My 68 deville has drum brakes and it's acting weird when I first begin to slow down. Most of the time when you first begin to slow down, the car will jerk left (assuming the left front wheel is breaking before the right), and sometimes it will give a slight jerk to the right. Rarely it will jerk back and forth a time or two while beginning to slow down.
After that initial swing to the left or right, it slows down as normal. Any ideas what might be causing this?
Sounds to me like something within the drums or drums themselves. I would think a hydraulic issue would be more consistent. I've had some drums do some funny things. Sometimes it's just a disassemble and cleaning that takes care of it.
If it were me. I'd start from scratch to isolate any issues. Bleed lines to eliminate that possibility. Visually inspect both sides for any broken springs, hold downs etc. I'd switch sides on the drums too and take it for a spin to see how it reacts. If the drums are slightly out of round it will do some grabbing and other funky things. Then go in for the full brake job.
When's the last time you replaced shoes and hardware or had drums spun?
I haven't had anything done to the brakes at all. Have owned the car since late last year and didn't drive too much this winter. How irritating are the drum brakes on these cars? Last drum brakes I worked on was an 85 toyota pickup and I swore after dealing with those brakes I would never do them again.
I had this problem when I got my sedan deville. It turned out the old brake hose had nearly swollen shut. If you go through all the things smelvis said. I only caugh this because it was nearly impossible to bleed one side.
What comes to my mind is you could've switched the brake pads. The pads set in one drum are a slightly longer one and a slightly shorter one. But they have a symmetrical shape, so it is easy to have both short ones on your right side and the long ones on your left side without really noticing it when installing, hence the pulling to left when you brake.
I drove around like this (only in the rear though) for a while and I never noticed, until it surfaced doing a brake test (on the brake test bench for yearly inspection) and I took apart the brakes. I had those brakes replaced by a workshop that time, because I was away and needed it done for an event.