R33, New Brake Upgrade Idea

[hardsteppa]

So you're basically taking a pot shot in the dark without any idea if you will actually get a gain, or not. You've truly got no idea and taking what is essentially a stab in the dark 'upgrade'.

You're obviously one of those people who is going to do it their way no matter what so carry on with it and stop posting about it.

come on man, come on....come on now.....come on. Seriously. Your first post in this thread came across as trying to pick an issue with me about calipers, on something I hadn't even said. Your further posts really didn't put forward any help either, poo-pooing a larger rotor as being any benefit, and then later even backtracking on that. I'm wasting my time explaining myself to you, but for what it's worth, it's not even the outright end result of it that it's all about, I like coming up with custom car projects, seeing what can be done and what will work. It's not something I'll spend 1000's on but a few hundred dollars, on something that could easily adapt to stock calipers? Sure, I'll look into it and see what can be done. Heaven forbid I post about it though and have my own ideas and not just blindly accept a 'no' to the idea from others. You'll also note Wing made a post above about how much would need to be ground from the caliper for a 340mm disc and it wouldn't be a good idea; did I just disagree with him and say, you don't know what you're talking about? No, I did not, I took his input on board, saw the validity of what he said and I do agree with it. I put it to you, it is YOU who are " one of those people who is going to do it their way no matter what ".

Anyway, I'm vented now...up to you, post what you want, but at least try to make it constructive to the topic if you do.

[FBRacing]

This completely is my opinion and what I see what works from my experience of being involved in racing for nearly 40 years and what I was taught from the generations before me from their racing experience. (I was born into a family of Motorsports enthusiasts)

If your pads are able to touch from top of rotor and as close to the hat as possible, you will have the best braking power possible. Once you go to a larger rotor and the caliper moves higher on the rotor, your braking force is reducing. You're not taking full advantage of the rotors capability. To gain true braking power utilizing a 340mm diameter rotor you'd have to use a caliper and pad combo that would bite on 95% of the rotor or more to be a worthy upgrade. Otherwise in my eyes and experience, you're filling up the wheel with unnecessary rotation mass and adding corner weight. I see it like adding chrome 20" spinning wheels and adding a carbon hood to say you're worried about weight.

Brake spring is a term I'm not sure if you understand but there is a point in the chassis that will act "springy" once you hard brake. Remember that these cars mounting points are simple stamped tin steel. It's the same concept of that of body flex around an apex hence people add chassis bars (i.e. tower bars and that alike).

So if you take in account of brake spring, unused rotor surface, increasing corner weight, and uneven wear to pads and rotors you end up taking several steps back in a performance and function stand point. If cosmetics supersedes function than you are on the right track. Don't get me wrong, it's great to see huge rotors filling up large wheels because frankly it's just funny looking to have all that empty space in there but I'm more a functional and practical type of gearhead. Probably why most of my projects never get past the body work stage with the exterior part. [emoji28]

So all in all, I'd personally find a suitable caliper or reduce rotor size while upgrading to drilled/slotted with matching pads. To me it's that simple.

[GTSBoy]

Totally ignores the concept of thermal mass and dissipation in braking, but nevermind.

[FBRacing]

Totally ignores the concept of thermal mass and dissipation in braking, but nevermind.

It's was kinda being implied by the drilled/slotted rotors

[FBRacing]

While eating dinner, I thought I should explain that the OP never mentioned he was going to track the car and with a $800 brake upgrade budget, that's why I suggested drilled/slotted rotors w/matching pads.

Drilled and slotted rotors do not decrease heat soak but increase it. Reducing rotor mass takes away the heat soaking properties. BUT.... If it's for a street car, this is ideal with this size of rotor. Rotors and also pads have a temperature in which they become most effective. These temps will be steady while driving on the streets but once on the track, rotor mass is what you want to dissipate heat at a higher rate. I could write a book on brakes and the science but that's for another time. [emoji57]

[FBRacing]

If you guys really care, here's a good publish on thermal properties on disc brakes. http://www.researchgate.net/publictopics.PublicPostFileLoader.html?id=528a549bd2fd64d9088b4641&key=9c960528a549bb5223

[GTSBoy]

Dude, you're talking to an engineer here whose professional work revolves around heat transfer.

Slotting does bugger all under any circumstances except to increase pad wear and make more money for the brake companies. Disc brakes worked really well for 50 years before slotting became all the rage. They don't work any better with slots than without, except where you have to clear something from the rotors like mud or mouse guts (ever driven over a mouse plague? If you haven't you'll never understand what I mean).

Your claim that brake temps will be more constant on the street than on the track ignores the two extreme, but rather common situations with street brake use. The first is that most of the time brakes are pretty well cold, meaning that you actually have to get some heat into them on any typical surprise brake application, especially if you have some decent pads in that require the temperature to work. The second is that the peak temperatures seen will probably be quite high if you do any sort of thrashing up and down hills. When you're coming down a long mountain road at 9/10ths your brakes get hot and they stay hot because you're leaning on them a large fraction of the time. When you're on a race track, you get major braking opportunities every 10-20 seconds. The brakes never get to cool all the way down and if you've got your rotor sizing big enough and your cooling air ducted to them, then they shouldn't go over the top of their working range. The range between max and min temps seen over a number of laps of a track shouldn't be as wide as the range between stone cold and max temperature seen on a street car's brakes, meaning that you're more likely to be in the pad compound's happy zone.

