Rear brakes hanging on

[Gavin Jeffrey]

Hi,
I have just completed my full rebuild of my disc (BUDD) and drum brakes on my 68 New Yorker
NOTE.. I used two left Budd calipers and just swapped the bleeder and brass feral to the other hole on one caliper which gave me a left and right)
The brakes are working well apart from an issue with the rear drums.
I have new rear shoes, new return springs and hardware, new wheel cylinders (correct disc brake ones), and drums machined and new rubber hoses (all 3) all backing plates cleaned and greased at the shoe slide points.
I have adjusted the rear brakes as i usually do so they have a light amount of friction and turning drum by hand it feels good.
After a short drive and a few low speed brake applications the rears are hanging on, car in drive at idle wont move.
What would possibly cause this, they are hanging on to the point where it struggles to drive, i have replaced everything, even the master cylinder, we flushed the system and they bled up nicely.
Its like they go out of adjustment.
I jacked it up after a short drive and could hardly turn the rear wheels, i cracked the master cylinder pipes and it made no difference which tells me it could me mechanical not hydraulic.
What's your thoughts guys
Thanks Gavin.

 

[69PHOENIX]

G'Day,
Not very Likely! But did you Chamfer the Leading Edges of the Brake Shoes ?
As I say Not very Likely the Cause but Possibly a Co-Contributor to Any Problem.
(I'll call that My 1.5 Cents Worth).
Tony.M

 

[Big_John]

i cracked the master cylinder pipes and it made no difference which tells me it could me mechanical not hydraulic.

Crack the bleeder at the wheel cylinder. You could have an issue with the rear brake hose. That seems to be a common failure lately.

Other things to check... Primary shoe (shorter lining) towards the front? Adjusters on the correct side and assembled correctly? Adjusters are left and right hand threaded. Honestly, I can't remember if the right hand thread goes on the right or left side, but that's not too difficult to figure out.

 

[rkrochen]

Just a few ideas to look for.
as mentioned when this happens crack the bleeders at the drums to see if there is residual pressure in the cylinders.
Next make sure that that both shoes are in contact with the anchor at the top. If they aren’t the emergency brake cables are too tight and after generating some heat there is enough expansion to create friction in the brakes resulting in dragging brakes.
Also make sure your primary shoe, the short one, is to the front.

 

[hemi71x]

I would have to agree with the response about the rear brake hose over the axle.
Collapsed internally.
Did you replace that in the rebuild?
Next logical step in the trouble shooting.

Oops.
I just re read your posting.
You state that the hoses were replaced.
Now I'm out of suggestions to give you.


I thought of this, on my walk around the block.
I am assuming that you have power brakes on the car.
Possibly the "rod" coming out of the booster is now improperly adjusted, to the back of the new master cylinder, causing the brakes to drag.

 

[Big_John]

You state that the hoses were replaced.

Gotta remember, especially in these days of offshore sourced parts, that "new" doesn't always mean "good".

 

[3C's & a D?]

If they aren’t the emergency brake cables are too tight and after generating some heat there is enough expansion to create friction in the brakes resulting in dragging brakes.

This would be my guess. Did you loosen the nut where the cable goes from one to two?

 

[rkrochen]

This would be my guess. Did you loosen the nut where the cable goes from one to two?

As usual a couple of pics would help a lot.

 

[Davea Lux]

Pull the rear drums and see if the top of the shoes are tight against the anchor stud. If they are not, the travel rod adjustment on the master cylinder is set too long. If there is no residual hydraulic pressure, next check the park brake adjustment. These cars are old and sometimes the cables get bound up and do not release properly. You might also try backing off the brake shoe adjuster wheel a couple of turns and see if that cures the problem. The automatic adjuster should take up the slack and give the proper clearance. As noted, if the brake shoes are installed backwards, this will cause the rear brakes to heat up, as noted, the shoe with the shorter lining always goes on facing the front of the car.

Dave

 

[oldkimmer]

If the brake shoes are not seated against the top pin the E brake cables may be stuck and need replacing. Kim