6 piston vs 4 piston with fixed rotor design

[luc]

Oh yeah. Between the 200+ less pounds over the front wheels and the 6-piston Brembos with manhole-sized rotors, the HPP has way more braking than you will ever need short of a track day. I suppose that’s not the worst thing to have on the street!

Also, the Brembos are super-cranky when cold. Loud grunts and groans until some heat builds up in the rotors, which takes some time due to the aggressive venting and brake cooling ramps in the underbelly tray.

The stoping power is unbelievable.

The “crankiness “ has nothing to do with the calipers or rotors. It’s the pads, more specifically the optimum temperature range that those pads are designed to work at
Ford tried to have a pads that cover a wide range and therefore it was/is an exercise in compromise

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[FordMustacheGT]

Is the extra weight and rotational inertia worth it

I did not notice any perceptible change in driving dynamics (outside of braking performance) when I upgraded my 4-piston brakes to 6 piston brakes.

Is there a reason why you are concerned about extra weight/rotational inertia?

I don't have any experience with the revised 4-piston rotors, but additional mass and rotational inertia of the brake setup would not be one of the main determining factors that I would personally use to make this decision. Especially since the 6-piston brake setup has generally been proven to be an effective brake setup for track use.

 

[CobaltFilly]

I did not notice any perceptible change in driving dynamics (outside of braking performance) when I upgraded my 4-piston brakes to 6 piston brakes.

Is there a reason why you are concerned about extra weight/rotational inertia?

I don't have any experience with the revised 4-piston rotors, but additional mass and rotational inertia of the brake setup would not be one of the main determining factors that I would personally use to make this decision. Especially since the 6-piston brake setup has generally been proven to be an effective brake setup for track use.

This.

6 for tracking the car/I have money to spend on looks (DM me if looking for a cheap[er] Brembo PP1 set brand new, I found a place to buy them and will link you the site).
4 for street/cost savings/canyon enjoyment.

 

[shogun32]

I found a place to buy them and will link you

Do tell

 

[PaddyPrix]

How do the 4 piston stock GT calipers fare on track with just a pad and fluid upgrade I wonder?

@TrueBlue22 I absolutely believe it. "Even" the 4 piston calipers (every car i've ever owned only has 1 or 2 pistons) will put your head through the windshield with ease.

I hate being Mr. "it depends", but a lot of it, from at least my experience, has to do with the track you're on, how fast you go, and most importantly, how much speed you need to shed in the braking zones and how often you need to do so.

I don't know where the bar separates working from not-working, but let's assume we're all about 4000lbs with driver, fuel, etc. At my home track (ACS) Joe Average in a GT is entering T1 at 120-150 and needing to get to about 40, so shedding 80+ mph, which will happen another 2 times 120-40 for T9, and 120-40 for T12. Stock car, stock pads, I blew right through that, and thankfully it's a Roval so I just went further down the NASCAR oval than I should have and brought shame to my family name. I came back the next week with G-LOC R12's and Motul RBF600, and could last a few more laps, but same result on lap 4-5, blowing right through a turn and thankfully escaping without damage/injury by luck, but still an issue on very high speed tracks.

Not to be a total failure though, as that combination seemed to be fine at another track (Buttonwillow) which is more of a momentum track with more brake zones but requiring much less braking effort, shedding 30 to maybe 50mph at most. If that was my local track, I'd probably say I've never had a problem with the 4pots and pad/fluid upgrades, because for that profile, it works just enough to not be a problem. I have yet to AutoX but from what I've seen, runs are mostly in 2nd so maxxing out what, 80-90(?) and guessing avg turns to be 30-40mph which sound like the 2nd track profile. That's probably why you see AutoX people saying they're fine on 4pots, as their runs are maybe a minute, whereas tracking will be multiple laps over a 15-20 minute session.

If from some combination you've added power, better tires, shedding weight, drive better, you'd then expect to enter brake zones at higher speeds, and have more to shed, which probably puts you in the 6 pot camp. Thinking safety first, if you're borderline there and thinking about it, it's still a fairly good safety investment as it isn't really all that expensive when you find the part numbers to the calipers, rotors, and pads, I did it for under $1k a few years back from my local dealership parts dept and ebay. Calipers and Rotors are about 200-250 each, and get yourself a set of stainless lines too.

That should be good for most, but also be aware that the non-PP crowd have a few other things to consider, as the PP1 has a little air deflector to scoop and swoop air in, and the splitter tray has ducting/ramps that flow into those deflectors. They also have a different part number for the brake booster and master cylinder with slightly larger diameters, but that's an issue for much later.


