Combination calliper/handbrake solutions are not as good as dedicated calliper/disc and independent parking brake solutions. The S14 and S15 both have rear combination brakes. A relatively straightforward conversion is to fit the rear brake setup from the Z32 300ZX.
The conversion consists of three main parts:
- Z32 rear discs and callipers, including replacement hoses
- Z32/S13 parking brake components and backing plate
- R33 handbrake cables
It is strongly recommended that you also replace the brake master cylinder with a Z32 item. This alters the braking bias, giving increased braking power to the new rear brakes. If doing this, it is a good idea to renew the seals in the unit.
It is recommended to refurbish the callipers too.
A suggestion to those looking to order any of the above parts new, particularly the handbrake cables, is to do so direct from Japan via Perfectrun.
I have received numerous requests for various part numbers for this conversion, so I've now listed down EVERYTHING you would need if buying all new.
R33 handbrake cables
Z32 parking brake mechanism
Z32 rear disc brake rotor
Z32 rear disc brake calliper
Z32 brake master cylinder
Tools required for this conversion:
- 12mm, 14mm, 17mm, 19mm, 21mm, 27mm and 32mm sockets
- Short and long socket extensions
- 10mm extra deep socket
- 19mm spanner
- 10mm brake pipe spanner
- 2 foot breaker bar with as long an over-bar as possible
- 3 stud hub-puller
Loosen wheel nuts, jack the rear up and remove the wheels. Remove the wheel centres.
Figure 2 shows what we start with.
Remove the split pins in the hub nuts on both sides (Figure 3). Replace the wheels and three nuts per side. Lower vehicle - handbreak on.
Using a 32mm socket, short extension and breaker bar (with over-bar), loosen the hub nuts. These are real bastards and you'll soon see why the over-bar is required.
Once loosened, jack rear on vehicle back up and place on axle stands. Remove wheels again.
Chick the front wheels and place in gear. Release handbrake.
Using a 19mm socket, remove the two calliper mounting bolts (Figure 4) and slide the calliper off the disc. Rest the calliper out of the way on the subframe.
Remove the disc from the hub. The amount of rust build-up will dictate how much effort required to remove it. If you don't want to keep the disc, some hammer action should to it...
The process many people follow next is to remove the knuckle from the subframe, then remove the hub from the knuckle. This is complete unnecessary and will add a couple of hours to the completion time.
The hub can be removed whilst attached to the knuckle. On the rear of the knuckle are four 19mm bolts around where the driveshaft passes through (Figure 5). Loosen these bolts using a short extension. You will need to turn the hub to gain access, due to the shape of the driveshaft. Remove the bolts.
Remove the hub nut. Attach the hub-puller and remove the hub from the driveshaft. Remove the back plate.
With the hub removed, you can clearly see the four holes that the bolts pass through to the hub. Note the large hole in the knuckle, above the driveshaft. The parking brake mechanism will pass through this.
Cover all contact surfaces and the driveshaft spindle with copper grease.
Pause for a minute to remove the handbrake cable from the calliper. Undo the 12mm bolt holding the mounting bracket to the calliper and remove the cable.
There is another bracket further down the cable attaching it to the crossbeam. Once undone, thread the cable out of the subframe and away under the centre of the car.
Thread the handbrake cable along the route of the old one and push the parking brake mechanism into place by pushing the mounting bolt though the knuckle hole mentioned earlier. The hole will be rusted and the bolt will need some 'teasing' to fit. In fact, you will almost certainly need to wack the hell out it to get it through fully!
Once the bolt is through, add the securing washer and nut using a 28mm socket.
Push the hub back onto the driveshaft and hand tighten each on the knuckle bolts. Remember that you will need to turn the driveshaft to gain access to each hole.
Tighten the bolts EVENLY (90Nm).
Tighten the hub nut as tight as possible. It will be tighten fully later.
Push the brake disc over the wheel studs and parking brake. Tighten a couple of wheel nuts to the disc to hold it in place.
You will need to adjust the parking brake by removing the rubber grommet and turning the adjuster (at the bottom of the mechanism). The shoes should be just touching the drum.
Time for the callipers. It is recommended to have something to catch the dripping brake fluid.
Make sure you have the callipers on the correct side. The bleed nipple should be at the top when the calliper is fitted. Fit them the wrong way round and you'll never bleed all the air out!
