S14 Brake Upgrade!!!

[Pento240sx]

Well I was thinking of upgrading my brakes. Like stock calipers and drilled rotors or 300ZX Calipers and drilled rotors? What do you NICO members think?

[flying_monkeee]

You'll never be unsatisfied w/ Z32 brakes... but you'd need more than just the calipers and rotors. In addition, you'll need conversion lines, hubs if you don't have 5 lug or redrill, and the Z32 17/16th inch brake master cyl. for optimum performance.

You don't really need the drilled, slotted, or drilled/slotted rotors. Most everyone will turn you away from this. The only reason I'm not is because I'm rocking the drilled and slotted rotors from Circuit Sports.

From what everyone is saying, they'll warp more and wear down the pads very quick. Most others recommend the Brembo Blanks... plus they're cheap.

If you don't want to do the whole Z32 upgrade (around 500 bucks), you can always just keep what you have and use high performance pads, i.e. Hawk HPS pads, Project Mu, etc.

[ag240]

300zx calipers, Brembro blanks, SS brake lines, 300zx master brake cylinder and good pads.

[DrifterXRPS13]

Can't go wrong with the z32 upgrade, they take a little getting used to if you have forced induction but that's only because it gets a little iffy at high speeds, muahaha

[Pento240sx]

Well they are selling me some 300ZX TT Calipers rear and front for 200 bucks im guessing that is cheap right?

[IanS]

When will you kids get it through your heads the drilled rotors do ABSOLUTELY NOTHING, they are for looks only. Do some research.

[Tulsa_S-13]

When will you kids get it through your heads the drilled rotors do ABSOLUTELY NOTHING, they are for looks only. Do some research.

Haha! 95% of the people on these boards have absolutely NO use for Z32 brakes besides aesthetic purposes.

Myself included for now

[lemon]

they don't do anything breaking wise.... but they keep heat down, and weigh less....

[Tulsa_S-13]

they don't do anything breaking wise.... but they keep heat down, and weigh less....

Actually they do.

Read this article:

Cut and paste from fresh alloy...

I posted this on the DGTrials board, thought you all might want to see it too.-- Since there's some discussion on various big brake upgrade kits, Erik asked me to do some calcs and make a post on what's important for brake systems.

First, some assumptions:1) The F/R brake bias set by the manufacturer is ideal, or close to it (this may or may not be true, but it gives us a reasonable target to shoot for)

2) All pads have the same coefficient of friction

Now, some general info:

The #1 thing to remember about bigger brakes is that the main goal is NOT to stop your car quicker! If you can lock up your stock brakes, you won't see much, if any, improvement in stopping distances with larger brakes. Larger brakes are used for their heat capacity, in turn giving improved fade resistance.

Also, more pistons does not equal better braking! The main benefit of more pistons is the ability to use a larger pad, which will last longer and have more heat capacity. An exception is when you go to 8 pistons or more, which typically use two separate pads -- supposedly the pad edge 'bites' a little better than the rest of the pad.

Ok...so if you want to figure out what effects various brake setups will have on the brake

bias, the key is brake torque. How do you calculate brake torque? Easy:

Torque = Force x lever arm

Force in this case is the pressure in the brake line multiplied by piston area of the caliper and the coefficient of friction of the pads.

The lever arm is how far out on the rotor you apply the force. For these calculations, we use the center of the pad as the "effective" rotor radius. And then you compare between front and rear, or various different caliper/rotor combinations,etc.

A few things to note:1) I already said earlier, we're assuming the coefficient is the same in all cases, so if we stick to just comparing different setups, then it doesn't matter (it's just a scale factor)

2) same with factors of pi, or 4 (from, say, using the diameter instead of the radius of the pistons to calculate area) -- as long as you're consistent in your calculations (i.e. as long as you're wrong consistently!), the results will still be valid. I'm going to leave out factors of pi and use the piston and rotor diameter instead of radius.

3) A sliding caliper has effectively TWICE the number of pistons as it actually has. So a single piston sliding caliper acts, in hydraulic terms, as if it were a 2-piston fixed caliper. The reason is because the piston presses directly on the inboard pad, but the caliper body itself acts as an "inverse" piston and pulls on the outboard pad via the pad frame (the part that arches over the top of the rotor). At any rate, there's a factor of2 you have to remember if you want to compare sliding calipers to fixed calipers.

