I finally got the engine, transmission and drive shaft in the car just before the 2023 GS Nats. I thought everything was going well until the old Holley carb that was fine before removal started spewing gas upon trying to reuse it. That was an easy fix with a rebuilt QJet from Everday Performance... until I snapped the idle adjustment screw. I finally got my nerve up and drilled it out. Now working great. We swapped on some nicer wheels and tires today. She was looking sharp. On the test drive I noticed the left rear tire locked up any time there was more than gentle brake pressure. We came back, took the drum off and cleaned it up. I'm thinking it is a wheel cylinder but now the shoes are contaminated and likely can't be salvaged. We doused them in brake cleaner and sanded the drum and shoes to try to get some more of it off. Still locks. I went to see if the rear master cylinder reservoir was low and as I was about to remove the cover, I see a drip of brake fluid from between the booster and master. Things I never touched are giving me issues. LOL That's the breaks with brakes, I guess. I'm seriously thinking of going rear discs if I have to buy a new master and a rear wheel cylinder any way. I hate drum brakes and the complexity the bring to everything.
Check your emergency brake adjustment. A too tight cable will cause the rear drums to lock during normal brake pedal operation. I ended up figuring this out after the rear end locked up on me during moderate to heavy braking, like deer or people crossing the center line. The adjustmet at the cable Y fixed my lock up problem.
I'm pretty certain it is brake fluid. It wasn't greasy and under the axle shaft was actually cleaner than above it. I cleaned it all up with brake cleaner and will check it again in the near future. The emergency brake is fairly well adjusted. I set it up when I put the transmission and crossmember back in. I also set the brake adjuster a little tighter. It was pretty loose but the parking brake still holds it on a slight hill in forward. I'm going to check the other side to see how the adjuster is set on it. Neither drags currently.
I've got rear disc brakes on my 70 Stage 1 and love them. The first 30 years I owned that car it never had a worthwhile emergency brake. Now it does. Four wheel discs are simple and plain work. No dozen spring loaded Rube Goldberg device there. They don't lock easily and survive repeated abuse better than drums. If they do lock, they track straight.
As an update, ScareBird is taking way too long to get a rear disc brake kit back in stock so I begrudgingly ordered a new master cylinder and a rear wheel cylinder. Total cost just under $50 so far and I've got more brake fluid than I can use in the next decade. I hate drum brakes but I guess I'll repair it until such time as it needs more service.
I agree . Rear discs are just another Saturday Car shows latest craze . Nothing wrong with DISC front Drum rear system . You can throw all the springs and hold downs for the rear brakes in 1 pile and I'll put every one where they belong . Guys who can't are the ones that get rid of their Quadrajet because they can't set it up properly .
Huh. Years, maybe 20 years ago I switched my rear (manual master cylinder) drums to disc using all GM stock components on my (heavy) 3,300 lbs drag car. 1970 SkyLark/GSX clone. Have to change my signature. Ran low, low 10’s at just below and above 130’ish mph last couple times out. Used regular four bolt GM flanges on a narrowed 9” Ford rear end. Can’t remember what I had stolen the brackets from. But the stock GM calipers sit on the very top. Olds Toronto perhaps? Had to get used to not applying the brakes too much after the stripe otherwise I’d be coasting to get to the return road. Had to play with master cylinders to get the piston bore diameters just right. Got it right on the second choice. Smaller bore creates more pressure. Helped to work at a parts store back then! Lol Stops with little brake pressure like it has power brakes… Wouldn’t be afraid to go mid 9’s with this setup when the Tomahawk goes in.
I’ve heard that before. Don’t know for sure?♂️. Definitely more surface area with the drums. They do fade faster than discs. All I know is when I switched to 4 wheel disc from just front disc. The car slows way quicker with less pedal pressure.
Drum brakes have more mechanical advantage. In many cases Disc brakes have more stopping power as they don't fade due to heat. If it's just a single short stop, drums win. If it's repeated or you're going 130, discs are better. Also, just for Greg. If the master was leaking at the back of the cylinder, its very likely brake fluid was sucked into your booster, so you should expect that to fail next.
My Stage 1 with 4-wheel disc brakes would disagree. That car will out stop the 350-4 speed car any day of the week and do it straighter and with less likelihood of a lock up/slide. At this point, it is the only thing I own with a drum brake of any kind. Everything else is full disc brakes. I agree. There's a reason almost nothing uses a drum brake for anything but a parking brake inside the rotor hat these days. Also, drums, if you ever get them wet, you have NO brakes for that first bit until they can shed the water. Discs clean themselves much better and faster. Been there, done that when my 71 GS was my daily driver in high school. I'll check my booster while I have it apart. Hopefully, it isn't full of brake fluid. It only seems to be the smaller, rear one that is way low. This would have been so much easier if I'd noticed while the engine was out before May.
I forgot how much I hate drum brakes! It took me half an hour to get the wheel cylinder line back in. It simply would not bite and thread onto the new cylinder. I've got it all back together after bench bleeding the master but need a buddy (or my wife) to help bleed everything.
There is a good reason aircraft use disc brakes or rotor/stator configurations. Greater efficiency in turning inertia into waste heat quickly and controlled.
One of the nice things about the big cars...EVERYTHING is bigger. It's like "Drum Brakes for Dummies". Even in the winter cold, and half drunk, I can still take these things apart and put them together again LOL! Echoing Mick Dundee... Devon
