Drum Brake Questions

[Jetaway]

Sorry if this is real basic stuff, but I simply don't know.

Vehicle: 1972 240Z

I recently pulled the rear drums to check the brake linings. Not quite gone, but getting close enough to replace. While I had the drums off, I checked the inside diameter of the drum with a ruler (no micrometer). Both drums had a ridge of sorts around, I guess the inside (towards differential) interior. I'm guessing that the ridge was the part of the drum that did not come into contact with the brake shoes.

Measuring across the ridge, one of the drums, even using such a crude device as a ruler, clearly exceeded the maximum stamped on the drum (10.06 inches, I believe). The other -- well, simply couldn't tell using a ruler.

Several questions:

Would I gain a few months of use simply by replacing the shoes?

Assuming one of the drums can be resurfaced and replacing the other with a new one -- is this a good idea? Or given that one drum would be new and the other near the end of its useful life, would the difference in stopping power be so great as to be annoying or even dangerous?

Should I replace the wheel cylinders even if they are currently working?

Finally, more of an opinion type question:

I looked up prices for components at the Z-Store (not always the cheapest but not always the dearest either) and figured it would run me roughly $200 to replace both drums and approaching $400 to replace both brake cylinders as well. I don't know if the brake cylinders have worn out, but given that I suspect they've given 39 years of service, I'm guessing it wouldn't be a bad idea.

The Z-store sells a disc brake replacement kit for early Z's for $350.00 (w/o rotors and calipers) and also has a kit that includes rotors and calipers for $770.00 .

I don't drive competitively (at least not competitively as in numbers on the side of the car;)) but I do drive my Z between 15,000 and 20,000 miles a year. I'm pretty easy on brakes, viewing using the brakes as a sign of failure on my part to anticipate traffic flow (went 150,000 from new in my Pontiac Aztek before replacement and could have gone further, but tired of having them checked). When in the mountains / foothills I have enough sense to downshift on long downgrades. So, the main advantage that discs have over drums, resistance to fade, isn't really a concern for me. Still, I'd imagine going to 4-wheel discs might stop me a few feet shorter in an all-out sweaty palms WTF! stop which is worth a few bucks. The other concern with _not_ converting is how much longer the original parts will be available for the Z.

Thoughts?

Oh -- I prefer to keep the car as original as possible, though with an electronic ignition and ZX 5-spd, "Iron Cross" wheels and gas tank filler lid from a '71 just because I like the look of the latch, "Smiling Jack" isn't going to win any concours. All in all, though, my preference is towards the original.

Chris

[5thhorsemann]

If it aint broke don't fix it. replace the worn out drum, turn the other. while its apart, REBUILD the wheel cylinders, centric makes a kit for them, got mine off of ebay for $10.00 each free shipping, had em in 2 days. takes like ten minuts to do each side. Peice of cake. this is the link to the parts

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=120648053522&viewitem=&sspagename=STRK%3AMEWNX%3AIT

[Powderkeg]

Chris,

If the brakes haven't been attended to for a while replace the shoes along with a kit with the springs , shims, etc.

If you have the original Aluminum drums I'd do my best to keep them viable as they are hard to come by. But you can also use the cast iron drums.

If your driving is pretty basic and you keep the brakes maintained I wouldn't worry about 4-wheel disk brakes. The original design is pretty bullet proof.

I live in the hills where to main road is dirt and have taken my 76 through some of the hilly roads of Mendocino leading to the coast.

The stock brakes have behaved perfectly even with the sudden stops behind the tourists from Marin in their Prius'...Prius's..Pri.....whatever!

If you are doing heavy duty performance driving/racing then I have to defer to others.

Dave

[Jetaway]

5thhorseman and Powderkeg,

Thank you both.

Rebuilding the cylinders seems like an excellent idea.

I might just go ahead and replace both drums because even the better one was a marginal call as to usefulness. I'll see if I can scare up a micrometer and check the yards, might just get lucky on this.

The originals were aluminum? You sure? I think mine are cast iron or otherwise ferrous. A magnet stuck to the fins and I assume that they wouldn't be cast iron on the outside and aluminum on the inside. Other way, maybe.

Chris

[gnosez]

Drums were made in both steel and aluminum (Brembo made them). Rear drums are more than enough for normal driving and with ZX calipers and rotors up front we run drums in our 240 race car (same set of Porterfield shoes for the past 3 years). I have about a dozen sets of stock shoes and will sell them for $20. shipped.