LittleBlueGT Posted August 3, 2006 Share Posted August 3, 2006 BTW the Ferrodo DS 2500 pads are desgined for street-autoX use. They have other pads for track use. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
PGT Posted September 1, 2006 Share Posted September 1, 2006 trying to find the info for '06 WRX rear calipers. Lighter than the LGT ones and possibly larger pistons....they use the same rotor. Could be a good upgrade for those with BBK's. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted September 1, 2006 Share Posted September 1, 2006 trying to find the info for '06 WRX rear calipers. Lighter than the LGT ones and possibly larger pistons....they use the same rotor. Could be a good upgrade for those with BBK's. Good idea, switching a little bit of bias to the rear again. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
PGT Posted September 1, 2006 Share Posted September 1, 2006 38.1mm is the piston size. Now, the Q is whether they are a straight bolt on. Would be interesting to try it out. I'd like to get black ones....though some red ones and a rattle can of hi-temp gloss black is ok too Link to comment Share on other sites More sharing options...
PGT Posted September 1, 2006 Share Posted September 1, 2006 actually, the brake guru has told me it's a fixed design, so not much improvement over the single floating LGT design. Lighter and cooler looking is about it. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted September 1, 2006 Share Posted September 1, 2006 it's a fixed design, why is that not an improvement? Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
PGT Posted September 1, 2006 Share Posted September 1, 2006 I'm not a brake guru, but that's what Ken from K&S/wrxbrakes.com just told me single piston/floating = 2 piston fixed for brake bias calculations. 2piston is more responsive and less prone to fade, but that's academic on rear brakes. Link to comment Share on other sites More sharing options...
LittleBlueGT Posted September 1, 2006 Share Posted September 1, 2006 I'm not a brake guru, but that's what Ken from K&S/wrxbrakes.com just told me single piston/floating = 2 piston fixed for brake bias calculations. 2piston is more responsive and less prone to fade, but that's academic on rear brakes. He is right, but more responsive, less weight, and less fade are all good things. So what about bias, is it same as OEM or does it shift some to the rear. Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
PGT Posted September 1, 2006 Share Posted September 1, 2006 same Link to comment Share on other sites More sharing options...
praedet Posted September 1, 2006 Author Share Posted September 1, 2006 Yeah, it is the exact same. I thought someone already tried to mount those calipers and said they weren't a straight install... Ted Link to comment Share on other sites More sharing options...
Waxiboy Posted September 4, 2006 Share Posted September 4, 2006 either Hovied or Opie mentioned that they are not a direct fit. Link to comment Share on other sites More sharing options...
zildjiank Posted January 4, 2007 Share Posted January 4, 2007 So according to your calculations Praedet, the Rotora 4pot front and 2pot (69.9/30.1%) rear are just about close enough to where the biasing should be for our the Legacy (70/30 being your recommendation)? What pad mu is that using??? Thanks for the info you've posted here...because of it, I've been having second thoughts about putting a BBK on the legacy that was specifically designed for another car ie- STI, WRX etc... I talked to Stoptech today, and I was advised NOT to buy a kit made for the WRX, as the piston sizing was drastically smaller than what they recommend...and the STI sizing was 2mm bigger than the WRX kit, but also 2 mm smaller than what they made their LGT specific kit, therefore it wasn't recommended to do that either, because of the biasing situation that you have posted up here (too much front bias)... If I PM you the piston sizing on the Stoptech kit, can you calculate out for me the bias they have on their kit for the Legacy? Link to comment Share on other sites More sharing options...
praedet Posted January 4, 2007 Author Share Posted January 4, 2007 I will PM you back, but the problem is that Stoptech does not release any of their specs, so I can't calculate anything for their brakes... All biasing calculations are done with an equal front and rear pad Mu... Ted Link to comment Share on other sites More sharing options...
praedet Posted January 8, 2007 Author Share Posted January 8, 2007 I updated most set-ups to include calculations if you use the Racing Brake 316mm modified rear shown here... I also added the biasing info for the Legacy GT Specific Stoptech 332mm Front BBK Ted Link to comment Share on other sites More sharing options...
edmundu Posted February 7, 2007 Share Posted February 7, 2007 Hey Ted, Using this calculator, shows the Brembo F&R setup actually improving the rear bias. And by just using the front Brembo's w/stock rears, is when you create more front bias. In driving with this setup, I feel the rear brakes grabbing more. You can actually feel the rear pulling down a bit harder. I previously had just the fronts, then both the F&R, and then also various pad combo's, along with ss lines. I think that the formula used to calculate the number's omitted a critical value, in the radial pad height. This determines the actual swept area of the braking system, and can shift how the brake bias moves. The Stoptech referenced formula has no provision for this, and assumes all brakes will have proportionately equal pad heights. Not true. The STI Brembo's are one of the largest production brake pads in the world, if this didn't matter then brake manufacturer's would use smaller pads, less cost, space, weight. Link to comment Share on other sites More sharing options...
praedet Posted February 7, 2007 Author Share Posted February 7, 2007 The pad height does not affect the actual force the brakes exert because only the piston has fluid behind it. But, a larger pad means that the force is spread out so you don't wear down pad's as quickly. For racing, that is what you want for sure! In actually, the higher radial height can hurt the total torque of the set-up because that meas the pistons might be closer to the hub, so the moment arm is smaller. The rear STi set-up actually moves the bias more forward because of the MUCH smaller pistons. What you might be feeling is the more rear bias due to stiffer suspension that doesn't allow for as much dive... Ted Link to comment Share on other sites More sharing options...
whitetiger Posted February 7, 2007 Share Posted February 7, 2007 I havent read through this entire thread but has anyone done calculations for bias with stock fron rotors and calipers and the rear RB BBK that uses the stock rear calipers but uses larger rotors(same diameter as the front rotors actually)? Link to comment Share on other sites More sharing options...
