stuck front brakes
zak5
01-30-2006, 04:59 PM
1979 G20
both the front disk-brakes are lightly stuck. They squeal when im not on the brakes above 20, and make the back end jump around above 40.
there was a crack in the from line, had to replace it and the two rear brake cylinders.
Thinking it's the master cylender.
Probably not the parking brake, because the rear wheels turn pretty easy even with the brake engaged.
both the front disk-brakes are lightly stuck. They squeal when im not on the brakes above 20, and make the back end jump around above 40.
there was a crack in the from line, had to replace it and the two rear brake cylinders.
Thinking it's the master cylender.
Probably not the parking brake, because the rear wheels turn pretty easy even with the brake engaged.
Bob1942
02-12-2006, 10:34 PM
1979 G20
both the front disk-brakes are lightly stuck. They squeal when im not on the brakes above 20, and make the back end jump around above 40.
there was a crack in the from line, had to replace it and the two rear brake cylinders.
Thinking it's the master cylender.
Probably not the parking brake, because the rear wheels turn pretty easy even with the brake engaged.
ZAK5 ...I am working on my brakes too ! just put in two new rear cylinders yesterday on my 88 G20...First I would jack up the front wheels and turn them by hand they should turn easy with just a tiny tiny bit of drag to them ---if so they are normal ! ...While you have the wheels up might as well check the front end parts for wear ... grab each wheel on top and bottom ... if you can move the wheel up and down and it goes clunk clunk you have worn ball joints or very loose wheel bearings (Check the wheel bearings to see if the movement is there ) Next try to move each wheel from side to side If you can, if it goes clunk clunk you have a bad Tie rod or steering linkage ...These things can cause your van to shake above 20 MPH and also have been known to cause brakes to do strange things ...NOW back to the brakes ...Master cylinders for drum brakes and disc brakes are different has anyone changed the master cylinder on your van ? are you sure you have one for front disk brakes ? The master cylinder in your van has compensation ports in the bore that allow the brake pressure to go down when the pedal is at rest ... These can sometimes get plugged and also sometimes they will not work if the master cylinder does not go back far enough to the rest posistion when you take your foot off the pedal ...A quick test for this is to remove the covers on the master cylinder and have someone GENTLY push the brake pedal while you watch...You should see fluid in the resevoir Squirt up in the center of the resevoir a little bit until the master cylinder piston passes the compensation port ...DON't get to close ! you can get squirted with brake fluid if your assistant pushes to hard or to fast ! Stand back and watch ! ...if you see the fluid in the resevoir Mound up from fluid squirting in or squirt up a little then your compensation ports are working ok ...If not you have a master cylinder problem OR the master cylinder piston is not returning to its full resting posistion ... Other things that can cause the front brakes to be stuck are ...Calipers the calipers must slide back and forth to equalize pressure on both sides of the rotor if they are rusty and stick this can cause your brakes to stick ON slightly ... To check this just take the Calipers off and see that the sliding parts on each end of the calipers are clean and lubricate them with brake grease then put them back together you can get brake grease at the discount auto parts stores for 99cents ...Some calipers also have metal parts on the ends that slide on the caliper mounting surface you can clean these with fine grit emery sandpaper or in some cases a fine file to get them to work better then put a tiny bit of brake grease on them too ... And you may have stuck caliper pistons if they are rusted and dirty the caliper pistons can stick in the caliper bores I would think this would not be likely because you would have to have BOTH of them stuck to do this , same thing with the brake hoses sometimes they fall apart INSIDE THE HOSE and plug causing the brakes to be on but BOTH of them would have to plug to do this...TO check this open the brake bleeder screw on each caliper, Fluid should flow out of it slowly by gravity if it does not that rubber hose has most likely got rubber pieces inside pugging it ( By the way this is a great way to bleed front brakes on a G-20 van it just takes time )... I don't know about the back end jumping ! I never heard of that ! You may also have those bad ball joints or front end problems I have seen vans shake above 20 miles per hour because the front end parts were worn and very loose ...Good luck ! Bob in Michigan
both the front disk-brakes are lightly stuck. They squeal when im not on the brakes above 20, and make the back end jump around above 40.
there was a crack in the from line, had to replace it and the two rear brake cylinders.
