Captain Obvious

Actually... Now that I think about it, I'm not so sure the retaining slider clips come with a new cylinder. I've done complete new cylinders in the past, but I don't remember if I had to re-use my old rusty clips. I know the dust boot should come with the new cylinder, but I'm not sure about the clips. I've got some pics of new cylinders downloaded and I don't see clips in the photos. Would suck to buy whole new cylinders for those parts and then STILL not have usable slider clips. :disappoin

Thanks guys. Yeah, I don't know anything at all about the ZX's, so I probably should have excluded them. Although, since you can pretty much drop-in some of the ZX distributors and modules into earlier cars, I suspect that not all of the ZX's have computer controlled timing. Not sure if I've asked the question correctly, so at the risk of beating a dead horse, I'll do it again. On the 260 and 280, there's a pickup in the distributor that sends a signal to an ignition module near the passenger's feet. When the ignition module near the passenger's feet sees the pulse from the distributor it cuts the current to the primary side of the ignition coil which causes a spark. That's all the ignition module does, right? There's no timing modification done in that module adding any additional advance or delay to that spark, right? It sees a pickup pulse - It breaks the primary circuit. That's all it does. Some propagation delay is inevitable, but that prop delay is fixed and does not change on purpose based on any RPM, vacuum, or temperature conditions. And just for curiosity, since we're talking about it... In the automatic trans modules, it switches which pickup pulse it pays attention to once the engine has warmed up, but other than that, the manual and auto are identical.

I'm not an ignition guy and I'm having a hard time even figuring out how to ask this question, but here goes... What are the sources of changes to base timing in the 260-280? Is there any spark timing control done in the ignition module near the passenger's feet, or is all the timing control done in the distributer with mechanical and vacuum advance? By that, I mean... I know they use the typical weights-n-springs mechanical advance in the distributer, and I also know they use a typical vacuum advance with an actuator on the side of the distributer, but is that it? Are those the only two sources of advance or is there additional RPM derived electronic controlled advance done inside the electronic ignition module? And no, I'm not talking about temperature switching between the two different pickups in the auto transmission cars. That's not RPM related.

Haha! Don't quote me on that one inch. It's been years since I've messed with the adjuster in detail. Let's say "around" an inch, OK? But... Now that I'm thinking about it... Is this on the brand new wheel cylinder, or on the old one? Seems very odd that a brand new, clean one would have any issues spinning the adjuster gear. If it's the old one, then I suspect you've got grunge in the threads on the hidden side of the adjuster wheel. If it's the brand new one... Hey... At least now you have a strong bubble-free stream to the rears now!

I don't think Rock Auto has either of those unless you buy an entire wheel cylinder. I don't think they offer the dust boots or mounting slider clips separately. I have seen them recently though somewhere... Probably ebay. Pretty sure about the dust boots. Less sure about the mounting sliders. Stupid design. :stupid:

I agree. Sounds like more than one issue at play here. Let me recap to make sure we know where you are at now... Originally you had brakes that went to the floor and took 2-3 pumps to get any pedal at all, and even after you got some pedal, it seems the braking was happening only on the front axle. In addition, you couldn't get fluid out of the rear cylinders when bleeding. Then... You bled right at the master, and again at the corners. After that bleeding, there is now a strong bubble-free stream of fluid out of both front and rear corners when bleeding, but you still have brakes that go to the floor on the first hit and require pumping once to get firm pedal. Is that where you are now? As for the rear adjusters, I really don't think there are any stops on that adjuster wheel. You're doing the adjusting with the drum off? If you keep turning it and watching the shoes spread, you will eventually reach the point where the adjuster stalk completely unthreads from the cylinder. From memory, I believe the threaded stalk is about an inch long, so you should be able to screw that adjuster wheel out about that much, and there is NO WAY you should be able to get the drum back on with the shoes adjusted out that far. If you can, then there is something seriously wrong somewhere.

You should be able to lock up the rear drums with the adjuster, and the adjuster wheel should not be difficult to turn until that happens. It's been a while since I've been in that deep into the pre-77 brakes, but I believe if you keep turning, and turning, and turning... And if by some weird set of improper circumstances occurs the shoes don't contact the drums... You'll eventually wind the adjuster stalk completely out of the cylinder. I don't remember any stops on that thing anywhere. You know that the two sides adjusters rotate opposite directions, right? "Bottom to top" should tighten the shoes. Can you hear the adjuster lever clicking over the teeth in the wheel as you turn it?

