280zx Four-wheel disc brake swap

http://www.the510realm.com/tech/brakes/280zxswap/index.html


The purpose of this article is to give you a clear understanding of how to install disc brakes from a Datsun 280ZX onto a Datsun 510 for better overall braking. Many enthusiasts want more horsepower under the hood without considering how to stop all that horsepower. The best advice from most long time 510 enthusiasts is to make the car stop as well as it goes. Doing it the other way around is dangerous and often leads to one more 510 headed for the crusher.

As with all modifications, patience is the major factor in making this conversion work. If you have it, you to can have a four-wheel disc 510 with more braking power than you'll ever need. This system was designed for a much heavier car so you'll undoubtedly be pleased with your 510's stopping power. The ZX rotors are 10 inches in diameter whereas the 510 rotors are 9 inches. The ZX rotors are also ventilated for better cooling and the calipers and pads are much larger than their 510 counterparts.

The parts you will need are found on the '79-'83 280ZX. There were some differences between the early and later calipers. The mounting holes on the '79-'81 calipers have a different separation than the 82-'83. If the '79-81 calipers are used a slightly different mounting bracket than the one detailed here must be fabricated to deal with this. All of the components I used for this conversion were from a fuel injected, two seat '83 ZX.

You will also need a small amount of steel tubing, access to a welder, a portable grinder, hacksaw, bench vise, and a drill press.

Get everything from the donor car that relates to the brakes: complete front struts, rotors, calipers, brake lines, (buy new flexible brake hoses), handbrake cables, handbrake assembly with cable from inside car, caliper mounting bolts, water shield, brake pads (buy new pads) and all the little bolts and clips. Get the master cylinder, the push rod, and the proportioning valve too. This complete braking system, from the master cylinder to the 4-wheel discs, is now on my 510. I didn't use the brake booster in this conversion.

Mounting Rear Calipers
You will need to fabricate a bracket to mount the calipers to the existing backing-plate mounting holes. There may be some adjustment needed to the brackets to get the calipers centered over the rotors. I ended up using a 3/16" spacer in the bracket between the axle housing and the caliper just to get the right alignment. See Photo#1 and Figure#1
The calipers have to be swapped right to left to allow the parking brake bracket to clear the body above it. The calipers were simply swapped, not inverted. The parking brake mechanism and "fork" are still on the top.

Get the car up on jack stands, front and rear, as high as you can. Remove the wheels, shocks, springs, parking brake cables, and half-shafts from the swing arms. Removed the swing arms and placed them in bench vice and removed the large nut from stub axle, taking care not to damage the threads. You will need to buy new nuts, Part #08911-24010. The old nuts are flattened on one side to keep them from backing off. Drive the stub axle out with a soft drift and remove the backing plates. Removing the backing plate could be accomplished with an oxy/acetylene torch or a plasma cutter, if you have access to either, without removing all of the other parts.

You can modify the ZX backing plates if you want to keep them. Simply enlarge the center hole to fit over the swing-arm hub like the old backing plate did. Replace the stub axle and secure the nuts.

Replace the swing arms, install the adapter plates, slip the ZX rotors onto the axles, bolt the ZX calipers onto the adapter plates, (remember, the LEFT caliper mounts on the RIGHT side and the RIGHT caliper mounts on the LEFT), put the springs back and reattach the shocks. Reattach the flexible hoses to the swing arm and run a short steel brake line to the bottom rear of the swing arm. Weld a small brake connection bracket here to attach another flexible hose to the caliper. Photo#2 & #3. If you feel there are too many rubber hoses in this system you could replace them using braided stainless steel hose.





Master Cylinder and Proportioning Valve
The ZX master cylinder and proportioning valve have also been included in this conversion. The master cylinder has a horizontal instead of vertical bolt pattern but there was clearance to drill new holes in firewall and mounting plate. If you don't want to do this, the earlier cars had a vertical bolt pattern like the 510. The proportioning valve is positioned on the inner fender wall below and in front of the master cylinder, Photo#4. Any location convenient to the master cylinder will do because you have to bend new brake lines to fit the proportioning valve. I used the collection of brake lines I got from the donor car, but you may want to use new lines here.



Parking Brake
I used all of the cables from the ZX and only had to relocate the stock underside hand brake adjustment mounting location a little bit. I drilled out the spotwelds and bolted it back in the new location. No cutting or modification of the cables is necessary.

Remove the passenger seat, and test fit the parking brake mounting bracket to the passenger side of the transmission tunnel. Photo#5. It should be located so the brake handgrip is even with the shift lever but doesn't interfere with the passenger seat. The mounting bracket can be either bolted or spot-welded to the tunnel. Be aware where everything is located under the floorboard before drilling or welding.

Drill a hole to the rear of the bracket for the cable to go under the floorboard. The size of this hole is determined by the size of the cable after the rubber boot, which seals the hole. Attach the cable from below to the handle.

Slightly re-position the 510 bracket for the brake cable bridle, Photo#6. The position is determined by the bridle after the brake cables are attached to the top of the caliper and pulled forward. The cables are fed BACK through the cross-member, over the swing arms and attached to the parking brake lever at the top rear of the calipers, Photo#7. Both of the holes in the cross-member will be enlarged for the larger ZX cables.

The old brackets on the cross-member are removed for this operation, the right one is replaced either by welding or bolting. This bracket uses a U clip to retain the cable at this point. The left cable is attached to another small fabricated bracket welded to the right side floor board just to the rear of the bridle bracket, and is retained with a U clip also, Photo#6. The right one is replaced either by welding or bolting on a new bracket. You could cut the bracket from the ZX cross member, but I suggest fabricating one, Figure#2. This bracket also uses a "U" clip to retain the cable at this point.

These cables are used intact, just as they were removed from the donor ZX, no cutting is needed. I also removed the brake lever from below the dashboard and covered the hole in the firewall.





Front Struts
When using the ZX struts, the springs are too large in diameter to fit inside the 510 towers. It is necessary to use a 510 spring and lower perch welded onto the ZX strut.

Use a hacksaw and make a cut just above the weld holding the perch to the strut. Don't cut into the strut tube. When you see rust in the cut you have just gone through the perch material. Once the perch is removed grind down the old weld again taking care not to grind into the strut tube. You can then weld the 510 perch (removed the same way) directly to the ZX strut. The location will depend on the length and weight of the spring you are using.

Test fit to ensure that the perch does not hit the top of the tire when it is installed. If you want to change the ride height this is the time to determine where the lower perch will be welded. Use some type of clamp under the 510 perch, set the car down, and measure the ride height. Adjust the clamp and perch to get the desired height before welding.

Use the 510 parts on the upper strut including the spring seat, bearing, dust seal, insulator, washer and Ny-Lock nut. The ZX struts have more negative camber built into them as the angle between the strut and spindle is different from the 510. Use a ZX strut insert with the strut.

One benefit of this conversion is it takes advantage of parts from only one donor car. I estimate the cost of all the above itemized bits and pieces would be about $150 at your local salvage yard. There were a huge number of 280ZX's sold in the US for the years '79 through '83.

The other benefit is awesome brakes. We used this conversion with Carbotech racing pads on our 510 that was entered in the One Lap of America, June 1998. With the light weight of the 510 and the HP of a 2.3 long rod engine, we were able to brake much deeper into the corners than the heavier cars in this event. This conversion worked well for me and with these guidelines, and a little patience, it should work for you too.



If you have any questions, or need any clarification about this modification, you may contact me directly at deans510@juno.com or call me at (925) 685-3423. I will be happy to help with any problems you may have, and would like all 510's to have brakes as good as mine.