VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 41 SD brakes

I dont have a problem with nails down here anymore but Tek screws have taken over.
Tony

I have to comment about "instant brake failure". That describes how most hydraulic failures happen, with no warning. I had that happen in my 38 Master a couple of years ago. Sometimes it is caused by old steel lines bursting, lines that look perfect on the outside.

Important that you said, "lines that look perfect on the outside." Moisture in the brake fluid can cause rust through from the inside of the brake line to the outside. Maybe brake lines should be replaced every 40 to 60 years according to the moisture in the area of the country you are in or if brake fluid is not regularly part of a service routine. The main reason I replaced my steel lines with stainless was a concern that stainless was less prone to rust through than steel lines. When I made the change I was replacing the original steel lines that even from the outside looked rusted. Rubber brake lines can also show cracking in the rubber and potentially break with age. A lot of money and safety concerns may be determined by the condition of one's brake system.

Good luck, Mike

Good evening, joining into this thread, and I've read it carefully, among others. Could you guys check my thinking and offer up any thoughts (I'm getting my '41 SD 5-Passenger back on the road during COVID after 20+ years sitting on blocks in my unheated garage...father son project and I've had it since I was in the 4th grade!)

After getting all the wheels/hubs pulled off, I decided to do a complete rebuild of the brake system...the MC and wheel cylinders had little to no brake fluid (DOT3 I am assuming left, rusted, frozen etc...my daughter couldn't budge the brake pedal and nothing happened. Hence, rebuild time. So, here is what I'm going with:

- MC: new one from COF
- Stainless lines from COF
- Reuse the brass junction blocks; Haven't pulled then from the lines yet, but assuming a can get them off and they are 'ok' after thorough cleaning.
- New wheel cylinders from NAPA
- New hoses (3) from NAPA
- DOT5 brake fluid for final fill/bleeding; Originally thought DOT3, but after searching the forums, looks like DOT5 for all the good reasons of no moisture absorption, easy on the finish etc.

Here are my worries and questions:
- Anything I should be considering/worrying about?
- I will use / reuse the copper/brass washers provided for the WC's and at the junction points...can you reuse the old ones?
- I thought I read someplace about putting a bit of "anti-seize" on the fitting's threads to keep them from binding up.
- Getting the brass blocks off the rear WC's looks to be tough...any suggestions (soaking etc.) so I don't bugger them up?
- My brake shoes and the drums are in really good shape from the original restore back in early 80's...they have less then 25 miles on them...anything from an age perspective I should be worried about? A bit of surface rust that will polish up well.
- I broke the RF brake retraction spring as I needed a wheel puller to get the drum off...I plan to replace all 4 of those springs...how about the conical ones? They all look good as do the j-hooks, but will take counsel.

The one area that I never touched back during the restore as a kid was taking the clutch and brake arms off the MC...I believe I have to do that for the new MC from Chevys of the 40s...I've got the shop manual, and seen in this forum that this seems manageable, but any thoughts on this? I don't have the J-1441 tool, but it looks like a hook can get the key out etc.

Lastly, I don't throw anything away from the old car...I'll clean up the cylinders etc. and pull all the parts out (keeping them together by wheel of course) such that perhaps someone else or myself can get them rebuilt...I'll check for pitting etc. in the cylinders.

I welcome any "gotchas" that you guys might offer up that I should be considering. I'm a bit worried about the stainless vs 'regular' metal brake lines and leaking at the wheel cylinders...any other sealant folks put on the threads where the fittings join the various cylinders, or is that a strict no-no so it doesn't get inside the cylinders etc.?

thanks

Chris

Stick with regular steel brake lines as they mate way easier in the junction blocks and will last another 80 years. Soaking everything can help but the junction blocks are all available at the vendors you mention. Likely the crush washers too as they should not be reused. I would cut the old lines off and mount the junction block in a vice and work on removing the lines that way.

Wheel cylinder quality varies as discussed earlier in this thread (I think - but it gets really confusing when someone takes the thread in a different direction. It's best to start a fresh thread)

For sure I would not use stainless lines unless you want a lot of leaks.

I would NOT be using stainless lines, regular steel or copper nickel is much more preferable, always use new copper washers where needed. I prefer dot 4 fluid as it will safely mix with dot 3 and either are more readily available compared to dot 5.
Tony

I agree with Tony on all points. I prefer to flush the brake system completely every 1 or 2 years. That removes the very small particles like the rubber worn from the seals and takes care of the concerns with moisture.

Mike,
Doing some research and came across the pictures of your brake system...thanks for posting! Very helpful. QQ: in your last picture you have what I believe are the "keys" that hold the clutch and brake arms to the master cylinder (in the shop manual it says use tool J-1441 to extract)...I've also read a small wire hook or a bolt which is what I think you are showing in your picture...can you tell me what size that is, approximately? Maybe 3.5" to 4" screw? Do you actually screw it into the key, or just kind of snag it and drag it out? I need to move the pedal arms from my old MC to a new MC that just arrived. I'd welcome any thoughts on how this goes or any 'gotchas'...again, "thank you" and the pictures are great!

