'41 master cylinder repair

[imported_fordmerc]

Is this a job to be tackled by a Packard novice? Except for access issues it looks like a standard master cylinder remove, repair, replace. Any comments?

[Guest imported_Speedster]

I've not overhauled a '41 Mastercylinder but if it's the same as a '37 then it's basicly the same as any other make.

Of course you will need an overhaul-kit for it.

If the '41s is mounted under floor board like the '37s I would seriously consider converting it to a later dual-chamber type. Much safer and it's a fairly easy conversion.

And since it's hidden from view, no one will know the difference.

I did that on my '37 1502 and it works great.

[Owen_Dyneto]

It's really no different than the master cylinder used in almost any other make of car for decades. Yes, just remove it, examine and decide whether to rebuild or replace, reinstall, and bleed the brakes. With brand new complete units so inexpensive, you might consider a complete replacement if the bore is pitted enough to require sleeving, though there is nothing wrong with sleeving if properly done.

[mrpushbutton]

Question: why did auto manufacturers go to dual-chamber systems? as a redundancy feature in the event a line breaks or blows. What causes that? rust, usually the line that runs from the front to the rear axle, due to rust, or an old flex line that has rotten.

I just go through the WHOLE brake system, all new, or re-sleved cylinders, new master or re-sleve using a modern kit, silicone fluid, stainless steel lines, new flex lines, new E-brake cable, set up and adjusted properly, and there you are, you have new brakes. I inspect the system stem to stern before every driving system and I always have good brakes.

The other reason manufacturers went to dual-chamber set ups is in the case of a collision, and in today's traffic and other motorists, if you get into a big enough collision, you are allready in big trouble, the having the time to pump up the dual system is pretty much out of the question.

[Guest imported_Speedster]

The main problem that I've personally experienced is that if one wheel-cylinder starts leaking or as in my case completely comes apart, you loose all the brake fluid, with a one chamber mastercylinder, but if you loose one with a dual-chamber system you still have brakes at 2 wheels to stop, and get home with.

Luckily the car I had that lost a wheel-cylinder was a '56 Chevvy, which had dual master-cylinder. The car was only about 3 years old at the time and I would never have expected it to come apart the way it did. It was probably made with a defective housing casting, since it cracked and a piece of it (where the tubing attached) blew out under pressure when hard braking.

[imported_fordmerc]

A dual chamber system is obviously better; is there a replacement dual chamber system for my car ('41 120)? No one has addressed what I see as a big problem: the column shift fulcrum runs through the master cylinder housing. This makes it look like a big job and also makes it seem that any replacement dual chamber system must be specific to this car. Or am I making things overcomplicated?

[Dave Mitchell]

Not sure if it is you making it over complicated - the system as is works just fine, and the job looks worse than it is. (You can take the chance to tighten up your linkage at the same time.) I have 4 41s and they all have excellent brakes. I have put over 60,000 miles on 39s and 41s, and haven't hit anyone or anything yet. The unit isn't that hard to change, and there are some 41 parts around, so you may be able to find a new one. Failing that, you can have your original unit sleeved back to standard if honing it won't take care of any pits. If you need to find someone to sleeve it, I can recommend someone that can do it for you, outside of those who advertize that service. Contact me if you need some advice. Dave Mitchell packard12s@hotmail.com

[mrpushbutton]

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: fordmerc</div><div class="ubbcode-body">A dual chamber system is obviously better; </div></div>

Ehhh--I stand by my previous post. Make the brakes you have functionally new and competent and you don't need a dual system (for that year vehicle). I have done dozens of brake jobs from 1927 cars on up, many, many from the 30s,-50s. Never had a problem, these are cars that are driven on caravan tours, not just trailer queens.

Of course dual chamber systems are better for everyday cars and beaters, where the mild steel lines can rust andflex hoses age. propely maintained collector cars are different.

[Guest austinsailor]

"Question: why did auto manufacturers go to dual-chamber systems? as a redundancy feature in the event a line breaks or blows. What causes that? rust, usually the line that runs from the front to the rear axle, due to rust, or an old flex line that has rotten. "

I've had 2 complete failures over the years. '48 chevy 1 ton, rubber hose broke. Didn't look bad, but was old. Real wakeup call.

Second failure, a '65 Ford. Going up a long snow covered hill, got as far as I could, spinning, let off gas, put automatic in reverse to slowly back down, zero brakes. Found later, after a harrowing, fast ride backwards down a snow covered hill, that an adjuster wasn't adjusting, one cup popped out of the cylinder when it reversed.

Having mentioned all that, I now have 4 old single system master cylinder vehicles and have no plans to convert. I check often, and test when driving and pay close attention to any change in operation. (slight change in pedal or feel).

[Guest simplyconnected]

Just a reminder, brake fluid sucks up water.

