When are rear wheel bearings needing replacement?
 

One of my rear wheels started making a metal-to-metal sound off-and-on when applying the brakes (1971 Fairlady Z-L). I pulled the drums and all looks okay. So, how do I check the rear wheel bearings for excess wear? How much slack movement is allowed?

Failed wheel bearings make a constant "whurrr whurrr whurrr" sound that gets louder and faster as speed increases.

If there is a metal to metal screech when you apply the brakes, that's usually a common sign that the pads / shoes are worn to / past the limit. How much material is left on the shoe?

Better than 1/3" of material and even. Springs looks good, drums look good. Sound is intermittent and sounds like when I had worn out brakes once.
How much movement up and down, in and out, should there be when I wiggle the axle? It's not making the whurr whurr sound at all. I wonder if there is enough slack that the drum is touching the backing plate when the brake is applied, although I don't see any marks. It just started happening so I parked the car and took the drums off to look.

Rubbing noise when applying brakes?
 

This just started on the '71 FairladyZ. When I apply the brakes I hear a sound like when there is rust in the rear brake drum, like a metal-to-metal sound almost. Intermittent, doesn't happen every time.

I pulled the drums and have 4mm+ of lining left on the shoes. No sign of metal-to-metal contact.

The shafts seem fairly tight, not like a wheel bearing has given up. When I rotate the hub there isn't any grinding sound coming from anything.

Any ideas what might be causing it? Anything else I can check?

Don't want a bearing freezing and dropping off a wheel .... :paranoid:

If you don't know when it was done, replace them, wheel bearings generally need cleaned and repacked about once a year.

I don't think that is practical with the early Z cars. The bearings are not in the drum but require total disassembly of the rear end, pulling both axle shafts with a slide hammer, etc. The bearings are sealed and cannot be greased. They must be removed/installed with a press setup. You must be thinking of a different bearing setup then there is on this car?

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This isn't a wheel bearing problem, so we don't really need to talk about wheel bearings all day. :D

There's not much we can tell you, other than inspect ALL brake parts thoroughly. Midas has been running a "free brake inspection" commercial on TV. Take it to them.

Looked it all over really closely and it looks like some excess grease from around the brake cylinder, brown stuff, may have heated up and dropped into the drum as there was a little spotty discoloration in the drum that came out when I sanded it with some 200 grit.
Swapped drums from side to side so I'll put it together and see what happens.

It is probably the brake cylinder is leaking. This happened in my truck but it got so bad that it caused a lot of shuddering when you braked.

Brake fluid getting onto the shoes is bad, and a new cylinder shouldn't be too expensive!

A 240z's rear wheel bearings are not sealed and require the same maintenance as the front. They are also not pressed in, they might be rusted in place after a few years though.

Regardless of what you consider practical, maintenance still needs to be done and parts will and do fail regardless of how hard you think it is to do it.

I'm at a loss how to grease them. There doesn't appear to be any way except to pull the shafts with a slide hammer and have them pressed off with a hydraulic press and then pressed back on.

The manuals I have, including the Datsun factory manual for S30s, doesn't address servicing them, just replacing them as above.

Where did the grease come from? It's definitely not brake fluid and there isn't any apparent on the shoes.

Then replace them while it's all apart or pull the shafts, clean out as much grease as you can and repack it as best as you can.

It's a dealership type of task. Don't have a slide hammer and from reading the shop manual it's not a task I want to take on.

If I have them do the whole rear brake system I'll have them also pull the shafts and replace the bearings. I don't see any way to get grease into them, even with a needle greaser.

Noise went away ...
 

Sanded the drums with 220 grit, same for the brake shoes. Wiped them down with clean rags and lacquer thinner. Checked everything for rubbing, etc.
4mm meat left on shoes. Greased wheel drive shaft universal joints (that's a bear to do ... damn zerts don't want to take grease.)

Checked freeplay on hubs; all tight.

Reassembled and test drove on highway. Brakes quiet. No rumbling, no slack in rear end.

I guess for now all is well with the FairladyZ-L (240 type JDM car, not 4 cyl roadster)

Thanks to you-all for advice and input!!

Minilite wheels and torque for lugnuts
 

Sent photos to the American distributor for Minilite. He says after examining them they are most likely the alloy version of the mag wheels so not a problem.
He also said they should have lug nuts torqued to 70-80 ft lbs, not the 60 specified in the Nissan shop manual.
He may also still be able to get the rare washer/nut set for the lugs!