Jump to content
Sign in to follow this  
FastWoman

Brake rebuilding time. Lots o' questions!

Recommended Posts

DONE -- on the rears, anyway.

I solved the mystery of the star wheel. It turns out the e-brake mechanism on both sides was partially rusted up, so that it wouldn't articulate. It beats me how the e-brake had worked like that, although it did. Anyway, the adjuster was frozen in two slightly different positions on each side, hence the catching of the star wheel on one side only. I guess I should use my emergency brake more often. I prefer to park my car in gear with the e-brake off, unless I'm perched atop a cliff or something.

Tomorrow I turn the car around and start on the fronts. That should be a much better job by comparison. I had forgotten just how much I hate drum brakes.

Share this post


Link to post
Share on other sites

Wow. Three test parts and you're getting good doubles. I know who I'm callin' next time I need a hardline replaced! :D

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.

Share this post


Link to post
Share on other sites
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.

I second that. From all the drum brakes I've worked on (mostly old domestic cars), S30 drum brakes are the easiest to work with. Doing the rear drums on a Z is an easy job, the only thing that can make it difficult is rust and that's what gratuitous use of penetrating oil is for!

Share this post


Link to post
Share on other sites

I got the fronts done. I had assumed the pads could use replacing, as the guy who inspected the car said they were maybe half worn. However, I found them only maybe a quarter worn. I just sanded the glaze off of them, hosed them with brake cleaner, and reinstalled with the new calipers. ;)

The right caliper had been replaced (by itself) shortly before I bought the car. Strangely, it was dragging the brakes just a bit, while the older left caliper was not. Also the left front brake hose didn't match the other three. More piecemeal work. I didn't really know how old anything was. The PO said he had just done the brakes before I bought the car. I asked him if that included the hydraulics, and he said it didn't. The hydraulics definitely needed an overhaul.

Captain, I still don't know how good my flare is. I might be missing a tiny bit of fluid, but it might be my imagination. I'll have to watch the reservoir. I also have a TINY bit of brake pedal sag, so I might have messed up the master a bit by running the seals over rust. Dunno. It's not bad, though.

The pedal feels fairly firm. I got a very good bleed on the fronts, but perhaps could have done better on the rears. I'll touch it up when I get the MityVac in. The parking brakes are much better. Still haven't gone for a test drive. It was getting dark.

I'll try not to be too down on rear drums. Yes, I can see how rear disc parking brakes could be difficult. I wonder why they're inside tiny drums and not clamped across the disc too.

Share this post


Link to post
Share on other sites

I am like Captain, 3 practice trys and making doubles-wow. Seriously though, I would suspect that area first for any problems. I tried doing my own flaring with two different tools and finally gave up because I didn't want my brakes left to 'chance'.Plus some of my lines ran inside the car and didn't want any leaks there.

As always Sarah you impress me with your mechanical ability

Share this post


Link to post
Share on other sites

Thanks, Steve! Yeah, wait a while longer before you decide to be impressed. That fitting might end up having a slow leak. If it does, I can always just buy another 30" line with fittings and leave it long-ish (by about 5"). I suppose I can make a loop in it to take up the extra length. Or maybe I can find a 25" brake line somewhere.

Fingers crossed!

Share this post


Link to post
Share on other sites
Jetaway,

There is a tool for this job.

http://www.summitracing.com/parts/WMR-W158C/

But I'm surprised it took that much force. I'm not that beefy but I usually just grip with a large pair of pliers and push in to compress. Then while holding the spring in, I can reach to the back and rotate the post with my free hand to engage the slotted washer.

I do these first before hooking up the return springs. The retainer helps to hold the shoes while I force the returns back on. Those are the ones that usually give more of a headache.

I guess I shouldn't rule out general physical decrepitness.

I'll have an opportunity to try your tip of putting the anti-rattle springs on before the return springs. After 400 or so miles of driving, apparently my rebuilding failed on one of the cylinders. I don't understand why.The bore and piston were clean, no rust, and no scoring. I had the rebuild kit(s) for the early 240Zs (built before 7/72 -- maybe a month off on that, mine is from 10/71). How it managed to fail while backing out of my garage rather than at speed, I will never know.

One possible thing, though it is a longshot. The Factory Manual, Chilton's and my primary reference, Autobook, shows the return spring inside the cylinder as having its larger end against the piston, smaller against the cylinder. But I know, on both of my cylinders, it was installed the other way because I had to jimmy it off the bolt-head like thing on the piston. The large end easily fits over this bolt-head like thing. But I'm not sure how it would make a whit of difference which way it is installed and that if it does matter,why did the cylinders work with the springs installed the "wrong" way?

Chris

Share this post


Link to post
Share on other sites
I'll try not to be too down on rear drums. Yes, I can see how rear disc parking brakes could be difficult. I wonder why they're inside tiny drums and not clamped across the disc too.

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?

Share this post


Link to post
Share on other sites
The Factory Manual, Chilton's and my primary reference, Autobook, shows the return spring inside the cylinder as having its larger end against the piston, smaller against the cylinder. But I know, on both of my cylinders, it was installed the other way because I had to jimmy it off the bolt-head like thing on the piston.

