Rear brake issue

[pbeechner]

Hey guys,

So, I've been having a problem with my rear brakes. About two weeks ago I started noticing slack in the hand brake and last week I realized that my right rear caliper was sticking and the pads were pretty much gone and the rotor was toast. So I got a rebuilt caliper, new rotors (both sides) and new pads. Did the caliper, rotor, and pads on the passenger side this past Saturday and thought I was golden. Now I'm having some strange symptoms. When the car is cold (been sitting for at least 3 or 4 hours) I can drive it up and down the road and there will be no rubbing on the passenger side (I checked the temp of the rotor side to side with an infrared thermometer to make sure). As soon as I drive more than 4 or 5 miles (i.e. the car and braking system warms up) there is rubbing and after another 2 or 3 miles I got a nice little cloud of brake smoke from the right rear.

I think the original caliper was fine, as I was able to compress the piston fairly easily when I removed it, but I installed the rebuilt one anyway. I bled the brakes properly and have better pedal feel than before.

I can only assume that something is happening to cause the pressure in the piston not to release once the car is hot. Could it be something in the lines or the booster? A bit at a loss on this one so any advice is greatly appreciated.

Thanks guys!

 

[quick01snake]

Possibly got pads for a gt? They are thicker and would do what you're describing.

 

[soccerman002]

That's what I was thinking as well - the rear rotors for Cobras are vented, making them thicker than the non-vented rotors on a GT, thus the GT's have a thicker brake pad. If you mix up the two, you can get symptoms like what you're describing. I've seen where auto parts stores (Advance, Auto Zone, etc.) will have the part #'s mixed up, or they won't have differing part #'s at all for the different brake components. Might want to start there.

 

[pbeechner]

Possibly got pads for a gt? They are thicker and would do what you're describing.

That's what I was thinking as well - the rear rotors for Cobras are vented, making them thicker than the non-vented rotors on a GT, thus the GT's have a thicker brake pad. If you mix up the two, you can get symptoms like what you're describing. I've seen where auto parts stores (Advance, Auto Zone, etc.) will have the part #'s mixed up, or they won't have differing part #'s at all for the different brake components. Might want to start there.

Yeah I was thinking that as well. I knew the rear rotors on GTs are not vented and the caliper was pretty tight to get on with the pads. When I get home from work, I'll check the part number on the box they gave me at advance auto parts.

From their website it looks like the Wearever Platinum Premium Ceramic P/N for the Cobra rear pads is PNAD627A while the part number for the GT pads is PNAD627. Looks like the Cobra pads are a special case of the GT pads.

Thanks guys!

 

[pbeechner]

I'm also not sure though, since the first time I drove it up and down the road after changing the caliper, rotor, and pads, I had smoke at the end of 1.8 miles. The next morning, I drove it the same distance to the end of the road, and each side was exactly the same temperature (+/- 5*), but once the car warmed up, by about 8 miles, I had smoke again and very hot rotor, caliper, wheel, etc. Then it was consistent having to stop every 2 miles or so on the way back and let things cool down a little.

So I'm not so sure that too thick brake pads would cause that kind of problem. Also while it was cold the next day, I was tightening lug nuts with the hand brake off, and could roll the car freely from that wheel, whereas I could not the day before. If it was just that the pads were too thick, I would be getting overheating rotor/caliper/pads from the get-go and not after a certain amount of time (i.e. car warming up)

Sorry about the wall of text....

 

[pbeechner]

So, I checked the part numbers and everything is good there. I have the correct pads.

When I got home from work, I pushed the car by rolling that back wheel and everything was free and happy no rubbing. I drove it 3 miles out, passenger side is the same temp as the drivers side. Drove it the three miles back, things are much hotter on the passenger side than the drivers side and I try to push the car by rolling that wheel and its completely bound up. Pulled the wheel off and loosened the bleed screw and got a spurt of brake fluid so the pressure in the piston clearly wasn't releasing.

Maybe a bad ABS pump? Not really sure where to go from here since it is only happening on one wheel and no others.

 

[006]

Did you grease the slider pins? (high temp grease under the accordion boots)

Also, another possibility could be a collapsing brake hose that is retaining the fluid pressure in the caliper.

 

[pbeechner]

Yep greased the slider pins and double checked that the caliper was able to move on the bracket.

Used new pins and everything.

 

[olgreydog7]

The GT pads will not fit. They are too thick. SSB sent me the wrong ones by mistake finally busted out the dial calipers when they wouldn't fit.

 

[1999marg]

Our cars have an automatic e-brake tensioner. It sounds like you need a little slack in the cable. When you pull up on the brake how many clicks do you hear? One or two?

You release the tension with a small allen key. Be careful because you do not want to completely unwind the tension spring. I have not been able to find a good write up on the procedure. However I was using google and not the search feature here (it is early). Check the road race forum it the new edge or termi forums are not helpful. I am sure that the track guys replace pads several times a year.

Cheers

Mike

 

[pbeechner]

I've set the slack on the hand brake correctly to prevent any sort of sticking. I've also double and triple checked that the pads are correct, and they are. Now when the car is cold, the pads do not contact the rotor.

Again, after the car is hot and the brake is sticking, I loosened the bleed screw and got a small spurt out which isn't supposed to happen....

I've got a wedding this weekend, but when I get back next week I'm going to replace the flexible section of brake line near the caliper in case it is swelling on the inside and preventing pressure release....

Thanks guys

 

[toomnymods]

What ended up being the problem with this??
I have the same issue on my 2014 mustang gt with only 9400 miles..
Drives fine when cold, drive it 2-3 miles and smoke the only right wheel is hot, cant barely push it with ebrake off when pads are hot but cold it moves fine

 

[OldSVTGuy]

I had a similar issue years ago. One side was VERY hot and ended up heat-cracking the rotor. Notice that there are two pins on each rear pad at the 12 o'clock and 6 o'clock positions. Notice the notches in the caliper piston. They MUST line up. If the pins do not fit into the notches, you will overheat. I had to replace the rotor and pads. One side was fine - I guess I lucked out but the other side the pins and notches were not lined up. No problems ever since.

Good luck!!