R33, New Brake Upgrade Idea

[hardsteppa]

so I've been running the GK Tech front caliper adapters and 324mm GTR discs for a while now and great upgrade, no issues with them, but...always on the lookout for bigger and better. I'm thinking along the lines of, I believe the r32, s14 etc use a 280mm disc and r33 uses 296mm, so if you used the adapters for the r32/s14 but on the R33 instead, it would space the caliper out far enough to fit a 340mm disc. There's a VW disc which is 340mm, 30mm thick, 5 hole (although I don't know the spacing yet), the height is a little off and the centre hole is the wrong size....so not perfect but mayyybe could be worked to fit. An Audi disc which is similar story with the specs. Another option is using an open centre disc and getting some centres made up to fit to the skyline hub, although this might not turn out right first go and would then be at the point cost-wise of just buying a D2 or similar kit.

Anyone have any thoughts or suggestions on this, or experimented with anything similar?

[GeeDog]

Running the same as you - GKTech spacers & GTR disks with GTST calipers, and they work pretty well. I think the VW & Audi rotors will have a different stud pattern. Anyone used the dual caliper brackets on ebay - sounds like an interesting idea but not sure how effective they would be.

[niZmO_Man]

Just throw an ATTKD or D2 kit on.

[hardsteppa]

Just throw an ATTKD or D2 kit on.

No. I'll tell you why. I like the build quality of the OEM Sumitomo calipers so would rather keep them. The GK Tech adapters are solid as a rock and cheap, so I would rather use them. A set of standard discs for VW's etc are only a few hundred bucks, machining at a local engineers 'should' be less than $150. So I can potentially get a solid, quality 340mm brake kit for under $500, and how much are your chinese 356mm brake kits, $2000?

I saw Holford Motors have already made an r33 2-piece rotor, but only using 324mm discs. Asked them about using the same hats but with a 340mm disc, he said couldn't see any issue with it but they're not keen to make any more brake kits, pity.

[GTSBoy]

I think I recall touting your OP idea back when you & I were having a bitch fight over the wisdom of using the adapters on R33 calipers. I'm pretty sure I said that spacing the R33 calipers out with the better designed R32 spacers would be a nicer option. With one exception. The larger the disc gets the more sketchy the contact of the pads on the rotor gets, and potentially the worse the grinding of the caliper material required (which was the core item in the bitch fight).

But, ignoring that concern, I would take your OP idea and raise the ante one notch. Don't restrict yourself to R33 calipers. The R34 calipers buy you another 14mm of rotor diameter, taking you right up into the same range as the 355 brake kits. Because you're using an adapter, you don't have to drill the car to take the bigger bolts. You just drill the adapter. Providing the contact pattern and caliper material removal issues don't become insurmountable, you'd be onto an even better setup for roughly the same price (caliper wise) and there might even be a wider range of rotors available if you're lucky.

[R31Nismoid]

How is the factory Sumitomo calliper better in quality to the Monobloc D2/ATTKD stuff, exactly?

[MrStabby]

How is the factory Sumitomo calliper better in quality to the Monobloc D2/ATTKD stuff, exactly?

And who cares on the relative quality anyway, if the D2/ATTKD etc stuff has been bashed up for many years by many SAUers and been found to be well up to it?

[hardsteppa]

How is the factory Sumitomo calliper better in quality to the Monobloc D2/ATTKD stuff, exactly?

I don't recall saying anything about which is better of the 2; that's something you've made an assumption about. I've never seen them firsthand, or had any experience with them to say. I consider the factory calipers a good unit though and I already have a set, so why would a pay the extra $$$ for new calipers? I just want the stopping power of a bigger disc, which I know from the 324mm upgrade, is enough to make a substantial braking improvement.

I think I recall touting your OP idea back when you & I were having a bitch fight over the wisdom of using the adapters on R33 calipers. I'm pretty sure I said that spacing the R33 calipers out with the better designed R32 spacers would be a nicer option. With one exception. The larger the disc gets the more sketchy the contact of the pads on the rotor gets, and potentially the worse the grinding of the caliper material required (which was the core item in the bitch fight).

But, ignoring that concern, I would take your OP idea and raise the ante one notch. Don't restrict yourself to R33 calipers. The R34 calipers buy you another 14mm of rotor diameter, taking you right up into the same range as the 355 brake kits. Because you're using an adapter, you don't have to drill the car to take the bigger bolts. You just drill the adapter. Providing the contact pattern and caliper material removal issues don't become insurmountable, you'd be onto an even better setup for roughly the same price (caliper wise) and there might even be a wider range of rotors available if you're lucky.

this is true, although it would still mean finding/buying R34 calipers which is an extra cost to the idea. I'd also think the pad overhang or grind the caliper further will be a bit more of a consideration with a 340mm disc, going 30mm bigger to a 354 disc will really be pushing it there.