Attach the new brake hose to the calliper and tighten. Remove the retaining clip at the top end of the existing brake hose. Undo the brake pipe fastener using a 19mm spanner and 10mm brake pipe spanner. Set the calliper aside. Quickly attach the new hose and tighten.
Slide the calliper over the disc and bolt it to the knuckle using the 19mm bolts previously removed. Tighten to 26Nm.
Assemble the brake pads, shims,pins and anti-rattle springs. This is almost exactly the same process as in my front pad replacement guide.
Now the fiddly bit. You need to unclip the handbrake cable from its channel and release it from the front handbrake bracket. Unthread it from the car.
Thread the new cable through, following the route of the old cable. Attach it to the front cable bracket.
That all sounds easy. Its not. Access is very restricted by the propshaft. On the left hand side the exhaust front box in also in the way!
WHEN BOTH NEW CABLES ARE ATTACHED, the front handbrake cable will need tightening. This is done via the bolt inside the cover of the handbrake lever (under the lever). You will need a deep 10mm socket. Pull the lever up five clicks, then tighten the adjuster. Pressure should be firm around five to six clicks.
Replace the wheels and fix with three nuts. Jack for car, remove axle stands and lower.
Torque the hub nuts to 250Nm.
Jack the car again and remove the wheels. Fit the hub nut split pins. Replace the wheel centres and fit the wheels. Lower and tighten wheel nuts.
Replacing the Brake Master Cylinder (BMC)
If not fitting a Z32 BMC, skip this next bit.
First and foremost, you need to remember that the chances are that any second hand Z32 BMC you get will probably be ten to fifteen years old. To be on the safe side, renew the pistons.
Changing the BMC is fairly straightforward, with a few precautions. You are dealing with lots of brake fluid, so ensure you don't spill any and have containers to catch drips. There is also a proceedure to follow before attaching the brake lines.
First, you need to drain the existing BMC. Place a container under the BMC brake pipes. Using a 10mm brake pipe spanner, undo the two brake pipes attached to the BMC and ensure the fluid is dripping into the container. Gently pump the brake pedal to drain all fluid from the reservoir.
Once drained, undo the two 12mm nuts holding the BMC to the Brake Servo. Pull the BMC away from the servo and lift free. Empty the container and replace. Attach the Z32 BMC and secure to the servo.
You will need two people for the next bit. Holding fingers over the two BMC brake feed holes, fill the reservoir with new fluid. Remove fingers from the holes and get your assistant to VERY gently press the brake pedal AND KEEP PRESSED. Cover the holes again and get your assistant to lift off. This will form a vaccuum and stop air being sucked into the BMC. Repeat this process several time to clear all air in the BMC.
Attach the two brake pipes to the BMC and tighten. Top up the reservoir.
The Z32 BMC uses a different fluid sensor connector, so you will need to cut or splice into the old connector with two new wires with female blade connectors. These will slide straight onto the blades on the reservoir.
You may struggle to clear all the air out of the BMC via the pedal. If this is the case, a bench bleed is recommended.
To hook up a basic bench bleed, you with need a short length of brake hose (flared both ends), two BN12 brake unions and a 1 metre length of CLEAR screen washer or aquarium hose.
Cut the brake and clear hose in half. Thread the brake hoses into the unions and connect a piece of clear hose to each unflared end. Attach unions to the BMC.
The BMC needs placing in a bench vice COMPLETELY level. Fill the reservoir with fluid and submerge both clear hose lines. Using a large screwdriver, push the BMC piston in and release. You will notice air bubbling out of the clear lines. Repeat this action until most air has cleared. Now you need to push the piston and hold it in. Very fine bubbles will still be released. These need to rise enough in the clear lines so that they won't be sucked back into the BMC when the piston is released. This will need repeating until the majority of fine bubbles have gone.
Now the tricky bit. Transfer the BMC back to the car and refit. Get an assistant to press the blake pedal fully and hold down. As quickly and seamlessly as possible (!), swap the bench bleed lines with the permanent brake lines. Release the pedal and preceed with the main system bleed.
Bleed the system
The entire brake system will now need bleeding. The order is:
I would say to do this twice, go fo a drive (check the pedal feel before driving off!) and do some hard braking, then bleed again.
And there you have it. Enjoy your improved braking.