EvilRufusKay Posted January 9, 2004 Share Posted January 9, 2004 So if your rear brakes do not work...but fluid will drain out on a gravity bleed. Pumping produces no pressure...do you suspect 1. Master Cylinder 2. Proportioning Valve or demons living under the vehicle? Quote Link to comment Share on other sites More sharing options...
Wagz Posted January 9, 2004 Share Posted January 9, 2004 Demons. Definitely. By gravity bleed, you mean just opening up the bleeders and fluid flows 'unassisted'? If that's the case there is obviously some kind of air breach that could be at the master cylinder or anywhere in the line to the rear brakes. I could be bad brake cylinder(s) too. Have you been underneath and inspected the lines all the way from the master? Quote Link to comment Share on other sites More sharing options...
ToplessZ Posted January 9, 2004 Share Posted January 9, 2004 Have you double checked the calipers too to make sure the pistons arent frozen. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 9, 2004 Share Posted January 9, 2004 Don't want to insult, but I've seen at least 10 people with the calipers on the wrong sides. Your bleeders are up on the top of the caliper, right? Jon Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 9, 2004 Author Share Posted January 9, 2004 None taken... My fronts are working fine...no stuck pistons...new cylinders in the rear. When I bought the vehicle the rears did not work...the cylinders were frozen...r&r'd them...no one was with me so I just gravity bled, adjusted the shoes to the proper spots, (just barley rubbing the drum) and left for home...rears still non-functional. went back the next day with a buddy and tried to bleed..pumping produces no psi to the rear...there are no leaks..lines are fine...original question...Master? propotioning valve? or Demons? PS this is my fullsize Bronco...a little too cold for the Z!!!! Quote Link to comment Share on other sites More sharing options...
Tim240z Posted January 9, 2004 Share Posted January 9, 2004 My $$$ are on the MC. Quote Link to comment Share on other sites More sharing options...
Wagz Posted January 9, 2004 Share Posted January 9, 2004 Yep. If you've done all of that, I think Tim is right. The MC is the most obvious culprit. ...or, it could still be the demons Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 13, 2004 Author Share Posted January 13, 2004 New MC no difference...until I took it back off and ran out the adjuster nut on the push rod!!! Now I have much better pedal (probably a little too tight) however the rears are still not working right. I still get no real psi out of them. Bleding them produces no fluid at psi. It simply drains out. I am going to call on a price for a Prop. valve. I heard about smacking these valves around to try and loosen it up if there is a piece of dirt in the seat. Anyone ever had any luck with that? If the dealer wants a big buck for the part a may nab one from the junk yard. demons..... Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 13, 2004 Author Share Posted January 13, 2004 $125.00 for the prop valve... I am going to try to "persuade" the one on the truck to work tonite!!! Quote Link to comment Share on other sites More sharing options...
Guest BigWhyteDude Posted January 14, 2004 Share Posted January 14, 2004 if the hammer doesn't work.. get a bigger one Andrew Quote Link to comment Share on other sites More sharing options...
Dan Juday Posted January 14, 2004 Share Posted January 14, 2004 Please forgive me if this sounds too obvious. A lot of trucks have proportioning valves that operate from a rod that moves according to the relationship between the rear axle and the frame. Rear axle close to frame=full brake pressure. Rear axle far from frame=minimum pressure. As the truck pitches forward under braking the rear lifts and hence the braking pressure to rear brakes diminishes to impede rear wheel lock up. When the truck is loaded there is less forward pitching so the rear brakes get more pressure for stopping. All this to say if you have jacked the truck up and set the frame on jackstands and let the axle hang you will be at the minimum pressure setting for the proportioning valve. Put the jackstands on the axle and you have full pressure. This may not apply to your truck but it came to mind when you said you had minimal pressure to the rear wheel cylinders. Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 16, 2004 Author Share Posted January 16, 2004 A lot of trucks have proportioning valves that operate from a rod that moves according to the relationship between the rear axle and the frame. Good point Dan, but this is a full size Bronco and there is no rear prop. valve. I appreciate the input!! Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 16, 2004 Share Posted January 16, 2004 There is something about this thread that is bugging the chit out of me. What the hell does "gravity bleed" mean? If you open the bleeders and brake fluid drains out, then you have the wheel cylinders mounted upside down. If this is the case you will never get all the air out. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 16, 2004 Share Posted January 16, 2004 If the master is above the wheel cylinder, then it will gravity bleed. Jon Quote Link to comment Share on other sites More sharing options...
EvilRufusKay Posted January 17, 2004 Author Share Posted January 17, 2004 There is something about this thread that is bugging the chit out of me. What the hell does "gravity bleed" mean? If you open the bleeders and brake fluid drains out' date=' then you have the wheel cylinders mounted upside down. If this is the case you will never get all the air out.[/quote'] Gravity bleeding is simply opening the bleed valve. As Jon said, fluid runs downhill. I could not have put the cylinder on upside down, the line would not make it to any other spot. Quote Link to comment Share on other sites More sharing options...
Pop N Wood Posted January 17, 2004 Share Posted January 17, 2004 So when the fluid drains out, how do you know if it is being replaced in the line with more fluid from the MC, or filling up with air from the bleed valve? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted January 17, 2004 Share Posted January 17, 2004 A good way to avoid air getting sucked in is to put a hose on the bleeder and put that into some brake fluid. This is also a good way to do a one man brake bleeding. You can leave the bleeders open and pump the brakes 5 or 6 times, no air gets sucked in, but the old fluid will come out. Then you just go close the bleeder and make sure the M/C is full and move onto the next wheel. Jon Quote Link to comment Share on other sites More sharing options...
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