Thinking it's the master cylender.
Probably not the parking brake, because the rear wheels turn pretty easy even with the brake engaged.
ZAK5 ...I am working on my brakes too ! just put in two new rear cylinders yesterday on my 88 G20...First I would jack up the front wheels and turn them by hand they should turn easy with just a tiny tiny bit of drag to them ---if so they are normal ! ...While you have the wheels up might as well check the front end parts for wear ... grab each wheel on top and bottom ... if you can move the wheel up and down and it goes clunk clunk you have worn ball joints or very loose wheel bearings (Check the wheel bearings to see if the movement is there ) Next try to move each wheel from side to side If you can, if it goes clunk clunk you have a bad Tie rod or steering linkage ...These things can cause your van to shake above 20 MPH and also have been known to cause brakes to do strange things ...NOW back to the brakes ...Master cylinders for drum brakes and disc brakes are different has anyone changed the master cylinder on your van ? are you sure you have one for front disk brakes ? The master cylinder in your van has compensation ports in the bore that allow the brake pressure to go down when the pedal is at rest ... These can sometimes get plugged and also sometimes they will not work if the master cylinder does not go back far enough to the rest posistion when you take your foot off the pedal ...A quick test for this is to remove the covers on the master cylinder and have someone GENTLY push the brake pedal while you watch...You should see fluid in the resevoir Squirt up in the center of the resevoir a little bit until the master cylinder piston passes the compensation port ...DON't get to close ! you can get squirted with brake fluid if your assistant pushes to hard or to fast ! Stand back and watch ! ...if you see the fluid in the resevoir Mound up from fluid squirting in or squirt up a little then your compensation ports are working ok ...If not you have a master cylinder problem OR the master cylinder piston is not returning to its full resting posistion ... Other things that can cause the front brakes to be stuck are ...Calipers the calipers must slide back and forth to equalize pressure on both sides of the rotor if they are rusty and stick this can cause your brakes to stick ON slightly ... To check this just take the Calipers off and see that the sliding parts on each end of the calipers are clean and lubricate them with brake grease then put them back together you can get brake grease at the discount auto parts stores for 99cents ...Some calipers also have metal parts on the ends that slide on the caliper mounting surface you can clean these with fine grit emery sandpaper or in some cases a fine file to get them to work better then put a tiny bit of brake grease on them too ... And you may have stuck caliper pistons if they are rusted and dirty the caliper pistons can stick in the caliper bores I would think this would not be likely because you would have to have BOTH of them stuck to do this , same thing with the brake hoses sometimes they fall apart INSIDE THE HOSE and plug causing the brakes to be on but BOTH of them would have to plug to do this...TO check this open the brake bleeder screw on each caliper, Fluid should flow out of it slowly by gravity if it does not that rubber hose has most likely got rubber pieces inside pugging it ( By the way this is a great way to bleed front brakes on a G-20 van it just takes time )... I don't know about the back end jumping ! I never heard of that ! You may also have those bad ball joints or front end problems I have seen vans shake above 20 miles per hour because the front end parts were worn and very loose ...Good luck ! Bob in Michigan
zak5
02-13-2006, 07:31 PM
Replaced the master cyleder, the front calipers and one brake hose. Still a little bit of squeal when the brakes aren't engaged, so I'm gonna try adjusting the master cylender better. It accelerates better and doesn't buck around at 50, though. So i guess that was how bad the brakes were sticking.
Those back bleeder nuts are a pain in the ass.
If you want a faster non-assistant way to bleed the brakes, I just press them down and jam a box inbetween brake pedal and the dash. They also have brake-bleeding tools for like 20$.
Thanks for the advice.
Those back bleeder nuts are a pain in the ass.
If you want a faster non-assistant way to bleed the brakes, I just press them down and jam a box inbetween brake pedal and the dash. They also have brake-bleeding tools for like 20$.
Thanks for the advice.
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