Quote:
Originally Posted by imag
Basically everyone is asking us to trust them. That's fine, but it's different than most industries, where I can really research the products I want to buy. I'm not used to it.
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Me neither. But over the 20 years I've been in this industry I've learned that reputations mean something. They are hard earned and quickly lost. I have also come to understand that I'm buying an experience, not a product. It's a bit like the guy who goes into a home improvement store to buy a drill. He really wants holes, not the drill!
Just because I may reason that one product is slightly better than another, the service after the sale can trump small differences in product offering. All it takes is some bad experiences with a company to undo any perceived product advantage.
Quote:
Originally Posted by imag
One metric I referred to before that I would like to consider is weight. It obviously cannot be looked at in a vacuum, but it is a relevant data point, as we all realize the benefit of unsprung weight reduction. If each of the main BBKs are probably going to be fade-free for 30 minute sessions, lighter is better. I don't know if anyone has data on caliper/rotor weight for each of the BBKs, but it would be nice to have.
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AP5700 (
Front 6-piston kit with 362x32mm 2-piece disc) --
Caliper weight, unloaded: 7.3 lb. / 3.31 kg
Caliper weight, loaded w/pads: 10.4 lb / 4.72 kg
Pad area: 72.50 cm^2
Pad thickness: 16.8mm
Rotor weight, assembled: 20.3 lb. / 9.21 kg
Notes: This kit was developed to fit many 18" wheels for those who wish to have a larger selection of track tire compounds. The matching rear kit is strongly recommended for optimum mechanical and thermal brake bias.
AP3750 (
Rear 4-piston kit with 330x25.4mm 2-piece disc) --
Caliper weight, unloaded: 4.7 lb. / 2.13 kg
Caliper weight, loaded w/pads: 6.7 lb. / 3.04 kg
Pad area: 48.62 cm^2
Pad thickness: 16.0mm
Rotor weight, assembled: 22.8 lb. / 10.3 kg (iron hat for long-life parking brake function)
Approval and backing by the legendary, record-breaking driver Steve Millen: Included in all AP Racing BBKs at no extra charge!
A note about bolted vs. floating kits. In our experience in designing and building aftermarket upgrade brake systems since 1990, bolted disc assemblies should be used wherever possible. The maintenance-free nature of this type of assembly clearly trumps any advantage of a floating assembly for most users. Only when the thermal capacity of the system is being tested regularly should a floating system be considered.
One drawback of floating systems on street vehicles is lack of proper maintenance. Race teams have a crew of mechanics that perform regular maintenance schedules, which includes an intense amount of brake servicing. For the street, we all just like to bolt them on and forget them. Floating disc assemblies, while definitely having distinct thermal expansion advantages in the upper temperature ranges, tend to collect brake dust, road grime, salt, etc., in between the bobbins and the hat. If cleaned out regularly, this poses few problems. However, most owners aren't up for the extra maintenance (or, more likely, aren't told about it by whoever sold them the kit). But if left to build up, this debris can actually start to prevent the disc from floating -- only now its location is not controlled.
Example: We have seen drivers who have stated their system performs normally when warm, but there is a pronounced steering wheel judder when left overnight. After driving for a bit, thermal expansion of the warmer rotors allowed the parts to become free again. Once hot, parking the vehicle leaves the iron disc just slightly out of plane with respect to the aluminum hat. During cool down, the disc "sticks" in this position due to debris and dust. Once warm again, the disc frees up and all is back to normal.
I am
NOT saying this happens all the time with all floating kits! But I am saying it is an issue (like potential rattling sounds) that is entirely prevented when staying with a bolted disc assembly. Talk to anyone with an R35 GT-R who goes over speed bumps or into driveways and hears his car sound like someone bumped into a dishwasher full of large plates. The large discs on that car overpower the float springs and leave drivers sure they have suspension components loosening up!
My rule of thumb: Only go to a floating assembly when it is proven necessary. Several AP Racing systems are sold in a floating arrangement for such applications -- the G's and Z's haven't been two of them. We have done full-floating, dedicated track kits in the past and can continue to do so if the demand is there, but these are not really something most people want to live with on the street. You guys with dedicated track cars -- get in touch with us and we'll work something out. It's a little pricier, but you'll be glad you did.
A better solution? AP Racing's Strap Drive system is the best of both worlds. The disc and hat are free to expand as needed and move slightly relative to each other -- and there are no moving parts to rattle or trap debris. This system is limited in availability at the moment, but could find its way into more kits in 2010. If anyone is interested, that is...
Chris