1973 brake issues (2 Viewers)

[WyoMike]

Brake pedal always goes to the floor even after bleeding and seating brakes. I have drum brakes all the way around. New everything at each wheel, all replaced with new not rebuilt. I have a new master brake cylinder too. All the parts are from CCOT. I have seated all the drum brake shoes and backed them off 3-4 notches. Everything has been bled multiple times. Shoes were rechecked to insure they are all 3-4 notches off/back from locked up position.
I’’m wondering if it’s the master cylinder. It’s different than what I took off. CCOT says it’s a replacement for my year.Here is what I took off, flowed by the new: Any thoughts??? Or should I say, HELP!

 

[charliemeyer007]

Along time ago they sold me that same crooked reservoir MC. I just put it on a few months back. It was still NIB and in the sealed bag. I had a hell of a time getting my brakes to work correctly, gallons of brake fluid bleed. I replace all the wheel cylinders they sold me too. Yes I will be replacing that MC too. I'll never buy brake stuff from them again. I remember the wheel cylinder issue when I ask about the parts they sent didn't match my order - Yea just put them on upside down and they will work... The fronts they sent were double acting not single like what was there. Oh and to be fair this was like 10-15 years ago.

 

[WyoMike]

Along time ago they sold me that same crooked reservoir MC. I just put it on a few months back. It was still NIB and in the sealed bag. I had a hell of a time getting my brakes to work correctly, gallons of brake fluid bleed. I replace all the wheel cylinders they sold me too. Yes I will be replacing that MC too. I'll never buy brake stuff from them again. I remember the wheel cylinder issue when I ask about the parts they sent didn't match my order - Yea just put them on upside down and they will work... The fronts they sent were double acting not single like what was there. Oh and to be fair this was like 10-15 years ago.

Thanks for the reply! I was worried about CCOT! Not happy to hear about the wheel cylinders!

 

[bikersmurf]

I've read that many aftermarket wheel cylinders don't have the bleeders at the top. In order to blead them the cylinders need to be tipped at an angle to get the last of the air out. I have no firsthand knowledge though... I rebuilt my Toyota cylinders on all corners back in '91.

I suspect that a combination of air and adjustment is the cause of your issues. I'd start by adjusting all the adjusters so that the shoes are tight against the drums, and seeing if that improves the pedal feel. Then tipping all the cylinders so that the bleeders are at the top and bleeding the brakes again.

I got tired of manual adjusters and bleeding the brakes and have 4 wheel disc brakes... they also work after water crossings. When my brakes were due, I did the swap on the front... and then about 5 years later I swapped the rears.

 

[WyoMike]

I've read that many aftermarket wheel cylinders don't have the bleeders at the top. In order to blead them the cylinders need to be tipped at an angle to get the last of the air out. I have no firsthand knowledge though... I rebuilt my Toyota cylinders on all corners back in '91.

I suspect that a combination of air and adjustment is the cause of your issues. I'd start by adjusting all the adjusters so that the shoes are tight against the drums, and seeing if that improves the pedal feel. Then tipping all the cylinders so that the bleeders are at the top and bleeding the brakes again.

I got tired of manual adjusters and bleeding the brakes and have 4 wheel disc brakes... they also work after water crossings. When my brakes were due, I did the swap on the front... and then about 5 years later I swapped the rears.

Thanks for the feed back! I’m starting to regret not switching to disk brakes now, but the drums never failed me in the past. (Other than adjusting them all the time!) I’ll try seating the shoes tight and see what happens. BTW the wheel cylinders looked identical to the ones I took out.

 

[charliemeyer007]

Outside they look the same. Inside the spring and cup support can be different. The slot for the shoes can be different - my old ones had a sloped slot on the adjusters (which I think helped keep the shoes centered if the downhill slope is toward the axle. Some shoes need thinned to fit into the slots. And this is all stuff that claims to be OEM or equivalent. Yea well IMHO a lot stuff isn't up to the claims.

 

[Grayscale]

With the slop-fit on the bleeder screw, there is a fine amount of being cracked open that the bleeder screws will just bleed-out, and not suck air in, with. It gets tricky, do I use an crescent wrench, or will a stubby 12-point, box-end wrench over the bleeder be too much weight to dial in just enough turn to only let hydraulic fluid out? Some folks use a bit of teflon tape to seal up the slop from the wheel cylinder threads / bleeder screw from sucking in atmosphere. I replaced each bleeder screw by putting a close fitting plastic bag over the master cylinder reservoir rubber lid, and used electrical tape around the reservoir to keep the reservoir from completely draining while wrapping the bleeders outside-end with teflon tape. After removing the plastic film, it is important that the bleeder hose goes up from the bleeder nipple, before it drains down into a bottle. Like the opposite of a plumbing-trap under the kitchen sink. You are trying to make air exit the system with the help of gravity; for this, I carefully place the drain-to bottle on the top of the leaf spring, iirc.

I once had a helper who would pressurize the pedal for a second while I was down there bleeding it, and quickly closing it before the pressure is put on with the pedal again. It is almost like the master cylinder draws air bubbles back from the lines when the pedal is retracting. Now, I have better techniques of how to make it work, solo. Also, I always remove a wheel, and put the axle on a jack stand. I do a brake bleed once a year, or more, as I'm not playing around with internal corrosion, and I like the reservoirs to stay looking new with fresh fluid. I'm stubborn, still running drum brakes, and just watched a rerun of the Lawrence Welk Show on PBS.