No. I'm with AxtellZ. Sounds like a master cylinder issue. Sounds like it needs to be primed. That, or it coincidently failed at the same time as your rear cylinder.

As long as the aluminum of the cylinder itself isn't pitted. The pistons came with a corrosion resistant coating of some type, and yours is obviously gone. I believe you can get new pistons, but once you pay for that, you might as well just have replaced the whole thing. So you're going in after this AND spindle pins? Now there's a thankless job!

Yummmmmmmmy! You're not thinking you're going to rebuild those puppies, are you?

I'm not much for the body kits, but I gotta say that I like the front profile of that.

The small one.

I'm sure you already know this, but just because the fluid level in your master cylinder is low, doesn't necessarily mean that you have a leak. At least not with simple disks like in the front. The volume behind the caliper pistons increases as the pads wear, and that extra volume is taken up by brake fluid from the master cyl reservoir. With rear drums, I guess it's not that clear... The rear wheel cylinders should always relax to the same position, so there shouldn't really be any change in the reservoir level at rest, but if your rear adjusters weren't working properly, that may not have been the case. The rear pistons may not have been pushed all the way "home" and you may have used some of the fluid from the tank to take up the extra volume. I know, I'm reaching here, but that's all I got. (On edit): Actually, thinking about it some more, the rear cylinders push directly on the shoes, not on the adjuster mechanism. So the pistons should not be pushed home as the shoes wear. The adjuster mechanism should hold the shoes apart, so I guess the same situation exists in the rear as the front. The brake fluid in the master cyl will drop as the shoes wear. What you could end up with if the adjusters aren't working correctly is excessive pedal travel. Only other info I've got would be that I've seen the same white crumbly corrosion on aluminum brake parts in the past. My theory is that it is a slow leak, and the brake fluid (being hygroscopic) is attracting moisture from the atmosphere and that combination of brake fluid and water is causing the aluminum to corrode. In any event, with all the issues you did find, it sure wasn't a wasted effort!!

I agree. Must just be a mistake in the docs. Sure is a good thing that I don't read directions, or I may have followed them!

You're talking about the pre-77 rear cylinders, right? They're very different than the 77-78's. I'm sure that spring you're talking about is supposed to fit narrow end snugly around the locating boss on the back of the piston and the wide end pushing against the inside of the cylinder. You're saying that all the pictures show that spring installed wide end against the piston???

Actually the rear disks with the parking brake that would stick on was not the "mini-drums inside the rotor" style. They had the parking brake function built directly into the caliper. The concept was sound, but they used some stupid roller bearing on the parking brake pivot shaft that would rust in place to the shaft. Hope it turns out that your flare isn't leaking. Out of curiosity, you originally started this because you were chasing a low fluid level in your master cylinder. Did you ever find the smoking gun for that?

Wow. Three test parts and you're getting good doubles. I know who I'm callin' next time I need a hardline replaced! Glad you got the adjusters figured out. Lube em up and, keep them dry (backing plate boots in good shape) and use the parking brake frequently enough to keep everything mobile. Doesn't have to be every time, but more than once a month. I've been inside lots of drums over the years, and I gotta say that the late 280's are one of the better ones. It's the simplicity, and the room to work. Don't hate the drums... As a matter of fact, I've had other cars with rear disks that I was actually afraid to use the parking brake because it would intermittently get stuck engaged. It was a bad combination... Steep driveway, manual transmission, parking brake that would stick ON, and a very worn engine with barely any compression left. Do the math.:paranoid: It was like Christine.

Phew... Right before I hit the post button, I realized how long that post was. I was worried that I was off track. When did I become so wordy...? :tapemouth I've had a bunch of flaring experience also, and it's a pain. Thankfully, I've never done enough of it to warrant buying my own flaring tool set, so I borrowed a double flaring set from a buddy and found that the mandrel that came with the cheap double flaring sets is crap. It didn't fit well into the tubing and was almost impossible to get decent results. I finally gave up and turned my own mandrel that was tight fitting into the hardline tubing. Results turned out much better. I would hope that the more expensive flaring sets have better accessories. Even so, I bet there's significant finesse that must be learned before getting good results. Make a complete single flare first? Make a partial single flare first? Make half the bubble flare and then rotate the tubing 90 degrees before finishing it? Now that you've been through it, you know the drill.