[R31Nismoid]

A larger disc won't give you stopping power. That comes down to piston surface area on the calipers themselves. You are simply altering the heat dissipation capacity, which means you can brake more times before fade.

Some detailed testing can be found here:

http://zeckhausen.com/Testing_Brakes.htm

Yes its probably Stoptech sponsored but if you look at the 350Z Track vs Street model test results with different rotors/caliper between the two there is only marginal stopping performance but the key point is the HEAT differential is massive and that's from the rotor differences, not the caliper.

[_Wing_]

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.

Edited July 11, 2015 by _Wing_

[Trex]

A larger disc won't give you stopping power. That comes down to piston surface area on the calipers themselves. You are simply altering the heat dissipation capacity, which means you can brake more times before fade.

Some detailed testing can be found here:

http://zeckhausen.com/Testing_Brakes.htm

Yes its probably Stoptech sponsored but if you look at the 350Z Track vs Street model test results with different rotors/caliper between the two there is only marginal stopping performance but the key point is the HEAT differential is massive and that's from the rotor differences, not the caliper.

The calliper will have more leverage on a larger rotor.

[hardsteppa]

A larger disc won't give you stopping power. That comes down to piston surface area on the calipers themselves. You are simply altering the heat dissipation capacity, which means you can brake more times before fade. .

well if it isn't 'the assumer'. A larger disc will give more stopping power, increase in braking leverage as above. If you actually read through the other info on the stoptech website it will tell that. If increasing the rotor size didn't change the stopping power then you could whack a massive rotor on the rear and leave the front unchanged, and it wouldn't affect the brake bias, and that's just not true now is it.

More importantly, it gives you more control through the brake pedal travel, which is a much bigger consideration in 'performance' rather than what can be achieved when pushing flat-out on the brake pedal, for my circumstance at least.

the key point is the HEAT differential is massive and that's from the rotor differences, not the caliper.

so from that, in your words I'd see a performance increase from just increasing the rotor size, and still keeping the stock calipers.

[hardsteppa]

Wings, you're right, the extra grinding is a concern; while I think that fitting the 340mm discs can be done (spoke to DBA thru the week and they are in the process of releasing a 340mmX30mm rotor, so would just need to get some hats machined up to suit) but the idea will go on the back-burner for the moment, other projects going on which are a priority. It would also be a bit of $$ to outlay for something that might not turn out 'ideal', so will just keep it on the drawing board for the time being.

[R31Nismoid]

well if it isn't 'the assumer'. A larger disc will give more stopping power, increase in braking leverage as above. If you actually read through the other info on the stoptech website it will tell that. If increasing the rotor size didn't change the stopping power then you could whack a massive rotor on the rear and leave the front unchanged, and it wouldn't affect the brake bias, and that's just not true now is it.

More importantly, it gives you more control through the brake pedal travel, which is a much bigger consideration in 'performance' rather than what can be achieved when pushing flat-out on the brake pedal, for my circumstance at least.

so from that, in your words I'd see a performance increase from just increasing the rotor size, and still keeping the stock calipers.

Yes I realise the leverage will change. Have you actually done any force calculations on it though to see just how much? Answer is likely, of course not.

[FBRacing]

so I've been running the GK Tech front caliper adapters and 324mm GTR discs for a while now and great upgrade, no issues with them, but...always on the lookout for bigger and better. I'm thinking along the lines of, I believe the r32, s14 etc use a 280mm disc and r33 uses 296mm, so if you used the adapters for the r32/s14 but on the R33 instead, it would space the caliper out far enough to fit a 340mm disc. There's a VW disc which is 340mm, 30mm thick, 5 hole (although I don't know the spacing yet), the height is a little off and the centre hole is the wrong size....so not perfect but mayyybe could be worked to fit. An Audi disc which is similar story with the specs. Another option is using an open centre disc and getting some centres made up to fit to the skyline hub, although this might not turn out right first go and would then be at the point cost-wise of just buying a D2 or similar kit.

Anyone have any thoughts or suggestions on this, or experimented with anything similar?

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. Have you changed out the master cylinder? 15/16 to 1" or bigger? Changing the master cylinder greatly increases pedal feel but also can be too much at the same time. Braided lines to reduce line surge? Or is this an effort to fill in your wheels more? The Akebono 370z calipers would suit your needs better than the Sumitomo R33 to fit over larger rotors. From there you can fit the 355mm rotors and maintain maximum pad contact without trimming the crucial material from the caliper. Just my suggestion.

[hardsteppa]

Yes I realise the leverage will change. Have you actually done any force calculations on it though to see just how much? Answer is likely, of course not.