[FBRacing]

Dude, you're talking to an engineer here whose professional work revolves around heat transfer.

Slotting does bugger all under any circumstances except to increase pad wear and make more money for the brake companies. Disc brakes worked really well for 50 years before slotting became all the rage. They don't work any better with slots than without, except where you have to clear something from the rotors like mud or mouse guts (ever driven over a mouse plague? If you haven't you'll never understand what I mean).

Your claim that brake temps will be more constant on the street than on the track ignores the two extreme, but rather common situations with street brake use. The first is that most of the time brakes are pretty well cold, meaning that you actually have to get some heat into them on any typical surprise brake application, especially if you have some decent pads in that require the temperature to work. The second is that the peak temperatures seen will probably be quite high if you do any sort of thrashing up and down hills. When you're coming down a long mountain road at 9/10ths your brakes get hot and they stay hot because you're leaning on them a large fraction of the time. When you're on a race track, you get major braking opportunities every 10-20 seconds. The brakes never get to cool all the way down and if you've got your rotor sizing big enough and your cooling air ducted to them, then they shouldn't go over the top of their working range. The range between max and min temps seen over a number of laps of a track shouldn't be as wide as the range between stone cold and max temperature seen on a street car's brakes, meaning that you're more likely to be in the pad compound's happy zone.

I agree with ya except on one thing. Drilled rotors actually have a function. They let pad gases escape. The reason for slots is to help the pads not to glaze by aggressively wearing the pad surface. But with technology today, most pads but not all do not need drilled and slotted rotors. So to me, I'd rather change pads and pay that money for harder bite in a shorter amount of time. Otherwise you're 100% correct and I already knew you were an engineer. You and a few others are the only ones with factual science to their posts.

[hardsteppa]

You and a few others are the only ones with factual science to their posts.

GTSboy is a perfect example of what I referred to previously, about taking opinions of others onboard when making my own decision. He and I have butted heads over the years over various topics but I would always take his opinion into consideration to some degree because I do know he has the smarts to validate his position, even if I don't agree.

Speaking of which, GTSboy I'm guessing from the earlier post in this thread that you would consider a larger rotor worthwhile, on stock calipers, for a street-driven car, would that be right? if not going to a larger rotor, then at least just sticking with the 324mm?

[GTSBoy]

Yuh 324 buys you much more thermal mass, so there's your first positive. You also get the increase in brake torque for any given hydraulic application, thus increasing front bias. As most GTSts I've seen have plenty of rear brake, I can't imagine that pushing the bias forward by that much is going to make the car brake worse. I would certainly expect to benefit from it on my car, as it is prone to locking rears. I'm just not so much of a fan of grinding caliper material away, which is why I haven't done it. Although when my rotors are ready to be replaced in a year or so, I'll be faced with the decision too either piss or get off the pot.

[Duncan]

The thing I think has been missed in this thread is that there is absolutely no reason to upgrade the factory brakes for street use...they are excellent.

Like FBracing said, if you are actually having problems for street use at most you could do with some better pads and maybe bleed the fluid.

[GTSBoy]

Well there's street use and there's street use. I would agree where "street use" literally means driving around town. But if you flog it through the hills you can get them fairly hot. Admittedly, I've not ever cooked my brakes doing that, but then I don't drive anti-socially enough either.

[Roy]

As mentioned a larger rotor gives higher heat capacity and faster cooling with the larger surface area, and it also gives you more stopping power by way of a longer lever arm; more leverage. All good things to have for better brakes.

OPs idea is good but it get's to a point where too large a rotor means you have to grind away at the calipers. There's minimal material in that location to begin with:

Grind any more away and you might as well take out the bolts and use a 380mm rotor.

There is such a thing called too much brake. Too much and you'll lock up with ease once rotor and pad temps reach optimal.

Wing...you have A-O link in your sig. Are you the fella behind the EVO-Brembo kits? If so can you actually speak to the point FBRacing makes about over braking....having too much force when all you really want to achieve is sufficient cooling?

I ask as I have run way too many brakes and didnt like the F50 -355mm setup. I found the F50 was ok on a 324mm setup but not as good as the F40 setup. I currently run F40 sized 4 pot caliper on a 343mm and am trialling a smaller piston area again on a 343mm once I get the car back on the road.

I have still found the best caliper rotor setup that you can bolt onto a Skyline is the 6 pot AP CP5555 caliper. It is no accident that it runs less piston area than std and results in awesome modulation on cars with the std booster setup and no ABS.

