Brakes grab like crazy....

[Dodgerdallas]

Im about to give up on this curse of a car,everything I do,even the simplist things never turn out right-now the Pwr brakes are grabbing,heres what ive done to them-
Replaced all lines front and back
all drums turned or new
cylinders new on front,refurbed on back-all match on each side
new shoes frt and back w spring and adj kits
rebuilt master cyl from oreillys
bled w new fluid
Heres what its doing-when the pedal is pushed,theres no resistance for 2 or 3'' and then it bottoms out and the brakes lock down hard and way over apply w very little foot pressure,ive tried adj the fronts by turning the wheels and getting the same drag on both but it doesnt make any difference,they still lock up hard.I tried what the manual said w the auto adjusters by backing and applying brake but nothing.Ive been working on cars for 30 years and its frustrating as hell I cant figure out a simple drum brake issue-anybody have a suggestion before I take it to the 21 year olds at Firestone so they can correct my problem?

[rt green]

power brakes?

[Dodgerdallas]

Just got back online-yes pwr brakes

[RIDGERACER383]

My dad was telling me about his Challenger he used to have doing the same thing and my 68 is doing it too.There's a block on the drivers side that your lines go into.Inside this block theres a ball bearing that can get stuck and cause this problem.Not sure if you changed that when you did your lines.It's a good place to start though.

[MrSnicks]

I didn't see that you have disc brakes up front so you don't have a proportioning valve, but you may need a new Distribution block. That's what the user above me was talking about. Brass block that all the brake lines go underneath the master cylinder.

Hope this helps.

Patrick

[RIDGERACER383]

That's it I was having a brain fart just woke up.

[matrout76]

Are you positive that the primary and secondary brake shoes are installed correctly?

If they are "backwards" they might grab...

[Cooter]

Factory POWER  brakes?

[Dodgerdallas]

I took them back off and looked,were the same as pictured on 66 service manual-one more thing, I took the lines off at each front cyl and blew the old fluid out from where the line hooks to the new MAster Cyl-could the passing air thru the junction on the frame sucked some fluid from the rear lines?? I didn't bleed them out...

[Cooter]

Any time you open a braking system, bleed ALL four wheels. Especially, with a proportioning valve.

[MrSnicks]

And when you do bleed the system start with the wheel farthest away from the MC and work your way closer. So Pass Rear, Driver Rear, Pass Front and then Driver Front.

Patrick

[six-tee-nine]

Do you have drums in the front with new pads?

I've seen alot of new brake shoes for drum brakes where the end of the braking material is too steep. Difficult to explain so I added a generic picture. If the edges are too steep unlike the picture below. The brakes dont really brake until the outer edge gets pressed hard enough against the drum and then they suddenly grab and lock up.

Easiest fix here is to file both outer edges away so that the angle becomes larger.

I hope you understand my primitive explanation......

[Dodgerdallas]

Thanks for the info,I finally broke down and let the shop bleed and adj the brakes-149.00 (don't ask) while they aligned the front end. I nabbed some spindles and brackets from a 73 E body w/disks so ill get rid of the dam drums...

[six-tee-nine]

Wise choise.
Drums were ok when there was  nothing else around but now they're a thing of the past. And with these heavy cars and the modern traffic you're better of with discs.