73 duster front brakes locking up when coming to a stop.

-
flathead31coupe

flathead31coupe

Well-Known Member
Joined
Aug 1, 2010
Messages
1,292
Reaction score
247
Location
indianapolis indiana
When I bought the car, the guy stated that the front brakes were locking up. But I didn't think that would be a big deal. Or a deal breaker when I purchase the car.
When you drive the car, if you push on the brakes slowly it will stop if you use the brakes. Normally the front will lock up , but as soon as you let off the pedal , it rolls again....
 
stock 4 piston KH or 73~76 single pistons or something else?

manual or power?

any other work done? any system parts replaced?

is it if you slowly brake it'll brake fine, but if you romp it it'll lock up and then release and roll fine once stopped?
 
junkyardhero said:
stock 4 piston KH or 73~76 single pistons or something else?

manual or power?

any other work done? any system parts replaced?

is it if you slowly brake it'll brake fine, but if you romp it it'll lock up and then release and roll fine once stopped?
Click to expand...
Stock power brakes...when you stop normal the rear locks up.....soon as you release it it rolls fine...it's been doing this since I bought the car..previous owner said it was locking up as well
 
Last edited:
does it lock up at first blush or further in the pedal travel as you slow down?

most likely it's a piston is cocking in the bore or sticking. possibly you've got worn pads causing the issue, but it could be any number of things: MC, warped rotor, etx.

ETA: check the lands on the caliper adapters & caliper to be sure that everything is moving freely and debris free. this includes the retainers as well.

time to pull them apart and service them.
 
junkyardhero said:
does it lock up at first blush or further in the pedal travel as you slow down?

most likely it's a piston is cocking in the bore or sticking. possibly you've got worn pads causing the issue, but it could be any number of things: MC, warped rotor, etx.

ETA: check the lands on the caliper adapters & caliper to be sure that everything is moving freely and debris free. this includes the retainers as well.

time to pull them apart and service them.
Click to expand...
Locks up at first push...I will ck it out thanks
 
disconnect the booster, pump it dry, then roadtest again.
IMO one of two things is happening;
1) the power valve inside the booster is broken, or
2) the pushrod is adjusted wrong.
If the problem persists with the empty booster, look to the pushrod.
If the problem goes away, replace the booster.

EDIT: see post #12
 
Last edited:
AJ/FormS said:
disconnect the booster, pump it dry, then roadtest again.
IMO one of two things is happening;
1) the power valve inside the booster is broken, or
2) the pushrod is adjusted wrong.
If the problem persists with the empty booster, look to the pushrod.
If the problem goes away, replace the booster.
Click to expand...
Thanks
 
AJ/FormS said:
disconnect the booster, pump it dry, then roadtest again.
IMO one of two things is happening;
1) the power valve inside the booster is broken, or
2) the pushrod is adjusted wrong.
If the problem persists with the empty booster, look to the pushrod.
If the problem goes away, replace the booster.
Click to expand...
Pump it dry?
 
Well I miss-spoke a lil, I said "disconnect the booster" whereas I shouldda said "defeat the booster"
I usually just clamp the line and pump the brake pedal until the vacuum is gone. I guess "dry" is the wrong word too.
I realized after I posted it but was too lazy to edit it.
 
AJ/FormS said:
Well I miss-spoke a lil, I said "disconnect the booster" whereas I shouldda said "defeat the booster"
I usually just clamp the line and pump the brake pedal until the vacuum is gone. I guess "dry" is the wrong word too.
I realized after I posted it but was too lazy to edit it.
Click to expand...
No problem thanks
 
So here's the latest. I had a chance to check out the break problem. Turns out it's not the front brakes that are grabbing but the rear drums period after inspecting each side. I noticed that there is no cross bar at the top of either side Between the brake shoes, the little flat bar. Also, there is no adjuspring Spring and set up that they just are is there on both sides, but there's no e break p stat connects the shoes to the cable that being said with all of that stuff missing. Is that why the brakes are locking up? Short shoe is on the front long shoe is in the rear. I also noticed that the rear shoes were really thin
 
Last edited:
I just got finished putting On the
Emergency brake hardware Springs adjuster
Cross bar that goes between the two break shoes ect.. I don't know what will happen with all of that stuff missing on both sides. But I know it should be on there. I will try it out tomorrow and see what happens.
 
If you run your car without the front brakes working, but with the rear adjusters now working,
then
there is a good chance that after several hard stops, or backing up to finish the adjusting job, the self adjusters will tighten up the rear shoes excessively, and now you have a new problem. This is probably why the previous owner took that stuff outta there.

IDK why your fronts are not working correctly, there are several possibilities. But I'm still thinking it's the booster, which is really easy to check. and that control valve is really easy to break, if yur not careful during the set-up.
 
AJ/FormS said:
If you run your car without the front brakes working, but with the rear adjusters now working,
then
there is a good chance that after several hard stops, or backing up to finish the adjusting job, the self adjusters will tighten up the rear shoes excessively, and now you have a new problem. This is probably why the previous owner took that stuff outta there.

IDK why your fronts are not working correctly, there are several possibilities. But I'm still thinking it's the booster, which is really easy to check. and that control valve is really easy to break, if yur not careful during the set-up.
Click to expand...
Thanks... It looks like somebody put new brake lines at the master. Cylinder down to the proportioning. Maybe they got the lines wrong. I need to see a diagram
 
flathead31coupe said:
Thanks... It looks like somebody put new brake lines at the master. Cylinder down to the proportioning. Maybe they got the lines wrong. I need to see a diagram
Click to expand...
i'll take: was a drum brake car didn't replace the distribution block/prop valve or got the plumbing wrong for $500 alex

but the rear brakes bobo'd up like that to work is just hack *** work. so i'd be SUS AF about everything else in the system. you're likely dealing with more than one issue, so know that going into it.
 
How about posting some pictures (disc brakes, master/booster, rear brakes (with drums off) and distribution block) of what you have.
 
AJ/FormS said:
no!
If the rear brakes are locking up, it is because the fronts are not working, and you are stepping on the pedal way harder than should be required.
Click to expand...
I'm totally going to disagree with you on this one. If he's missing parts an the back brakes are not assembled correctly how would the front brakes have any effect on the crap that's going on inside the rear drums.?
 
flathead31coupe said:
I just got finished putting On the
Emergency brake hardware Springs adjuster
Cross bar that goes between the two break shoes ect.. I don't know what will happen with all of that stuff missing on both sides. But I know it should be on there. I will try it out tomorrow and see what happens.
Click to expand...

The emergency brake struts and cable levers have no effect on the hydraulic system.
They are part of the "secondary mechanical brake system" required by most laws.
 
Inertia said:
The emergency brake struts and cable levers have no effect on the hydraulic system.
They are part of the "secondary mechanical brake system" required by most laws.
Click to expand...
The emergency brake parts may not be engaged in the hydraulic parts. But try using your brakes when half the parts are missing and things are floating around inside the drum. Just a broken hold down spring pin can cause brakes to lock up.
 
Thanks for all the replies. When I can spend more time on the car I will try and get pics it is a factory 340 car..factory power disc brakes..not sure why the parts were missing from the rear...but they are there now...also it has a 81\4 rear end..may be it was changed....I thought it should have been an 8 3/4
 
8.25 was stock in '73

8.75 was only offered in SBP and thru 72 (for a-bodies)
 
You must log in or register to reply here.
-

Back
Top