Ok...so lets throw some numbers out here.

Stock 240sx non-ABS front brakes (CL22VB):

- Single piston sliding caliper- 54.0mm piston diameter-252mm diameter rotor-45mm wide pad ('width' is the radial dimension of the pad, following the terminology in the FSM)

effective rotor diameter: 252-45 = 207effective piston area: 54^2 x 2 (<-sliding caliper) = 5832"brake torque" = 1207224

Stock 240sx rear brakes (CL9H):

- Single piston sliding caliper- 34mm piston diameter- 258mm diameter rotor- 40mm wide pad

Effective rotor diameter: 218effective piston area: 34^2 x 2 = 2312"brake torque" = 504016

front brake bias = 1207224 / (1207224 + 504016) = 70.5%rear brake bias = 1 - front brake bias = 29.5%

So those are our baseline numbers.

To compare, let's see what happens if you put 300ZX brakes on the front of a 240sx...

300ZX front brakes (OPF25B)

- 4 piston fixed caliper- 40.45mm piston diameter-280mm diameter rotor-50mm wide pad

effective rotor diameter: 230mmeffective piston area: 40.45^2 x 4 = 6545"brake torque" = 1505350

front brake bias = 1505350 / (1505350 + 504016) = 75%rear brake bias = 25%

Now if you put the 300ZX rear brakes on too, what happens?

300ZX rear brakes (OPZ11VB)

- 2-piston fixed caliper- 38.1mm diameter piston- 297mm diameter rotor- 36.5mm wide pad

effective rotor diameter: 260.5mmeffective piston area: 38.1^2 x 2 = 2903"brake torque" = 756231.5

front brake bias = 1505350 / (1505350 + 756231.5) = 66.5%rear brake bias = 33.5%

Just for completeness, Q45 brakes (2-piston sliding, 43mm pistons, and 280mm diameter rotor) and stock rear brakes give 78.5% front brake bias.

I don't have piston sizes, etc, for the Altima/180sx brakes, unfortunately.

OK. So that gives us a range that we can work with -- 67% to 75% front brake bias. I'd be wary of using any less front brake bias than ~67% because that could cause the rears to lock before the fronts -- not good.

ARRIGHT, NOW...

Suppose you want something bigger

Let's do an example. For concreteness, let's assume that we're going to use 4-piston fixed calipers at each corner with equally-sized pistons in each caliper (but different front and rear), 323mm (12.72") front rotors, and 309.7mm (12.19") rear rotors (those are commonly available sizes from vendors such as Wilwood, Coleman, etc).

What piston sizes do we want in order that the front brake bias be, say, 70%?

Well, of course it's just the reverse of what we did up above.

front brake torque: FBT, rear brake torque: RBT

FBT / (FBT + RBT) = .7

One equation, two unknowns...how do we solve it? The astute reader will notice that the equation above is insensitive to multiplying both FBT and RBT by the same constant factor (say multiply everything by 1.5) -- this amounts to either scaling up the rotor size on each end by that factor, or scaling the piston areas on each end by that factor.

Let's constrain the piston areas so that the TOTAL piston area is the same as 300ZX front brakes + stock rear brakes (this is probably the limit where you'd get too mushy a pedal if the total piston area gets any bigger)

So we have:front piston area + rear piston area = 6545 + 2312 = 8857

let's solve for the rear piston area and we'll use that to eliminate the rear brake bias term in the previous equation.

rear piston area = 8857 - front piston area

and remember our equation for brake torque is:

brake torque = effective piston area x effective radius

first let's rearrange the brake bias relation to solve for FBT:FBT = 2.33 x RBT

plugging in for FBT and RBT (and assuming a 50mm pad width):(front piston area x 273) = 2.33 x ( (8857 - front piston area) x 259.7)

front piston area = 6103

or, front piston diameter = 39.06mm (1.54")

now we can find the rear piston area = 8857 - 6103 = 2754

or, rear piston diameter = 26.24mm (1.033")

Of course, you can't get calipers with just whatever piston sizes you want, so you'll have to juggle available piston sizes, rotor sizes, etc, etc to determine what will work. For instance...the combination above won't work because the piston sizes are too small (nobody I know of makes a caliper with 1" pistons), for example. Conclusion: In this case, you either allow the overall piston area to increase, thus likely requiring the use of a bigger master cylinder for proper brake feel, or you can leave the rear brakes alone and recalculate for just a front big-brake upgrade that would give the proper brake bias.

