abes Posted December 4, 2009 Share Posted December 4, 2009 I have an '83 280zx that I started having braking problems with recently. The brakes worked perfect before i made some changes. I replaced my stock brake pads with porterfield Rs4, Replaced my brake fluid with ATE Super Blue (dot4), resurfaced my disks, put new slotted front rotors and swapped out the stock rubber lines with stainless lines on all four corners. I bled the brakes and watched that the m/c never went empty. Drove it round for a while and noticed that It took alot more effort to stop the car than before. I put about 60 miles on it thinking that the pads needed to be broken in but nothing... I called porterfield ask their opinion and they recommended I drive it some more to put some additional break in miles.. 200 miles later nothing... I then re inspected, re-bled the system and noticed my rear pads aren't wearing through out the entire surface on the inside. The brakes need to pressed pretty hard to make a decent, sudden stop. It's also very difficult to lock them up, kind of fades to a stop. Here are some pics: REAR DISKS INSIDE (L) ® OUTSIDE FRONTS Maybe the calipers don't have the free play to slide back and forth under load?? I decided to take all of the calipers off the brackets and clean/ grease the slide pins which the calipers bolt on to hoping this would solve it.. 60 miles later..NOTHING. Here are some pics of my Booster and M/C for Sh & Giggles. Some residue underneath but it doesn't seem to be wet. I never had one problem with the brakes before. They stopped great. I thought this would be a simple first upgrade, no such luck.. PLEASE HELP.... I don't know what else to do. Thanks.. Quote Link to comment Share on other sites More sharing options...
S130Z Posted December 4, 2009 Share Posted December 4, 2009 I would start over in the rear with new pads and rotors in the back. AdvanceAutoParts has them for chead, I think I paid like $40 for new rotors and pads the first time I swapped them in the rear. That is an odd wear pattern in the rear for sure. After I swapped to all AdvanceAuto stuff I could lock up my rear tires pretty easily, but the front ones are obviously harder to lock up. Give that a shot and see what happens. Good luck! Quote Link to comment Share on other sites More sharing options...
stravi757 Posted December 4, 2009 Share Posted December 4, 2009 The brakes need to pressed pretty hard to make a decent, sudden stop. It's also very difficult to lock them up, kind of fades to a stop. Maybe you MC is going bad. Quote Link to comment Share on other sites More sharing options...
at-jefft Posted December 4, 2009 Share Posted December 4, 2009 I bled the brakes and watched that the m/c never went empty. Just covering the basics here: but did you bleed the m/c? Quote Link to comment Share on other sites More sharing options...
mark Posted December 4, 2009 Share Posted December 4, 2009 Did you go thru the bedding procedure that porterfield recomends? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted December 4, 2009 Share Posted December 4, 2009 Check if the back of the pad is completely flat. I had a set of Hawks that had small bumps in the metal plate right where the caliper makes contact. That tilted the pad so the bottom (closer to the center of the rotor) edge made contact first. Quote Link to comment Share on other sites More sharing options...
SHADY280 Posted December 4, 2009 Share Posted December 4, 2009 ^ i second that, the rear has the tabs for the e-brake, the pistons spins and can make the pad tilt Quote Link to comment Share on other sites More sharing options...
abes Posted December 4, 2009 Author Share Posted December 4, 2009 The pads are new and I did contact poterfield re. the break-in. I guess the next step would be to bleed the m/c cylinder and see if that helps. I just don't think it would do nything becuase it never went empty or even close to it. Any other suggestions? Thanks guys.... Quote Link to comment Share on other sites More sharing options...
abes Posted December 4, 2009 Author Share Posted December 4, 2009 Check if the back of the pad is completely flat. I had a set of Hawks that had small bumps in the metal plate right where the caliper makes contact. That tilted the pad so the bottom (closer to the center of the rotor) edge made contact first. I checked and the tabs are in the slots. I wish it was that easy.. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted December 4, 2009 Share Posted December 4, 2009 It doesn't seem likely that bleeding the MC is going make the pad and disc surfaces mate properly unless there is so much air that there is almost no pressure in the rears. I would focus my attentions on how the caliper is seated on the bracket, etc. If you haven't already done it, with the wheel off and a good light, I'd be looking at the bracket/caliper/pad/disc interactions to see what's not fitting together properly. Also, you said that you had the discs resurfaced. I'd put a straight edge across the discs looking for unevenness. Perhaps they didn't cut them correctly? I had an issue with that the last time I tried to have my discs cut at the local parts store. I've since decided that discs are a wear item like pads and will just replace them and the pads together from now on. Discs for our cars are relatively cheap and the hassle when it doesn't work out just isn't worth it. Quote Link to comment Share on other sites More sharing options...
nosebleedZ Posted December 5, 2009 Share Posted December 5, 2009 Get a cheap micrometer & check the rear rotor thickness versus the FSM, Haynes, etc. If you had them turned at a parts store, they probably cut them under minimum thickness which would negate the pad to rotor engagement. Seriously, some parts stores give a 5 minute brake lathe course to most employees...LOL. Quote Link to comment Share on other sites More sharing options...
74_5.0L_Z Posted December 5, 2009 Share Posted December 5, 2009 Are these race pads? Race pads don't work very well until you have a bunch of heat in them. On the street, you will probably never get them up to operating temperature. I use the hawk HP plus pads on my car which does mostly autocross. My pads have to work while cold or moderately hot, and I have been happy with the Hawk pads. They do generate some dust and wear the rotors noticably though. Your rear inside pads are obviously not wearing correctly. Is the outer edge of the pad contacting the structure of the caliper? Is the caliper slider perpendicular to the rotor surface? Quote Link to comment Share on other sites More sharing options...
abes Posted December 5, 2009 Author Share Posted December 5, 2009 Are these race pads? Race pads don't work very well until you have a bunch of heat in them. On the street, you will probably never get them up to operating temperature. I use the hawk HP plus pads on my car which does mostly autocross. My pads have to work while cold or moderately hot, and I have been happy with the Hawk pads. They do generate some dust and wear the rotors noticably though. Your rear inside pads are obviously not wearing correctly. Is the outer edge of the pad contacting the structure of the caliper? Is the caliper slider perpendicular to the rotor surface? The pads are porterfield "street" pads which a lot of people on the forum use and have been very pleased with. As far as the sliders, my stock pads wore evenly and when i checked they seemed to be perpendicular to the rotor. Quote Link to comment Share on other sites More sharing options...
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