If replaced every three years, it will never have enough water to cause rust AND you get the golden opportunity to 'cycle' those bleeder valves.

[mrpushbutton]

DOT-3 brake fluid is hydroscopic (sucks up water) I do my brakes in silicone fluid, no worries, great brakes.

To me the brakes are the most important thing to have "right" on an old car. For the safety of yourself, your family and other innocent motorists I fell that it is imperative to know that the antique car you are driving can stop every time you press that pedal down. I just redid the brakes on my "other car" (Chevy II, not a Packard!) a few years ago. I bought four new wheel cylinders, new flex hoses, new master cylinder and new pre-bent and flaired stainless steel lines. I think all of those components were about $600. In roughly eight hours I had the cylinders changed out, the new flex lines in, and the new stainless lines installed. You have to reuse the brass distribution blocks (fittings) but they were fine, like new.

I was taught to take apart the new cylinders, clean off the cosmline from the parts, use lacquer thinner for the metal parts and denatured alcohol for the rubber parts. I paint the exposed cast iron on the master and wheel cylinders to control rust, then coat the moving parts with the fluid I will be running the system on, in this case (and any other car I touch) Silicone fluid. Put it all together and have had great brakes. I still inspect the system at the beginning of every season.

Brake work is cheaper than collision/body work.

[Guest imported_Speedster]

Yep, Dot-5 Silicone fluid, Great Stuff.

[Guest simplyconnected]

You DOT-5 guys (I use it in my Harley), you do a great sell for the newer system. I don't want to hijack the thread, but please warn about the dangers of mixing even the smallest amounts of DOT-3 and DOT-5. Also, touch on the huge compatability issues with the rubber parts used in classic cars (bloating, in both the master cylinder, and wheel cylinder rubbers). If you buy eBay NOS parts, DO NOT put DOT-5 in your system!

I too, am VERY safety aware. But the un-knowing restorer who puts DOT-5 in an old system will lock his own brakes up, THINKING he is doing the right thing by spending a lot more money on fluid that was not made for, and is incompatable with his system.

I have seen the results from mixing these brake fluids. It's real nasty, and I don't know how anyone could salvage the brake lines afterwards.

Silicone (DOT-5)brake fluid is designed for HIGH HEAT, that most classic cars just don't have. It is far more expensive than DOT-3, and doesn't have any advantage over DOT-3 systems that are properly maintained. In fact, silicon systems feel spongier. Instead of mixing with, it moves water, causing it to 'pool' in isolated areas (usually in cylinders).

DOT-3 has rust inhibitors built in, and yes, it sucks up water faster than Scotch. Changing DOT-3 every few years ensures two things; the rust inhibitors are still working, and the fluid is not saturated. I think of it this way; if water somehow enters my brake system, DOT-3 will capture and dilute it, like ethenol (gasohol) does with water in your fuel tank. Let's face it. The whole system only holds about two cups of fluid. Changing fluid in both systems is recommended every few years. - Dave Dare

[mrpushbutton]

Here is my brake system mantra. I don't believe in using old NOS wheel cylinders and wouldn't trust a car "fixed" with them. The rubber is old and not formulated for today's fluids. The old cylinders used alloy pistons, which cause electrolysis between the piston and cylinder housing. I would no more use a 25 year old M/C than 25 year old tires.

<span style="font-style: italic">begin rant:</span>

I am a big believer in silicone brake fluid. I worked for 12 years as a mechanic for a large vintage car collection (over 100 cars) and we had one of everything in terms of engines, transmissions, brakes, electrical systems--we saw it all. The cars that were set up with silicone brake fluid ALWAYS had good brakes, even after sitting in storage for years. The Dot-3 (regular brake fluid) cars were hit and miss. Some were OK, others had no brakes, the fluid had turned to Jello inside the master cylinder or the alloy pistons had welded themselves into the wheel cylinder bores by electrolysis.

A couple of things if you are going to go over to silicone:

You need to take apart the (hopefully NEW) wheel cylinders, wash the metal parts with lacquer thinner, the rubber parts with denatured alcohol--this gets the shipping cosmoline off of the parts. You then need to coat the parts with whatever fluid you are going to run the system on--is silicone, coat with silicone. If Dot-3, coat with dot-3.

If you have not replaced the hard lines, you need to flush them out, there is residual dot-3/paint remover left in them.

Plug the lines, fill with denatured alcohol and let sit for a couple of days, drain and blow out with compressed air.

When you bleed the brakes with silicone fluid, go the old fashioned route and have someone sit behind the wheel and pump the brakes S-L-O-W-L-Y. Very slow, deliberate, full strokes, no jack-rabbit pedal pumping. It's more difficult to get all of the air out of silicone fluid, you will have to bleed the brakes a couple of times to get all of the air out. Bleed them, drive the car for a bit and do a re-bleed.

