barbom143 Posted June 24, 2009 Share Posted June 24, 2009 I am embarrassed to ask this question. First you learn "right to tight, left to loosen" then you learn about brakes, but I can't figure this out. 76 280 Z with LS1 and auto. Front brakes are Toyota 4 Runner four piston, rear are Maxima disc. After making the brake swap, I was unable to get any rear brakes and the front brakes would drag to the point that they would heat up and bind. I have tried to solve the problem by adding an adjustable proportional valve, removing the proportioning valve completely, bleeding the brakes, blowing out brake lines with air, bleeding both the master cylinder and calipers multiple times. Tried two different master cylinders (both rebuilt), changing the rear calipers twice and adjusted the master cylinder push rod All I have accomplished is making the front brakes not work at all but not improving the rear. When you push on the brake pedal, it feels like it depresses the master cylinder to the stop without building pressure. I am out of ideas. Quote Link to comment Share on other sites More sharing options...
Trevor Posted June 25, 2009 Share Posted June 25, 2009 did you change the Master Cylinder to a 15/16" dia. bore cylinder from a 280ZX? You might be running out of MC stroke before moving enough fluid. Quote Link to comment Share on other sites More sharing options...
roger.svoboda Posted June 26, 2009 Share Posted June 26, 2009 you may have the freeplay maladjusted. Quote Link to comment Share on other sites More sharing options...
zedman240 Posted June 26, 2009 Share Posted June 26, 2009 Make sure your master cylinder is made for rear discs (15/16); standard zed masters are setup for drums. Quote Link to comment Share on other sites More sharing options...
barbom143 Posted June 27, 2009 Author Share Posted June 27, 2009 I have a 15/16 MC but what would I need to do to change it to set it up for rear disc? I have lenghtened the push rod to compensate for the change in m/c. Running out of stroke before moving enough fluid is the best description of how the pedel feels. Quote Link to comment Share on other sites More sharing options...
rags Posted June 27, 2009 Share Posted June 27, 2009 Did you swap the rear calipers right to left, left to right so that the bleeders are on the top of the calipers? Quote Link to comment Share on other sites More sharing options...
barbom143 Posted June 27, 2009 Author Share Posted June 27, 2009 Toyota on front are on top, Maxima on rear are midpoint of caliper. Quote Link to comment Share on other sites More sharing options...
rags Posted June 27, 2009 Share Posted June 27, 2009 Post a picture of the rear caliper as it is mounted. If the bleeder is truly midway then the top half of the caliper will be filled with air. Quote Link to comment Share on other sites More sharing options...
barbom143 Posted June 28, 2009 Author Share Posted June 28, 2009 Too tired tonight to figure out how to post a picture. About 40-50% of the piston is above the bleed valve. Monday or Tuesday I will remove the calipers and bleed them with the valve at the top. Thanks, I will let you know what happens. Quote Link to comment Share on other sites More sharing options...
barbom143 Posted June 29, 2009 Author Share Posted June 29, 2009 We have some brakes!!!!! Do the pistons self adjust? I got them as tight as possible but they still need fine tuning. The adjustment on the piston only allows 90 degree turns. I couldn't get another quarter because then they would not slide back over the pads on install. There has to be some sort of self adjustment to take up slack as the pads wear. Does anyone know how to speed the process? Quote Link to comment Share on other sites More sharing options...
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