The Mazda 323GTX came with four wheel disk brakes from the factory, but even these can be improved. Many car owners have noticed brake fade or warped rotors after repeated high speed stops. This is do to the small size of the stock rotor and it's inability to dissipate heat. Another problem area that can be corrected with this brake upgrade is the the rotor placement. The stock location puts the rotor behind the hub, making replacing stock rotors an all day event.
A common, and well documented, upgrade for the GTX is to replace the stock rotors with factory rotors from the 1989 Mitsubishi Gallant VR4. This is commonly known as the VR4 Brake Upgrade. This is a simple bolt on upgrade with minor grinding work needed and some unconventional uses of the press. The rotors needed are the 266mm diameter versions. The Gallant also used a 256mm and a 276mm rotor, make sure you get the right rotor. I used KVR replacement rotors for my upgrade and was able to buy them locally for a good deal. I used for KVR part number MI332. For what it's worth, the KVR rotors were stamped BREMBO on the edge.
In order to mount the rotors on the outside of the hubs, the wheel studs also need to be replaced. I am using longer RX-7 wheel studs. The rear wheel studs from the 87-93 Mazda B2200 can also be used.
IMPORTANT! I am told the RX-7 studs do not work on stock wheels, the shoulder is too long, and you will run out of thread when you tighten your lugs.
You will also need to replace the calipers. The swap was first done using front calipers from the 90-94 Familia GTX, sourced from overseas. Since these are not easy to come by, the guys at Cork Sport have determined that the US Protege/Escort GT/MX3 use the same calipers. CorkSport also sells the complete kit, no need to hunt for your own parts. As it turns out, any bone stock '95+ Ford Escort Wagon or Coupe calipers may be used. Just look for the numbers 22V / 14 stamped on the caliper body. I am using calipers removed from a Ford Escort wagon. Some calipers I was looking to grab were actually stamped 22V / 13. Be sure to look. Your stock brake lines can be modified to work, or you can replace them with Ford units. I made a custom set of lines from parts I source through various vendors. I spent more time, and probably as much as the ready made sets sell for. Save your time, buy the lines that are made for our application. I used KVR pads Part No. M7353 for a Escort GT or Mazda MX3 1.8 V6. Porterfields have also received rave reviews. You probably want the R4S compound. I use these on my turbo Miata with great results.
The only part that is not a direct bolt on is the rotor. You will need to grind about a 1/4" off the ends of the hub ears. This modification is required to allow the rotor to sit flat on the hub surface. There is a lip on the inside surface of the rotor that you may not notice this if you simply slide the rotor over the hub.
10 15/32"
1 51/64"
.945"
.882"
Getting Started
Note: I started my brake upgrade when doing a motor swap and replacing my suspension, so my installation procedure and pictures may not be the best sequence if you are only doing the brake upgrade.
Starting on the outside of the car, I raised the car, supported it with stands, and removed the front wheels. You will need to remove the whole knuckle assembly. I started by removing the brake caliper, axle nut (29mm), tie rod end, ball joint and strut. I also removed the front sway bar to allow more room to work when I replace the suspension.
That is the easy part. To remove the hub from the knuckle I had to use a few methods that don't come in the hydraulic press instruction guide. We actually had to hang the assembly with a pair a chains to press out the hub. Not safe, and not recommended., but effective. Do not set the the assembly on the rotor to press it out, remember, the hub is bolted to the rotor. I remembered after 2 or 3 good pulls on the press handle, "Why isn't that thing moving?"
I used a standard bearing splitter to remove the bearings from each hub, but do not forget about the bearing spacers. I kept the spacers with the hubs they came from, and I was able to reuse them. I kept both sides completely separated so I could reinstall the hub from the knuckle it was removed from. With one race installed in the knuckle, I was able to measure the space with a micrometer. After some basic math, it was clear the origianl spacers would work. I re-used the No. 8 and No. 10 spacers.
After the hubs were removed, I knocked out the factory studs and moved over to the belt sander. I installed 60 grit paper, and started to remove material from the 'ears' of the hub. I removed about a 1/4" from each 'ear' to allow the hub to be placed inside the rotor. This process took about 25 minutes per hub. I also installed the new RX-7 wheel studs at this point. When I test fit the rotor, I noticed the splines from the wheel studs were not allowing the rotor to seat completely on the hub. If I would have measured this, I could have removed the part of the spline that stuck past the hub face. I just used the press to seat the rotor on the studs.
Before bolting everything back together, I put the hub and knuckle in the blasting cabinet for a quick cleaning before applying a coat of black paint. I always like to clean parts before reinstalling them. It makes installation go smoother, and allows me to clean parts of the car I usually don't get to.
Everything went back together with no complications, just a lot of measuring to make sure the spacers that came out of the car could be used again. I don't want to pull this thing apart any time soon. At least with the rotors on the outside of the hub, replacement will be a lot easier next time.
I picked up some Timken bearings and seals for around $60 at the local auto parts store, it appears the standard 323 uses the same parts, good news for us. Be careful to keep the assembled knuckle in a clean environment if you not installing them right away, the bearings are exposed to the environment until you bolt them on and install the front half shafts.
The calipers I'm using are from a late model Ford Escort, they have 14 22V stamped on the caliper body. Look closely, my last trip to the yard I came home with 4 sets of 14-22V's and one set of 13-22V's. They all seemed to be pulled from the same make, model and year Escort.
I disassembled the caliper and cleaned it up in my blasting cabinet. After a thorough cleaning, I shot it with some gray lacquer and installed a rebuild kit. This is another time were spending a few extra bucks up-front would have saved me a lot of work. Brake caliper rebuild kits are a dying breed, the ones I bought took over 3 weeks to be delivered. If I had to do it over again, I would buy remanufactured calipers in the beginning, and saving me the extra work.
Update - Since acquiring the Eastwood Powder Coating System, I decided to re-do my calipers. I disassembled the caliper and separated the two parts that make up the housing. I cleaned the caliper and carefully taped off the parts I didn't want powder and sprayed on some bright red powder. 30 minutes later I had nice red calipers that will hold up better than spray paint or lacquer.
The way Mazda should have done it, and the way it should look when you complete the 'VR-4 Brake Upgrade'.
The new KVR vented rotor. I ordered mine coated and slotted through a local retailer.
It's easy to see the difference with a side by side comparison. There is a lot more material (and weight) on the VR-4 rotor.
New wheel studs are needed with the rotor swap. I used RX-7 studs, but need to use spaces with factory alloys.
New calipers can be sourced from late model Ford Escorts. Just look for the numbers 14 22V stamped on the side.
The 'ears' on the stock GTX hubs need to be ground down to fit inside the rotor. A 1/4" is removed from each 'ear'.
After the grinding is complete, the new studs can be pressed into place. Be sure to clean the hub after grinding on it.
While everything was apart, I took the time to clean and paint the hubs, dust shield and spindles.
The junkyard calipers after some cleaning and a coat of laquer. The rebuild kits can take some time to order.
Stainless steel brake lines are available for the GTX. They help to maintain good pedal pressure, and are cheaper than factory replacements.
I decided to use KVR pads. I'm told they make a nice street pad, and I got a good deal on them when I ordered the rotors.
Rotors
Brake Lines
Front Pads
Calipers
Wheel Studs
When I found out I couldn't use the stock wheels with the wheel studs I installed, I bought some 5mm spacers to mount behind the wheels. These are the $8.00 versions and are not hubcentric.
Since the calipers were not on the car yet, I took them apart again and powder coated them. With no engine yet, I find myself powder coating everything.
