GTOguy

I don't like the look of the 'rear right' photo showing the spring on the star adjuster arm ....it shows virtually no tension on the arm, and isn't enough to even load the short red spring that holds the arm in place off the shoe table. Verify correct spring kit, no grooves in backing plates where shoes ride (can be ground and re-welded---must be lubed slightly) and no cracked wheels or clicking wheel covers. Also verify drums are round and true. A click click click generally means out of round, somewhere.

alexandervdr

you mean that there may not be enough preload/tension on the long grey spring I encircled?

Frankie the Fink

I will ask this one more time only. Are you 100%, absolutely, positively SURE you have the adjusting torpedoes on the right sides ? The end of the threaded part should say "L" or "R". A simple test is to rotate the pawl wheel downward as the adjuster plate would do and ensure the brake shoes EXPAND on each side...

alexandervdr

I checked it, and used it enough to adjust the brakes to be sure

Frankie the Fink

You can try a MikeM experiment....put the drums on about 1/2 way (or a little more) and spin them slowly while somebody applies the brakes gradually. Peer around the edge and look for shoes moving around or any binding actions. Short of that - I'm am with GTOguy (Jeff) wondering if you have the right rebuild parts...

bluestreak63

Have you tried taking them both apart, lubing all lube points and putting back together?

What about you wheel cylinder hardline? Could it be contacting metal when you're braking?

MikeM

Here is a little better picture from GM to compare to.

alexandervdr

the rebuild parts are a complete drum brake overhaul kit from ZIP for a 64 C2, including new drums, cylinders, shoes, springs, etc etc

63 fuellie

being new here I hate to but in but I would cut the drums to make sure they are round-new parts are not made too well

GTOguy

Correct. Looks like there is little or no tension on that spring. The blue spring holding the heels of the brake shoes together looks like it's pretty relaxed, too. Those are normally straining a bit, even with the adjuster backed off.

GTOguy

Look at your photo vs the factory illustration. The factory photo is what I'm used to seeing....gaps between the coils because the springs are under tension, not sitting there slack.

alexandervdr

I cut the surface of the drums with #120 sandpaper and brake cleaner. That made the noise almost completely disappear. It must be said that my car and exhaust are super silent, so with a slightly more noisy one I would never hear it. DOn't feel anything in the pedal neither. When googling 'clunking drum brakes', I get a ton load of references, seemingly not an out of the ordinary problem. I'll tackle all the other suggestions in the next days (spring tension, run-out, test while on stands...)

alexandervdr

I checked and the whole assembly link 5.105, spring 5.107 and the L-shaped bracket (middle red circle) is under tension. The left bottom stud of the L-bracket (green) is pulled firmly against lever 5.103 (or shouldn't it?) .

Frankie the Fink

Here is a picture of a drum brake system with the adjusting torpedo completely turned in (shoes contracted fully) and there is STILL some tension on the spring over the adjuster.

Your system has no apparent tension on the same spring even with the adjuster turned out several turns expanding the brake shoes. it does indeed look off.

alexandervdr

You mean this red (encircled green) spring ?

Frankie the Fink

That would be a YES.

superpm

Looking at the OP's pictures in post # 6, it appears there may be more tension on the spring over the adjuster on the Rear Left than on the Rear Right. Or is this just due to a difference in the camera angle?

alexandervdr

I'll check

Frankie the Fink

I looked over the Zip 64 Deluxe Drum Brake complete overhaul kit. I don't see an issue with the components but can't say for a certainty. I also don't see anything wrong with the installation. Its bothersome that the tak-tak occurs on both rear wheels as its unlikely a single component failed identically on both sides at the same time, also the noise seems to have appeared after the brake overhaul.

I'm stymied unless the noise is normal and may disappear after some driving...nothing of the like happened with my 63 brake overhaul with NAPA parts however...

alexandervdr

thanks for all the efforts, the brakes are working fine apart from the noise. It's still some weeks to go before we get out of the rain season. Sometimes one needs to take a rest to get back to the problem. I may focus om some other smaller issues I need to resolve.

I got some whining in the (new) gearbox, but that got solved with some additive, and there is a slight 'no load' whine in the rear end, and installing the antenna (I need to remove the muffler...), wipers that work great but don't pump water, installing the controls buttons for my bluetooth/siri system, etc. Plenty of work