VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 1941 SD Brake Bleeding

I have reassembled my brakes, new lines, MC, WCs etc. The forums and manuals have been a great help. Tomorrow I plan to fill the system, bleed each wheel per the shop manual. A couple of clarifying questions:

1. About how much brake fluid on a ”˜41 SD should I expect to go through for an entirely dry system? I want to make sure I have enough and I know not to let the MC ”˜pump dry’.

2. When you bleed each WC I assume you have the brake drums off so you can see the brakes moving and once all the air out but the drum back on and make final adjustments using the WC adjustment wheel.

3. When brake fluid comes out of the bleeder valve into my partially filled bottle, that fluid should be discarded and not used again in the system...correct?

Any other hints/tips to make it all go well? My daughter will pump the pedal slowly and I will open and close each bleeder valve into a bleed bottle.

Other ”˜gotchas’ I should avoid are welcomed.

Bleeding is done with the drums ON!

If you "pump" the brakes with the drums off, you will push the pistons and cup out and have fluid all about. Not good!

I don;t know that you need to have your daughter pump slowly. Briskly will do better I think.

After you gain access to each WC and are ready to loosen the bleed valve, do this:

a. Shout "OK honey, pump 'em"

b. After hearing a few strokes shout "hold it." She then stops pumping and holds hard pressure on the brake pedal. (If pressure on the pedal is removed and the pedal is allowed to return before you close the valve then air will be sucked back into the WC).

c. After air has escaped the open valve, close the valve and repeat the process until nothing but fluid comes out. Sequence: RF, LF, RR, LR.(Someone please check me out on this sequence)

d. Check the fluid level in the MC and refill it as necessary.

As Ray advised do it with the drums on. Run the WC adjusters out evenly to where you can just get the drums on. Then turn the each WC adjuster clockwise looking at each end on, (Notice which way they turn when adjusting before getting the drum on.)

Do the adjustment until you lock the wheel to where you cannot turn it with strong arm and hand force. Then back off four to five notches, split between front side and rear side. It should then turn with a little drag noise from the shoes to drum friction. Repeat after having driven and vigorously exercising the brakes for a few miles and stopping at red traffic lights..

Good luck,

Charlie

BTW: I sent you a PM about buying your old MC and WCs from you.

I was taught that you always start with the wheel cylinder that is farthest from the master cylinder. That would be right rear, left rear, right front then left front.

Thanks to everyone for their posts to my questions...and this morning, I did go back and re-read the manual, carefully...to summarize, I will:

1. Bleed with the drums on; per Charlie, ensure that there is appropriate amount of drag of the shoe against the drum etc. and from Ray, making sure that the drums are on to keep the pistons in place and not have fluid shoot all over.

2. Re-reading the manual, in bold on page 127: DO NOT reuse fluid that has been flushed through the system. Got it! Not sure how I missed that the first time.

3. The WC bleed sequence should be: LR, LF, RR, RF as noted in the 1941 Shop Manual, page 126. I will keep the MC half full (or more) and my trusty assistant daughter will pump fairly quickly to keep the fluid moving out during bleeding operations.

Note also that I'm using DOT5 so I won't be having to worry about paint damage if something leaks, but I'll be checking all of the junction blocks and hose/MC/WC connections frequently.

Thanks again to all...I'll post some pics once this is done (having some challenges with that), and I'll keep everyone appraised if I have issues...Thanks all!

Charlie, I didn’t see a PM in my queue...I am not sure what I will do with the old parts and lines but definitely not throwing them out. The WC’s say Borg-Warner on them as I recall...frozen solid even after soaking in denatured alcohol. I haven’t touched the MC yet but I did take the little square plug out of it and the end plug and reused those along with the ”˜key’ for the clutch and brake arms.

My old brake lines I have but the one going from the mid-frame junction block to the rear brake hose got damaged when I took it apart...it was a beast to get off. I assume all of this could be rebuilt and reused so I won’t throw anything away.

Hi Chris,

You just added a key piece of information that is relevant to your situation.

While Dot 5 is great from a moisture resistance perspective it does have quite an affinity to absorb air. So tell you daughter to be active but not aggressive when she is pumping the pedal.

I do not want to convert this post to the never-ending Dot 3, 4, 5 debate but wanted you to be aware of that characteristic of Dot 5.

Once you get all the air out of the system things should be fine. I would have at least a quart bottle.

