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Old 05-15-2019, 03:30 PM
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Testing the Rear Brakes

I've been having some trouble with my rear disc brakes on my 05 TJ. When backing down an incline and I apply the brakes to stop the front tires lock up and slide while the rear tires continue to roll. I have bled the brakes (first time out of order) 2nd time I just bled the rear brakes in order. Prior to bleeding the brakes I could turn the rear tire with some effort while someone was applying pedal pressure. After bleeding I could not manually turn the rear tires. I thought I had remedied my trouble but it still will not stop while backing down an incline (front locks up and rear continues to roll). I have stomped on the brakes while driving 35 mph on the asphalt and the brakes do not lock up (ABS I assume), but they seem like they take a longer distance than it should to stop. How do I test my rear brakes? I need to be able to know if they are working correctly and if they aren't I need to know how to test them to see if they are after I make corrections.

Craig

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Old 05-15-2019, 09:09 PM   #2
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Are the caliper pistons stuck? How long had it been before the first time you flushed the fluid?

After a few hard stops, are the rear hot like the front?

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Old 05-15-2019, 10:07 PM   #3
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Drum or disc?
If drum, adjust them
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Old 05-15-2019, 10:39 PM
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Disc Brakes. Haven't checked the temp, but I will. Bought this Jeep used last year and changed the fluid just the other day. So....I have no idea how long if it ever had been changed before. I know the pistons in the calipers aren't completely stuck because they will apply enough pressure that I cannot turn the tires by hand when it is lifted. I just don't know how much the rear caliper are actually working or how to check to see how much they are working.
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Old 05-15-2019, 10:56 PM   #5
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I like to test for locking up in dirt or gravel
If you have abs you can pull the fuse...
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Old 05-15-2019, 11:34 PM   #6
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Not being able to turn by hand is not much force vs when you are driving and actually use the brakes.
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Old 05-16-2019, 07:47 AM   #7
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You can put the rear up on jack stands, put it in 1st gear, bring it up to ~2000rpm, then slowly apply brakes and feed it gas to try to maintain 2000rpm. If the brakes are working, they should be able to stall out a manual or fight the torque converter in an auto to a standstill, no matter how much gas you give it. If the engine wins, you've got a brake problem.
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Old 05-16-2019, 09:01 AM   #8
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Disagree.... the rear brakes only supply about 1/3 of the stopping power of the fronts (1/4 of total) and are not likely to exceed the torque of the engine multiplied by first gear and final drive ratio...
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Old 05-16-2019, 10:39 AM   #9
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Disagree.... the rear brakes only supply about 1/3 of the stopping power of the fronts (1/4 of total) and are not likely to exceed the torque of the engine multiplied by first gear and final drive ratio...
The rears will stop the tires from turning on jack stands and will hold them there with the gas floored at least mine will in 2hi, have not tried 4lo.
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Old 05-17-2019, 11:45 AM   #10
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Master cylinders for disc and drum rear are different. Could be the master cylinder was changed by po and wrong one was installed. Rear disc take more fluid movement and higher pressure than drum. Check that you have the correct one installed.
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Old 05-17-2019, 02:14 PM   #11
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I guess brakes vs engine could vary based on rear gear ratio I never tried it w airplane gears....

Re master cylinder.... pretty sure they are the same.

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