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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: gold84gmc on April 23, 2009, 09:44:04 pm
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i dont know if its just how they were designed or what...but i have a 3/4 ton so the brake are pretty big (especially the drums) but they dont brake very good, and i have plenty of pad left, so i adjusted the height-sensing valve for the drums and they work better but i wish they would work better
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Are they adjusted properly?
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Are they adjusted properly?
im pretty sure they are....for the drums all you do is back up and pump the brakes right?
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No. Take the drums off and inspect. If you can take a pic of both sides for us. Make sure your primary and secondary shoes are on correctly and that your hardware is in good shape.Make sure the wheel cylinders are dry. Clean them off with simple green and water and dry them thoroughly. Adjust them manually until there is a slight drag. Make sure the adjusters move freely.
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ok i took off my drum today and took a couple pics of it (passengers side), everything looks fine to me, and theres a tiny bit of drag so i dont know if these brakes werent too powerful from the factory or what
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If you find they are adjusted properly check all your brake hoses. the ones that go out to the front wheels and the rear axle (flex lines). sometimes when pressure is applied they will bow out like a baloon and waste pressure.
I have a 3/4 ton too and when all is working properly they'll stop the truck with a ton of sand pretty dang quick. empty it'll stop fast enough to give me a headrush ;D
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If you find they are adjusted properly check all your brake hoses. the ones that go out to the front wheels and the rear axle (flex lines). sometimes when pressure is applied they will bow out like a baloon and waste pressure.
I have a 3/4 ton too and when all is working properly they'll stop the truck with a ton of sand pretty dang quick. empty it'll stop fast enough to give me a headrush ;D
well i do know that the front brake hoses arent blown but could be replaced and im pretty sure the back one is the same...so would that be my problem?
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Your tiny pix don't help any. Can you resize them or take another pic of the whole thing? Do you have a height sensing proportioning valve in the back?
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If you find they are adjusted properly check all your brake hoses. the ones that go out to the front wheels and the rear axle (flex lines). sometimes when pressure is applied they will bow out like a baloon and waste pressure.
I have a 3/4 ton too and when all is working properly they'll stop the truck with a ton of sand pretty dang quick. empty it'll stop fast enough to give me a headrush ;D
well i do know that the front brake hoses arent blown but could be replaced and im pretty sure the back one is the same...so would that be my problem?
By blow out I don't mean they popped as in a hole in them. Have someone step on the brake pedal hard and feel the brake lines, if you feel any lumps, they need replacing. it may need to be bled too.
If they stop weak, either the pads/shoes aren't adjusted right or theres a leak or pressure loss somewhere. Could be leaking wheel cylinders in the back or leaking calipers in the front or a bad master cylinder. Look for signs of leakage everywhere. When I adjust the brakes and look for that slight drag, I do it with the tire on it for the extra weight. While you're there break the glaze on your drums and shoes. Snad them with (I like) a 36 grit paper on shoes and drums. If its shiny, sand it until it's not. Same on the front rotors and pads. That will improve any grip loss from glazing or contaminants.
To check your calipers just try to move them left to right (as sitting in the seat) if they move much a caliper may be stuck.
If you haven't bled the system it probably needs it. you can flush it out with straight alcohol to clean any grime out and use compressed air to blow it out (make sure the air source has a drier to prevent moisture from getting in the lines. Water or air in any part of the system is your enemy. Air compresses, losing force between the pedal and wheel, and water will get hot and boil, creating air in the system.
look for any signs of leakage at the master cylinder, calipers, wheel cylinders, brake hoses, and along the hard lines. On the wheel cylinders in the drum brakes, peel back the rubber boot a bit and if theres anything wet inside, you need a new wheel cylinder. If you have to bleed the whole brake system, I'd get new calipers and wheel cylinders any way. They're around here $15 for calipers (2 needed) and $9 for wheel cylinders (2 needed). The master cylinder should be around $20 or so. I think (don't cause me if I'm wrong) ;D All 3 brake hoses are $30 or so. For about $100 you can replace everything except the hard lines and be all set for yearas to come. and then you only have to bleed the brake once (I hate that job).
I'm assuming you bought the truck used and don't know the history or it has been sitting for a good while.
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im going to try feeling the rubber hoses today (probably going to replace them anyways), i have already replaced both wheel cylinders, both calipers, and the master cylinder. a little while ago brake fluid used to leak out the top of the master cylinder (from under the cover) i think it was from having to push on the pedal hard because ever since i adjusted the height sensing valve it hasnt leaked.......as for history of the truck i do know that the previous owner used to haul a 5th wheel camper with it so i dont know if that couldve affected the hoses or not
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im going to try feeling the rubber hoses today (probably going to replace them anyways), i have already replaced both wheel cylinders, both calipers, and the master cylinder. a little while ago brake fluid used to leak out the top of the master cylinder (from under the cover) i think it was from having to push on the pedal hard because ever since i adjusted the height sensing valve it hasnt leaked.......as for history of the truck i do know that the previous owner used to haul a 5th wheel camper with it so i dont know if that couldve affected the hoses or not
If you replaced all that, aweseome. hauling a 5th wheel won't necessarily hurt the hoses, it's mainly time and brake fluid that get to them. there may be air in the lines or its a high possibility that height sensing valve isnt set right or could be bad, MAYBE. Someone else will have to chime in about the height sensing valves though because I've never even seen a pic of one, let alone worked on one.
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i know that the height sensing valve is working because where it was set originally the rear brake barely even did anything unless i had a load in the bed...so i adjusted it and now the rear brakes work better when the beds empty
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Your tiny pix don't help any. Can you resize them or take another pic of the whole thing? Do you have a height sensing proportioning valve in the back?
well i dont know how everyone puts there pics on here so that when you click on it they get bigger....and yes i have a height sensing valve...i already adjusted it
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They use a picture that is larger than your listed 128x96. upload one that is 600x400.
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i tried that and it says "file too large maximum attachment size 128kb
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Your pix still don't help, just a single pic of them will be good so we can make sure everything looks good. You can simply bypass the height sensing valve and see how it works. They always fail on these trucks.
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Your pix still don't help, just a single pic of them will be good so we can make sure everything looks good. You can simply bypass the height sensing valve and see how it works. They always fail on these trucks.
i took the pics like that because if i take a pic of the whole thing you cant see the hardware because the axle shaft is in the way...and my height sensing valve is fine on my truck
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Glad to hear.