Over the winter I replaced all the brake lines, wheel cylinders and the master with new ones, on my 57 Skyliner. I installed a dual master with a power booster. Everything works properly except the left front assembly vibrates badly when the brakes are applied. The severity and frequency of the vibration is proportional to the speed of the car. The front drums are new and of course so are the shoes. So the first thing I did was install new shoes. That didn't help. Next I had the drum turned on the hub and that didn't help either. I should mention that before I did this work, it would had a mild form of this vibration when braking hard at highway speed.

So I am at a loss trying to figure out where this problem is coming from.

Did you flip flop  the wheels maybe front to rear to make make sure the wheel/ tire is not the issue?

thank you. That will be my next move! I think I will swap at the front to see if it switches sides. The tires look brand new by the lack of tread wear but they are 12 years old!

If there is no joy with the tire swap, swap the drums side to side.  If the trouble follows......

Quote from: flatbedfred on 2024-06-22 07:03thank you. That will be my next move! I think I will swap at the front to see if it switches sides. The tires look brand new by the lack of tread wear but they are 12 years old!

Although there's virtually no tread wear replace the tires.  They deteriorate internally and can cause significant damage when they "let go".  I can't find the picture now but someone posted a picture of the damage caused by a blowout and it was significant.

Oh I totally agree. I just got the car last year and I will be replacing them.

Quote from: terry_208 on 2024-06-23 08:32Although there's virtually no tread wear replace the tires.  They deteriorate internally and can cause significant damage when they "let go".  I can't find the picture now but someone posted a picture of the damage caused by a blowout and it was significant.

Might be my tire failure.....

Quote from: Ford Blue blood on 2024-06-24 07:02Might be my tire failure.....

Yes, it was your tire failure.

Fred, just a thought...could you have accidentally swapped the primary and secondary shoes when reinstalling? I did a field repair at the Street Rod Nats once and swapped them. Had a good shake when applied.

JayBird,
thanks for your reply. I did check for that and they were correct. I swapped the two front wheels and the problem appears to have moved to the right side. I would now describe it as right side and middle, my perspective because I am sitting in the drivers seat. I am replacing the tires with new ones in a couple of days.

Let me share one more item that I have experienced. You say that you added a power brake booster and dual master cylinder. I did the same on my wagon and experienced a pretty good shudder afterwards. What I fund was, the small piston/plunger that goes between the booster and master cylinder had to be ground about 1/8 inch sorter in length. With the engine off, there was no drag on the brakes. With the engine running and providing vacuum to the booster, the piston was slightly actuating the master cylinder. This drug the rear shoes and caused the shudder. My booster/cylinder kit came from summit and I have no idea who the manufacturer was. hope this helps.

Jaybird,
thanks for that information. Tomorrow I am getting my new tires installed so we will see what happens. Incidentally in regard with what you mentioned, the center shaft end in the booster is supposed to be adjustable in and out to correct for that problem. I wasn't able to adjust mine.

So I have my new tires on and that is good. My braking vibration problem was solved when I had the second front drum, the right side drum turned. I imagine that, two new drums and both were out of round, out of the box.

Back in the day, turned all drums and rotors new or not.

Yup....