First thing you need to know--I'm stubborn and cheap. I don't pay anybody to work on my stuff if I think I can do it for myself.......
I noticed the brakes on my wife's 69 Bug were getting a little sloppy/loose/spongy. Bought and installed new brake shoes on all 4 wheels (including 'breaking loose' the adjusters on 2 of the wheels). The old brake shoes were obviously old, well-worn in the case of 5 shoes, and old and cracked looking in all instances. Then I adjusted the brakes to right before the shoes are draggiing on the drums. Then began the process of bleeding the brakes....
On the 2 rear wheels, when I went through the bleeding process, there is very little-to-no brake fluid apparently being pumped to the rear brakes. The brakes are still loose-feeling. Should I start at the brake lines where they meet the wheels and work back to the master cylinder (assuming the lines are clogged, etc) or at the master cylinder and work out to the wheels (assuming the master cylinder or master cylinder assembly-under the fuel tank-are at fault)? Which is the most likely problem in anyones opinion?
Brakes question
- Speedy Jim
- Posts: 2290
- Joined: Sat Feb 15, 2003 12:01 am
Brake hoses. After ~40 years, the rubber inside swells up and clogs
the hose. Do all 4.
After you get that sorted, you may find that the pedal is still low/squishy,
even though you bled them 100 times. It is a characteristic of new shoes,
in that they won't match the drum diameter until they have "worn in".
Short answer: Don't assume that low pedal is due to air in lines.
the hose. Do all 4.
After you get that sorted, you may find that the pedal is still low/squishy,
even though you bled them 100 times. It is a characteristic of new shoes,
in that they won't match the drum diameter until they have "worn in".
Short answer: Don't assume that low pedal is due to air in lines.
-
- Posts: 3011
- Joined: Fri Apr 20, 2001 1:01 am
Some comments related to brake work:
You should get a good strong squirt of fluid out of all 4 bleeder valves. If the rear is weak, the pistons may be stuck in their bores or the hoses swollen shut like Jim said. Very common. Replace all rubber brake hoses with good quality items. Tear apart wheel cylinders and clean them up, or just buy new. It's your (wife's) life you are chancing with shortcuts and penny stretching. Brakes are not a place to cut corners, most other stuff can wait.
Adjust shoes so tight that the
wheels won't turn, before bleeding. After bleeding, adjust shoes again so that you can just hear the shoes drag, but can't feel much resistance when you turn the wheel. Easy in the front, harder to feel in the rear because of the natural drivetrain resistance.
Before adjusting rear shoes, loosen the handbrake cables completely. Otherwise shoe adjustment won't work as intended.
Before adjusting the front shoes, tighten the wheel hub nuts to spec to eliminate free play in the wheel bearings. (That could throw your shoe adjustment off)
Go out on a test drive to allow parts to settle, then come back and re-adjust. Most likely they got loose already. Repeat until they start holding adjustment (partys have found their resting position and won't move around anymore).
Jan
You should get a good strong squirt of fluid out of all 4 bleeder valves. If the rear is weak, the pistons may be stuck in their bores or the hoses swollen shut like Jim said. Very common. Replace all rubber brake hoses with good quality items. Tear apart wheel cylinders and clean them up, or just buy new. It's your (wife's) life you are chancing with shortcuts and penny stretching. Brakes are not a place to cut corners, most other stuff can wait.
Adjust shoes so tight that the
wheels won't turn, before bleeding. After bleeding, adjust shoes again so that you can just hear the shoes drag, but can't feel much resistance when you turn the wheel. Easy in the front, harder to feel in the rear because of the natural drivetrain resistance.
Before adjusting rear shoes, loosen the handbrake cables completely. Otherwise shoe adjustment won't work as intended.
Before adjusting the front shoes, tighten the wheel hub nuts to spec to eliminate free play in the wheel bearings. (That could throw your shoe adjustment off)
Go out on a test drive to allow parts to settle, then come back and re-adjust. Most likely they got loose already. Repeat until they start holding adjustment (partys have found their resting position and won't move around anymore).
Jan
- Marc
- Moderator
- Posts: 23741
- Joined: Thu May 23, 2002 12:01 am
If the drums are glazed, the brakes will lose effectiveness even if the properly radius-matched and the hydraulic system is spot-on. Turning the drums so they present a virgin surface for the new shoes to seat into is the "right" approach (for the cheapskate approach, at least scuff the friction surface up with some coarse sandpaper).
If the drums are turned beyond the standard-lining limit (9.114" for your `69 Standard Beetle) it will take approximately forever for off-the-shelf replacement shoes to wear in to match them - and by the time they do, they will be worn very unevenly, real thin at one end and like-new at the other. The equipment needed to properly radius-grind the linings to match the drum diameter is not commonly found anymore outside of specialty shops which do the actual relining of the shoes in-house, because on most drum-brake-equipped cars it's just not as critical as it is on the 50+ year-old design of bug brakes. A little-known fact is that it's actually legitimate to turn the drums an additional .040" beyond the "limit" diameter cast into them IF you fit thicker "oversize" linings (and properly radius-match them, of course)....but that's as big as they should ever go; if you demand more-than-average resistance to heat-fade - i.e. much mountain-road service - it's best to keep the drums on the thick side.
#1 rookie mistake when servicing `65-up brakes is to install the adjuster screws upside-down so that their angled slots are not properly matching up with the ends of the shoe frames. This causes all sorts of erratic behavior. I recommend you double-check that first.
If the drums are turned beyond the standard-lining limit (9.114" for your `69 Standard Beetle) it will take approximately forever for off-the-shelf replacement shoes to wear in to match them - and by the time they do, they will be worn very unevenly, real thin at one end and like-new at the other. The equipment needed to properly radius-grind the linings to match the drum diameter is not commonly found anymore outside of specialty shops which do the actual relining of the shoes in-house, because on most drum-brake-equipped cars it's just not as critical as it is on the 50+ year-old design of bug brakes. A little-known fact is that it's actually legitimate to turn the drums an additional .040" beyond the "limit" diameter cast into them IF you fit thicker "oversize" linings (and properly radius-match them, of course)....but that's as big as they should ever go; if you demand more-than-average resistance to heat-fade - i.e. much mountain-road service - it's best to keep the drums on the thick side.
#1 rookie mistake when servicing `65-up brakes is to install the adjuster screws upside-down so that their angled slots are not properly matching up with the ends of the shoe frames. This causes all sorts of erratic behavior. I recommend you double-check that first.