bryant2482 Posted February 26, 2018 Report Share Posted February 26, 2018 Hey guys so I ended up replacing my front rotors, calipers, master cylinder and pads. I am now dealing with my back drums locking up before my fronts. I have bled them all the way around and still having no luck! Running out of ideas, need some imput, thanks 1 Quote Link to comment
metalmonkey47 Posted February 26, 2018 Report Share Posted February 26, 2018 You sure you've gotten all of the air out of the front brakes? Bench bled the master cylinder? 1 Quote Link to comment
datzenmike Posted February 27, 2018 Report Share Posted February 27, 2018 Assume this is for a 720? MM's right. Air may still be trapped. See those two little bleeders on the side of the master cylinder? Crack them open slightly and have someone push down on the brake gently. Have a rag handy to catch the fluid and any bubbles. Hold the pedal till you close the bleeder so it doesn't suck in any air then let it up. 2 Quote Link to comment
bryant2482 Posted February 27, 2018 Author Report Share Posted February 27, 2018 Ok I will try that and see what happens 1 Quote Link to comment
datzenmike Posted February 27, 2018 Report Share Posted February 27, 2018 Do you still have the old master? I'm no fan of the cheap rebuilt crap from NAPA and the re-pops from China. Often the seals are torn or folded during assembly, some have aluminum shavings in them. When possible get a rebuild kit and do it yourself. It's cheap and surprisingly easy and it's done right. 1 Quote Link to comment
mklotz70 Posted February 27, 2018 Report Share Posted February 27, 2018 I'll a quick bit to Mike's bleeding suggestion. I would take out the pedal linkage and have your helper use a dowel or long rod to completely push the piston in the m/c as far in as it can go. The point of bench bleeding is to get all the air out and the brake pedal/linkage will not bottom out the piston.......so it can leave a bit of air in it. If you can have the m/c level by jacking up the back of the truck when doing it, even better. 3 Quote Link to comment
banzai510(hainz) Posted February 27, 2018 Report Share Posted February 27, 2018 maybe its a truck and the backs lock up ezer anyways? 1 Quote Link to comment
datzenmike Posted February 27, 2018 Report Share Posted February 27, 2018 They should lock together. Fronts do most of the stopping and weight shifts forward increasing front wheel traction and decreasing rear wheel. 620s have a load sensing device that increases pressure to the rears when carrying a load. I don't know about the 720. Quote Link to comment
bryant2482 Posted February 28, 2018 Author Report Share Posted February 28, 2018 I couldn't get around to it today but I'm going to bench bleed it again and bleed the hell out of the rest of the system. I'll go through a full bottle to make sure it's air free Quote Link to comment
hang_510 Posted March 1, 2018 Report Share Posted March 1, 2018 Have you adjusted the rear brakes? Quote Link to comment
don51o Posted June 30, 2018 Report Share Posted June 30, 2018 I installed Datsun 1200 rear wheel cyls. 1/16" smaller bore. Quote Link to comment
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