Brake Shoes Not Retracting

[MNSubbie]

I have a 48 Merc sedan with a strange brake issue: The LF brake shoes are VERRRY Slow to retract after you let up on the brake pedal.

Step on the brakes, and on that one wheel, the shoes stay out in contact with the drum---------until about 15 minutes go by. If you give it time, it will eventually retract. Or you can force the shoes back to the rest position with a couple of big screw drivers. The LF is the only wheel that does this.

The car has all new brake lines, wheel cylinders and master cylinder. Not sure exactly how long ago they were replaced, but all are shiny and like new.

Before I start taking things apart and replacing stuff that doesn't need to be replaced, I thought I'd see if someone here on the Forum has an idea of what my problem is.

Thanks in advance for your help

 

[Automotive Stud]

A collapsed hose will cause that. crack the brake line loose and see if it retracts. Or something could be mechanically binding. Can't say without taking it apart and looking at it. Plenty of new parts can be bad these days, can't go by that.

 

[oldbugger]

I think its easier to open the bleeder if it runs out and the wheel turns free it may be that rubber hose

 

[cadillac512]

I think its easier to open the bleeder if it runs out and the wheel turns free it may be that rubber hose

Agreed...this is the first step. If the shoes immediately retract when you open the bleeder,it's the hose or line going back to the master cyl. If the shoes don't, look for a sticky wheel cyl piston(s).


Terry

 

[Ronnieroadster]

If the wheel cylinders are import quality I have found they do exactly what you describe.
The cups in the wheel cylinders at least the ones I recently have had issues with caused the wheel cylinders to not retract like the good old USA made originals. One wheel cylinder was worse that the other however both were what I consider absolute junk!
Solution to the problem at least for me is rebuilding the originals with good USA made wheel cylinder cups.
Ronnieroadster

 

[Gene1949]

I had an identical issue many years ago. I finally traced it down to the hose on the passenger side.

It was check valving

 

[1948F-1Pickup]

The hose thing happens ALL THE TIME.
A company I used to work for got a mystery deal involving a Suburban and a 3" stack of service invoices related to a pull under braking. (wheel alignments, brake inspections, frame/suspension checks, etc. were on the invoices from 4 or 5 dealerships) We were told it was a carte blanche as far as the bill, as long as we could 100% fix the vehicle.
It was the right side brake hose. Parts $22.80, diagnosis $2700. I kid you not. Took us a about 1/2 hour with a pair of pressure gauges.

 

[Flathead Fever]

We kept the vehicles for about 15-years at the phone company, hundreds of vehicles and in the 30-years I was there I never once saw a brake hose fail or get a restriction in it. I know it happens. We did change the brake fluid every two-years like you're supposed to so that might have helped. I would definitely replace them if they were any older than 15-years.

We did have a recall for the right front brake hoses on the 1978 Chevy C50 trucks. They mounted the battery box above the brake hose and battery acid would leak onto the crimped metal end until it rusted away. Then the hose would blow off. I never saw one fail, but they were definitely rusty, we had to replace all of them and then keep an eye on them at every service.

 

[MNSubbie]

Thanks everyone, for your thoughts and ideas. I will try the bleeder screw as the first step---makes the most sense. Will let you know what I find

 

[MNSubbie]

Here's the story:
Replaced both front whl cylinders cause I didn't like how they looked inside (not smooth)
Checked all front lines and hoses, and connection bolts
These things were no help

I am embarrassed to tell you that my problem was the Return Spring. The side that was slow to retract was stretched, and comparing it to new on the bench it was over 1/4 in longer.
Replaced all four springs with new ones from Dennis Carpenter and my problem disappeared.

Guess sometimes its the little things that are the most important

 

[FritzJr]

MNSubbie, thanks for letting us know the eventual solution to the problem. Often these threads are left with no conclusion.

 

[1948F-1Pickup]

Here's the story:

I am embarrassed to tell you that my problem was the Return Spring. The side that was slow to retract was stretched, and comparing it to new on the bench it was over 1/4 in longer.
Replaced all four springs with new ones from Dennis Carpenter and my problem disappeared.

Guess sometimes its the little things that are the most important

Yup. Thanks for the conclusion.
All the little stuff adds up. On the later self-adjusting style brakes, I had a
junior mechanic get the little metal cable UNDER the semi-circular cable guide- that side never auto-adjusted correctly and caused the vehicle to have a brake pull.