Wow, I hope I got all the math right.

Ok, now try it yourself! It's fun, I swear!

Asad

[IanS]

they don't do anything breaking wise.... but they keep heat down, and weigh less....

Wrong, and you wrong. Learn some physics. brakes are nothing more than a heat sink.

Convert kinetic energy into heat. That means mass is required unless the braking can dissipate the heat as fast as it is produced (Carbon/carbon braking).

Cross drilled rotor more look than actual performance.

Every single Porsche GT3 cup car (save for the "entry level) comes with slotted rotors or solid. Cross drilled is not even an option and for good reason. Under those specific circumstances. The mass reduction of the cross drilled rotors will actually make the brakes fail quicker than a full face/slotted face rotor.

[jr_ss]

You don't need the Z32 BMC.... Stock is just fine for just the front conversion. If you plan on doing the whole Z32 brake swap f&r then you'll need to upgrade to it.. My stock auto MC and BB work quite well with the front calipers...

FYI, adding larger wheels/tires increases rolling weight, therefore, bigger/better brakes are needed more. I upgraded mine because the 18's were taking a noticable amount of foot pressure to slow my car.

[Dittoz7]

I Think They Look Cool...I Want Them.

[hbpignosePA]

what are your power goals?

turbo or no?

if N/A is ur choice (and even if low boost is what you are looking for)

go with q45s

they clear stock rollers (nice to have a set of stock wheels for inspection/ or winter tires)

15s clear them if ur not baller and want 18s

they are cheaper and certainly enough for a street car

[Pento240sx]

So what you nico members mean, is that it will be the same thing to have stock brakes, to having 300ZX brakes right? Why waste 200 dollards on what you could get with your stock brakes right?

[hbpignosePA]

no its nice if ur modifying your car to do brakes and suspension, i just think z32s are a bit overkill for a street driven car

[Pento240sx]

Every single Porsche GT3 cup car (save for the "entry level) comes with slotted rotors or solid. Cross drilled is not even an option and for good reason. Under those specific circumstances. The mass reduction of the cross drilled rotors will actually make the brakes fail quicker than a full face/slotted face rotor.

So your telling me that, slotted face rotors work a little bit better than any kind of rotors

[jr_ss]

no its nice if ur modifying your car to do brakes and suspension, i just think z32s are a bit overkill for a street driven car

I'm going to correct your statement...

They are overkill if you plan on keeping it lightly modified, such as intake and exhaust on the KA. If you plan on a motor swap, or even boosting the KA, you should upgrade your brakes. Just because it's a street driven car, does not mean it doesn't need bigger brakes. There are plenty street driven cars out there with gobs of power that need and can take advantage of larger brakes.

Z32 brakes are by no means anything close to factory s13/s14 brakes. They are 4piston calipers w/ 11in rotors, designed to stop a car that weighs 4-500 pounds more than ours given the platform oreintation.

Use your judgement, I personally vote, suspension first then brakes if you are looking to improve on the handling of the car... Then again my opinions are biased, because I'm rocking more power, bigger wheels and Z32 brakes...

Spend the money the way you want to, it's your cash, not anyone elses... Just don't rice out the car...

[hbpignosePA]

did u see my above post?

if its street driven and boosted i would still go the q45 route...

still have 11 in rotors, still designed for a car that is 500+ the s chassis

AND u dont have to worry about as many wheel fitment problems

if ur not over 250 HP i think its overkill and way too much stopping power, when u would be just as satisfied w grippy tires and 2 pistons

[The Inflicted]

Q45 brakes are a very worthwhile upgarde. I've got a pair on my S14 and only paid $50 for both rotors and calipers. The calipers still had good pads left in them, too!

