ApexAddict

I'm looking into getting some 6 piston calipers for my Miata. I was wondering if anyone has issues with the Wilwood rotor hats. Goodwin racing was claiming that their 10 bolt rotor-to-hat design was more "consistent, reliable, and stable." Is this true? They make it seem like you shouldn't trust the Wilwood design but I have a hard time believing Wilwood would sacrifice our safety just to make a few extra bucks. What are your guys' thoughts?

aidandj

iTrader: (5)

From google.





On an 11.75" rotor you are looking at a .05" difference in radius

Pretty small difference.

ApexAddict

Right on, yeah I read that they fit under the same wheels as the DP4s. I'm interested in hearing about what people have to say about the 6 bolt rotor hats versus 8 bolt or 10 bolt designs. What's your opinion on running the Wilwood 6 bolt hat/rotors?

Savington

iTrader: (31)

6-bolt = 11", 8-bolt = 11.75. Everyone prefers the 11.75

ApexAddict

Ahh gotcha. So I was having a discussion with a gentleman about the BBK and he was saying that if you don't have the 4 piston calipers on the rear, you'll have to have a heavy bias on the rear to even it out which defeats the purpose of having the big rotors on the front due to lack of heat generated. Is this true or is he full of ****?

aidandj

iTrader: (5)

For one. You can't increase rear bias without going to a larger rear caliper.

2: IMO 6 piston calipers are already probably more than you need. The 4 piston properly sized for the Miata has worked well at may hp levels. 6 piston just adds weight.

acedeuce802

iTrader: (1)

He is somewhat correct. It is not advisable to do a 6 piston Wilwood in the front and leave the rears completely stock (depending on what stock is for you). The rear does need balanced out, though. The Miata is already front biased, and becomes even more front biased when putting good tires on it (I assume you'll have 200tw tires at least, if you're considering these brakes). If you make the front brakes stronger, the lockup force will be lower. But since the rear brakes have remained the same, you're now using less rear brake when the fronts lock.

I'm not sure how the balance works out with 6 piston fronts, but a good combo is 11.75" 4 piston front, and 11" sport rotor rear (whether you use sport caliper, or non-sport caliper spaced out).

ApexAddict

Yeah that's true, I'm aware the 6 pot is more than I need. I just want the life/heat capacity of the 6 pot, especially since it's only 250 bucks more than the 4 pot. Do they really add THAT much weight? I can't imagine they do.
Yes I'm running RE71rs with intentions of switching to NT01s by the end of the year. And if I were to go with the 6 pot, I'd definitely be going with the 10.9" sports in the rear. I'm curious if the 6 pot would work well with the sport rear or if I should just say **** it and get the 4 pistons in the rear.

Does anyone have any experience with the 6 pots?

aidandj

iTrader: (5)

Appears to be about 1.3lbs per corner + pad size weight.

ApexAddict

Oh wow, that's not TERRIBLE but definitely something to consider. I know I should be fine with 4 pot in the front and the 10.9" kit in the rear, but part of me just wants to say **** it and go all out. I just don't want to get 4 pot in the rear if I don't have to, although if I buy it with the kit I save 250 bucks.

aidandj

iTrader: (5)

Oh and fluid weight if you want to get ---- about it.

zellers88

iTrader: (1)

Why not go for the Superlites then? Or the new Stoptech kit.

thumpetto007

iTrader: (15)

^yeah. If you want to spend more than the wilwood radial mount, just buy the top of the line stoptech, and make everyone cry and wet their pants at the same time.

On a side note, I was surprised to find out that all the options for miata are fixed rotors. I would have expected floating rotors at those pricepoints.

Oh, and if you need a handbrake, stick with oem sports rear calipers. There are no aftermarket options that have any real world practicality. Unless you custom make a handbrake, I guess.

ApexAddict

I ended up going with the wilwood 6pot up front and 4 pot in the rear. I blame it on the combination of too many beers and peer pressure from my friends.

LanceMach

As soon as I read that last post, I knew this was you!! If your brakes arrive while you're out, don't get pissy if they end up on my car! Don't worry though - I'll let you drive it at Thunderhill...

PS I'm telling Shaun you stole his tagline

PPS Did I mention two and a half weeks to LEMONS!!

Savington

iTrader: (31)

He is full of ****. If you'd like more detail than that, I can provide, but that's the short answer.

