Dragging brakes (1 Viewer)

[hammerheadfistpunch]

Taking alternate theories as to why my brakes are dragging? My shop accidentally put contaminated fluid in my brakes a month or so ago and its been a nightmare getting it right again. They eventually replaced my calipers, ABS module LSPV and Master cylinder and cleaned and flushed the lines but I am still getting brake drag. I don't know if its still the contamination issues or if its setup wrong. FSM says to check the clearance between the MS piston and the booster rod and they assure me its in spec. What would the next step be? When they replaced the master with the rest of the hardware they had to reuse the reservoir but they cleaned it out first, the symptoms came back so they brought in a new MS with new RES and installed it but my brakes are still 180 degrees F (rear) and 160 degrees (f) front after even just a moderate cruise through town. Plus I get a bad vibe at speed from the drag.

New soft lines?
New hard lines?
Would it matter at this point or would it be a complete re-redo of the entire brake system?

I need to get this fixed.

 

[baldilocks]

What indications are you getting that the brakes are dragging?

 

[hammerheadfistpunch]

What indications are you getting that the brakes are dragging?

Hot brakes, driveline lash, decreased acceleration, vibrations at speed that are getting progressively worse, and listening to them with the engine off in neutral scraping.

I mean it could be something else (bad VC is my next guess) but These symptoms come and go everytime I have the brakes worked on. Im on my 5th or 6th master cylinder

 

[baldilocks]

It's time to dig into it yourself. I would be very interested to find out if the booster and MC clearances are rigged properly.

More and more often here lately, we are seeing posts by members who have had bad luck at shops.

I'm subscribed to this one .

 

[ZackR]

Have you checked the brake hoses? Old/worn hoses can result in fluid not flowing back when pressure is released which results in drag on that caliper. This happened to me on my old Volvo and after several "repairs" in the shop it would still drag (the wheel was hot to the touch). When I replaced the brake hoses it solved the problem.

 

[Rivman1243]

You need to have the soft lines replaced, anything that isn't metal needs to be replaced

 

[hammerheadfistpunch]

You need to have the soft lines replaced, anything that isn't metal needs to be replaced

I would think so too, though they should be lined like a PS hose so I can't see that being a big part of the problem. And if they are...that would mean new calipers too, right? since the contamination would move downline to the calipers.

 

[hammerheadfistpunch]

It's time to dig into it yourself. I would be very interested to find out if the booster and MC clearances are rigged properly.

More and more often here lately, we are seeing posts by members who have had bad luck at shops.

I'm subscribed to this one .

Sigh...I hate working on brakes. I hate bleeding brakes. and I don't want to waste my weekends on this...but I am tired of taking it back in.

 

[ZackR]

If you plan to do the soft lines spring for some braided ones from Slee (or equivalent). Since everything else is new you'll be in good shape afterward.

After a saga like that I'd also be hanging my head low in thought of doing more brake work.... you are on the home stretch.

I'd recommend the gear wrench flex flare nut wrench set (+ PB blaster) for replacing hoses. Also lots of fluid (keep topping up the reservoir as fluid leaks out) and a way to plug the old lines while taking them off to minimize air into the system.

GearWrench 81911 6 Piece Flex Flare Nut Wrench Set Metric - - Amazon.com

 

[Red Merle]

I would check to be sure the booster and MC are adjusted properly. If the booster pin is sticking out too far, that might cause the MC to start activating the brakes.

 

[ZackR]

And one last comment - focus on one wheel at a time, do the inner and outer hoses there and flush with new fluid. This will help minimize pockets of air in different parts of the system.

 

[hammerheadfistpunch]

Thanks all, sounds like checking the booster/ms interface is step one and brake lines are step 2.

 

[Tools R Us]

... but my brakes are still 180 degrees F (rear) and 160 degrees (f) front after even just a moderate cruise through town.

