Legionnaire

Just thinking out loud here - could it possibly be that calipers are incorrectly centered on rotors? I mean, axial offset might cause that. One pad touches rotor prior to the other, and therefore gives that mushy feel at the beginning pad engagement and longer than expected travel, and when opposite pad engages - solid deceleration.

By TC light you mean "slip" light I'm thinking? GTSBoy is correct, it's there so that Nissan could unify dashboard diagnostic and indication circuitry. It's meaning as an indicator is different depending on model though - on GT-t's it blinks when traction control kicks in, on GT Fours it blinks when TCU detects inequality of wheel speeds and engages ATTESA.

wait... you have traction control BUTTON?? In ENR34?? What happens after you press it?

Did you look at bosch.com.au website? Their catalogues say they have all 3 bosch compounds available for skylines (I assume you're talking about sumitomo calipers) - Ultra, Qikstop and Eco. Part numbers for quickstops intended for sumitomo calipers appear to be 0 986 AB4 258 for front and 0 986 AB4 269 for rear pads.

cobrAA, about your initial question - there was a thread on V36/Z34 akebonos some time ago, some info has been posted there. Akebonos, while not bad, don't make a very good upgrade for R32-34 skylines IMO because of lug mounts, uncommon pad shape and weird caliper construction, in that it uses narrow pad, but requires wide annulus rotors. There also was some unfavourable feedback about their use on track, can't remember where I've seen it exactly though. But if you're after similar upgrade, I have a couple ideas for you: you can use Z34 rotors - bolt right on to your hub, 355x32mm - and get yourself some OE brembo calipers with radial mounts. Your options include Audi R8 rear calipers - 4 piston brembos, 2x(38+42)mm pistons, radially mounted, take super-common brembo f40 pad shape, run on 356x32mm rotors. Other option, Gen III dodge viper calipers, 4 piston brembos front and rear, front 40+44mm pistons, rear 38+42mm pistons, all four run on 355x32mm rotors, radial mounts, take F40 brembo pad. Can be bought off American ebay for reasonable price. There are other similar options out there, but those I think are the most suitable ones. I'd suggest 38+42mm pistons, they are a bit smaller than your current factory GTR brembos, so your m/cylinder will be fine, and increased leverage from the bigger Z34 rotor will compensate for slightly lower piston area, so you won't need upgraded rears. This approach basically gives you everything you asked for - quality OEM calipers, parts for caliper repair are easy to find and cheap, readily available and relatively cheap OEM rotors that fit without modifications, and pads available in almost any compound you can think of. You'd only need to make caliper adapters, since calipers have radial mounts that won't be a problem.

I'm not questioning your knowledge, but I fail to see how with _incresed clamping force_ I have decreased stopping power. Or, to be more precise, what does travel of pistons have to do with force they generate, because very little force is produced while they travel and majority of force is generated when there is no travel left and pistons push pads against rotor face. True, using same M/cyl as before we'll have to displace more fluid to make pads contact rotor surface (increased pedal travel), on tandem m/cyl this may result in rear pads making rotor contact earlier that front pads, but once pistons are displaced and pad-rotor conact is established, a caliper with pistons larger than factory - like the one mentioned above - will result in more stopping power (braking torque) due to increased hydraulic ratio and fluid incompressibility (sp?). Or do you mean the situation when m/cyl runs out of travel and "bottoms out" because of excessive front piston area and therefore insufficient fluid capacity to move all pistons out far enough? In that case - I agree with you, there will be almost no front braking at all.

I would strongly advise against this upgrade - SRT8 calipers (300C, grand cherokee, charger, challenger, whatever) have some ridiculous construction - they are basically 2 x two piston modules bolted to a sliding caliper bracket, with only one bolt per each end of a twin-piston module (talk about caliper stiffness)! This link will also give you an idea about their construction. Since they are el-cheapo 3-piece calipers with steel brackets, no one ever bothered to make differential pistons - that would have introduced the necessity to separate left modules from right ones which would be too expensive and time-consuming to assemble, so all pistons are of the same diameter, and they are HUGE. 4x44mm pistons, that gives gigantic piston area of 60.82sq.cm (sumitomos are 51.28sq.cm), you'll never be able to balance them with rears, car will be heavily front-biased, constantly overbraking front wheels and stopping distances are likely to be increased. Same calipers can be observed on non-AMG W221 merc S-class without performance brake package, so the most performance-oriented chrysler caliper is the most basic merc one. Pad is also of pretty unique shape, so the choice of pad compounds may be somewhat limited

