"Brake Failure" (luckily still on jack stands)

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dibbons

dibbons

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With Dorman 13910 bleeder kit in hand and a neighbor kid looking for work, I decided to bleed the power brakes on the '65 Formula S which has been off the highway for about 3 years now (stripped, sandblasted, painted, 904 rebuilt). The motor (rebuilt 10 years ago but now with fresh paint) still sits to one side, but with the vehicle raised all around on jack stands, should be a piece of cake.

First bled the factory single master cylinder (already been replaced about ten years ago when vehicle purchased-and booster rebuilt at the same time by "experts" I shipped it to). Not a problem there but the little bubbles kept rising from the bottom for quite a few sessions of pumping.

I can never remember on which wheel to begin the bleeding, in my own mind I can rationalize reasons to begin both left front or then again, begin right rear. I took a break and made an internet search. The site I found suggested right rear and work your way forward. Agreed.

While bleeding the right rear I found the pedal would not pump up. Discovered three leaks: right front bleeder was loose, metal line from body to the rubber hose over the differential dripped, and the last line to the right rear wheel where it exits the "Y" that sits on top of the differential (with the bolt that doubles as a vent) dribbled a little. Secured those problems best I could, always a compromise between not tight enough (leak) and too tight snap/strip.

Definitely purged some air from the rear wheel cylinders. When I got to the third wheel (right front), a mini-drop of brake fluid landed in my right eye. Ran off to flush with bottled water followed by some "artificial" tears I store in the fridge. Forgot to mention earlier, don't have a 9/32" brake bleeder wrench, so had to use a 1/4" drive socket, with two or three extensions on the 1/4" drive ratchet. No way to place a little hose on the bleeders that way, so cleaned things up a little along the way (Simple Green, baby wipes, paper towels, oil absorbent pellets for all that did not land in the plastic tub underneath).

When I got to the last wheel (left front) the brake fluid stopped shooting out forcefully. Maybe by then (bleeding the other three wheels first) there was no air left in the lines. Not sure if that is expected or something wrong there.

Now we had some pedal, although its standard height is not very far off the floor. That used to concern me when I first put the vehicle back on the road, not knowing what the static factory position of a power brake pedal should be on a 1965 A Body. But my worries were relieved finally when I read somewhere (don't remember where now) that the pedal was now designed to be more or less even with the gas pedal to make it more comfortable/convenient for the drive to move his/her foot from the gas pedal to the brake (and back again). Of course, that is not the case with manual brakes (like we have on our '65 Signet converible).

Now for the final test, will the wheels all stop when the brake is applied? Of course, all testing was done without power assist (no motor to provide the vacuum). First, had to reinstall the rear wheels/tires (front tires were not removed).

I found the right rear wheel stopped like a champ. The left rear wheel and right front wheel spun freely with the brakes applied. The left front wheel stopped but there was a cyclic scraping sound while the wheel spun before the brakes where applied. It's 2:00 PM now and I'm hungry, so maybe tomorrow I will be motivated enough to find out why two wheels are on "strike".

brake bleeding day.JPG
 
(whew!) By interpreting your title, I almost expected something bad was going to happen - like car slipping off one or more jack stand and - - - .
It can indeed be a work in progress, to do all you have to with getting all the systems attached and operating. Only suggestion would be that M.C. could be replaced with a 'dual' chamber. Good luck and stay safe (in more ways than one).
 
Make sure your brake shoes are adjusted properly. This in itself has a lot to do with pedal height on a drum brake car. Next invest in a pressure bleeder. They sell a brand called Motive that is reasonable and invaluable. You can buy different adapters for all kinds of cars.
 
I agree brake pedal height on drum brake cars is largely determined by properly adjusted brake shoes to drum clearance. It's a "feel" that has kinda been lost, because old mechanics are retiring/dying and cars have been being built with 4-wheel disks for well over 2 decades, now.
You can hand adjust the shoes up close to the drums so that the drum can be just slid on/off without forcing it on. Of course, the shoes have to be centered on the backing plate to get an accurate "feel".
 
A method I have used and was taught back in the 70’s is to use a screwdriver thru the adjustment slot to pry the star wheel adjuster front to rear while in between adjusting the brakes. As said it’s a feel thing but I adjust the wheel until there is very little movement front to rear of the adjuster. You do the same on all 4 wheels. Now if you wind up with a brake pull one way or another, that’s another procedure.
 