The Miata is front-biased from the factory, same as every car on the planet (because lawyers). As you add sticky tires, the natural bias shifts rearwards, not forward as you said. The easiest way to see this is to take the "sticky tire" to its unnatural end, where the front tires have so much grip that the car actually does a stoppie at max braking G (i.e. rear tires are completely off the ground). At that point, you need massive front bias and very low rear bias, but since your brake bias is still as-delivered from the factory, the natural bias moves rearwards.

IOW, as you add mechanical braking grip, you need less rear brake.

The 6-pot doesn't provide substantially more heat capacity than a 4-pot, unless you're talking about the heatsink capacity of the caliper itself. The rotor makes the biggest difference. The pads in the standard DP6 are still 12mm, and the shape is largely similar to the DP4 shape.

Remember that a properly-spec'd 6-piston will have similar stopping power to the stock caliper or a 4-piston. All the Wilwood offerings use a 3.00" piston area, spread across either 4 or 6 pistons. The OEM caliper is a 1" bore, which gives an area of ~3.14". The OEM Sport caliper is ~3.55 (IIRC) and the Stoptech 38/36 option is somewhere in-between 3.14 and 3.55 IIRC (easy math to do for someone else).

The same is true in the rear - all the 4-piston options have the same bias as the stock 1-piston sliding caliper. You don't need to augment your 6-piston fronts with 4-piston rears, since the stock 1-piston rear provides the same or similar clamping force.

I do, from years and years ago. They had slightly better pedal feel, no measurable improvement in pad life, and dramatically higher running costs. I removed them after a handful of events and went back to my DL4s.

This is a good question.

Leafy

iTrader: (1)

I know, you would think the less drag on such low powered cars would make floating rotors all the rage for miatas.

ApexAddict

I CAN'T WAIT UNTIL LEMONS

Savington

iTrader: (31)

He's full of **** because he assumed that a 4-piston caliper will provide more bias than the OEM caliper. That's a fundamental misconception of how properly-designed BBKs work.

Then he makes it worse by claiming some crap about unused thermal capacity. Let's look closer at that. Let's say you have stock 1.6L brakes and you are having trouble with the fronts due to pad fade. The only solution is to go bigger, so you do. You buy the biggest, highest-bias BBK available, which would be a 36/38 Stoptech STR43 on an 11.75" rotor. You leave your rear brakes stock, then buy some pad combo that will actually produce proper bias (something like a full high-temp race pad in the rear and something made of foam or chewing gum in front). Physics dictates that because you have not changed the rate of deceleration (no tire change, no suspension change), the car is still generating the same amount of heat, and because you've altered the bias "properly", that heat is still being applied to the front and rear brakes in the same proportion as it was before. The only difference is that your front brakes aren't overheating, because you've substantially increased the thermal capacity of the rotor. The only way to produce LESS heat in the front brakes, as your friend claimed, is to increase rear bias beyond where it was before you added the BBK in the first place.

So dude makes a bad assumption, and then espouses some crap that wouldn't be correct even if his original assumption was correct (which it wasn't). If someone told me that story in real life, I would nod politely and never listen to another word they said.

Yes, you would have been fine with your 10.9" OEM Sport brakes. I assume you bought the FM Powerlite kit, which shifts bias slightly rearwards. That's not a bad thing, but the Powerlites are purely a weight reduction exercise. No Miata actually has thermal capacity issues in the rear, even with the stock un-vented rotor and stock caliper, so any change made should be in search of weight savings. Unless you are building a pointy-ended competition car, I wouldn't bother.

The only legitimate reason to select the 6-pot Dynapro is for the bling factor. I give the same spiel to everyone who calls asking about DP6s (they give similar pedal feel to the DP4, minimal additional thermal capacity, no improvement in pad life, added weight, more expensive pads, WAY more expensive calipers if you ever need to replace one). Almost everyone ends up with a DP4, or if they need the thermal capacity/life expectancy, the Superlites. The few who do select the DP6 after hearing my spiel counter with "I like the way they look and I'm OK with spending the extra money for the appearance", and that's 100% OK with me, because they do look pretty sweet.

ApexAddict

Damn it, I should've spoke with you before I pulled the trigger on this damn brake kit. You're basically the Bill Nye of motorsport right now.