Another negative contribution, honestly, how'd you get to be an administrator, they handing that out for free in Bourke St mall one day or something? And now you're saying yes there will be an increase in stopping power through leverage, despite you previously saying a bigger rotor alone would give no increase in stopping power?? Jeez mate that's 3 for 3, not doing so well there now are you buddy?

As for doing mathematicals on it, what am I, a Formula 1 racing team?? Next you'll be claiming it's not worthwhile unless I have them made out of carbon fibre or I'll just be adding extra weight. Calculations, yeah mate I put A to the power of the K and came up with a square root of your mum.

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. Have you changed out the master cylinder? 15/16 to 1" or bigger? Changing the master cylinder greatly increases pedal feel but also can be too much at the same time. Braided lines to reduce line surge? Or is this an effort to fill in your wheels more? The Akebono 370z calipers would suit your needs better than the Sumitomo R33 to fit over larger rotors. From there you can fit the 355mm rotors and maintain maximum pad contact without trimming the crucial material from the caliper. Just my suggestion.

FBRacing thanks for your input, it's appreciated when people contribute something useful, even if it's disagreeing with my ideas and theories. You're right of course about can be too much brake, I don't think I'll have that worry only increasing to a 340mm rotor, by my calculations this will give a 4.9% increase in braking torque from the current 324mm rotors, so a little bit but not huge. If I was going to swap out to different calipers, and bigger rotors that won't fit under my current 17in rims then I'll be looking at a much higher cost, in which case I would look to one of the off-the-shelf upgrades that has been tried and tested. The idea behind what I had proposed originally was to get as much 'brake' as I could on a budget, preferably under $800.

[FBRacing]

I didn't completely understand what you are trying to achieve. This is the first time you mentioning you're retaining 17" wheels. With this in mind this is what I suggest. Retaining the stock Sumitomo caliper from the R33. Going back to the original 296x30 rotor size but in a better material and drilled/slotted. Use a matching pad that compliments the rotor. Largest mistake people make is mismatching pad to rotor. Do a complete brake fluid flush and bring it up to DOT5 to raise your boiling point. Change all rubber lines to steel braided. Your cooling temps would dramatically increase, stopping power increase, and a term in F1 racing that is called brake spring to come down to a minimum. You could also utilize duct work from your front bumper and aim it to the rotors if you're really heating them up that quickly. Believe me or not, the 296x30 rotor is an exceptionally large rotor for the size and weight of a R33. If you do the work yourself and shop for prices, you'll be under your $800 budget and have better braking power than trying to go larger. I see a lot of shitty brake upgrades these days and makes me scratch my head.

Also, you seem like the person that even if a mechanical engineer that specializes in brakes would suggest on what you should do when you ask for their advice, you'd be hard headed enough to say you're wrong cause it goes against your theories or ideas. Not everyone on here is fresh out of high school. There's a great deal of people who have been around the block more than a few times that have experienced what you're going through. Trust me, you're not the first one to try to do a "budget" big brake kit. I hope you find what you're after.

[R31Nismoid]

Another negative contribution, honestly, how'd you get to be an administrator, they handing that out for free in Bourke St mall one day or something? And now you're saying yes there will be an increase in stopping power through leverage, despite you previously saying a bigger rotor alone would give no increase in stopping power?? Jeez mate that's 3 for 3, not doing so well there now are you buddy?

As for doing mathematicals on it, what am I, a Formula 1 racing team?? Next you'll be claiming it's not worthwhile unless I have them made out of carbon fibre or I'll just be adding extra weight. Calculations, yeah mate I put A to the power of the K and came up with a square root of your mum.

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.

[Anfanee]

man the idea of people fiddling with brake kits so much is worrying.

Get a set of decent rotors and pads made to suit the standard brakes and job done.

PMU pads and rotors are not that expensive.

[hardsteppa]

Going back to the original 296x30 rotor size but in a better material and drilled/slotted.

Also, you seem like the person that even if a mechanical engineer that specializes in brakes would suggest on what you should do when you ask for their advice, you'd be hard headed enough to say you're wrong cause it goes against your theories or ideas. Not everyone on here is fresh out of high school. There's a great deal of people who have been around the block more than a few times that have experienced what you're going through. Trust me, you're not the first one to try to do a "budget" big brake kit. I hope you find what you're after.

once again thank you for your input, and thank you for taking the time to write a detailed post. What would you see as the disadvantages of keeping the 324mm instead of reverting back to the stock 296mm rotor?

Also hard headed, well maybe. I do consider I take onboard any opinion or advice that would seem to have merit, and use such information in forming my own opinions on something. I certainly wouldn't say I just accept it straight up as absolute, without considering it's source and validity; one would be just as foolish to do that, as if one were to disregard it outright and not taking information from other sources into consideration at all.