Following applies to the 1600 & 2000's. 1500's used a large nut to retain the axle, and not sure on the part numbers for those vehicles.
inner oil seal 38212-04101 outer oil seal 43234-18401 [combined seal and retainer] rear wheel bearing 43215-08000 bearing collar 43084-10600
SAFETY NOTE: use jackstands to solidly support the vehicle before attempting any work around, or under the vehicle. Safety goggles must be worn when you follow the procedure about removing the retaining collars.
Decided to look at the rear wheel bearings. A pain to get them out, but they should repacked with fresh grease every 24,000 miles. It is rare to find anyone who has actually done that.
If the rear of the brake backing plates look clean, and free of caked on gear oil and dirt it should be a simple job to pull the axles and repack the wheel bearings.
In my case, one side was heavily caked in old grease and dirt. Steam cleaning away as much as you can before you start will make things go quicker.
You'll need an axle puller. Most autoparts stores have the cheap ones for around $50, or you can rent them for $5 a day. [Quite a few roadster owners have managed to pull them by hand, but I have not been so lucky.]
The drums came off easily, as I had smeared a light coat of anti-seize on the axle flanges, last time I checked the brakes, to keep the aluminum drums from bonding to the steel axle flange.
Disconnect the emergency brake clevis pins, and springs.
After bleeding the brake lines dry, unscrew the brake lines to the wheel cylinders. Once the lines are free of the wheel cylinders, wrap the brake lines with plasic, or cover them with a plastic bag retain with soft wire or rubberband. If you saved those old plugs for the wheel cylinders, it will help to cap them too.
Remove the brake shoes to keep them clean and dry.
Removed the four nuts on the back plate. SAE threaded, and 1/2" size across the flats. They have built in nylon lock washers... pain to remove with finger. The can be replaced with 5/16" SAE fine thread grade 8 lock nuts.
Once the four nuts are removed, attach the slide hammer and slam away. Usually after a few taps the axles come out. It was obvious gear oil seeping past the inner seal had washed out the bearing grease over the years. If caught in time, and the bearings still feel smooth, they can be repacked with grease while still on the axle. Good insurance to replace that inner seal.
Make of note about the NUMBER and thickness of the shims installed between the backing plate and axle. The shims are used to adjust the amount of preload on the bearing, and should be reinstalled.
As you check the bearings, they should rotate smoothly with no noticeable drag, or "bumps" during rotating. With the axle standing on the ground, press your weight against the bearing and feel it again. Once again, should be smooth and free of any "bumps".
One bearing felt fine. I used "Brake Cleaner" to remove the traces of old grease to clean the bearing (keep in mind you do NOT want to get solvent on the brake shoes. Once the bearing was clean, and air dried (NEVER use compressed air to spin a dry bearing), I repacked it with wheel bearing grease.
On the other axle, which had the backing plate caked with dirt, the bearing had a few 'bumps' in it, which warrantied replacement:
IF YOU NEED NEW wheel bearings:
You'll need: new outer seal (combined seal and retaing new wheel bearing new retaining collar.
The pressed on collars are a one time use item, problem I have seen on the Datsun Roadster's is the axle is only good for maybe three "press jobs". I've taken to CUTTING off the old collars...
Using a dremel tool with a thin cutting disc at maximum rpm I'll slice about 2/3rds the way through the collar. Then with the axle supported on the backside of the collar... I'll use my handy cold chisel and 4# sledge hammer. Takes quite a few blows into the cut I started with the dremel tool, but the collar splits open and drops off. [USE SAFETY GOGGLES!]
No spec in the Datsun manual, but the my Mazda manual specified that the new collars should be pressed on with a mininum of three tons of force (I know most do not have a pressure gauge, but if is feels like it went on too easily... there might be a reason why)
The wheel bearing was knocked clear by holding the backing plate, while taping the end of the axle against a block of wood on the floor.
Label the bearing as it comes off, as to which side it came off of. [Emergency brake lever point towards the rear of the car.]
Measure the OLD bearing, and the NEW bearing. They should be identical. If not Any difference in thickness should be adjusted by the shims to insure a proper preload.
Quite often the grease that was original packed into the bearing will be dry and stiff. Use CLEAN solvent to wash it out, and repack with your favorite wheel bearing grease. It is important not to mix different base types, so I always use lithium based grease around the garage.
Drop off the axles with the new outter seals, bearings, and collars and backing plate at your friendly machine shop. There is a small spacer between the bearing and the end of the axle. This spacer must be used, as the inside edge is radiused to match the axle flange. Most shops just press the new bearings on, in which case the retaining collar should require at least 3 tons of force to press on. If the collar goes on with little resistance, the axle MUST be replaced.
Sigh... Safety first. A fellow roadster owner was killed when his car flipped on him after loosing the axle on a turn. New wheel bearings had been installed a few weeks before, and I believe he decided to save a few bucks and reuse the old collars.
Shims - assuming preload was correct originally, and you kept track of the number of shims used, it is a simple matter to compare the thickness of the old bearing vs. the new bearing. If the bearings are the same thickness, then use the same number of shims. If the NEW one is thinner than the old bearing, you'll need to reduce the number of shims. Like wise, if the new bearing is thicker, you'll need to add more shims. [Shims typically are 0.003" thick, but the replacement items I had were either 0.003", 0.004", or 0.009" thick!]
It is easier to slide a couple of bolts into place to hold the shims up while reinstalling the axle. Usually the axle will slide in, but a light tap on the axle flange may be required (I use a piece of 2x4 to prevent damaging the wheel studs.).
Reattach the emergency brake clips, springs. Refit the brake lines, and BLEED the brakes before putting the wheels back on. Always use the same type of fluid that is in the system.
While the car is still firmly supported by axle stands: Check the differential level. Check the driveshaft flange bolts (they do loosen with time, one reason I like using locktite on them. Wise to check BOTH ends on 5 speeds)
Enjoy that sunny afternoon drive!