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Do I really need to convert from Single to Dual Bowl Master Cylinder? I am about to order my stuff from CJ Pony and wonder if the upgrade
to the dual bowl master cylinder something I need. Do MC's fail often? Have any of you made the change.
Can I buy a master cylinder from the local parts house a lot cheaper and get the same results?
 

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If you plan on really driving your car a dual bowl is a safe and smart way to go .I used the m/c from a 67 works .
 

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Do I really need to convert from Single to Dual Bowl Master Cylinder? I am about to order my stuff from CJ Pony and wonder if the upgrade
to the dual bowl master cylinder something I need. Do MC's fail often? Have any of you made the change.
Can I buy a master cylinder from the local parts house a lot cheaper and get the same results?
For safety, IMHO, YES. Master cylinders do fail but you have four wheel cylinders that can fail. With a single bowl if one wheel cylinder fails you have no brakes. With a dual m/c and a wheel cylinder goes out you still have some braking power.
 

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1965 Mustang Fastback GT350-Tribute Restomod. 2019 Shelby GT350.
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It's a risk vs. reward decision that you have to make. Many authentic vintage cars still drive around with single bowl, but they probably don't drive a lot. Plus, their braking systems are generally well-maintained.

I drove and auto-crossed my '65 for 10 years from '84 to '92 with a single bowl and drum brakes. I have since converted to dual-bowl. If you get a fluid leak with a single-bowl you could lose brakes at all four wheels. With a dual-bowl, you'll likely only lose two wheels. Is it mandatory? No. But all US cars after '66 were mandated to have dual-bowl for safety.
 

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IMHO, absolutely! It’s an inexpensive upgrade and one area where it’s not worth cutting corners.
 

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Do I really need to convert from Single to Dual Bowl Master Cylinder? I am about to order my stuff from CJ Pony and wonder if the upgrade
to the dual bowl master cylinder something I need. Do MC's fail often? Have any of you made the change.
Can I buy a master cylinder from the local parts house a lot cheaper and get the same results?
Do you NEED to? Well, not really.... any more than "do you need to wear boots in the snow?". The question is... "Do you trust your existing braking system?", taking into account that any modifications you make must be done correctly or they won't have any value. I've seen dual-bowl installations where the failure of a brake circuit STILL resulted in the complete loss of braking for one reason or the other.

Can you buy a master from the local parts house? Sure. Raybestos MC36440 and use the original pushrod for disc/drum, Raybestos MC36222 for manual drum/drum. Not sure what you'd use in a '65-66 with power drums.
 

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Do you "need" a dual bowl. Absolutely not.

One of the unsafe items on a vintage Mustang is the brake system but it ranks far lower on the list than the spear-o-matic steering column, no side beam protection, no crumple zones, no safety bumpers, no ABS, no head rests, and the list goes on.

Do you see my point?

Put one on if you want just know you don't need to.
 

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I have had a single bowl fail before. A little scary for a sec. But I was already driving sensibly, down shifted at first then when I was going slow enough I bumped it to neutral and started easing out on the hand brake. I put a new single bowl back on that car for it to be "correct" and all the fluid was replaced for the first time in a long time. That is what makes them last longer, anyway.
 

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Im generally not a fan of removing parts that are serviceable and doing their job. If you are changing it anyway its worth the small amount of cost increase and labor to cut your chances of losing all brakes in half.

Thats a good return on investment.
 

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Do you "need" a dual bowl. Absolutely not.

One of the unsafe items on a vintage Mustang is the brake system but it ranks far lower on the list than the spear-o-matic steering column, no side beam protection, no crumple zones, no safety bumpers, no ABS, no head rests, and the list goes on.

Do you see my point?

Put one on if you want just know you don't need to.
I think a good braking system can avoid some of things above. And they do have a crumple system of sorts, not nearly as advanced as today car, but here are pics of my car after hitting a wall in my 65 A code 4 speed convertible at 50mph back in 1993. I walked away with a scratch on my hand from hitting either the window crank or door handle after it did a 360 in the air. And the top was down and my lap belt was super snug as it always is.

