VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Bleeding brakes

Trying to bleed brakes and I came across this

Another angle
All wheels had a standard bleed fitting, but this wheel had this. How do I bleed with this thing?
Thanks
Mike A

Remove the little bolt in the center and bleed by lossening the valve.
The little bolt is only a plug in the bleeder valve opening. 1936-1950 wheel cylinders made by Delco had this feature. You could also remove and discard the bolt and leave it out or install a new bleeder and discard both that and the original bleeder.

Chevgene,
Thank you for info, I was hoping it was that easy.
-I bled 3 of four wheels and need to pump brake to get pressure.
-i hope the last wheel is the culprit.
Mike A

I.Help! Tried bleeding brakes using the one man little bottle and check valve system from harbor freight following what I thought to be the correct process, but pedal goes to the floor until I pump it a few times.
1. Started from driver rear, next driver front, next passenger rear and finally passenger front.
2. Is it possible my new master cylinder is defective?
3. When I pump pedal I can see fluid moving in my master cylinder reservoir(hopefully normal)
II. Is this the only proper way to bleed below?
1a. I watched a video showing two people(one pumping 5 times, holding down o 5th.
2a. 2nd person opens bleed valve until steady stream of fluid escapes then closes.
3a. This process is repeated at each wheel.
I am getting depressed, I want to drive my 38.
Thank you,
Mike A

Mike -

I was always taught to bleed - 1-left rear, 2-right rear, 3-right front, and finally 4-left front. You might try that next and see if it helps. Sounds like you still have air in system. Are brakes adjusted up properly??

Jim.

Jim,
I went by the chevy manual
http://chevy.oldcarmanualproject.com/shop/1938/38csm115.html
My biggest concern is the master cylinder is defective.
Your suggestion makes sense and that is what I thought until I read the manual.
Thank you for the advice. I think i will try the two person method.
Mike A

Check all fittings to see if any brake fluid is leaking, including the brake light switch.

If you pump the pedal slowly several times, and it builds up pressure, but still feels soft, then air is the big culprit...took me 4 tries to get most of the air out.

While looking in my MC fill hole with a flashlight, I pumped the brake with my hand, and the only time I saw fluid move was when I released the brake, and the fluid shook for a split second.

In the end, I have found that vacuum pump bleeding worked better with silicone fluid, as the fluid is less disturbed at the MC. I used a Lisle vacuum pump, similar to the HF pump.

I'm at 3rd attempt. Thank you for the advice, it all helps.
Mike A

I have never had good results with vacuum pump bleeding methods on older systems you will pull air into the system in older systems. The best way is to use two people. Keep the reservoir full and one person pumping on command and one opening and closeing the bleeder valve. I have never used the pressure pot on top of the master cylinder like was used by many Chevrolet shops.

Hello everybody,

1st: The rule is to begin at the wheel most far away from the main cylinder...rear right as written before.

2nd: Because I have no man to help me I use a system called "Easybleed" sold here in Germany.
It uses the air pressure of a tire.
There is a bottle you fill with brake fluid, and it is to be connected with an self made adapter to be replaced with the main cylinder filler cap during the bleeding proceed.
Of course there were a lot of usual caps for most modern cars coming together with the kit when I bought it but I asked a friend from here to bring me an original 1940 cap to adapt it for that system when he came to visit me in last may.

Everything installed the pressure of the tire will allow me just to crawl from wheel to wheel opening the bleeder screws and service everything alone without need of any helpmate.

Because there is involved a bottle filled with brake fluid the main cylinder will never run ot of fresh fluid and I can do the whole bleeding proceed within few minutes alone.

To feed the system by pumping the brake pedal includes a risk always. If you press the pedal very deep and you reach zones you will never touch during normal driving there might be some corrosion inside the main cylinder and the rubber rings at the piston might get a damage when touching usually untouched maybe rusty zones inside the cylinder.

So I am very happy with my airbleed system...

Stefangermany

that is the same "pressure " method used at Chevrolet shops for years.

I've never encounterd much trouble bleeding brakes and I don't always follow the longest line first...I'll do it all "willy-nelly" and everything comes out fine...Inch travel on the pedal and rock hard...But, everything's new and bench bled first...A little adjustment needed...New fittings, a clear tube and a jar with some fluid...I could be wrong, but I have a theory that eventually trapped air will rise to the master...Law of physics...But, old car masters are pretty low...