Been a while, so I'm going from fuzzy memory: The 77-78 rear adjusters... Assuming there is enough travel as to require adjustment: When you APPLY the parking brake, the adjuster lever hooks a tooth on the wheel and turns it. When you RELEASE the parking brake handle, the gear wheel should not move and the lever should ratchet past the teeth on the gear. You should be able to hear the lever "click" as it snaps past the teeth on the gear. The teeth on the adjuster wheel and the location of the lever is designed such that there should only be rotation in one direction and that direction is different for each side of the car. So you really don't have to do much pre-adjusting on the adjuster wheel before you put the drum on. Just get the drum on, and then pull and release the parking brake handle a whole bunch of times until you stop hearing the clicks on let-off. Goes like this: Pull up - Hear some creaking from the cables and springs and such. Release - Hear three (if memory serves) clicks as the adjuster lever ratchets past the teeth on the gear. Pull up - Hear some creaking from the cables and springs and such. Release - Hear three clicks as the adjuster lever ratchets past the teeth on the gear. --- Repeat the above a couple of times until --- Pull up - Hear some creaking from the cables and springs and such. Release - Hear TWO clicks as the adjuster lever ratchets past the teeth on the gear. --- Repeat the above a couple of times until --- Pull up - Hear some creaking from the cables and springs and such. Release - Hear ONE click as the adjuster lever ratchets past one tooth on the gear. --- Repeat the above a couple of times until --- Pull up - Hear some creaking from the cables and springs and such. Release - Hear NO clicks. You're done. From that point on, as the shoes wear and the travel increases, you will eventually reach the point where the parking brake lever will cause one click on release and then the next time you apply it, it will adjust one click. Does that until you replace the brakes next time or rusts solidly into place. Since the rear of the car is already off the ground and the wheels are off, I usually pull off the drums again and just have a quick peek at the shoes and make sure they are aligned pretty much in the middle of the backing plate. Wiggle the shoes around a little bit, "unadjust" the wheel a couple of teeth, put the drum back on, and adjust them again. If your shoes need a lot of adjustment (meaning they are pretty far from the drums) you should hear multiple clicks when you release the handle, and if you're not, there's something wrong with the adjuster system. I apologize if I answered a whole bunch of questions that weren't asked... I was on a roll.

Not to be a smartass, but if the radiator is always full..... Are you sure you're looking for a coolant leak? I once had a car that would lose coolant slowly over time, and I spent years looking for that leak. Never a spot on the ground. No signs of coolant anywhere in the engine compartment. Compression test turned up no clues. Turns out that I had a tiny tiny pin hole in the radiator, and it would only leak when the engine temperature and coolant pressure peaked after you shut it off. A hair thin stream of coolant would spray out of the front of the car, cleverly missing even the grill slats, leaving behind no trace of wetness anywhere. It hit the ground about five feet or so away from the car, half of it probably evaporating before it ever even hit the ground. I finally discovered it one day when I was standing a couple of feet in front of the car and noticed a slow growing warm wet spot in my pants. It turned out to be my car whizzing on me. That's my story and I'm sticking to it. On that occasion anyway!

Don't get me wrong... I'm not questioning the belief that there are materials better suited to this application than Delrin. I'm sure there are LOTS of better choices. I just happen to already have Delrin in stock and it's very easy to work with, that's all. I picked that one for all the wrong reasons. Kinda like looking for your car keys where the light is good. And again, I'm not pushing for Delrin or anything, but if I'm reading the datasheet correctly, they list the melting point at 175C. That ought to be enough, right? Does look like fun. I drove a Fiero for years and years and I feel for that guy. I think I've talked with him in the past.

Yeah, that's a good point about the exhaust manifold. It's hot. As for what to make the insulators out of... I was thinking Delrin (acetal) because it machines like a dream. Well, that and I have it on hand. Haven't checked the thermal conductivity and it's probably not as good as ceramic, but it's gotta be a whole lot better than steel!

I'm not a thermo expert but I'm skeptical about the amount of heat that is conducted up through those mounts. I guess any little bit helps though, right? In any event, After you drill the mount hole larger, I'd be happy to make some plastic insulating inserts for you once you get to that point. Now that you aren't using the mechanical fuel pump at all, how about completely re-routing the fuel lines across the firewall and onto the driver's side fender instead. Don't ever mount it to the block at all. I'm sure I've seen pics here on the forum somewhere of that mod.

Unfortunate to think it might come to that, but yeah, that would be a tough sell.