mechanical vs. hydraulic brake systems

[hardtimes]

Originally Posted by machine girl

That's still a big problem, stock brake parts or hyd brake parts, china junk is about all we can get, NOS stuff is out there but$$ . the shop rebuilding brake clys, and master clys with stainless sleaves will be the way to go. stainless wont rust and very hard.

Amen to these sentiments, as they are exactly what I have encountered !
I am/was fortunate to know a old time model a expert who talked me out of putting hyd on my '30 roadster. He had NOS brake parts and the skill to show and teach me how these mechanicals ought to work. Yeah, they work as he stated they would, but like said....you had better know how to maintain/ PM them regularly...for safety sake.
BTW...For anyone contemplating putting hydraulics on a Model A, there are good and best types to use. DO NOT settle for good (i.e.-'39/'40 WAGNER type). Install the best available (Bendix) which are 'self energizing'. These were used on huge Lincoln zephyr cars which weighed twice as much a Model A, and are used by those with the $ and in the know.
As stated by others here, many hydraulic installations were 'butcher jobs' that were not equal to a proper installed mechanical system.

[Mike V. Florida]

So what have we learned

Either system properly installed and maintained with good parts will stop your A with ease.
Either system put together with poor parts and poorly maintained will not.

[stewwolfe]

Well said Mike!

[Kevin in NJ]

For a car that is not driven much hydrualic brakes will fail. (possibly weather dependent)

Note, this is for all cars with drum brakes. My experience is based on owning 60's Mustangs and a 39 Ford.

The reason goes into the physics of daily temp change and how materials expand and contract at different rates. Living in NJ I can see a daily temp change up like 40 degrees plus high humidity.

These daily temp changes allow for the juice to be pushed past the seals and pulled back into the piston area. This allows for the dirt to be lightly washed with liquid and eventually dry to form crude preventing the piston from moving.

This occurs reguardless of type of fluid or if you have a stainless sleeve installed.

With the 39 we had tried everything from all NOS wheel cylinders with new rubber to silicon brake fluid and those brakes had some sort of problem every spring (practically). From one piston on one side to both rear brakes just not functioning. The Mustang has less problems, but I go out of my way to drive it all year round. My most recent problem was the quality of the brand new name brand brake hoses. A few years ago I put all new brake parts onto the car. Well the front right hose swelled at a crimp and would let the fluid through and not back which locked up the wheel.

Then there was my conversation at a car show with most of the participants. I knew most of the people for the like 40 or 50 cars of all years and makes. Like half the people either had symptoms of brakes not working or they admitted directly that one or more rear wheels were not working and did not plan to do anything about it!!!!

So I have come to the conclusion that juice brakes, especially the early designs, are not a wise choice for a car that sits. Quite frankly they are unsafe. You are even more unsafe if you are running around with a single master cylinder so any single failure makes sure you have no brakes. Heck, I converted my 65 Mustang over to a dual for safety. It is so cheap to do you have to be nuts not do it on a none show car.

One the other hand, the mechanical brakes done right will just keep on working. Other then some lubrication and the occasional adjustments my brothers 31 coupe has been running with the same brakes since arond 1970 when the car was put on the road.

[BRENT in 10-uh-C]

Originally Posted by machine girl

again, brent is long winded and off topic. brent get back to the question drop all the fluffy stuff. no need to use the form to
advertise your shop. that's what your doing when you say come to my shop.

What did I do to get you all riled?? Is this a response because you do not agree with my opinion which differs from yours?? He asked if anyone actually changed them back. I answered his question!

And, I pretty sure I did not try to sell him anything so what does it matter if I suggested he come to my shop to drive a Model-A? Maybe if I had suggested that he come by my house to drive one, it would be different?? Come on, ....play nice!!

[whirnot]

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Originally Posted by machine girl

again, brent is long winded and off topic. brent get back to the question drop all the fluffy stuff. no need to use the form to
advertise your shop. that's what your doing when you say come to my shop.

I thought it was a good answer, showing a lot of knowledge on the subject. Lighten up a little.

[Bob Johnson]

There is NO ADVANTAGE to mechanical or hydraulic brake systems from the pedal to the shoe. Both act like levers. There is a ratio of the pedal movement to the shoe movement. The pedal will move several inches producing a shoe movement of factions of an inch. For a mechanical system the ratio is determined by all of the lever lengths. For a hydraulic system it is determined by the lever lengths and the size of the master and slave cylinders. If each system is set up correctly the pedal will move the same distance for each system to move the shoes the same distance. So the shoes will see no difference between the to systems.