The EVO Brembos with their 46 and 40mm pistons are huge and having experienced the feel difference from going from AP CP5555 to F50s on the same rotor size with similar pad...well, they had a lot more bite and far easier to lock. Though found they were still ok to modulate. Going from F50 with its 44/40 pistons to the EVO Brembo with 46/40 is a fairly big jump again on the front of a Nissan

If you are running 324mm in a 17" wheel I think its a no brainer to stick with what you have...and just optimise. I know my car was fine with those brakes for years and I kept going back to them after trialling various brake setups as they performed so well and in some cases worked better. I only gave up on them as the car has quite the appetite for front rotors as Sandown was hard on brakes so moved to a 343mm rotor with a better, more snug radial mount caliper to fit under my 17" wheels.

[FBRacing]

I just realized that Hardsteppa never disclosed what his cup of tea is. This for track, weekend warrior, daily? I have been placing my suggestions in thought of a daily driver with occasional light touge. Maybe the OP can shed some light on what he's aiming for and as a group be able to better suggest what could work for him.

[Michael's R33]

I got these work like crazy. I swear Ill never go back to standard brakes again lol

[_Wing_]

Wing...you have A-O link in your sig. Are you the fella behind the EVO-Brembo kits? If so can you actually speak to the point FBRacing makes about over braking....having too much force when all you really want to achieve is sufficient cooling?

I ask as I have run way too many brakes and didnt like the F50 -355mm setup. I found the F50 was ok on a 324mm setup but not as good as the F40 setup. I currently run F40 sized 4 pot caliper on a 343mm and am trialling a smaller piston area again on a 343mm once I get the car back on the road.

I have still found the best caliper rotor setup that you can bolt onto a Skyline is the 6 pot AP CP5555 caliper. It is no accident that it runs less piston area than std and results in awesome modulation on cars with the std booster setup and no ABS.

The EVO Brembos with their 46 and 40mm pistons are huge and having experienced the feel difference from going from AP CP5555 to F50s on the same rotor size with similar pad...well, they had a lot more bite and far easier to lock. Though found they were still ok to modulate. Going from F50 with its 44/40 pistons to the EVO Brembo with 46/40 is a fairly big jump again on the front of a Nissan

If you are running 324mm in a 17" wheel I think its a no brainer to stick with what you have...and just optimise. I know my car was fine with those brakes for years and I kept going back to them after trialling various brake setups as they performed so well and in some cases worked better. I only gave up on them as the car has quite the appetite for front rotors as Sandown was hard on brakes so moved to a 343mm rotor with a better, more snug radial mount caliper to fit under my 17" wheels.

In that regard I don’t believe it’s too much brake, that actually sounds like the opposite - too little brake and/or too aggressive of a pad / mu / coefficient of friction. With a smaller rotor you have less fine control over the locking and unlocking points, and with too aggressive of a pad or a mu that is all over the shop as heat rises you’re compounding the issue. That’s why I like Project Mu HC-CS pads as it’s coefficient of friction is super consistent:

They’ve graphed HC+ against HC-CS. Even though they are similar pads, they have quite different characteristics some of which cannot be graphed, so unless you’re running the exact same pad with the exact same friction area then it’s hard to pinpoint your issue with the lockup.

HC+ isn't even "bad", I mean imagine driving on pads like some of these, how are you meant to apply consistent braking?:

Modulation and feel are the things that can’t be quantified on a graph, however I think they are even more important than outright coefficient of friction & temp ratings. The bad thing, or good thing depending on how you look at it, is that it can only be learned through experience.

Here’s an example of Evo 350mm Brembo’s with standard Skyline 297mm rears (non Brembo).

This guy was lapping Wakefield Park raceway in 1.03 on Skyline non-Brembo brakes all around. He upgraded the fronts to Evo 350mm Brembo’s, keeping standard Skyline rears, and he dropped his lap time by 0.8-0.9 seconds for a best of 1.02. That makes him one of the fastest S-chassis’ at Wakefield Park.

[timmy_89]

I have been running the Alpha Omega Racing kit for the last few events I've competed at and have been extremely impressed, looking forward to fitting their soon to be released rear kit. Going from a stock setup with T3 rotors and upgraded pads to the Alpha Omega kit with the same pads made almost a 2 second difference to my times at Wakefield Park. I have actually just posted a review on the kit as I have had a few members asking me about them, I will post the link in my signature when it is posted

[Roy]

Dont mean to sound like a non believer but 2 seconds? Were you having fade issues with std setup? Were you running same tyres, susp alignment.... No improvement in driving? 2 seconds is a Huge gain and frankly never seen such an improvement unless original setup was a huge compromise with fade

[PranK]

I don't have much to add cause i'm a little dumb in this area. I love big brakes, I love how they feel and I love how they look, thats about the limit of my science.

I think theres been a little sway on whats on topic, I think OP had an idea only and wanted to discuss, I'm not sure there's a particular use case (street, "street" or track) or what other options are better. Please correct if I'm wrong, this is just a chat about a potential option.

Big VW discs are *likely* 5x112. Depends on the car though obvs.

[4zfed25]

I think standed brakes with good pads and rotors will take anything you can throw at it up to 300kw. My 33 has sloted f and drilled r rotors race pads f and stock pads r and idi 17 hot laps on Mansfield nz (1:23s) brake where putting off flames at the end of the straight the lot and where soled as a rock. Stoped due to oil temps. Thats my 2cents