Karterde03

Hey guys, I have someone that’s trying to sell me his Stoptech 4 piston caliper SQUARED setup, meaning all 4 calipers have 4 pistons. I know this will mess with the brake bias won’t it? I do track my Z and that’s the only reason I’m interested in them.

He is saying $1200 for the bundle of all 4 Stoptech calipers, Concept Z slotted Rotors, and StopTech Pads.

DarkZ03

iTrader: (11)

Is this a makeshift kit, how come it has CZP rotors?

Karterde03

I’m not sure, looking at the pics it looks like the CZP rotors... He doesn’t recall the name of the actual manufacturers of the rotors. Pads were Stoptech though.

Perhaps I wasn’t specific enough in my questioning. I want to purchase these, but how will it impact me on the track?

Karterde03

Is a 4 piston setup bad, and if so, can you please give me the specifics and the facts. Thank you

Freise

The larger pad than the stock "staggered" size might result in more bias in the rear which is generally undesirable. Rears locking before fronts (where weight wants to transfer) will give you squirrely/unpredictable braking. Running larger brakes are done for cooling efficiency, looks, or both. Since the rear brakes do less of the brake work in general, a squared setup is usually done for aesthetics over function and you'd need a method to readjust bias.

bealljk

iTrader: (13)

I run AP 4pot kit and it behaves likes OEM. I will be the first to admit I do not need this much braking capacity but I am horribly turned-off by OEM (non-brembo) brakes on these cars (and just about any car). I would yield to what DK Mura, Mic Velo, Terrasmack, Jim Stevens(SP??) and the others that have actual track experience.

Karterde03

Do you have any track experience with the brakes then? Thank you for your input!

my fear is that when ABS kicks in and the wheels lock up, the back ones would as well, and will almost be like having a hydro handbrake, causing me to slide...

MicVelo

This is a well founded fear. Improper bias can indeed lead to some tail happy antics while NOT actually drifting. Messing with brake bias using traditional means isn't really recommended on a street car, simply because todays Zs (and most every car built after 2000) control F/R brake bias via the ABS system; that is, electronically. In order to use a proportioning valve, one must re-route around (and eliminate) ABS. Not worth doing just to add BBK to the rear. [Note: I may be wrong here as I've not kept up on the technology; maybe this IS possible nowadays. Look into it.]

In the old days - very old considering the last time I messed with proportion and bias was on an already 15 year old race car with no electronics nearly 40 years ago - and using a proportioning valve and a balance bar dual master setup was easy enough to set up due to its mechanical nature. Hydraulic, cockpit adjustment valve and a bias bar between the MC rods, easy to adjust between or during track sessions. But this isn't applicable here unless you're running a dual master setup.

All is not lost though.

Are the rear discs of the StopTech setup smaller? Are the calipers both the same F&R? That is, identical ST-40s? Or, if different (smaller) rotors, are the calipers sized for the different rotors?

If so, might be an OK swap since the size differential does afford some F-R bias just by the physical nature of the rotors and caliper size difference.

You can also cheat by using lower coefficient pads in the rear. While this isn't an optimal situation (given you'll need to buy a full set of pads F&R and throw away half a set either front or rear depending on which axle you're doing), it is doable. Back in my race days, we were able to buy either Datsun Comp or Ferodo half sets so that we could stagger the friction materials. Not sure you can do that with street pads nowadays. (And, unless you were a big dollar, big serious, higher racing class roadster owner (there weren't any), we had rear drum brakes which were available in half sets regardless.)

In any event, don't give up hope. Go check out the setup. Bring a tape measure and calipers to measure everything up. As I said. if the rear set is physically smaller, you may be OK. The four piston arrangement will give you that extra bit of heat rejection capability that you need for a dual purpose car.

Karterde03

Thank you for the write up MicVelo.

after questioning the owner, all 4 calipers are nearly identical, same with the rotors. The pads are still in the calipers... so he is unsure if they are all 4 the same...

Karterde03

Well the owner told me $1200 picked up this weekend, and reached out to me after I questioned him about them nearly 2 months ago. Told him all of the information I gathered from you guys, and said $1000 is my top dollar.. Seller declined, and left the group.

Thank you for all of the information guys!

dkmura

iTrader: (64)

Mic has provided a pretty complete explanation, but let's also consider vehicle dynamics as well. While the Z33 has a close to 50/50 weight distribution statically, under heavy threshold braking that balance can dramatically change towards 65/35 or even 70/30. That's a lot of weight shifted towards the front of the car, and very little left on the rear. While Mic is correct in saying that you can play with things like the coefficient of friction of brake pads, or a brake bias bar, to reduce the braking efficiency of the rear brakes, this is always a work-around compromise.

IMO, having a "square" brake setup doesn't really offer any advantages. Even the OEM Brembo setup that I've raced with so many years means using comparable pad compounds and results in a wear rate of 3:1 front-to-rear pad/rotor replacement on average. Yes, OEM brake bias and ABS setups engineered by factory engineers have limits and I've exceeded them plenty of times. Still, I wouldn't want to carry a bigger caliper/rotor combo in the rear unless I absolutely needed to. Why? As others have said, locking up the rears is not a pleasant experience at speed. Also, carrying any excess unsprung weight doesn't carry any performance advantages.

So, having said my $0.02, I'd say go ahead and inspect this brake setup and take careful measurements. But I wouldn't buy it unless it offered some tangible engineering advantages .

Karterde03

Thank you DK. I think I will try to find some used brembo’s, as the Stoptechs didn’t work out for me regardless. If you know anyone who’s selling some, let me know 😉

thank you once again to everyone for their input!

MicVelo

https://my350z.com/forum/brakes/6249...-calipers.html

Same seller also selling half an Akebono set.

g356sp

The other guys have covered this all pretty well, but here's a little more info:

Brake bias depends on pad friction, rotor size, piston size, and to a small extent the pad size.

If the rotors are the same size front and rear but the rear calipers have smaller pistons, they exert less force = less braking power. Whether the full system is appropriately sized for the application is a different story.

DarkZ03

iTrader: (11)

Karter I would suggest something a little out of the box. Buy the kit and sell the rear, use that money to buy a matching kit for the rear (2 piston) reason I suggest this is cause the front come with the brackets that relocates the calipers to a better position to prevent knock back. Not all kits have this.

DarkZ03

iTrader: (11)

I fully understand this, as just bought the Nismo caliper kit... later I found out through research that it's basically the same kit as the 13" Stop Tech Throphy sport kit for these cars, also a lot cheaper.