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??? :ermm:

Share this post


Link to post
Share on other sites

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??? :ermm:

I think they are pre-77 cylinders, yes. They look like they were born with my '72 but I am beginning to put nothing past a determined P.O.;)

Yes, they are pre-77s. I'm looking at my downloaded service manual right now. Yes, the drawing has the big end against the piston. When I dismantled them, the springs were as you remembered, and as I reinstalled.

Weird, huh?

I really don't see how you could hope to keep the spring from wandering around in the bore if it were installed per Service Manual.

Chris

Share this post


Link to post
Share on other sites
I really don't see how you could hope to keep the spring from wandering around in the bore if it were installed per Service Manual.

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! LOL

Share this post


Link to post
Share on other sites

Captain, all I can point to is one rather corroded cylinder. Maybe that was the smoking gun. I have no idea how long the fluid was leaking. I usually check the fluids with every oil change, but perhaps not reliably enough. I don't think the twisted-up brake line that I replaced was leaking. Anyway, in my experience, when there's a leak, even a slow one, it's brake rebuilding time. There's usually lots of stuff like I found. In the end, I straightened out one corroded cylinder, two corroded calipers (one of which wasn't really all that old), old brake fluid that needed flushing, some brake hoses that might have been past their prime, and some rusted-solid emergency brake mechanisms. I may have one master cylinder to go.

I finally got my MityVac today, so I'll do my final bleed tomorrow. I wasn't aggressive with the first bleed, because I didn't want to screw up my master cylinder. I might not have been successful in that regard. We'll see...

Share this post


Link to post
Share on other sites

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!!

Edited by Captain Obvious
Hadn't had my coffee yet

Share this post


Link to post
Share on other sites

Well, that's true. However, the fluid had disappeared over maybe 2000 mi. I suppose I might have explored more, but as far as I could ascertain from the PO, the brakes had been "maintained" (replacing a part here or there), but the hydraulics were at least 15 years old for the most part, without the benefit of regular use at various points in their life. So a light had already gone off in my head when I first bought the car that a brake rebuild would probably lie not far down the road. ;) In fact I was tempted when I first got the car to tear into the brakes, but the car seemed to stop fine, and the engine was begging a bit harder for my attention.

Share this post


Link to post
Share on other sites

Well, I've bled my brakes with my fancy MityVac. The verdict? I didn't think it did as good a job as an assistant and a manual opening/closing of the bleeder screw. Anyway, my brakes work, and I can stand the car on its nose, but the pedal is still somewhat soft. The pedal travels maybe 2", making a light wheezing noise as it travels. Of course the brake shoes are not perfectly shaped to the drum yet. They have a VERY smaller diameter than the drum, so I imagine the rear cylinder travels just a bit further for now. Would that make the brakes somewhat spongy?

Any thoughts? Buy more brake fluid, and do it again?

Share this post


Link to post
Share on other sites

Take a bottle, fill it with brake fluid 1/2 way

Run a hose from the bleeder to the bottle, submerge it in brake fluid and crack the bleeder

Go top off the the brake fluid and start pumping, do it about 10 times and check the fluid

Repeat the process 3-4 times per wheel.

Close the bleeder before you remove the hose!

Share this post


Link to post
Share on other sites
Well, I've bled my brakes with my fancy MityVac. The verdict? I didn't think it did as good a job as an assistant and a manual opening/closing of the bleeder screw. Anyway, my brakes work, and I can stand the car on its nose, but the pedal is still somewhat soft. The pedal travels maybe 2", making a light wheezing noise as it travels. Of course the brake shoes are not perfectly shaped to the drum yet. They have a VERY smaller diameter than the drum, so I imagine the rear cylinder travels just a bit further for now. Would that make the brakes somewhat spongy?

Any thoughts? Buy more brake fluid, and do it again?

A slightly vague pedal is normal until the brakes bed-in. As you said, the shoes and drums are not the same diameter so the shoes flex more than normal unlit the diameters match. The pads in front will do the same thing to a lesser degree until bedded in. The bed-in will take a few hundred miles.

The brake fluid level for the front brakes (larger reservoir, closer to firewall) will drop slowly as the pads wear. The rear brakes will not do this. The rear brake slave cylinder will always return fully unless they are stuck for some reason.

Share this post


Link to post
Share on other sites

Thanks, guys! Well, I guess I'll drive the car a few hundred miles and see how it goes.

Rob, I've not tried that technique, but it sounds good. I have a check-valve bleeder that does almost that, except the fluid doesn't re-enter. I do the last couple of squirts by having someone depress the pedal for me while I burp the bleeder plug.

Share this post


Link to post
Share on other sites
www.silverminemotors.com offers a more complete kit for less $$. I have their stage 4 front & rear and it was worth it. The fronts are from a Toyota 4runner & the rear are a Mustang GT 500

Thanks for the information, I have been looking for a complete system at a fair price for some time. I wanted vented discs, 4 piston front and rears single or dual piston to work with e-brake.

Question - front disc are 10.8" and rear are 11.8". Normally the larger would be on the front. Will the 11.8" disc work on the front?

Planning to buy 16" wheels - any suggestions?

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.