Newer cars with all disc brakes are a piece 'o cake...No bleeding...I start with a bench bled master, then do the rotor pads and push back towards the master...Usually no overflow at the master...Jaguar's are super simple...All that's needed is a screw driver in the rear and a large torques in the front...Done in a New York minute...The '47 takes 10 times longer...Stinking drum brakes...But, you get the hang of it...And probably only have to do it once...Then there's the parking brake cable...Does the fun ever end...?

I have had quicker success with the pressurized fluid container as the fluid isnt "shaken" during the pressurizing process.
With most british cars "pumping" the fluid in from the wheel cylinders and extracting the fluid from the master cylinder can does work.
The vacuum at wheel cylinder can give false indication as air can be drawn in around the bleed screw threads.
Tony

Where can i find one of these or what haste others used to replicate?


Still have air in my lines, but can't seem to keep master cylinder full while bleeding with help. What a pain in the neck.
Thanks
Mike A

If, for whatever reason, you are unable to keep fluid in the master cylinder, you will not eliminate air in the brake system.

The 38 master cylinder is small and access is a whole a little larger than a golf ball under driver floorboard. The picture I posted is a GM tool used to monitor master cylinder fluid level While bleeding brakes. The adaptor neck connects to the master cylinder filler whole while the clear bottle allows you to see fluid level.
-someone sits in car and holds brake pedal down while bleeding, but also has to monitor fluid level.
Not fun

Understood.

This is what I use to bleed the brakes on my stuff. I have even used it on my '53 2 ton with a hydrovac and it worked perfect.

http://www.motiveproducts.com/

I saw this bleeder highlighted on one of the car shows, Gearz or Motorhead Garage or such. Product seemed to be the answer for a "one guy operation".

Fill master cylinder and crack one bleeder screw open at a time and let it drip until you see no bubbles,I use the gravity bleeding method when I have no one to help me which is 99 percent of the time. When I replace a part I will fill it with brake fluid before installing and then crack the bleeder to get the rest of the air out and need no help most of the time.

We use a pressure brake bleeder in the shop. Keeps master cylinder full and pressurizes system. On e man goes around and opens each bleeder one at a time. I can do my 6X6 in ten minutes. It is also very handy to check for leaks as the system is under pressure. They range from simple $30.00 units to $500.00 commercial units like we use. It's the only way to fly.

I use the vacuum sucker and if used properly it works great.

you build up the vacuum first and then whatch the flid run through the clear plastic tube. When no bubbles can be seen your done.
Be sure to follow the bleeding sequence in the shop manual for your year and model car.

When the bleeder nipple has provision for a hose I keep open end under fluid and allow to gravity bleed, when no bubbles appear give the pedal a couple of quick pumps and close that bleeder. Then move to next bleeder.
Tony

Mike: I had thought about doing something along the lines of this (with 1,021 projects going on at the same time, haven't tried it yet):

Take the MC nut cover off, see if I can find an equivalent PVC cap/brass nut cap/plastic, etc.
Drill hole in the middle of that equivalent cap, tap with 1/4"NPT, put a brass 1/4" barb in there, screw it in the MC.
Get a canister like the hard plastic 20oz cup that comes with a HVLP spray gun, add a barbed fitting to the bottom.
Secure the cup vertically somewhere near the MC, at about 12" above the highest brake line, and attach clear tubing on the barbed ends.

20oz should be plenty, and you can watch it from all 4 sides.

If you are using silicone DOT-5 like I am, it will take awhile for the bubbles to migrate upwards. Might have to heat up the fluid to speed up that process.

In this weather, probably will take a week or two per wheel for the bubbles to migrate.....

Wonder if anyone has used speed bleeders? Very popular in the motorcycle community, I thought of trying them out on my next car's scheduled brake work.

I bought the smallest pump style garden sprayer I could find that had a hose and wand on it. Cut off the wand and put a 1/4" barb to pipe thread fitting on the end of the hose. Drill and tap the appropriate master cylinder cap to accept the 1/4" pipe thread. Connect everything, fill the sprayer tank with a few ounces of brake fluid and pump it up. Every wheel cylinder is now pressurized ready for bleeding. If I remember total cost of the pump sprayer and fitting was less than $15.