If you want alloy caliper and also run 280x30mm rotor, then you should pick R32 GTS-t/GTS-4 caliper.

or you can use 1-mm thick titanium shims under pads - you'll have both correct piston reach and good heat insulation. Or use different rotors

Mine had diagonally cut silver pieces too (R33 GTS-t brakes), apparently this plate profile helps with vibrations somehow, I've seen exactly same thing done to STI and some euro cars' backplates, so your kit is the correct one

How did you figure out that 370Z has 320mm rotors? If that's correct, it should be equipped with sliding calipers. If Akebono calipers aren't modified on that Z (like cut/rewelded lugs) then there will be no trouble with putting them on your car.

About rears - that's not as easy a question as it might look, there are two different p/n's for 4wd R33 rear rotors and it has something to do with production date - what is yours? Diameter and thickness may be different. If you have pre-01.96 model, then they are same as S13, 266x9mm, and should be fairly easy to find. If yours is post-01.96, then things get slightly more complicated, e.g. I couldn't find one for a sensible price, and diameter is also unclear, but they are cross-referenced as a replacement for A31 cefiro and C33 laurel rotors. Are your rear rotors vented or solid?

First of all - do you know piston sizes of the calipers? They may be useless for you. Second - you can always buy them and let them lie on a shelf while you're getting yourself all necessary components, including rear upgrade, a bargain is still a bargain. Not an option if you want a quick solution though.

Yep, he uses OE replacement rotors off W163 Merc ML, so if you find rotors locally, you can save money on delivery and order brackets only. Rotors will have to be modified - mounting redrilled to 5x114.3 and hub hole extended to 68mm.

A few general tips on what to look for: 1)you'll unlikely find something that would bolt straight up to the hub, so look for calipers that have radial mount holes (parallel to rotor surface), not axial mounts. This makes adapters much easier and cheaper to fabricate 2)look for calipers that take common and readily available pad shape. There is no point in buying a set of calipers and then discover that you have to order a set of pads from the only place that sells them half the earth away, and you need to sell your kidney to buy them and wait for a couple of months for delivery. 3)look for calipers that has variety of pad compounds available for it. This is not exactly same as previous point, because not all common pad shapes have high-performance pads available. And vice versa - not all common pad shapes are available in street compounds. 4)look out for pad friction patch (also known as radial depth, pad swept area, annulus, etc), as a pad too wide/too narrow/oddly shaped can limit your selection of rotors big time 5)look out for rotor thickness and diameter that calipers are intended for. This can also limit your rotor options or effectively make your brake "upgrade" an actual downgrade, say when you buy beautiful calipers that take rotor only 16mm thick 6)calipers should be common enough (or use internals that are common) to be easily rebuildable/refurbishable. Calipers that cost, say, 2k new, can be found for 500 in average or poor shape, but will perform just like new when you throw two $50 rebuild kits at them Well, those are the gudelines. And try to do lots of reading and develop general understanding for brakes, so you could understand what you really need and why, and tell whether a particular set of calipers is suitable for you. SAU contains wealth of knowledge on the topic, but is not the only source of info.

You don't necessarily have to spend 8-10K on the brakes in order to have nice calipers and good braking, you just have to do a bit of research and think outside the box a little. E.g. a set of rear calipers off an Audi R8 would make a good upgrade for the fronts - just an example.

330mm nissan rotor 334mm toyota/lexus rotor 334mm vw golf R32 two-piece rotor (offset is very little though) 340mm audi tt-s rotor 345mm merc rotor 345mm audi rotor (3 different offsets) make up your mind

Depends on what result you're really after. If higher brake torque and faster deceleration is what you desire, then starting with rotor size is a poor approach. If you enjoy the look of massive and shiny chunk of cast iron behind the rims, then it's a good way (not as good as two piece rotors, but still not bad), but keep wheel size and offset considerations in mind. If you want both, then you're in for big buck expenditure

Remsa's aren't exactly used on all euro sport cars, brands like Pagid, Textar, Mintex and Brembo are used. "Remsa are approved as a replacement pad for most euro sport cars" would be a more correct statement. With that said, they are a good pad, inexpensive, quiet, performs well, throw relatively low amounts of dust and has wide temp range.

