Brake upgrade FAQ by JMortensen

11 minute read

Brake upgrade FAQ 

Compliments of JMortensen @ http://forums.hybridz.org

8-24-2005

Brake FAQ - Hopefully this will be of some use to everyone.

What to do about Z brakes?

The stock Z brakes are adequate for street driving, autox, and drag racing.
The stock Z brakes are adequate for street driving, autox, and drag racing.
This is not a joke. Even with a V8 or turbo pushing lots of hp;
The stock Z brakes are adequate for street driving, autox, and drag racing.

This is especially true if you upgrade the pads to suit your driving. KVR, Porterfield, Hawk, and others make proven pads and shoes for aggressive driving in Z's.

If properly maintained and if cooling ducts are added, the stock brakes can even be used for road racing. The faster you get the more intense the maintenance will be to keep them race ready. Bleeding between sessions and adjusting shoes between sessions are common practice. Turning the drums to precisely the same ID is also a good idea for a road raced Z. Stock brakes are lighter than just about anything that you'll put on the car as an upgrade, so autoxers and drag racers looking to put their car on a diet should consider the weight penalty of an upgrade.

OK now that's out of the way. So lets look at some braking upgrade options for Z cars.

FRONT BRAKES

The 4 piston caliper: The Toyota 4 wheel drive pickup trucks from about 79-85 will bolt directly onto the Z strut and will work just fine with the stock non vented rotor. This upgrade will require the minor step of trimming the backing plate to make room for the new larger caliper. It is also recommended that the larger 79-81 280ZX master cylinder be used, since the 4 piston calipers displace quite a bit more fluid. Although the master cylinder isn't absolutely necessary, the pedal throw is a bit long without it. Fits most 14" rims.

The VENTED 4 piston caliper: This is the same as above, but uses an '84 300ZX vented rotor and a different caliper from a 89-95 4wd pickup or 4/89-91 4 Runner. This caliper is an S12W and is stamped as such. These parts do not just bolt on unfortunately. A spacer is needed between the rotor and the hub to line the rotor up with the caliper correctly. This spacer is available from www.modern-motorsports.com and is a different thickness for 240 and 280 hubs (260s as usual have 240 hubs in the early part of the year and 280 hubs in the latter part). This is a substantial upgrade from the solid rotor 4 piston caliper upgrade because the vented rotor can shed a lot more heat than the solid rotor. Fits most 14" rims.

The 300ZX rotor/280ZX caliper mod: blueovalz came up with this one, and I grabbed most of this info off of the zhome.com website, so check me for accuracy Terry. Use an 84-86 NA (which is a vented 4 lug) 300ZX rotor along with a 280ZX front caliper. It is a floating caliper, so there is less potential for interference with wheels than a 4 piston caliper. The Z strut is threaded, and the ZX caliper is threaded. Solution: drill out the threads in the strut with a 15/32" drill bitand slide the bolt through to attach to the caliper. The caliper also needs to be spaced out to center over the rotor. A simple washer of a thickness around .160" (may vary) should get the caliper centered with early hubs. Later 280 style hubs are thicker and place the hub too far inboard, requiring the rotor mounting surface on the back of the hub to be turned down. The outside diameter of the 300ZX rotor is a bit too large as it comes from the factory, so the rotor also needs to be turned down about 1/4" total to fit inside the rotor. From there it all just bolts together. The bad part about this mod is that the rotor is a wear item, and this machining needs to be done every time they are replaced. A different more difficult solution is to cut the caliper mounting ears off the strut, position the caliper correctly on the full size rotor, then weld the ears back on. This will add 1/8" to the length of the ears and then the off the shelf rotor will work, but obviously this is a pretty advanced modification and only those who are very experienced with fabrication should even consider it.

The Arizona Z Car Wilwood: This is really a racing brake setup. Aluminum hats attach to 280 hubs (you'll need to swap out your 240 hubs for 280 hubs if you have a 240 or early 260) and then the cast iron 12.2" x 1.2" rotors bolt to the aluminum hats. A caliper bracket bolts to the strut and locates the caliper correctly over the rotor. The calipers are Wilwood Superlite 4 piston calipers. The rotors are just a tad over the weight of the original cast iron Z rotors, but are MUCH larger and can take a huge amount of heat. This upgrade does require some modification to the control arm to allow the rotor to clear the end of the arm near the ball joint. Fits some 15" rims. www.arizonazcar.com

The Arizona Z Car 13" Wilwood: Same as above but with 13" rotors and Wilwood 6 piston calipers. Requires 16" rims www.arizonazcar.com

The Modern Motorsports Extreme 13" PBR: This system uses an aluminum hat and a cast iron rotor. The PBR caliper is a stock piece from a Cobra Mustang, so brake pads are as close as the local auto parts store. The calipers have dust seals, where Wilwood calipers do not. Opinions as to the importance of the dust seals is mixed. I personally think that they are a good idea on a street car, but not absolutely necessary for someone who is looking at the brakes frequently (weekend warrior autoxer or track day type who regularly bleeds their brakes). www.modern-motorsports.com

The Mustang Cobra: This braking system uses new hubs from Modern Motorsports and a stock 1994-2004 Cobra rotor, along with a caliper bracket and a 2 piston PBR caliper. The advantage to this setup over the aluminum hat style rotor is that you can go to the corner auto parts store and buy a rotor. The disadvantage is weight. The Arizona Z Car and Modern Motorsports rotors weigh about 13 lbs assembled. The Cobra rotor is much heavier at ~25 lbs. www.modern-motorsports.com

REAR BRAKES

Z-Quip early 280ZX brakes: Z-Quip is no longer in business, but this kit included nothing more than a pair of caliper brackets which allowed early ZX rotors to be used with early ZX calipers on a 1st generation Z car. This wasn't much of a performance upgrade, but did make servicing the brakes quite a bit easier and looked nicer than drums as well.