LittleBlueGT Posted February 7, 2007 Share Posted February 7, 2007 The pad height does not affect the actual force the brakes exert because only the piston has fluid behind it. But, a larger pad means that the force is spread out so you don't wear down pad's as quickly. For racing, that is what you want for sure! In actually, the higher radial height can hurt the total torque of the set-up because that meas the pistons might be closer to the hub, so the moment arm is smaller. The rear STi set-up actually moves the bias more forward because of the MUCH smaller pistons. What you might be feeling is the more rear bias due to stiffer suspension that doesn't allow for as much dive... Ted I have a brake fetish, that's why I love you! Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
praedet Posted February 7, 2007 Author Share Posted February 7, 2007 I actually have the calcs up on the first page for every Front Brake set-up with the RB 316x18mm stock caliper rear set-up. Just noted it in the initial post. My Set-up as of this Friday will be Stock front with the rear RB kit, so 70.2/29.8 bias Link to comment Share on other sites More sharing options...
edmundu Posted February 7, 2007 Share Posted February 7, 2007 The pad height does not affect the actual force the brakes exert because only the piston has fluid behind it. But, a larger pad means that the force is spread out so you don't wear down pad's as quickly. For racing, that is what you want for sure! In actually, the higher radial height can hurt the total torque of the set-up because that meas the pistons might be closer to the hub, so the moment arm is smaller. The rear STi set-up actually moves the bias more forward because of the MUCH smaller pistons. What you might be feeling is the more rear bias due to stiffer suspension that doesn't allow for as much dive... Ted I respectfully disagree. The pads have alot to do with braking capability. If they didn't then you would only need to increase piston size. Which in of itself will only allow a higher pinching point, but put thru the same size pads, and it results in almost identical braking. Except the larger psitoned caliper's will be able to lock up the wheel that much easier. There's a reason why swept area has everything to do with pad size & rotor size, and not with piston size. A cars ultimate braking capability lies within the whole package, and basing that solely on piston area and rotor size isn't telling the whole story. I have had a few of the mentioned combo's, and the addition of the rear brembo's, clearly gave more bias to the rear. It was felt in the seat, by the additional pulling from the rear. Link to comment Share on other sites More sharing options...
praedet Posted February 7, 2007 Author Share Posted February 7, 2007 Talk to Stoptech and AP then Link to comment Share on other sites More sharing options...
LittleBlueGT Posted March 7, 2007 Share Posted March 7, 2007 Installed KW2 coil-overs. 400/400 spring rates (note much stiffer then OEM especially in the front) Stock rotors, SS lines, Bobcat pads on all 4. I have an ABS defeat switch. Before coil-over install the car was too front-biased. Easy for me to discern this with ABS defeat engaged. After coil-overs install the car is ever so slightly too rear-biased. I will be getting AP BBK with ferrodo 2500 street pads, but keeping my same rear set-up. Depending on the real (not advertised) difference in mu between the bobcats and Ferrodo pads I wonder if this will change my bias even more to the rear. Once I get my BBK on I will have to select a rear pad that gives me the appropriate bias. Any suggestions? Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
praedet Posted March 7, 2007 Author Share Posted March 7, 2007 SS-Ms... How does it act w/ abs? Any hint that the rear is locking up first? My setup w/ KWs is going to be VERY rear biased based on your observations Ted Link to comment Share on other sites More sharing options...
LittleBlueGT Posted March 7, 2007 Share Posted March 7, 2007 SS-Ms... How does it act w/ abs? Any hint that the rear is locking up first? My setup w/ KWs is going to be VERY rear biased based on your observations Ted Even with ABS it can hint at it when I drive on pure ice (which was the last 3 days on the highway recently). The car needs to be slightly front biased mechanically to be safe, I knew that, but now know it for sure! Full tune of 68HTA, KSTech 73 MAF, Racer X FMIC and ID1000s................by the DataLog Mafia!!! Link to comment Share on other sites More sharing options...
praedet Posted April 18, 2007 Author Share Posted April 18, 2007 The Front and Rear Legacy Stoptech Kit w/ an upgraded suspension is very close to full lock-up front and rear at the same time. I found this out during bed-in while braking in a slight turn.... If it had been too rear-biased, I would have swapped ends. Too front biased and I would not have continued slowing down at the same rate as the rear lightened and started to swing No ABS intrussion during the above maneuver Ted Link to comment Share on other sites More sharing options...
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