That reminds me of an incident back in the 1970's when the California Highway Patrol was performing random roadside inspections. I was driving a '63 Pontiac Grand Prix and got into the left turn lane to avoid the inspection ahead. The light was red and the brake pedal went all the way to the floor as the vehicle slowly began to come to a stop, but it only slowed down, did not have time (or enough braking efficiency) to make a complete stop at the light. So I made a U-turn, using the left turn lane at the signal, but against the red light because it hadn't changed yet. Lucky no traffic at the time.

The CHP never caught on to my "escape". I found that the reason the brake pedal kept getting closer and closer to the floor, as time went on, was because the brake shoes (four-drum system) were out of adjustment.

Pontiac Grand Prix.jpg
 
When I drove the '65 Formula S (mentioned in post #1) down here to Mexico from California, I stopped in Tijuana on the way and had a brake shop adjust the drum brakes. About ten minutes later down the highway, I smelled some awful burning.

I called the shop that had adjusted the brakes and they sent someone over to back them off a little (working on the side of the road). Then I made it the rest of the 950 miles down here to La Paz.
 
Along with proper adjustment, be sure the self adjusting hardware is good and moving freely. There are two star adjusters, a left thread and right hand thread, be sure they are on the correct side and the star does not have any stripped teeth.

I was taught the way to adjust when the adjustment is close, is to back up at 5-10 mph and pump the brakes several times.
 
That procedure is correct, but if my memory serves me correctly, the self-adjusters were removed (now manual only). Will verify the type as soon as I remove the drums.
 
dibbons said:
That procedure is correct, but if my memory serves me correctly, the self-adjusters were removed (now manual only). Will verify the type as soon as I remove the drums.
Click to expand...

I ordered all new stuff from R A couple years ago for my Signet. Mostly I needed the cables but figured replacement star adjusters would be better than 52 year old OEM's. My old parts turned out to be almost perfect but the new (off-shore) silver colored ones had very rough and blunt teeth. The plate that triggers them, to rotate, would no way engage so turned out to be useless. I suppose the moral of this is to order higher price stuff for the best quality, or dress up original teeth as necessary then wash and lube and install.
 
I always adjusted the shoes till there was a slight drag, sometimes a slight scrap scrap scrap as the wheel was spun.

Then apply the brakes a few times and check the wheel again. Adjust if needed.

Do for all wheels.

Finally as stated above backup and apply the brake a number of times. I realize you can't do that just yet. Assuming you do have auto adjusters and they are installed correctly the brakes will take care if them selfs.
 
I removed the left rear wheel and drum and don't see any leaking or anything out of place. I wonder if the cylinder is just stuck/not expanding due to the years of sitting? I hope I don't have to resort to the operation in this video:



left rear brake.JPG
 
peel the outer (dust)seals back, and if you see corrosion or fluid the cup seals are leaking. I don't know if new wheel cylinders are available for your app or not, but you may be able to put a kit in them. I used to do that all the time, you just need to hone out the cylinders. It used to be just a couple of dollars for each kit, but that was decades ago.
 
I found this diagnosis idea (see quote below) and found I can push in on the wheel cylinder that works fine (on the right) and cannot push in on the wheel cylinder on the problem child (on the left). This is pushing inward on the top part of both/either brake shoes.

"The wheel cylinder can become seized:

Over time these may becoming rusty or filled with dirt which is usually a result from failing boots. Wheel cylinder has both a front and rear piston, therefore two in total. Either one or both pistons can become seized. To determine if the wheel cylinder faulty, you should be able to push the pads inward from one side to the other if the pistons aren’t bottomed out. If not, then have a second person, being extremely careful, lightly depress the brake pedal. Do not got too far as you do risk pushing the piston out completely. In order to remove the drum, the automatic adjust can be backed off through the small hole in the backing plate. If that fails, then you may need to cut the hold down spring pins on the backing plate or remove the wheel cylinder completely. As for repairing the issue, you can rebuild the wheel cylinder yourself, have someone rebuild the unit for you, or purchase a new replacement."
 
[1] A stuck wheel cyl will give you a high pedal, not a low spongy pedal.

[2] My guess as to your problem: 10 yr old m/c. They corrode internally. No problem with normal operation, as the seal do not move far with normal brake application. Everything changes when you bleed the brakes. The seals bottom out from the extra travel of the bleeding process, & 'run over' the built up corrosion. Seals get torn & leak, no brakes or poor brakes is the result.
 
Any Factory Service Manual with give you the proper bleed and adjust procedures. If your system is original the correct procedure is to just start to replace everything. Your hard lines are probably clogged/rusty inside. The hoses and wheel cylinders will be done as well. Safest, cheapest route to get to the glass shop....have it towed.
 
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