This is the way to bleed brakes without all the fuss and amateur inventions:

a. Get a suitable short-throw box end 6-point Snap-on wrench. (Doesn't have to be a Snap-on but one of high quality.)

b. Fill the MC.

c. Get the missus. (Promise her a Coach purse next Christmas) Instruct her to pump the brake pedal and to hold them and to not let up until you holler "OK." Explain the the left pedal is the clutch and for her to ignore it. Then to pump and to do so again every time you yell "Pump." To do the pumping action until you yell "Hold! Upon the "hold" command (well, make it sound like a request) loosen the bleed valve. All you are looking for is a steady stream without any sputtering. Close it back when that cycle is done. Them to yell "pump" again. Ignore her "what?" Just yell louder.

d. Start at the farthest WC and work to the shortest in distance through the lines. Generally, that will be Left Rear, Left front, right rear and then right front. Get under the left rear. Get back out from under the left rear.

e. Again instruct the missus on what to do. She has forgotten by now. Don't worry, they all do. Be long-suffering. Any sense of frustration in your voice may bring on either tears and/or a job quitter. Hard to get 'em back out there after they have walked off the job. Is too. And, you can forget love and affection for a right smart while.

f. Go to the left rear with the speed that would jaw-drop a NASCAR tire changer. Wear knee pads.

g. Repeat "e" above. You were too slow.

h. Bleed the left rear. Scoot to the left front.

i. Bleed the left front. Scoot around to the right rear.

j. Repeat "e" and "g" above. It took you too long to get from the left front to the right rear. I suggest moving under the car from left front to right rear instead of around it. Much shorter distance. It will halve the elapsed time factor. (see time and motion studies.)

k. Bleed the right rear.

l. Bleed the right front.

m. Now. (This here is critical) Ask the missus if she has any "pedal." Calmly explain that you're asking whether when the pedal is pressed hard it is reaching the floor or is a couple inches off it. Repeat explanation. Give up and tell her to just mash the da-- pedal whilst you look at it. She may tear up. Ignore her.

n. If you have hard "pedal" you are done. If not, you may need a new missus.

you're welcome and Good luck,
Charlie

Excellent advice, Charlie, however:

1) The missus can no longer tell the difference between a soft & hard brake pedal.

2) Why do I have to be the one that wears knee pads?

3) I am using silicone brake fluid. Like the missus, it takes forever for the unwanted air out of the system, so I probably will bleed one corner each week.

Thanks everyone for the great suggestions. Has anyone used any of these techniques on their 38 or equivalent setup. The master cylinder in its designed location sucks makes a brake bleed quite challenging. It sounds like an adaptor to master cylinder with a clear reservoir is the key like the original gm style tool.
Thanks everyone, I your suggestions are gold.
Mike A

Unless I'm missing something here, I do not see any difference in bleeding brakes on a 1938 or my 1951.

J 713 tool for sale here. Click and Scroll down

http://www.vintageautotools.com/chevrolet-tools-brakes.html

The sight referred to is where i got the model number and picture. I didn't think they sold them, but just displayed vintage tools. I sent them a message to see if tool is for sale.
Thanks
Mike A

I saw SALE-TRADE-RENT in the ad, thinking the tools were for sale.

Good luck.

Gene would know more about this, but the J 713 tool appears to be a filler. It would be used to re-fill the master cylinder after bleeding. Without a slight bit of pressure in the bottle it doesn't seem that it would be effective for bleeding. It would be handy to fill the MC with minimal mess. I use a turkey baster myself.

It is just a way to keep the master cylinder full or nearly full while bleeding the brakes. Any bottle with hose sealed into the lid, held upside down and tube end below full level on M/C will work.

I think we have a world record for the longest brake bleeding thread ever

Ah...Specialty Tools...I have a ton of them...Used to hit the "flea markets" years ago...I use them for wall hangings...lol
I can think of one that flummoxes a lot...It's a simple burlap bag sewing gadget...It used to be a game It'd play...Bring them to the shop each Monday morning and see who could guess what it was used for...Interesting, over coffee and donuts...

Turkey basters...? Don't let the misses catch you using "hers", when you can't find "yours..."

Kevin,

It's like a Murphy Law.

If you borrow something from the kitchen or an item that is thought of as belonging to the missus, it will be missed by her before the sun goes down. Will too.

To the missus, her scissors, small funnel, any knife from the knife drawer or block, needle and/or thread (she will know how much thread was on the spool to a quarter of an inch), .her flashlight, her sponge or scouring pad, a pot (any size. The bigger the size pot to more likely you to leave it out in the rain), her light hammer, colander and yes, baster, too, etc. Anyone have anything to add?



One has to concentrate when borrowing from the missus. Go get it, use it and then take it right back. The last part is the hardest because you have to abandon whatever you're doing to take the stinkin thing back. Who can do that? I can't, either.

And, always, she know good and well you had it last. Does too!

Charlie

Even if you do put back immediately you will always catch you if you do get it out of the kitchen without getting caught.
Tony

It's much safer going to the Dollar store for kitchen supplies. Helps to keep peace on the home front!