You would't want to - they weight a tonne each (I think it's mass is close to 14kg, but can measure when I have time), offest is wrong for most wheel designs, and they require 18" wheels. Also you can use smaller rotors and get just as good braking as with these - cooling and pads with higher friction are your friends. There is a guy here who races his R32 with R34GTT calipers and factory-sized rotors. Other than that - yes, as per GTSBoy's post, caliper adapters are needed. 280->324mm adapters might work, and you'll 100% have to file the edges of your calipers to make them sit lower on the rotor, see attach

or stock pads

If you intend to do a brake upgrade later on, then take size of your possible future rotors into account, that's basically the only thing that affects rim size other than looks

A convenient way to measure brake bias would be as simple as a pair of manometers, one connected to the front and other to the rear brake circuit. This method won't tell you anything about brake torque though, so if you're after torque, then that would have to be some kind of dyno. Bias on our cars, even with valve described above, is not constant, that's the idea behind proportioning. The harder you brake, the more the f/r pressure inequality and more front bias you get. To confirm this you can do several easy calculations. Let's once again look at BNR32 prop valve, 20x0.4. Pressure in kgf/sq.cm, rear pressure is calculated as per formula above, [line pressure - knee pressure] * ratio + knee pressure front pressure___rear pressure__bias front/rear ___10__________10__________50/50 ___20__________20__________50/50 ___30__________24__________56/44 ___40__________28__________59/41 ___50__________32__________61/39 ___60__________36__________62.5/37.5 ___70__________40__________64/36 ___80__________44__________64.5/35.5 ___90__________48__________65.2/34.8 __100__________52__________65.8/34.2 ... __150__________72__________67.6/32.4 ... and so on. Some cars have proportioning valve that changes knee point according to weight, so they get different bias for different weight distribution, yes, but reduction ratio remains constant. Nissan 4x4's have variable knee and 0.18 reduction if I'm not mistaken.