 

[charliemeyer007]

I like my one man brake bleeder - Mighty-Vac. But yes PIA with the new sloppy fit bleeder screws. I tried thick good grease first - still bubbles from leaking around the bleeder screw. Teflon tape would seal once but start leaking on the second bleed cycle. Got the can of Permatex that like 70 + years old I got from dad - Yea no bubbles.

 

[bikersmurf]

I really like vacuum bleeding also.

Recently I've been doing "two man" bleeding, but still solo. It has worked but it's a bigger PITA.

 

[nabbasi]

With the pedal going straight to the floor, that makes me think master cylinder.

Did you bench bleed the master before installing?

 

[nabbasi]

And to add to the bleeding conversation, I’m a big fan of the motive power bleeder if you’re working solo. Or even if you aren’t.

I used one at a road course I used to run and could do a full fluid exchange in between sessions if necessary.

Have used it on 8-10 vehicles in the last 12-13 years and the hardest part is figuring out the best attachment at the reservoir. If you can swap out the adapters depending on vehicle / master cylinder reservoir, as long as the jug still holds pressure (only need 12-15psi).

 

[DSRTRDR]

the fluid has to go somewhere if the level in the master cylinder goes down when you are bleeding - chase where it's going - it must drip somewhere . . .

 

[Skreddy]

When bleeding, definitely have all the wheel cylinders tight or snug against the drum then back off when done bleeding. If you have to wrap the bleeder screw threads with anything to keep them from leaking, they are garbage. They seal on the cone face at the end, not the threads.

Did you readjust the booster to master cylinder pushrod when you installed the new master cylinder?

Did you bench bleed the master cylinder?

 

[Shark56]

Did you readjust the booster to master cylinder pushrod when you installed the new master cylinder?

I was just going to ask this question as well.

I would check that first.

When adjusting Drums, did you tightenen until they drag hard. Then press the pedal a couple times to seat them and recheck.
(Or can you not get any pedal to even check that)

 

[Pighead]

Did you bench bleed the master cylinder?

That was going to be my first question

 

[peesalot]

Put vise grip on both front & rear soft line, step on pedal, if its hard it's the wheel cyl's, if it goes down, it's the MC. I second the statement above about needing to manually fit the new shoes to the adjusters with the slope in adjuster head installed correctly. Using vise grips on the soft lines is alot easier than running adjusters out tight. FWIW when you get it going, adjust the shoes with rims bolted on, run em tight so they drag and spin it around block, if they get hot back em off 1 more. For bleeding, I have always been lucky and just gravity bleed, all open, pour fluid in MC, sometimes have to vibrate the rear backing plates on 40's with dual WC's.

 

[Grayscale]

If you have to wrap the bleeder screw threads with anything to keep them from leaking, they are garbage. They seal on the cone face at the end, not the threads.

I'm not sure that this is why the brake bleed isn't going well for the op, but, the bleeder screw threads need to seal air from getting in the cylinder when the bleeder's cone-face is not snugged up against the wheel cylinder, during the bleeding operation. I could be wrong, but there is less than atmospheric pressure in the system because after pumping the pedal, it squeezed hydraulic fluid out, and until the master cylinder pistons retracts back to the reservoir, the system has low pressure.

Here is one aftermarket example: Domestic Cars Application Guide - Speed Bleeders - Russell Performance Products - http://ps.russellperformance.com/powersports/mc/speed-bleeders/ And without fancy ball-check-valve: Dorman 12702. I've sealed the threaded portion with teflon tape, the same direction/rotation that they install, and the screws opened and closed multiple times without issue. l have original OEM wheel cylinders, with Teq on the casting, that I can check on, if wheel cylinder quality is being called into question, but, I think that it is just a design-issue.

@charliemeyer007 I'd keep the greease as far away from the brake system as possible, or at least I use brake parts cleaner to remove grease or oil contamination from hydraulic or brake parts. My pickup has an issue with oil getting on the boot that protects the slave cylinder, and I'm on my third slave cylinder during the last seven years or 20,000-ish miles.

 

[WyoMike]

Thanks everyone for the input.

First off - I did not bleed the MC before I installed it. Didn’t know about that until it was pointed out to me.

Last night I found more information on other mud members with the same or similar problem with CCOT wheel cylinders. I agree with everyone there has to be air in the system. So before I try anything else, I decide to pull apart the rear wheel cylinders.

It was recommended to install the plastic cup vertically until submerge to insure no air was trapped there. No one had photos so here’s what I did and what it looks like:

Second photo is hard to see but I’m installing the cap/cup vertically.

I did this to both rear wheels and bled the brakes. What a difference! I had brakes!
Brake pedal goes about a third down before pads move but they try to brake. It does take two pumps of the pedal to get good stopping power.

 

[WyoMike]

Hopefully what I did was what everyone was talking about. If not, it still worked for me but I could be missing something too.

I did not take time to do the fronts. Was just getting impatient. I did bleed all four wheels. I successfully drove her out of the garage, stopped backed up multiple times attempting to give the shoes a chance to seat.

By the way, today was the first time since about 1991 she has been driven! Big day even though tons of work yet on the brakes.

 

[WyoMike]

What exactly is this:

This looks like a potential source of air bubbles. There are no leaks around it at all. Just curious if it could be letting air in?