That is nothing for brakes, hardly warm. It's normal for disk brakes to touch the rotor, this heats them before even touching the pedal. When used, even moderately spirited, it wouldn't be uncommon to see double or triple that temp. Brakes work by turning energy into heat, those numbers would be on the cold side, most brakes are more effective at higher temps.

... Plus I get a bad vibe at speed from the drag. ...

I doubt it's from drag, any smoke, strong smells, pedal pulsation ? With brakes that are having drag problems, it's not uncommon to see 1000F+.

 

[BILT4ME]

Why would they have NOT replaced the hoses? Anything rubber MUST be replaced, as that is what swells up from the contamination!

Disc brakes drag all the time to some degree. There are no springs or anything to release them from contact with the rotor.

If your REAR brakes are hotter than your front, I would look at the adjustment of the LSPV and they are SUPPOSED to equalize the system with the vehicle at "normal" load and adjust it to equalize the pressures in the system. The FSM details this info.

You state your rotors are operating at 160°F and 180°F. What is the CORRECT temperature supposed to be?

 

[hammerheadfistpunch]

Why would they have NOT replaced the hoses? Anything rubber MUST be replaced, as that is what swells up from the contamination!

Disc brakes drag all the time to some degree. There are no springs or anything to release them from contact with the rotor.

If your REAR brakes are hotter than your front, I would look at the adjustment of the LSPV and they are SUPPOSED to equalize the system with the vehicle at "normal" load and adjust it to equalize the pressures in the system. The FSM details this info.

You state your rotors are operating at 160°F and 180°F. What is the CORRECT temperature supposed to be?

Before I starting having brake problems I was looking at 90 rear and 110 front tops.

 

[hammerheadfistpunch]

That is nothing for brakes, hardly warm. It's normal for disk brakes to touch the rotor, this heats them before even touching the pedal. When used, even moderately spirited, it wouldn't be uncommon to see double or triple that temp. Brakes work by turning energy into heat, those numbers would be on the cold side, most brakes are more effective at higher temps.



I doubt it's from drag, any smoke, strong smells, pedal pulsation ? With brakes that are having drag problems, it's not uncommon to see 1000F+.

When my brakes were REALLY bad in moab I was firewalling the throttle to maintain 40 to get back to town and the brakes were about 600 f

 

[hammerheadfistpunch]

That is nothing for brakes, hardly warm. It's normal for disk brakes to touch the rotor, this heats them before even touching the pedal. When used, even moderately spirited, it wouldn't be uncommon to see double or triple that temp. Brakes work by turning energy into heat, those numbers would be on the cold side, most brakes are more effective at higher temps.



I doubt it's from drag, any smoke, strong smells, pedal pulsation ? With brakes that are having drag problems, it's not uncommon to see 1000F+.

The reason I suspect the brakes is because the vibration goes away for the first few days back from having the brakes worked on again, then it returns. I guess it could be from something else, but its logical to assume its brake system related.

 

[Tools R Us]

Why would they have NOT replaced the hoses? Anything rubber MUST be replaced, as that is what swells up from the contamination! ...

Why would they automatically replace them? Brake fluid is water based, oil is well oil, floats on water based. Have seen slight oil contamination where the oil floated, never got into the system, only need to be removed, then flushed, never more of a problem. Each case differs, have also fought them were all of the rubber needed to be replaced, but that would be rare, the exception.

... If your REAR brakes are hotter than your front, ...

Somewhat normal, especially when lightly used. The rear brakes have less cooling fin/area, also, in use, the air under the rear of the rig is warmer, the front and rear don't cool evenly, not perfectly the same.

 

[Tools R Us]

When my brakes were REALLY bad in moab I was firewalling the throttle to maintain 40 to get back to town and the brakes were about 600 f

Now we are talking problem, does it still do that?

 

[Tools R Us]

The reason I suspect the brakes is because the vibration goes away for the first few days back from having the brakes worked on again, then it returns. I guess it could be from something else, but its logical to assume its brake system related.

You know where assumptions get us right? More info, what type of sound, change with speed, pedal pulsation, feel it in the steering, seat, transfer shifter, etc?