After that you'll be set for a long time.

Dot-3 is fine if you own one car and want to fuss with it from time to time. Working in a big collection, there is never that kind of time available. We converted the cars to silicone per the above and never had to worry again.

[Guest bkazmer]

The chemistry difference is DOT 5 silicone, but if all you want is more heat resistance over DOT 3 , use DOT 4 (still mineral oil based)

[Guest imported_Speedster]

I also read somewhere that there is a Dot-5.1, which is a polyethylene-glycol based fluid, like Dot-3 and Dot-4 are,

But I've not heard any specs on it, such as temp-range or moisture-adsorbtion.

It seems strange that they would number it so close to Dot-5.0 silicone fluid, unless it is similar in function?

[Phils38cpe]

I have been using DOT 5.1 in a Fiero clutch system for a few years with great results. A Fiero clutch hydraulic system suffers from heat problems and 5.1 helped me out quite a bit.

[Guest imported_Speedster]

Phil,

So the difference in 5.1 must be the high temp capabilities, only?

Can you go directly from Dot-3 to Dot-5.1, without completely cleaning the system, the way you have to when going to 5.0 silicone? It seems logical that you could, since they are the same chemical base.

[Guest simplyconnected]

mrpushbutton raises a good point about today's seals. They are formulated for use with every kind of brake fluid. So how do I get today's seals in my vintage master cylinder and wheel cylinders? You mentioned electrolysis between cast-iron cylinders and alloy pistons. What pistons should be used instead?

Your rebuild departs from oem, scrapping nearly all the original parts and overhauling with new (modern) components.

I have had DOT-3 in some cars well over ten years, I am embarrassed to say. But, it never turned to jell-O. That's a bit extreme. Your cars must have sat for many decades without any motion. Did they drain the gas?

No, I will maintain my DOT-3 system. It works well in many millions of cars, and has never failed me, yet. Modern seals, older formulas, it doesn't matter. DOT-3 is good with them all.

None of my cars require high-heat brake fluid. DOT-3 for me.

[mrpushbutton]

Describe your car, I'll stay <span style="font-weight: bold">behind</span> it in the dream cruise

(AKA Nightmare crawl)

I have reused old cylinders when I had to (new replacements just weren't available) by having the old cylinders sleved in stainless, then honed to the diameter for a new piston, seal,spring combination out of a currently offered modern wheel cylinder. It's a brake wheel cylinder, they still make hundreds of different sizes/mounting styles every day.

Between the Raybestos and Wagner catalogs I have been able to find exact replacements for either the whole cylinder or innards to fit into an old cylinder, some of the 1920s cars where I redid the brakes were odd cylinders where no replacements were available. do a sleve job and put the innards of the right size modern wheel cylinder in and I have the modern rubber and steel piston.

quote: <span style="font-style: italic">Your rebuild departs from oem, scrapping nearly all the original parts and overhauling with new (modern) components.</span>

yep--gladly. The last thing I want is pitted cylinders honed out such that the pistons (which are an alloy) are now loose in the bore. No one is going to see the wheel cylinders. No judge is going to dock points for an inauthentic wheel cylinder they can't see. I want to know that the cylinders are as good as they can be, the hard lines are either new or damn good looking, not something you see on a Michigan car, that there are new flex hoses and a properly rebuilt master. It is hard to find a cosmetically identical master cylinder, I have sleeved those and used the kit from a new M/C, again, having the latest, name brand quality parts. New hardware kits on the shoes, the proper linings depending on vintage (early cars used a woven lining that can't reliably be replaced with modern-style shoes)

I know of cars that were done (right!) in the 1980s with silicone fluid and they have great, firm pedal and have never given a lick of trouble, nor required any undue upkeep. And they all stop beautifully.

[Guest simplyconnected]

It's a 1955 Ford Customline. I'm at 12 mile and Woodward, in Royal Oak. I'm also listed in the North Woodward directory. <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mrpushbutton</div><div class="ubbcode-body">...I have the modern rubber and steel piston.</div></div> Steel pistons, outside the fluid? Are they stainless? I am familiar with stainless caliper pistons but not stainless pistons for drum brakes. Do you have a source we can buy them from? Why not use an alloy piston within your stainless sleeve? They have no reaction.

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: mrpushbutton</div><div class="ubbcode-body"> Between the Raybestos and Wagner catalogs I have been able to find exact replacements for either the whole cylinder or innards to fit into an old cylinder...</div></div> I noticed, the catalogs offer just the rubber cups. Can you tell me who sells individual parts, or are you buying rebuild kits? - Dave Dare

[mrpushbutton]

I get most of mine at Glendale auto parts in Farmington Hills (where I live) they have a store in Southfield, 10 mile/Telegraph, my high school buddy Larry is the manager.