Be very observant and make sure you can see the difference between air coming out the bleeder nipple and air sneaking in around the threads of the fitting. The air sneaking in around the threads can mis-lead you. You want to get rid of all the air coming out the hole in the fitting.

Sounds good Rusty...thanks! I got the brake drums on the front wheels and I have an appointment where I need to take a break, then I'll finalize the rear wheel drums and start the bleeding later this afternoon / evening...more to come. I appreciate you taking the time on the 'hints and tricks' and I'll keep folks posted. Everything looks great on the wheels themselves, and the fronts now have a nice 'drag' to them pre-bleeding...more to come! Thanks all.

caf

Chris,

You may find this discussion on Chevytalk of DOT 5 bleeding interesting and helpful:

https://www.chevytalk.org/fusionbb/...ompressible+liquid/fromsearch/1/#2765708

I've used DOT 5 successfully for decades in both my antique Chevy, a '36 pickup, and my street rod, a sbc Chevy 350 powered '32 Ford roadster. Be advised going in that it's not easy to bleed and has other issues too.

Ray W

Reconsider the word farthest. The farthest distance fluid has to travel from the MC to each WC (through the lines and hoses) is to the LR, LF, RR and RF. We're not talking linear distance as the crow flies from the MC to each WC.

Have I got it right?

Don't listen to me until we get this straight and confirmed. My brain isn't working too good anymore. Go figure.

Charlie

Dont pump the pedal fast as this causes the fluid to mix with air and will be a PITA to bleed out, slow pedal movement is better. Start bleeding at the longest fluid travel 1st and when only getting fluid go to next longest. I often go through them all a 2nd time for 1 or 2 pumps.
Tony

Thanks Tony! We will go slow and steady...I like the ”˜go around’ twice notion...biggest challenge now is to get my assistant/daughter to focus and get out to the garage and get this exercise done! ????

If your situation is like mine was you will probably have more success with your daughter than your wife.
Tony

Started the bleed this afternoon but discovered fluid oozing (not a big flow) with each pump at the MC where the brass block connects to back of MC. It is tight but appears the copper washers not holding...disappointed as it looks like I will need to replace those...can that be done with MC in place or best to take the MC out and double check it?

Also do those washers have to be the exact I.D. of the bolt or could they be slightly larger...not sure I can find that exact size.

Thanks

Those copper washers can be problematic. My experience is that they have to be a lot tighter than you would expect. They work because you crush the rings on the face of them to seal on the faces of the master cylinder and the brass block.

The inside diameter is not where they seal. It can be slightly larger but no too large. I visually center the washer as I tighten the joint.

It is also very important that both of the sealing surfaces that the washer mates with are clean and smooth.

I assume that you are using new washers. I have not had good results trying to reuse them. Once the ridges have been flattened it is really difficult to get them to seal again. I keep a supply on-hand.

Chris,

If you don't have spare copper washers, try annealing your used washers. Hang the washer on the end of a horizontal rod or screwdriver, then using a propane torch, heat the washer till it begins to glow red--careful not to melt it. As soon as it begins to glow, you can let it air-cool or quench it it water. Either way will result in the copper being softer and better able to conform to the mating surfaces of the brake line fitting. If you have a used copper washer that you don't need, I recommend you practice the procedure on it before doing it on the washers you need. The only real caution is to not overheat it and cause it to melt. On your practice washer, try to bend it by hand. If it's used, you probably won't be able to bend it. Then, after annealing try to bend it--it should be soft enough to bend easily.

Mark

Thanks Rusty...everything is super clean. I did use the old ones as I wasn't confident in using one slightly larger (which is new of course)...paying the price for that now! I'll redo it and also look at Mark's comments about annealing etc. I think with some new washers I can get it all tightened...unfortunately it's back under the car to get to the MC...I will see if I can get the block off without popping the MC out again, but may end up doing that again just to get things cleaned up and to make sure it is all really tight...it wasn't that bad, but the cylinder was dry and empty. More to come...thanks for the counsel guys!

caf

I bought a box of 50 washers (Dorman 725-014) when I ordered hoses and wheel cylinder kits for my ”˜37 From Rock Auto. I needed 6 for all the wheel cylinder connections.

You can get these washers at most of the chain auto parts stores.

I forgot about the “work hardening” characteristic of copper until I read Mark’s post about annealing the washer.