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| | | | Joined: Apr 2005 Posts: 926 Shop Shark | | Shop Shark Joined: Apr 2005 Posts: 926 | I have another truck now. Recently did a re-po for a friend and was paid with a 1976 Chevy one ton duallie flatbed. I know it's too new,but it looks a lot older than it is. Has a 12 foot bed with a beefy headache rack,HydroBoost brakes,tilt column,16.5's,454/4 speed,and was air cond.,but will have on-board air soon. Seems to run good,drive nice but has little if any front brakes,though everything appears to be in good shape;the brake fluid was low when I went to get it so I topped it off,and got good pedal but when I stop the rear brakes lock real easily. I'm thinking the proportioning valve is tripped;is there a way to re-set it?
Speed
Last edited by speed 6351; 02/05/2010 8:26 PM.
| | | | | Joined: Apr 2003 Posts: 942 'Bolter | | 'Bolter Joined: Apr 2003 Posts: 942 | Not sure about the proportioning valve, but I would bleed the whole system and see what that would do. With the rears locking like that, you could have air in the lines. When you topped off with fluid, which pot was low, Front or Rear?
You also may have leaking wheel cylinders.
Bill
'60-'72 Chev/GMC Fan
GMC 9500 Fan
Detroit Diesel Fan
| | | | | Joined: Nov 2005 Posts: 6,100 'Bolter | | 'Bolter Joined: Nov 2005 Posts: 6,100 | Hy speed6351, is the brake system warning light hooked up? You can test the switch with a meter or a test light, if the valve has shuttled over, the terminal will be grounded. If the valve has shuttled over to close off the front system you can attempt to reset it. First bleed the front calipers, they will gravity bleed, once you have them bled as best you can, then pump up the brake pedal and have someone crack open a rear bleed screw, if you do this with the ignition on, and the wiring on the combination valve the light should go out when the valve shuttles towards the rear system, be gentle, or you'll send the valve all the way to the rear. Sometimes you have to chase it back and forth a bit, hope that helps. | | | | | Joined: Apr 2005 Posts: 926 Shop Shark | | Shop Shark Joined: Apr 2005 Posts: 926 | Thanks for the information. Testing showed the valve hadn't tripped,so I did an experiment;I drove the truck up to about 30 mph and jumped on the brakes a couple of times.   Apparently,something was stuck,and this jarred it loose,now the brakes work fine. I guess I lucked out! I've been driving the truck every chance I get,working out some problems and burning up what gas is left in the right tank so I can drop it and replace the sender. Other than that and the excessively slow wipers' speed,the truck's about as done as it's going to be for a while. Thanks again for the information on the brakes though;now that I have two of these trucks,odds are that one or the other will eventually put me through the wringer on brake troubles.  Speed | | |
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