Not sure how they compare to Z32 brakes but I can tell you that they're much more confident than the stock brakes I had, and you don't have to upgrade anything else in the system.

[IanS]

So your telling me that, slotted face rotors work a little bit better than any kind of rotors

Slotted rotors help scrape away pad glaze, so the brakes tend to fade less, they also help eject hot gasses adding to this effect.

If you are going with Z brakes, you dont need anything but solid rotors. Cost/benefit ratio just doesn't add up.

If you stick with stock brakes, get some good quality (read Hawk/Ferodo) pads, some slotted rotors, and some braided steel lines. Bleed the system with Dot 4 or Dot 5.1 brake fluid, and you will have more than enough braking potential to handle anything but the heaviest of track duties.

I think Z32s are overkill for a street car. Once my current set of Hawk pads wears out, I will be switching to Q45s.

[Pento240sx]

I think Z32s are overkill for a street car. Once my current set of Hawk pads wears out, I will be switching to Q45s.

Well I think im going to go with the Q45 brake upgrade, did a little research and I liked the way the Q45 brakes turn out and how you don't have to do as much as the Z32 brakes, so tomorrow im going to a junkyards trip to see if I find some brakes. Wish me luck nico members.

[jessetang]

I always wonder if changing to a larger rotor means better stopping power since the rotor is bigger, meaning more stopping power? The contact area between the pad and the rotor is still the same, but since the pad has moved outward, meaning more stopping power.

Of course, this is just my thinking.

[IanS]

I always wonder if changing to a larger rotor means better stopping power since the rotor is bigger, meaning more stopping power? The contact area between the pad and the rotor is still the same, but since the pad has moved outward, meaning more stopping power.

Of course, this is just my thinking.

You are correct, because the contact area of the pad on the rotor has moved further from the center of the hub, it has more functional torque. This does not mean it has more stopping power though, it means it will take less hydrolic force to do the same job. Also as I said before, the larger rotor has more mass, meaning it can absorb more heat.

[i240sx]

You don't need the Z32 BMC.... Stock is just fine for just the front conversion. If you plan on doing the whole Z32 brake swap f&r then you'll need to upgrade to it.. My stock auto MC and BB work quite well with the front calipers...

FYI, adding larger wheels/tires increases rolling weight, therefore, bigger/better brakes are needed more. I upgraded mine because the 18's were taking a noticable amount of foot pressure to slow my car.

so if a 240 is an automatic you don't need to change the BMC, it will work great with just z32 front brake????

[Tulsa_S-13]

so if a 240 is an automatic you don't need to change the BMC, it will work great with just z32 front brake????

That is correct. I'm correctly running Z32 fronts and S13 rears with automatic brake booster and S13 brake master cylinder. Pedal feel is great, probably a little more bias up front then needed, but the setup feels much better then the stockers.

[i240sx]

That is correct. I'm correctly running Z32 fronts and S13 rears with automatic brake booster and S13 brake master cylinder. Pedal feel is great, probably a little more bias up front then needed, but the setup feels much better then the stockers.

so how do you know if you have an auto brake booster..do you mean like auto transmission come with auto brake booster...if not correct me..
Modified by i240sx at 12:45 PM 8/22/2008

[CRIPES]

Q45 brakes are a very worthwhile upgarde. I've got a pair on my S14 and only paid $50 for both rotors and calipers. The calipers still had good pads left in them, too!

Not sure how they compare to Z32 brakes but I can tell you that they're much more confident than the stock brakes I had, and you don't have to upgrade anything else in the system.

i've got J30's on my 98 kouki and they're wayyy more than enough

[jr_ss]

so how do you know if you have an auto brake booster..do you mean like auto transmission come with auto brake booster...if not correct me..

Modified by i240sx at 12:45 PM 8/22/2008

If your car was an automatic at one period in it's life, it has or rather should have the auto brake booster. The automatic trans cars had a larger brake booster to accomodate the increase in weight (auto trans is heavier than the man trans).

[Pento240sx]

Is it true what I read, that the cross drilled rotors start to crack after a while.

[IanS]

Is it true what I read, that the cross drilled rotors start to crack after a while.

Yes, they will crack sooner or later.