* I assume no responsibility, I mean just look at all my sizzurps and uzis.

 

[Walt]

I did not notice any perceptible change in driving dynamics (outside of braking performance) when I upgraded my 4-piston brakes to 6 piston brakes.

Is there a reason why you are concerned about extra weight/rotational inertia?

I don't have any experience with the revised 4-piston rotors, but additional mass and rotational inertia of the brake setup would not be one of the main determining factors that I would personally use to make this decision. Especially since the 6-piston brake setup has generally been proven to be an effective brake setup for track use.

Because it affects acceleration and overall handling, for that reason people spend thousands on lightweight rims and 2 piece rotors. The Ecoboost isn't already the most powerful car so I'm just not sure if the downsides are worth the extra braking performance.

Though I have no experience with this and not sure if I would even feel the difference, just something I've been told by people saying that BBK aren't always worth it if you don't need it.

I think I'll probably end up with the 6 pistons anyway, maybe I'll try once more with the fixed rotor design and go from there.

 

[luc]

Because it affects acceleration and overall handling, for that reason people spend thousands on lightweight rims and 2 piece rotors. The Ecoboost isn't already the most powerful car so I'm just not sure if the downsides are worth the extra braking performance.

Though I have no experience with this and not sure if I would even feel the difference, just something I've been told by people saying that BBK aren't always worth it if you don't need it.

I think I'll probably end up with the 6 pistons anyway, maybe I'll try once more with the fixed rotor design and go from there.

?????..nothing is ever worth it if you don’t need it……
People that spend thousands on lightweight wheels and 2 pieces rotor are either doing it for show/look or they competitively track their cars
In which categories, if any, do you fit in ?

 

[Walt]

?????..nothing is ever worth it if you don’t need it……
People that spend thousands on lightweight wheels and 2 pieces rotor are either doing it for show/look or they competitively track their cars
In which categories, if any, do you fit in ?

Well that's what I'm trying to decide here. I'm hoping for opinions of those that have done the same. I did blew through the stock brakes but I have not tried better pads and proper cooling yet. Since I'm replacing all rotors and pads now I was thinking why not upgrade to 6 piston all together but maybe others have got the 4 pot setup working that could chime in here. It's not about the cost it's more about the other factors like extra rotating mass. Don't know how much of a problem that even is, I'm hoping to find out here.

 

[luc]

Well that's what I'm trying to decide here. I'm hoping for opinions of those that have done the same. I did blew through the stock brakes but I have not tried better pads and proper cooling yet. Since I'm replacing all rotors and pads now I was thinking why not upgrade to 6 piston all together but maybe others have got the 4 pot setup working that could chime in here. It's not about the cost it's more about the other factors like extra rotating mass. Don't know how much of a problem that even is, I'm hoping to find out here.

The brembo are obviously better but it’s part of a package with larger and heavier rotors that consequently have more thermal mass and extra cooling with air diverter on the lower control arms and special air ducts/channels in the under tray
What make the most difference is pads. Get a set of “normal “ rotors and some real track pads. No street pads that will overheat and fade after a couple of laps on tracks
If that doesn’t work, you can always upgrade to the 6 pistons but you will still need to address cooling

 

[Buldawg76]

After researching front rotors for my 4 pot GT calipers I found that the change from wheel side cooling veins to hub side cooling veins on our mustangs was before 2-3-2020 were wheel side cooling and after 2-3-2020 they were hub side cooling veins so my base brake eco with a build date of 12-8-2020 has hub side cooling veins on the 2 piston calipers already with 13 inch rotors. On rock auto you have to search closely since the wheel side cooling rotors are still being sold for the 4 piston calipers along with the hub side cooling 4 piston rotors, double check part numbers and pics of rotors to ensure you get the right hub side cooling rotors.

Just an FYI.

BD

 

[paulm1]

I'm debating between upgrading to the 6 pistons or get rotors from a 2022+ model for my 4 pistons, that are apparently fixed by having the cooling veins on the proper side.

Is the extra weight and rotational inertia worth it for the 6 pistons (on an Ecoboost model)? I'm planning to combine either with a JLT brake hose kit for cooling.