Chris,

You actually thread the screw into the key to pull it out. I'm pretty sure it is fine threaded. Will look at my pictures later.

Good luck, Mike

It is threaded thus most any screw that sorta grabs the threads of the key will be enough to pull it out. For a stubborn key, propping the car up on its nose will induce the effects of gravity and that will help a heap .

You're welcome.

Charlie

BTW: I really doubt that a brake line or other part of the hydraulic brake system will jus suddenly and completely fail with no warning. A leak will occur first thus lowering the amount of brake fluid, and far in advance of any catastrophic failure. Application of the brake pedal will give a sense of something is not the same as expected. Don't ignore it.A situation where the pedal just suddenly goes to the floor without any preamble signs of trouble is merely something that has been passed on as an excuse for one having ignored tell-tell signs. If you think about it, the system will always give you warning. You will know something way before sudden, complete failure. Will too. Even the hoses will leak first. Even the connections will leak first. Even the cups will leak first. You get the picture. There is no dooms-day failure. The failure is the person behind the wheel.

BTW2: Anyone with direct knowledge of a sudden catastrophic brake failure with no signs whatsoever of pending trouble prior to the event, I would like to hear about it. If there are no signs of the brake lines or hoses leaking then not to worry. Just always pay attention to keeping the master cylinder (MC) full and what you feel through your foot's sense of touch. Needing to re-fill the MC over short intervals is a sure sign that something is amiss. Then is the time to check for a leak. In the meantime, enjoy the ride and keep your money in your pocket. All accidents begin at least five steps in advance of the event. Remember when fluid is low in the MC the pedal will fill different. Leaks start out very small.

Thanks Charlie and Mike...the old MC is out of the car, so I will find the right bolt/screw to get this key out...and being able to shake it etc. to have gravity help me will be beneficial. I'll reach out if I get totally stuck, but the weekend project is ahead! Appreciate the fast response.

Chris, here are some more pictures. The screw used to retrieve the key doesn't appear to be fine threaded. Pack the key cavity with ordinary chassis grease. The outer screw can be routinely turned squeezing grease back of the key and into the mess bushing where the pedals are attached to the master cylinder. Seems that it would be common to ignore lubricating this area, but best practice might be to fill the grease cavity whenever you change your brake fluid.

Charlie has more imagination than I do so I will let him tell you the consequences of forgetting to keep the key and bushing lubricated.

Good luck, Mike

Mike,

I bet you're dumping that lube question on me because you don't know.

The answer is that you don't really have to lube. Sure a grease fitting will fit the hole in front of the key but I don't think grease is necessary because the bushings have grafite or something already in them. Pumping grease in there could do some good or in some application of the car actually do harm. Like on dirt roads where the grease will collect grit.

Anyway, others like Gene, Chipper, et al will have better knowledge on this than I do. I yield the remainder of my time.

Best,

Charlie

In response to Charlie's post about "catastrophic" brake failure. I also have never seen or heard of that type failure without visual degradation (rusting or mechanical damage) of the the steel line. I have seen a few hose failures due to a weak crimp between the hose and connector. The other failed hoses were old and had visual degradation, mainly cracks in the outer rubber coating.

I just finished a rebuild of the brakes on my '37. The "clue" was that the left front brake was grabbing. That was the indicator that the wheel cylinder was leaking. I did not ignore it.

Thanks for the pics! I got the key out, per the discussion of just grabbing it with a screw into the key hole...slid right out! Helps to have the MC on the bench I would imagine. As I reassemble, I'll take a look at the convo on lubing it up a bit...I love the dialogue. When I pulled the key out, I could tell there had been something in there...not sure if it was old grease or old brake fluid. A mess...but well on its way to being loving healed. Right now on the hunt for new brake shoes as the RF brake lining just fell off the shoe as I was cleaning things up a bit...a sign from God to replace all 8 shoes even though low miles, they have been sitting for many years! Cars have a way of telling us what to do I guess. Thanks again to all...happy 4th of July!

Well, I have no dog in this fight, but I HAVE had an instant failure and it wasn't on a classic.
It was on an '89 Ford pickup that had been in Alaska, around a lot of salt, I think.
Imagine driving for years, with excellent brakes, and then, when making an easy stop, with modest pedal pressure, the pedal going instantly to the floor!
Fortunately, this was in a friends yard, at 3 mi/hr, so no harm was done.
I'm not sure why the second brake circuit didn't work, but I did replace all the flex lines immediately.
The trouble was that one of the fittings on a front line had disintegrated and finally let go when ti saw some pressure.
The brakes on my '34 truck aren't very good, but they don't have flex hoses either.
Wilson

Most people believe that dual master cylinder brake systems will always have at least one half of their brakes functional. It is far from the case. They do have a little more safety than single systems but not as much as people believe. Brake system maintenance and frequent inspections are critical to all our safety on the road.