace 8 wheels simply for brakes. I decided on the C6 brakes for many factors.

Have you looked into interference issues, along with what it will truely cost you, such as adapters/brackets, lines, etc.? Are both of these calipers 'bolt ons' minus an adapter?

Also, your Z4 will be a blast to drive with that amount of power!

2001CamaroGuy

iTrader: (6)

I'm upgrading to 18" rims this weekend (the factory 17" rims were bent.... previous owner....). The porsche brackets are $200 for the set (front and rear). I'll need new lines either way. Same with rotors. Overall the Wilwood setup would cost 3-4 times what the Porsche setup will. I'm trying to 'ignore' the cast aspect (for now... in the end it is a big factor) and focus on performance gains of each setup.

Believe me, I can't wait to swap. This 190hp at 6000 rpm and no torque is getting old (though I did walk a guy in a new V6 Camaro last night.... that was a presently surprising...).