You need to cool whatever brake pkg you go with. Upgrading to 6 piston will buy you a little more track time before you cook the brakes but you will be right back to where you started without cooling. Here's what I did, https://kennybrown.com/collections/...ront-brake-cooling-duct-kit-2015-2024-mustang I think I could have kept my stock brakes and been fine but I upgraded anyway.

 

[MrMike]

I'm debating between upgrading to the 6 pistons or get rotors from a 2022+ model for my 4 pistons, that are apparently fixed by having the cooling veins on the proper side.

Is the extra weight and rotational inertia worth it for the 6 pistons (on an Ecoboost model)? I'm planning to combine either with a JLT brake hose kit for cooling.

If you want better handling and better braking, you are going to add more weight to the front end no matter what. If you're concerned about money, get a set of take offs and/or PM Cobalt about where he found the 6-pot calipers cheap. If you're still concerned about weight after that, get lightweight wheels and 2-piece rotors.

I would get a set of air deflectors similar to what was linked in the thread instead of a brake hose cooling kit. They're easier to install and proven to be very effective.

 

[TeeLew]

Well that's what I'm trying to decide here. I'm hoping for opinions of those that have done the same. I did blew through the stock brakes but I have not tried better pads and proper cooling yet. Since I'm replacing all rotors and pads now I was thinking why not upgrade to 6 piston all together but maybe others have got the 4 pot setup working that could chime in here. It's not about the cost it's more about the other factors like extra rotating mass. Don't know how much of a problem that even is, I'm hoping to find out here.

First, any brakes will work if you don't use them.

Second, The 14" brakes are actually pretty big and pretty powerful. With correct ducting and standard venting, the disc temps shouldn't be an issue. The problem is these aren't the performance caliper for this application, so manufacturers don't offer good track compounds for the 4 piston caliper. EBC makes decent AutoX pads, but they won't put up with full track duty.

So you go to the bigger 6-pot caliper and 15" disc on the front. Now you have a significant amount more disc mass (which reduces the magnitude of disc temp swings), added a bunch of pad surface area, added a bunch of pad compound options, and reduced the workload on the whole system. If you're spending time on a track, this is really the best option.

Will it marginally slow acceleration? Yes, It will. Will it add unsprung mass? Yes, it will. Do I think any of this is perceptible? No. Do you need it anyway? It all depends on how hard you use them.

 

[NightmareMoon]

With enough cooling and the newer vented front rotors and very high temp pads you may be ok with the 4 pistons. You'll need keep great high temp track brake fluid in there too, because it will still be running hot.

I had the JLT ducts for a while, but TBH, they aren't that fun to remove/reinstall, and they get crunched easily between the tire and body if you're running wide tires. Not that fun, but its doable. Mine were a mangled mess by the time I removed them in favor of the Vorshal deflectors

I already had underbody air channels even larger than the PP ones, but I love the deflectors/belly pan combo. They're also completely maintenance free and I do think the brake cooling is better with ducts+deflectors than it was with the JLT hoses.

Terry at Vorshlag knows track cars and brake systems well. OTOH for dissenting opinion, one track guy did point out that the deflectors don't work that well for the outside wheel in a corner when its turned in, while hoses will work for that time. (they do work great on the straights after that) I think overall the the deflectors zero maintenance, work great, and easier to remove/replace if you need to pop them off for inspections.

With the 6 pistons or the 4 pistons, if you splurge and get two-piece rotors you can save some of that mass. The calipers themselves are not rotating mass, but they are unsprung. I wouldn't worry at all about the weight penalty of the larger brakes. The mass means thermal capacity, which is very much a big help for your issues.

Anyway its not a bad call to try the rotors and see if you can go up in temperature range in fluid and brake pads and see if its good enough, but the vented rotors really will work better with air supplied to them. Any air supply scheme you use will transfer over to the 6 pistons if you make that upgrade later.

 

[Walt]

I already had underbody air channels even larger than the PP ones, but I love the deflectors/belly pan combo. They're also completely maintenance free and I do think the brake cooling is better with ducts+deflectors than it was with the JLT hoses.

The perfect solution for me would also be running the deflectors, but that would mean getting a GT PP splitter and belly pan. Those shipped to me together with the deflectors, after tax and duty would be close to $1500. The hose kit is only $400. It unfortunately means changing back to the fog lights after every track day and removing everything for inspection.

Modifying the stock bellypan with ducts would still require me to purchase a secondary belly pan to pass inspection reliably without raising eyebrows and have them looking at the rest of my "OEM" looking mods.

Shipping costs for such large items are just ridiculous even though it weighs next to nothing.

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