Braking Question

Joseph James

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1968 Sport Fury. Manual drum braking.

I recently drove this car. I hit the brakes at around 50 mph. Lots of shaking. Any ideas? Once I got below 35, the shaking stopped.

Parking brake is disconnected. I haven't had time to investigate. I may only have front brakes working. I also have a leak. Brake light came on. I plan on going through the entire brake system. Just curious about the shaking that I got.
 
1968 Sport Fury. Manual drum braking.

I recently drove this car. I hit the brakes at around 50 mph. Lots of shaking. Any ideas? Once I got below 35, the shaking stopped.

Parking brake is disconnected. I haven't had time to investigate. I may only have front brakes working. I also have a leak. Brake light came on. I plan on going through the entire brake system. Just curious about the shaking that I got.

Shaking can be caused by a bunch of different things. I suspect that as you brake light came on that you probably have a leaking wheel cylinder that has contaminated the brake linings with fluid. This causes the lining to get sticky and grab the drum until enough force builds up to break the bond. It will do this repeatedly and cause the shaking. Rebuild the brake system, hoses, linings, cylinders and shoes and report back, check all steel lines for corrosion while you are at it. This would also be a good time to replace the master cylinder also. If you see obvious fluid leakage into the booster unit, it should be replaced at this time also. (A bad booster won't cause shaking, but if it has fluid inside it will fail in short order).

Dave
 
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If the car has sat for a good while, it's possible that rust in on the inner surface of the drum. As the brake shoes encounter this rougher area, the brake shoes can "grab" onto those rougher areas and not so much on the smoother (non-rusted) areas. But that should wear off with increased use, by observation.

Otherwise, probably some drum "out-of-round" situation? Did the whole car shake? Did the steering wheel vibrate and try to self-turn slightly, side-to-side, as the shaking was going on?f

Make SURE to match the width of the brake shoes now on the car.

As mentioned, the master cyl won't cause shaking by itself. Initially, I'd be more concerned with the condition of the items at the wheels. After that's done, a new master cyl can happen at any time.

Just some thoughts,
CBODY67
 
Out of round front brake drums or a lateral out of round front drum will do this. I had it on my Polara after even with a brand drum Auto Zone specials.
Replaced the one drum and it was fixed.
 
Thank you guys for the input.

The car sat before I got it. I bought it in July and have drove it three times. It needs a rebuild on the engine but I am more concerned with the brakes right now.

The shakes only happened above 40 mph. Brake light came on when I had the idle up to keep it from dying. I get the light when I really press the pedal hard. I suspect a leaky wheel cylinder.

I am going to go through the entire brake system. The fact the parking brake has no resistance worries me. Plans are to replace the drums, wheel cylinders and hardware along with the shoes.

This is the last car I am ever going to buy. I'm 47 now, so I have no qualms about rebuilding everything on this Fury.
 
Thank you guys for the input.

The car sat before I got it. I bought it in July and have drove it three times. It needs a rebuild on the engine but I am more concerned with the brakes right now.

The shakes only happened above 40 mph. Brake light came on when I had the idle up to keep it from dying. I get the light when I really press the pedal hard. I suspect a leaky wheel cylinder.

I am going to go through the entire brake system. The fact the parking brake has no resistance worries me. Plans are to replace the drums, wheel cylinders and hardware along with the shoes.

This is the last car I am ever going to buy. I'm 47 now, so I have no qualms about rebuilding everything on this Fury.

If you are getting no resistance on the park brake you have a broken brake cable (not common), seized or broken rear brake adjusters or a bad wheel cylinder.

Dave
 
As the brake light comes on with hard pressure coupled with no park brake, I suspect one or both adjusters are bad.

Dave
 
Thanks, Dave.

I don't want to pull the engine myself but I may do it so I can keep the car at home and work on the brakes. No use going if I can't stop. Brake cable looks intact so far. I checked at the handle and back to where it splits to two cables.
 
I suspect there are several things going on. The light coming on when you press the pedal hard may be due to air in the brake lines causing the switch on the prop valve to trigger. Check the fluid level. If it stays constant that means no leaks, a good thing. Check the shoes and drums next for the shaking. As others said they may be rusty from a lack of use. If not badly worn you can have them turned at a brake shop for a little cash. Replace the shoes at this time too. I do recommend inspecting the rear axle seals while the drums are off. If you see oil leaking this should be fixed too. More expensive but a lot cheaper than replacing a differential. The hard part is the outer seal. It sits behind the bearing and bearing replacement is the only way to replace it. You do have to be careful when removing the axle to not let the thrust pin at the end of the axle fall out of place (one on each side). Very easy to have this happen. I've had it fall down inside the housing and had to remove the differential because of it. Royal pain here. Used a dab of epoxy to hold it in place while reassembling everything. On the passenger side is an adjuster to set the axle side play. Make sure the shop that removes the bearing doesn't damage it in any way. Another royal headache to fix. Use a reputable shop for this and make sure they are aware of it ahead of time. The bearing will need to be greased after install. I used a needle attachment for my grease gun.
 
Rebuild the whole system since it is new to you for piece of mind.
 
Worn out front end can also cause a lot of shaking when braking at speed. Is the shaking felt through the steering wheel or through the body? Is the brake pedal shaking? I’ve seen worn out front ends shake at speed under braking but not at lower speeds. FWIW
 
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