Also, tomorrow's to-do list on my last "free day" before classes start again(and also procrastinating knocking out the final copy of my syllabus plus preparing my first week's lectures):
1. I finally got in the replacement wheel cylinders, so I'll be pulling the rear drums and fitting those tomorrow. Hopefully I can get them fitted without removing the brake shoes or the like. The last time I looked at them, they were basically perfect, and I really hate doing drum brakes. I know the springs are set up wrong on one side of my car, and I should correct that, but did I mention that I hate doing drum brakes, and that's one of my least favorite parts? Hopefully I can work the old cylinders out and fit the new ones without undoing the springs.
BTW, it's worth mentioning my great dislike of working on drum brakes.
Of course, I'll need to bleed after that.
I'm KIND of putting it off, though, because caught up in the postal system miasma now is a rebuilt "PDWA" valve. PDWA is the "Pressure Differential Warning Actuator." Basically, it's a sort of H shaped block that has lines for the front and rear brakes passing through opposite sides of the H. The cross of the H has a shuttle valve sealed off with O-rings, and there's an electrical switch that sits on top of the shuttle valve and is tied to a light on the dashboard. The idea behind this whole set up is if there's a failure in one of the brake circuits, in response to the "pressure differential" between the two circuits, the shuttle valve will move and light up the switch.
The system has two issues. One is that it's bloody useless, since your foot will tell you about brake failure far faster and more reliably than a light on the dashboard. The bigger issue, though, is the shuttle valve gets leaky. When that happens, two things happen. One is that brake fluid leaks out around the switch, so it's a source of a slow loss of brake fluid. The second and bigger issue is that it can allow "crosstalk" between the front and rear circuits, which, among other things, kind of defeats the purpose of even having independent systems and can also throw off the brake bias a surprising amount.
Some folks plug the leaky switch with a bolt, which stops the leak but not the cross-talk issue. Someone out in California actually gave me, for the cost of shipping(and return of my old one) one that he "fixed." He use to sell these, but got out of the business a while back and just has a few kicking around. Basically, this one has the shuttle valve removed completely and then a plug brazed in place that completely blocks the connection between the two sides.
Since there's no mail tomorrow, it won't be here for sure. I'll most likely put off the rear cylinders because I only want to deal with opening and bleeding the system once. I'll also have an excuse for not doing them since, if I haven't mentioned it, I don't like working on drum brakes. Usually when I do calipers/cylinders I can be lazy and gravity bleed them(just open the bleeder valve and let it sit for an hour or so). The PDWA is far enough "up" in the brake system(it's close to the master cylinder) that I can't be too lazy on gravity bleeding it because the master cylinder will likely run dry if left unattended with bleeders open. Of course, it's also high enough that I probably have a pretty good chance of the air working its way out if I just let it sit overnight. I'll either get out the Mightyvac, which is a pain when you need to bleed that much brake line, or hopefully my wife will humor me and spend a few minutes sitting in the driver's seat and listening to me say "up, down, up, down, how's it feeling?" a million times. BTW, since brakes have no power assist and you also have one axle with disks(4 wheel drums can usually do okay without assist since drums tend to self-apply once started), the pedal on an MGB is rock hard. It's a bit disconcerting the first time you drive one, but you quickly get use to it, and you also quickly notice any sponginess or hydraulic problems. I drove my other car today for the first time in probably a week or so, and aside from trying to step on the phantom clutch and reaching down to the console constantly, I jerked it around pretty good the first few times I stopped it.
2. I need to figure out what's going on with the speedometer. Everything past the transmission is good, which means it has to be something inside the transmission. Hopefully if I drop the driven gear out, I'll see the issue. Fortuantely, the ones for this transmission are available(the transmission in the car when I got it had issues there, and the driven gear was an NLA one that I finally tracked down for $100). Of course, I dread doing that since I'll lose some oil out of the transmission. That's not a huge deal aside from the fact that this is a "side fill" transmission-it has a bolt in the side that you remove, and keep pumping oil in until oil runs out the hole. I do it with a hand-operated pump that screws on to a quart bottle of oil, and it takes 47 pumps to transfer a full quart(yes, I've counted). Hopefully I won't lose that much. Still, though, in a home garage, there's not really a better way to fill it.