HOWEVER there is a difference in the shoes and the drums. Typically the hydraulic systems uses large cast iron drums and shoes. These can be somewhat self adjusting. Often the mechanical system uses worn out steel drums.

I have driven properly set up brakes of both types and they perform the same.

Bob

[Charlie Stephens]

I would like to add my 2 cents worth here for what it is worth. The mechanical brakes I am comparing are not Model A but ‘32 (on a ‘32 car) which should be close enough. The original ‘32 brakes were a similar design to the Model A but the drums were 12 inch cast iron compared to the 11 inch steel (except for the late ‘31’s) drums on the model A. I bought a ‘32 roadster in ‘69 with the intention of restoring it. I went through the brakes. The tracks on the backing plates were welded up and ground back to specification. The drums were 12.030 or less. The drums were turned and the shoes arced. I essentially had new brakes. I drove the car with these brakes for about 10 years and 5000 miles. I decided I needed a little more power and reliability and replaced the Model B engine with a 4 cylinder Mercruiser Marine engine from about 1970. When I upgraded the engine I converted to hydraulic brakes. I chose to use the brakes for a ‘46-‘47 Ford. I used all of the components from the ’46-‘47 system except the master cylinder mount. I designed a master cylinder mount that used the original ’32 pedal assembly and had the same lever ratios from the ’46-’47 system. I hate it when people mix and match components from different systems and then complain their brakes don’t work right. All of the drums were under 12.030 and were turned and the shoes were arced. The wheel and master cylinder cylinders were new. It was nice at that time that you could get “Made in USA“ parts that worked. Again I had essentially new brakes. And now for the comparison. When initially adjusted (including road testing and fine tuning) the mechanical brakes worked excellent. I guess I would buy the statement that “properly-adjusted mechanicals are as good as hydraulics”. After about 1000 miles one of the wheels would tend to lock up first in a panic stop causing the car to pull in a stop. This meant it was time to adjust the brakes again. Main problem being you didn’t know you had a problem until you tried to make a panic stop. Over another 5000 miles on the hydraulic brakes they were never adjusted and never had any problems. The hydraulic brakes had a firmer feel to the pedal. Where do I stand in the debate? If I intended to show a car it would have mechanical brakes. If I planned to spend 10 years restoring the car I would have mechanical brakes that I could depend on working when I finished the restoration. If I intended to only drive to local shows and out to breakfast the car would have mechanical brakes. If I intended to drive the car a lot and/or at high speed (55 mph +) it would have hydraulic brakes. If I expected that a non-restorer such as a wife, daughter or son, drive the car I would have hydraulic brakes. I can deal with brakes that pull. I would not expect anyone who was not familiar with old cars to deal with brakes that pull. Essentially either system is good if properly built/restored. The mechanical system is probably easier for the average person since restoring it is essentially rebuilding each part to its original specification. The hydraulic system requires a little more ingenuity in terms of brake line routing, master cylinder mounting, rear brake drum/backing plate clearance, etc.

In answer to converting back. I bought a ’31 RDPU in ‘72. It was a poster child for how not to convert to hydraulic brakes. The drums were over sized. The shoes were soaked in brake fluid. Some of the brake lines were copper. The hoses were so old that they leaked brake fluid through the rubber. The front spindles were from a later car probably to go with the brakes. None of the brake lines were properly clamped. The master cylinder was mounted on the firewall without additional reinforcement (stress cracks were starting to appear). If I had known how bad it was I probably would have flat bedded it home. The guy I bought it from was driving it on a regular basis. I removed everything and replaced it with an original mechanical system because I felt it would be much safer. Unfortunately (or maybe fortunately) I didn't drive it long enough with the hydraulic system to make a comparison. If the hydraulic brake system was basically sound I probably would have just rebuilt it. Sure glad I got it for a good price.

Charlie Stephens

[hardtimes]

Hey Charlie,
Well stated and from practical experience also ! I also would never let a family member drive my 'restored mechanical brake' car...for same reasons stated by you !
To reinforce what you said of 'pulling' and locking up experience (and your '32 was fords 'improved' mechanicals,eh). Not long after my mechanicals were done and supposedly working perfectly, with maybe 500 mi on them, I was in 3 lanes of lalaland traffic following 35 mph speed limit. I was in #1 lane when left two lanes stopped, as this huge woman came running across all lanes in the middle of a block. I caught some motion between cars on left and for some reason....slammed on mechanicals as hard as my leg could push. New steel belt Cokers with new brakes!! I slid all four tires with left front locking first and pulling me that way. The huge woman stopped dead front of me and actually laughed as I slid to with a few inches of her 300 +/- torso !! I near lost control in that left side drift and immediately regretted not installing Bendix hydraulics ! Got me to heavily thinking what would happen in a real emergency !!

