Troubleshooting brakes

[DustinfromOhio]

A few weeks ago I noticed my brakes were acting erratically during hard stops, pulling to one side of road or the other and lacking good stopping power. I pulled the front wheels off and the pads and rotors looked great. After a couple more times driving my pedal is pretty well to the floor and my brake light is on and beeping. I pulled rear wheels off, adjusted rear drums which were way out of adjustment and reassembled. This fixed the Ebrake but brake issue remained. I then flushed all of the brake lines with new Dot 3 and bled everything. Does this sound like a bad master cylinder? There are no leaks in the system and no brake work done in last two years or more.

 

[Goatman]

Flush the entire system. Everything. TJs like to pollute the brake fluid. I had 3 rotors lock up due to shitty fluid. Had less than 30 miles from when I bought it. PO just stuffed new pads on all 4 corners too. Be sure all parts that need grease have grease. And be sure to re-gear all pads afterwards. I'd replace them if at all questionable. They are cheap. Be sure the fluid in the master is clean too.

 

[mrblaine]

A few weeks ago I noticed my brakes were acting erratically during hard stops, pulling to one side of road or the other and lacking good stopping power. I pulled the front wheels off and the pads and rotors looked great. After a couple more times driving my pedal is pretty well to the floor and my brake light is on and beeping. I pulled rear wheels off, adjusted rear drums which were way out of adjustment and reassembled. This fixed the Ebrake but brake issue remained. I then flushed all of the brake lines with new Dot 3 and bled everything. Does this sound like a bad master cylinder? There are no leaks in the system and no brake work done in last two years or more.

Nothing in or about the master will cause erratic stopping and a pull to either side.
If the pedal went to the floor and turned the light on, the system thinks there is a leak. Go over it again and make sure that the piston travel in the rear wheel cylinders isn't what caused the light to trip. Don't drive with the light on, try to turn it off by stomping the brake pedal a few times to shift the shuttle valve back.

Typically, the side to side pull under braking is due to way too much toe out or you have bad wheel bearings.

 

[Mjv]

If there are no external leaks there is fluid getting by the seals in the master or the ( proportioning valve). Im not sure wranglers have these. They distribute different pressures to front discs, and rear drums. Maybe someone with better knowledge will jump in.

 

[Mjv]

Nothing in or about the master will cause erratic stopping and a pull to either side.
If the pedal went to the floor and turned the light on, the system thinks there is a leak. Go over it again and make sure that the piston travel in the rear wheel cylinders isn't what caused the light to trip. Don't drive with the light on, try to turn it off by stomping the brake pedal a few times to shift the shuttle valve back.

Typically, the side to side pull under braking is due to way too much toe out or you have bad wheel bearings.

X2

 

[DustinfromOhio]

Re-adjusted the rear drums. Flushed and bled all the lines. Still the same issue, pedal goes to the floor and light comes on but will go off if I stomp on it a few times.

 

[mrblaine]

Re-adjusted the rear drums. Flushed and bled all the lines. Still the same issue, pedal goes to the floor and light comes on but will go off if I stomp on it a few times.

The light tells you that it thinks there is a leak or you have a lot of air in the system. How are you bleeding it?

 

[Goatman]

Does the pedal come up after you stomp on it or does it continue to go to the floor?

 

[DustinfromOhio]

Does the pedal come up after you stomp on it or does it continue to go to the floor?

It comes back up. After stomping a few times the pedal seems stiff/normal but then quickly depresses back to the floor.

 

[dbbd1]

Just because I have to ask...

Are the caliper bleeders on the top side of the caliper or the bottom side (should be on top)?

 

[mrblaine]

Just because I have to ask...

Are the caliper bleeders on the top side of the caliper or the bottom side (should be on top)?

I've resisted because he did not mention anything about replacing those parts. I hope I've been wrong.

 

[RobertJ]

How are you bleeding the system? The symptoms you're having now sound like air in the lines.

 

[DustinfromOhio]

Lol they are on top. I haven’t removed or replaced any part of the brake system since purchase several years ago. I’m going to throw a new master cylinder on this week, see what happens. After that I’ll recheck toe as Blaine suggested although I believe I remember him stating once that excess grease from tie rod boots could migrate to the rotors and cause erratic braking so that’s a possibility as well for the left and right issue?

 

[DustinfromOhio]

How are you bleeding the system? The symptoms you're having now sound like air in the lines.

Crack the bleeder, have a buddy swiftly push pedal to floor and hold, close bleeder, release. Repeat as needed.

 

[Goatman]

What order did you bleed the brakes in? Did the master ever suck air as you were bleeding? Are all blenders tight?

 

[RobertJ]

Crack the bleeder, have a buddy swiftly push pedal to floor and hold, close bleeder, release. Repeat as needed.

I am not the biggest fan of that method. If I were you, I'd either invest in a reverse bleeder or spend some time doing a gravity bleed. Gravity bleeding takes time, but it works 9/10 when I'm having trouble bleeding brakes. I recently replaced every hard/soft brake line along with calipers/cylinders and did a reverse bleed. After that, I had a soft pedal and then I took the time to gravity bleed and after had perfect brakes.

The way I do a gravity bleed/flush is I start with the rear/passenger side and let it drip for at least an hour while watching the fluid level in the master cylinder. Then I spend at least 45 minutes on the rear/driver side, 30 on the front/passenger and then 15 on the front/driver side.

Good luck either way.

 

[DustinfromOhio]

Replaced the master cylinder last night, pedal is great and light is off. During test drive I noticed a slight pull to drivers side during heavy breaking. I’ll recheck toe as Blaine recommended above.

 

[RobertJ]

Replaced the master cylinder last night, pedal is great and light is off. During test drive I noticed a slight pull to drivers side during heavy breaking. I’ll recheck toe as Blaine recommended above.

Glad it worked out for you. Did you have to bench bleed that MC before installing?

 

[DustinfromOhio]

Glad it worked out for you. Did you have to bench bleed that MC before installing?

I did. It was actually a real pain because I couldn’t get a good seal with the plastic plug they gave me, have to get creative.