ZX/Maxima swap: The rear wheel drive Maxima (79-83?) had a rear disk brake bracket which could be used on the rear of a first gen Z and would allow the 82-83 280ZX rear rotor and caliper to bolt directly on. This was a very popular setup, but the caliper brackets have become increasingly hard to find.

Modern Motorsports 240SX/300ZX: Modern Motorsports sells a caliper bracket which correctly locates a 240SX caliper over a 11" 300ZX solid rotor.

Arizona Z Car rear Wilwood: This is similar to their front brake kit, except the rear uses a slip on rotor. The rotor consists of an aluminum hat and a cast iron rotor which is 12.2" in diameter and .83" thick. The caliper bracket locates a Wilwood Dynalite 4 piston caliper correctly over the rotor. This system provides no ebrake functionality, so ebrake is removed entirely. It does come with a line lock which can serve as a temporary parking brake but will not work at all in the event that hydraulic pressure is lost in the brakes. Some have reported that the line locks can leak down their pressure, so watch it if you park on a hill. Might be a good idea to use a wheel chock in addition to the line lock in that event. www.arizonazcar.com

BACKING PLATES

Concerning backing plates and how to modify them: All of these modifications will remove the backing plates, except the non-vented Toyota 4x4 mod which only requires minor trimming with tin snips to work, and alternatively if you want to remove the backing plates you can in that instance too. The downside to removing the plates is that water will get on the rotors more easily when driving in the rain so that first stop after driving in the rain for 20 minutes won't be very good, and there is more of a possibility of a stone or a piece of trash on the road getting thrown up and caught between the rotor and the brake pad.

5 LUG BRAKES

Some people are switching to 5 lug hubs for better availability of wide rims (4 lug tend to be mostly available in FWD offsets).

The early 300ZX 5 lug front hubs will work on a 1st gen Z with some slight modifications and the vented Toyota brake upgrade from Modern Motorsports is available in a 5 lug version to fit.

Modern Motorsports and Arizona Z Car also offer aluminum 5 lug front hubs with their Extreme and Wilwood braking systems discussed above. Rear hubs can be redrilled for 5 lug, or Modern Motorsports now offers a 4340 billet stub axlein 5 lug.

ADJUSTABLE PROPORTIONING VALVES

The proportioning valve cuts the pressure to the rear brakes so that under very severe braking the front wheels lock first. Front wheels lock = car goes straight. Back wheels lock = car spins. When you change the front or rear brakes from stock you lose the ratio of front to rear brakes which the stock proportioning valve was designed for. The way to properly address this issue is to install an adjustable proportioning valve. The stock proportioning valve must be removed and the adjustable valve gets plumbed into the line that goes to the REAR brakes. Pressure can be adjusted up or down until proper brake bias is restored. Proper brake bias is when the front brakes lock BEFORE the rears. Two types are the knob style with infinite adjustment, and the lever style which usually has about 5 settings and is used by racers to cut down the amount of rear brake over a long race, since the car burns the fuel off and the rear gets lighter as the fuel level goes down. The knob style is probably a better choice for most people since it can be more finely tuned.

STAINLESS BRAKE LINES

Stainless brake lines are a very good idea and they provide much better pedal feedback. If you haven't replaced your stock 30 year old rubber brake lines, consider this cheap and effective upgrade.

MASTER CYLINDERS

The stock master cylinder is really unsuitable for any 4 piston caliper upgrade. It works marginally for the Toyota 4 piston calipers, but really increases the pedal throw. A 79-81 280ZX master is a nice upgrade and is suggested by Modern Motorsports and Arizona Z Car when using their brake kits discussed above. There are two masters in the ZX's. The early one has dual reservoirs and fits onto a Z booster. The later one has a single reservoir and has the reservoirs clocked 90º making it incompatible with the Z booster.

Here is the correct ZX master (79-81):


And here is the incorrect later master (82-83):


OTHER STUFF:

There are lots of one off setups which I didn't discuss here, as I thought they weren't common enough to warrant it. Big Red Brakes from a Porsche have been fitted to a Z, and Z32 brakes have also been used. There was also another setup sold by JSK and another by scca and these guys are no longer selling their kits, so I didn't include them. Racing master cylinders setups with dual masters also weren't included. This FAQ does not cover every situation and every possibility, just the common ones.

Some of the more obscure ones are covered in this thread: http://forums.hybrid...ad.php?t=104735

LAST THING:

If you find an error in the above or missing info that needs to be there, please point it out. If you choose to modify or work on your own brake system, you do so at your own risk.