748663
 

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Do you need a Dual Bowl master-If you know your system is in excellent, non failing condition, NO
If there is a question in your mind "If my brakes fail" can I survive, are they non fail able?
So the other side of discussion. The advantage of the dual bowl brakes is you decrease your odds of COMPLETE brake failure by 50%.
If you have a brake fail on the fronts, the rear still brake, of course if a fail in rear-fronts will provide braking.
We lived, survived the 50's, 60's and most then were single bowl.
Decide if the more modern designs are advantageous to your needs.
 

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Good comments already, presenting both sides.
Here's the deal, though....
...when your master cylinder fails, your foot goes to the floor, regardless of single or dual circuits. Terrible feeling, for example going through an intersection when you've got the red light and a failed MC.
You just can't prevent every possible contingency. Crap happens regardless of best planning and the most detailed and obsessive caution.
I was very impressed by the comment by one member who rallied for 10yrs with single circuit and drums!
However, that said, I have a dual circuit MC and disc brakes.
But, but, but, I get the cheapest tires!
You'll often hear family guys say they dont skimp on the safety of their family when it comes to tires. I say Crap! I've had the best tires blow out as often as the cheapest.

So, coalescing all those opinions about several vaguely related safety topics, the bottom line is "how is Fate going to treat you?" AND do you really think you control Fate?

Check your bank account and your DIY skills, and go with your gut. Everybody has different levels of confidence and different perceptions.
Make your own decision...and dont fight Fate. Accept it.
Read Zen And The Art Of Motorcycle Maintenance.
:)
 

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Actually, I believe the statistics work like this, each bowl has a particular failure rate, say for grins, 10% of every time you drive the car, it will fail (just for explanation sake). Now with two bowls, your failure rate is now 10% times 10% or .1% so rather than it being 50% safer or 5% its actually a monster difference at 0.1%. Sooooooo, yes its worth it, now if you are planning on converting to disk brakes up front in 3 months, I would probably ride it out on the jelly jar for 3 months and get the right master for Disk brakes - different master for drum vs disk. If convert from drum, you will need more than just the master, do your homework and design the system correctly or you won't be happy till you eventually get it right.

One last comment, I would say that a car that sits half a season needs it more than one that is driven daily. Brake fluid absorbs water and when it sits, it eats...
 

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Actually, I believe the statistics work like this, each bowl has a particular failure rate, say for grins, 10% of every time you drive the car, it will fail (just for explanation sake). Now with two bowls, your failure rate is now 10% times 10% or .1% so rather than it being 50% safer or 5% its actually a monster difference at 0.1%. Sooooooo, yes its worth it, now if you are planning on converting to disk brakes up front in 3 months, I would probably ride it out on the jelly jar for 3 months and get the right master for Disk brakes - different master for drum vs disk. If convert from drum, you will need more than just the master, do your homework and design the system correctly or you won't be happy till you eventually get it right.

One last comment, I would say that a car that sits half a season needs it more than one that is driven daily. Brake fluid absorbs water and when it sits, it eats...
Actually, that failure rate remains unchanged, since it is usually a wheel cylinder, line or caliper that fails and not the master cylinder.
 

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A properly maintained system, with occasional change of brake fluid, is about as safe as you can get. I would never tell someone not to do the upgrade, and in fact have done it to cars, and sold the required parts to others. My own cars have not been altered. But they have been maintained. About 12 years ago I replaced almost the entire brake system on my 55- All four wheel cylinders, all the brake shoes, all the steel lines, and all the hoses. Mainly because they were old. The shoes had plenty of material, but they were the ones on the car when I got it from my Dad, over 20 years earlier. Same with the wheel cylinders- They were not original, but they were quite old. The hoses were probably original, and the steel lines certainly were.
 

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Do you "need" a dual bowl. Absolutely not.

One of the unsafe items on a vintage Mustang is the brake system but it ranks far lower on the list than the spear-o-matic steering column, no side beam protection, no crumple zones, no safety bumpers, no ABS, no head rests, and the list goes on.

Do you see my point?

Put one on if you want just know you don't need to.
If your brakes fail then those other safety issues you list really come into play.

My car was 30+ years old before the MC was converted, so yes single bowl will work...until something happens to create a leak in the system.
 

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Actually, that failure rate remains unchanged, since it is usually a wheel cylinder, line or caliper that fails and not the master cylinder.
The failure rate example is for a single point failure of any kind in the system, comparing the statistics of one braking system vs 2 isolated systems, does not matter what the failure itself is in this example.
 
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