Mark99GT

The passenger side rear brake has been grinding lately, so I was attmepting to diagnose the problem today. I jacked up the rear of my car (in neutral with the parking brake off) and tried to spin wheels by hand. The wheel was EXTREMELY hard to rotate and you could hear the brakes grind while I was turning it. How freely should the wheel spin? Im thinking the rotor is warped, so I think Im gonna do an entire cobra upgrade. Ive been wanting better brakes anyways.

I was looking online and found a 13" rear upgrade. Are there any fittment issues with a 13" rotor? I think the standard cobra rotors are like 11.65" right? I think the 13" drilled zinc coated rotors all around would look pretty good.

At the same time I checked the driveshaft. If is wiggles back and forth a little bit the u-join is shot right?

thanks

djdalfaro

I think you're right on the warped rotor... the stockers just don't cool enough... I have the same problem on the front and mine was a warped rotor... I also plan on going 13 all around if they fit.

Mark99GT

anyone know if 13"s will fit all the way around with the proper mounting hardware? and play in the driveshaft is a worn u joint right? thanks

GodAmGT00

Okay first off, the rear tires, even in Neutral won't spin all that freely. You have a lot of shtuff connected to them, that won't let it "free wheel."

If you hear grinding, pull the caliper off, and remove the rotor. Look at both sides of the rotor. Almost sounds like one of your rear calipers is frozen shut. Not a biggie, I've seen a TON of Mustangs w/ rear caliper issues. Funny enough, mine just froze up not too long ago, mostly in part of the rubber boots deteriorating, leaving the guide pins exposed..

You really should replace the caliper, since rebuilding calipers is a bitch if you've never done one before... Requires a lot of patience..

Now, for your other question. Cobras have 13in brakes in the front, 11.65 in the rear. There's no need to push the rears to 13's, unless you were road coursing the car. The reason for this is, the rear brakes are basically only there to slow down the driveshaft.. Well, they do slow the car down, but not nearly as much as the fronts..

Lastly, which way does your driveshaft wiggle?? Can you see any of the rubber boots on the u-joints moving? If not, go back to the rear axle, and watch the pinion flange, and push up and down on the driveshaft. If the pinion flange goes up and down, it's just about that time to rebuild your rear end... If you can see just the axle wiggling, at the u-joints, then go ahead and give em a toss...


JT

Mark99GT

yeah, i figured it was supposed to be a little difficult to spin the wheels, but I was pulling on it almost as hard as I could (im a pretty big, strong guy) to get the wheel to turn. The car also stops on its own while rolling in neutral as if i applied the brake. I wanted the new brakes anyways, so i'll probably go with the whole upgrade. thanks. ill take another look at the drive shaft too.

ShadowDrake

13" brakes will fit all around, but you'll be paying quite a bit for a kit for the rear because it wasn't on any stock stangs (the mounting setup for the caliper in the rear is different than the front). You can find a kit from a Cobra for only $350-400... but a company like Baer will charge much more than that. 11.65" for the rear will be good enough, it'll just look a little small. It seems much more normal than 13" all around though.

The only requirement for 13" brakes is 17" wheels.