Exactly, knee point is adjustable in a certain range, but reduction ratio after that point (steepness of slope on your graph) is fixed - in this case it's 66.6%, or to be more precise, 1:3. This is Tilton graph by the way, with 1:3 reduction, or __x0.33 in Nissan terms. The following info is for those who are interested in knowing how proportioning actually works and why it's needed, or can't grasp at all what we're on about here. Car has to have its braking front biased, mainly because of weight transfer during deceleration. The weight gets transferred to the front, forcing tyres against the road and allowing more deceleration to be realized through increased grip. That's why front brakes are often stated to do most of the braking job, which is true up to a point. Of course this weight doesn't come from nowhere, it's removed from the rear axle, so rear tyres have lower grip under brakes and therefore less potential for stopping the car. Those are the basics, and are described very nicely on stoptech website. How much weight is transferred exactly - that depends on a lot of things, car weight and CoG, suspension stiffness, tyre grip, etc. Car manufacturers know all these parameters and spend thousands of hours test driving their cars and optimizing brake bias. They draw several graphs in the process, e.g. for a fully loaded car and for a car with only driver inside. One of the good examples of such graphs is attached, pic no. 1. It's a great pic and it's very useful for further explaination. Notice that there is a range of desired f/r brake pressure ratios depending on car load. OEMs often target the lower curve, as it implies more front bias (more safety and stability), and try to tune factory fitted prop valves so that they closely approximate the lower curve. How they tune brake bias exactly? Most modern cars, and almost all nissans manufactured after ~2002 are equipped with electronic brake force distribution, and therefore have no mechanical bias valves, they rely on electronics to get the job done. It's actually a good thing, because they can follow ideal curves much closer and can compensate for more input factors and external conditions. That's also why modern ABS and EBD usually work together and are controlled by a single ECU. Our cars are much simpler than that though, so we have mechanical bias valves, which is much worse that EBD, but is still much better than no proportioning at all. Most of mechanical prop valves have a drilled piston and a spring inside, see attached pix. On pics no. 2 and 3 the piston is black, on the fourth it's gold in color. Brake fluid flow is not restricted when the piston is floating freely on the spring. But when line pressure is high enough, it overcomes spring resistance and forces piston against its seat. From this point on fluid travels only though the hole in the piston, so pressure after (downstream of) the piston rises slower than in front of it. Pressure at which piston shuts its circuit is usually called "knee point". Spring stiffness determines knee point (at which it changes rate of pressure increase), while hole diameter determines reduction ratio after knee point (determines rate of pressure increase). This method of pressure reduction gives us only two straight lines to work with, and two straights are actually a pretty poor way to approximate a curve, but it's still approximates it better than only one straight line Now to the numbers. Nissan FSMs usually have info about proportioning, often in BR section, subsection Service Data and Specifications. They look like a pair of numbers. First number is knee point in kPa (psi, kgf/sq.cm), second number is reduction ratio, or reduction multiplier, which is applied above knee pressure. The calculations that determine line pressures after knee point are pretty simple and are applicable to any prop valve that uses same reduction principle. Let's take BNR32 as an example. It has 20 kgf/sq.cm or 284 psi x 0.4 prop valve. This means that up to 20 kg's line pressures in front and rear circuits are identical. Above that point rear line pressure rises at lower rate than front pressure, rear pressure rise is 0.4 times front pressure. So if line pressure is 10 kg, then front pressure is 10 kg, rear is also 10 kg; if line presure is 40 kg, front circuit receives full 40 kg, rear pressure is [40-20] x 0.4 + 20 = 28 kg. All the pressure above knee point, 20 kg in this example, is reduced by some factor, 0.4 in this case. Adjustable prop valves allow knee point adjustment, but reduction ratio remains unchanged. Some of the valves are continuously variable inside certain range, others have preset points as can be seen on the graph in badhairdave's post. The problem with Tilton valve, which has 0.33 reduction ratio, is that if I adjust it to have factory knee point of 20 kg, I might end up with lower than factory rear pressure everywhere, so I'll either need larger rear brakes (pads with higher CoF, bigger pistons, bigger rotors), or softer suspension, or accept underperforming rear brakes and increased stopping distances. If I increase knee pressure to, say, 28 kg, I may get rear lock-up at light braking because of increased rear bias at low pressures, but still underperforming rears at heavy braking with line pressures above 95kg. With higher than desirable reduction ratio the situation is reversed - underperforming rears at light stops and tail-happy car at heavy braking if knee point has been chosen incorrectly. I know of readily available valves with several different ratios, but I would like to know factory ratio as I want to calculate bias vs. line pressure curve that is considered optimal for the car by Nissan, and want to engineer my future brake upgrade from there.

Thanks for the tip, I agree, it is a solution, however all external prop valves that I'm aware of only Tilton publish thier reduction ratio - it's 0.33 (67% reduction); Wilwood is not so clear, they state "Maximum reduction of 57%", but don't clarify whether this value is constant of not, don't state knee point adjustment range and have no graphs to refer to. I might contact their tech department to find out. Factory Nissan in-built prop valves on Z-, R-, and S-chassis (and many others) almost always use 0.4 ratio (60% reduction), except for S15, which uses much higher 80% reduction, but very different knee points for different chassis, with Silvias having the highest knee at 40kgf, and GTR32 having the lowest at 20kgf. Unfortunately I couldn't find full FSM for R33 and R34 in english (or any other language for that matter) that would contain such info, and driving an R34 I'm a bit concerned as to whether they used reduction ratio similar to S15 or kept original 60% reduction. Porsches of different generations use at least 5 different prop valves, they are external to BMC and ABS, non-adjustable in-line type, all have 0.46 reduction ratio, have 5 different knee points (18, 33, 45, 55, 60 bar) and cost very reasonably. I might try one of those. The idea behind the question is to figure out what brake bias is considered optimal by Nissan themselves, make some calculations and tables/graphs and to try to work from there.