Wilwood Dynapro 6 Piston Calipers
 

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?

From google.

http://www.wilwood.com/Images/Calipe...ount-cm-lg.jpg

http://www.wilwood.com/Images/Calipe...ount-cm-lg.jpg

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

Pretty small difference.

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?

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

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 shit?

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.

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).

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 fuck it and get the 4 pistons in the rear.

Does anyone have any experience with the 6 pots?

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

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 fuck 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.

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

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

^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.

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.

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!!

He is full of shit. 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.

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

I CAN'T WAIT UNTIL LEMONS :yippee:

He's full of shit 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.

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.

Wut. Everyone in this thread told you not to.

True. But nobody really explained it in detail. Anyone can tell you whatever they want but unless it's broken down for you, it's hard to believe what they say. I mean, afterall, it's the fucking internet. It's hard to believe what people say. But, in the end, I called FM today and changed the order to just the DP4 up front and the stock calipers in the rear with the sport rotors. Sure it might not be as pretty, but it doesn't fucking matter when it comes down to squeezing out the best lap time. Now I have 800 more dollars to put into power upgrades once I figure out exactly what I want to do.

So Andrew takes the time to write up a detailed explanation for you, you only listen to his advice, then you go and order from FM instead of him? I wouldn't expect much more advice to come your way.

OK man... wat? Here are some quotes from this thread:

They told you the same things I was told when I was thinking to go with 6-pots... except with even less detail. I ended up with dynalites (dynapros weren't as common then) and I am happy with them, though bling of 6 pots is awesome.

Ah, no. You'll notice that he bought the BBK before Andrew really dropped the knowledge.

I had already ordered the kit before he posted.
That picture from google addresses the dimensions of the calipers and the other post doesn't address my question about balancing my brake bias with a 6 pot up front. Sure people gave me advice, but Andrew's post was really the only one that addressed my question...

For the sake of thoroughness in this thread, I'll add that the DP6 is a much bigger pain to change pads in: pads can only be loaded/unloaded from the bottom (so must be removed from bracket to change pads) and the two slider pins, while easy enough to pull if you know what you're doing (pocket screwdriver works well) are way more troublesome than the simple W clip on the DP4 or a standard bridge bolt on the ST42.

Completely agree with everything you've noted about DP4 vs. DP6 except for this only because as a blanket statement it is not completely accurate - it depends on which DP4 we're talking about. The ~10% greater pad volume of the DP6 vs. DP4 lug mount translates almost linearly to ~10% longer pad life. There IS more pad life here. But, that difference may be less than 1 full track day on a high power car and therefore not a dramatic enough difference to make a case for that caliper especially with other variables in the mix. But "no improvement" is completely true if the DP6 is compared to the DP4 radial (or ST42 for that matter) because the DP6 has less pad volume, making those other 4pot options the lighter and longer lasting choices.

Interesting, I was under the impression that the DP6 was the same as the DP4 as far as changing pads goes. I'm glad I wound up going with the DP4 over the DP6, I don't know what I was thinking when I ordered the stage 2 kit.

Emphasis mine. Yes, 10% longer life, but most people aren't willing to stretch the pad life to the point where that would make an appreciable difference. Actually getting that extra 10% out will mean measuring pad depth after nearly every session, and it may even mean swapping pads at lunch or mid-weekend, something most people aren't willing to do. So in practice, for most people, 10% can be effectively rounded down to zero.

Agreed

In your defense, I can say that Nick was a bad influence on you: he spent most of that weekend at Thunderhill brainwashing you with his American Iron "Bigger is Always Better" mentality!

I'd say you would still get 10% more regardless. Because with what you're saying, is it sounds like you're assuming one would get every last lap out of the DP4 pads but change the DP6s out when they get close to being done. In that case, they'd have about the same life. But if you change out both pads when they have say 3mm left or if you change both out when they get as close to the end as you're willing to push it, you'll still be getting 10% more from the DP6. I know this is worded horribly, but I can't really express what i'm trying to say over the internet.
Yeah Nick was a bad influence :nono:

Two friends, both with Miatas. They do track days together. They probably do other stuff together, but this is a family-friendly post, so we'll overlook their implied extracurriculars.

One friend has DP6s, the other has DP4s. The friend with DP6s gets 10% better pad life.

Both friends are getting ready for their next track day. They've got their Hoosiers (for the track day bro), they've got their sunscreen, they've got lube for the hotel the night before. Both friends decide to check their pads. The friend with DP4s notices that his pads are 80% worn, down to just 1.8mm. He decides to install fresh pads, because going to the track with 1.8mm of pad is ill-advised.

The friend with DP6s, eager to display his dominance, checks his pads, expecting to benefit from his 10% better pad life. His pads are worn down to 2.52mm, or 10% less than his friend with the DP4s. (DP4s wore 7.2mm total, DP6s wore 6.48mm total). He.....also decides to install fresh pads, because going to the track with 2.52mm of pad material is ill-advised.

In the real world, 10% just isn't enough better to make a difference. :party:

That's a valid point. Also, lube is for pussies. Tell them to man up.

That's my boy!

I blame his mother...

Huh, that is nice to know my radial mounts have big pads. They also fit under 15x7 avanti storms with sticky wheel weights and no spacer.

Nice. I saw a post about the BBK fitting under 15x8 RPF1s but it looks too close to allow sticky weights.

If you have an interest in maximizing pad life you need to swap sides of the pads after every stint anyway with same sized pistons (to work against tapered wear).
In that scenario you change pad when they are done, and 3mm thicker pad means 3mm more to wear down before change.

With the fast (w) clip this adds about one minute per wheel inspection.
I'm probably stupid for doing this but when the taper is visible after 15min, why not add the routine (which also makes you look at the pads regularly).

For endurance it's a big difference if pads live 0.8 or 1.2 race.
But if the difference is 1.4 and 1.8 race it doesn't matter (you will start on new pads regardless to skip swapping).

That's actually a good point, especially since you typically have at least an hour to kill between each session.

Wilwood didn't answer me when I asked if this could be done, so it's good to hear of someone doing it. I've been tearing up even their H compound pads for too long but now Savington has pointed me at Hawk DTC 60s which will hopefully last longer and not overheat in the last 25% of a long stop.