I pulled the rear calipers and brackets off of a 2000 mustang GT yesterday and now I'm really wanting the bigger discs. Can anyone give me a yes/no on if the Cobra rear discs will fit with factory 15" 10 slot/hole wheels? I see where the how-to says "you may have clearance issues" and I see a post that says "I have 15 inch rims so I went with GT brakes", but I didn't even pop a wheel off yet. I figured I would double check here before I go buy Cobra rotors just for mock-up and possibly have to return them. I tried to search but didn't find a definitive answer.

The cobra rear discs are listed as about 10mm larger diameter than my front discs. 296mm to 286mm or 11.65" to 11.28". I read that I have to clearance the GT bracket for the width of the cobra rotor... but i'm just curious about the diameter. I peeked my head in behind my front brakes and it seems like there is at least 1/2" to 3/4" of room between the caliper and wheel.

 

I have Cobra brakes on the back of my truck, and I don't feel that they're so large that they would interfere with the 15" wheel based on the diameter of the wheel, but rather the way the wheel is designed. If the barrel of the wheel is too small, that may cause fitment issues. I don't have the wheels you mention, so can't speak to whether they will interfere or not.

 

These are my fronts. The overall diameter of the cobra rotor is 3/8" larger. It looks like there is 5/8" or 11/16" for sure. It seems like it should fit.... unless the single piston rear caliper sits much higher on the rotor than the dual piston caliper on the fronts, or there is something else I'm not thinking of. If nobody happens to reply who has done it with these wheels then I will just give it a go I guess.

Also, before I start, I would love to hear if you are still happy with the brake swap after some time? Did you run into any problems with the rotor walking/wobbling, wear, or any issues with installing?

 

I have been running them since around 2016 or 2017. I have not had any serious issues, aside from pad wear being uneven. The set I installed back then were just replaced last weekend, and weren't completely gone, just replaced for peace of mind. They wore in a taper, and I believe that may have been caused by the caliper piston not being aligned properly with the brake pad. There are raised nubs on the backside of the inner and outer pads. There are also two triangular recesses in the caliper piston. The raised nubs on the brake pads are supposed to sit in the triangular recesses on the piston. I noticed that mine were not, and I noticed that the nubs were basically ground off of the brake pads. I didn't notice any braking issues related to this, just the uneven pad wear. But only time will tell whether that was the issue, or if the issue is related to something else in the swap.

One thing to note is that replacing your brake fluid at the recommended interval is a must. I had quite a bit of rust behind the driver's side piston boot, which ended up seizing the boot, and tearing it. I ended up having to do a partial rebuild on the caliper to clean it up and install new seals. I did not regularly change the brake fluid and attribute at least some of the rust to the moisture buildup from the old brake fluid.

Another thing to note is that hooking up the E-brake can be a pain due to the spring that surrounds the cable. It likes to get in the way as you'll discover, but I remedied it last weekend by cutting three of the coils out of the spring. That gave me just enough exposed cable to be able to insert into the arm on the caliper without too much force.