Auto Posted August 29 Share Posted August 29 I’m going to start with what I did. I bought new shoes new drums new hardware and wheel cylinders for the rear also new brake lines for the rear that go on the axle. I also deleted the load sensing valve and put a 97 YJ proportioning valve on so now I only use one line to the rear that should be everything to the rear. I also did the WJ brake booster and MC swap. I thinks that all I’ve done now after doing all this I’m running into a major problem my brakes go to the floor when my truck is running but when I turn it off and bless the air pressure it’s back to a hard pedal. I’ve tried a different booster a different MC nothing changed that’s all I’ve tried so far. Any kind of idea will be appreciated thanks. Link to comment Share on other sites More sharing options...
Pete M Posted August 29 Share Posted August 29 when that happened to me, it was a bad booster. Link to comment Share on other sites More sharing options...
Auto Posted August 29 Author Share Posted August 29 I bought another booster tried it and it did the same thing. Link to comment Share on other sites More sharing options...
AZJeff Posted August 29 Share Posted August 29 Two questions: 1. Did you bleed the system COMPLETELY and in the proper order? 2. When you swapped boosters, was the booster new, or used? Likewise, was the MC new? Link to comment Share on other sites More sharing options...
Salvagedcircuit Posted August 30 Share Posted August 30 I did the WJ booster upgrade. You need to check over every part of your braking system with a fine tooth comb. Check: -brake bleeder screws. They can get clogged or in my case deformed from over torquing. the bleed hole should be circular not oval. They will no longer flow brake fluid properly when deformed. Thus your system will not bleed. -brake bleeder screw threads in the calipers. If there are only a few threads, it's no good. The after market calipers have incredibly poor quality control. I went through 4 sets of calipers before I found one that was rebuilt properly. -correct length caliper slide pins. Mine were from a different caliper and punctured the back of the brake pads. -teflon sleeve on the caliper slide pins. They are necessary for the proper function of renix era brake calipers. They are often omitted on rebuilt calipers. -grease up slide pins generously with brake lube -check the caliper piston for pitting. A newly rebuilt caliper came with a piston so badly pitted the surface looked like swiss cheese. I found brake bleeding to be significantly easier using speed bleeders. These have a ball bearing inside the bleeder to reduce air in the system on the brake pedal return swing. To me it was worth the ~$14 to not have to bug someone else for an hour or so while debugging. Link to comment Share on other sites More sharing options...
Auto Posted August 30 Author Share Posted August 30 AzJeff I did bleed everything completely and yes new MC was also bench bleed. Link to comment Share on other sites More sharing options...
Pete M Posted August 30 Share Posted August 30 was the different booster new? "pedal to the floor when running" is going to be a bad booster or master. not much else in the system. Link to comment Share on other sites More sharing options...
Auto Posted August 31 Author Share Posted August 31 Pete M everything was new I tried two new boosters and MC Link to comment Share on other sites More sharing options...
zomeizter Posted September 1 Share Posted September 1 OP, ensure your rear drum shoes are adjusted correctly, there should be a little drag on the drums while spinning the rear wheels by hand. This should get your brakes in order if the circuits are fully bled. Link to comment Share on other sites More sharing options...
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