[eagle]

Originally Posted by Slowplane

....so if I run multi-grade detergent oil, I should dump my mechanicals, or switch to an alternator??

Yeah...and then put on whitewalls and a stone guard!

[JOES31]

All I can add to all this is one good thing about mechanicals is that you can store the car without worrying about the master cylinder leaking, wheel cylinders leaking due to inaction. My fathers car had Mel Gross restore his brake system back in 1993, then the car was garaged until a year ago, and the brakes are as good as ever.

[Vonn Ditch]

without appearing as a wise-ass, I'd like to know the basis for that statement. Are there owners who have switched to hydraulics and wish to affirm the claim? Has anyone switched back?

Yes, I have switched every model a I've owned to hydraulic brakes, except for the one I bought that already had them. I have never switched back. I drive my cars, they are not garage art or cute parade cars. Same with my early ford V8 cars, I don't consider the original brakes on them adequate for today's driving either. If I can't stop just as good as the guy in front of me, I'm going to get in trouble. I know what mechanicals and early hydraulics are like, and I won't be using them.

[Patrick L.]

Originally Posted by Bob Johnson

There is NO ADVANTAGE to mechanical or hydraulic brake systems from the pedal to the shoe. Both act like levers. There is a ratio of the pedal movement to the shoe movement. The pedal will move several inches producing a shoe movement of factions of an inch. For a mechanical system the ratio is determined by all of the lever lengths. For a hydraulic system it is determined by the lever lengths and the size of the master and slave cylinders. If each system is set up correctly the pedal will move the same distance for each system to move the shoes the same distance. So the shoes will see no difference between the to systems.

HOWEVER there is a difference in the shoes and the drums. Typically the hydraulic systems uses large cast iron drums and shoes. These can be somewhat self adjusting. Often the mechanical system uses worn out steel drums.

I have driven properly set up brakes of both types and they perform the same.

Bob

There is a big difference between energizing systems and non-energizing like ours. In the day of mechanicals and even early hydraulics energizing systems hadn't been figured out.
I've seen many non-energizing systems on both types, but, I can't remember seeing energizing ones on any mechanicals. Maybe they are out there, I just haven't seen one that I can remember.

[mshmodela]

In the end break shoes mechanically put force upon the drums and there by the wheels.

[Tom Foster]

Originally Posted by Slowplane

....so if I run multi-grade detergent oil, I should dump my mechanicals, or switch to an alternator??

Of course, becuz they're all interrelated, doncha see. Using better oil will lead to better engine life, which means you'll want to drive it more, which means you'll want better brakes, and when you get better brakes you'll want it to start and run better, and so on, and so on.
It's a slippery slope we're on here, my friends. Just keep on using that ground-up dinosaur oil that's been in it since you pulled it out of the barn ten years ago, since by G_d that's what Henry put in there!
(Please, ever'body, the last paragraph was a Stephen Colbert-style rant and was intended wholly as satire.)
Fearless

[29ModelA]

My mechanical brakes stop well, but they have the bonded pads. I can lock up all 4 wheels but it takes effort. I recently drove a friends Model A with the proper pads on the front only - his brake rod to the rear brakes was completely removed. That car stopped like a modern car dang near. I would almost say it stops better than mine.

I have seen no reason to go hydraulic.

[Patrick L.]

Originally Posted by mshmodela

In the end break shoes mechanically put force upon the drums and there by the wheels.

Well, that statement about mechanical force of the brake shoes is correct. It just depends on the amount of that mechanical force on both ends. How much force one exerts on the pedal vs how much force is transmitted to the drums or discs, and, there lies the rub [ so to speak].

[mshmodela]

Recall power steering? It aids the mechanical steering system. Power breaks does the same... Makes it easier for the driver.

[Patrick L.]

Originally Posted by mshmodela

Recall power steering? It aids the mechanical steering system. Power breaks does the same... Makes it easier for the driver.

Not really. But there is no sense arguing with you over it.

[mshmodela]

LOL, argue?