Mechanical brakes, what i did

[CWPASADENA]

Originally Posted by Kevin in NJ

Before anyone jumps out and just starts modifying their cars let us think a bit about this.

Disclaimer: I am not saying this lever mod is good or bad. It certainly has technical merit, but I think it is not something the average guy wants to do as the brakes have to be done with attention to details as the front brake shoes have to be set up tight to the drums.

My first question comes from the comparison of any mod to original.
Does it really get you any worthwhile advantage in real life?

Do they really work better than factory?
We do not know for fact if any mods are better then factory.

We do know properly restored to original brakes work great.

There needs to be a quantitative set of data to determine if the changes are really anything good. Not just someone who thinks it works better then what they previously had experienced.

For example, using the same body or same type of body (weight distribution is important) one would first restore the brakes back to factory.
Then using a repeatable technique measure the brake power. The car would have to be run until the shoes were fully wore in to the drums. Once max braking is achieved with the factory set up, record the numbers.
Then change the levers and re run the tests.
Then change to the floaters.

Until these types of tests are run the ideas of changing the brake system are a nice novelty. All we know is a person changed the brakes and found them to work great- but compared to what? How much had the pedal travel and effort changed? Saying "it seems to be less pressure" is not very good, the person is comparing against what?

When compared to the fact just properly restoring the factory tolerances is known to give great brakes why complicate matters?
Lets be real. Many have troubles with just bringing the brakes back to factory. Most are doing band aid repairs and then throwing in some mods in hopes of better brakes. In the process skipping steps.


If real science was applied we might find the modified brakes are 10% less braking or only 5% more braking under certain conditions like running 65 MPH. At what point is it worth making the changes given how cars are driven?

Of course, the science may also find the mod significantly improves the brakes.

Again, I am not trying to knock CW's idea as it may be a very good idea.

I am just adding some perspective for all to consider. We should not be running out and changing stuff willy nilly just because one person did a change and he thinks it works great. (I am not trying to put down CW, just put perspective on a larger issue)


From a historical context. We know the A brakes are the Fords first attempt at a 4 wheel brake system. There were several variations during production. If you take the time to surf through the 1928 to 1939 service bulletins you will see the evolution of the Ford mechanical brakes. Ford did go to a floating brake system using wedges front and rear by the end.

The A brakes certainly were not the best that Ford could have produced.
They were learning as they go.
We know for FACT that properly restored the brakes are only limited by the small tire contact patch of the original tires.


Finally,
My opinions based on some facts:
The original mechanical brake system is the best choice if you are using the original wheels and tires.
A car with more HP, 16" wheels and radial tires would make me think seriously about going to hydraulics.
Hydraulics are not the best choice for cars that are not driven much. They will fail if not used frequently.

Kevin,

I will certainly agree with you that for a proper comparison, there needs to be a proper engineering study. Base line test information needs to be determined with a properly restored original brake system. Then change only the front levers and re-adjusted the brakes and repeat the tests. The "base line" test results and the "as modified" test results can then be compaired.

If someone would like to undertake this, I would be glad to assist.

Actually, it would be real easy to make up a set of levers with two holes in them, one for the "stock" length lever and one for the "Modified" length lever. This way, it would be very easy to switch back and forth between "stock" and "Modified".

I would never suggest someone put the longer levers on their car unless the complete original brake system is in very good condition. All the modifications in the world will not overcome a worn out brake system.

Again, This is just what I did and I am not suggesting anyone modify there brakes in this manner.

Chris

[CWPASADENA]

Originally Posted by MikeK

Thanks Chris for a thread about a totally new mod that stirs controversy. That's been missing here for a while. Now someone needs to start one about how they adapted a modern vacuum booster to the cross-shaft for mechanicals.

NOW, This is an interesting idea!!!!

Chris

[CWPASADENA]

Originally Posted by Marco Tahtaras

I started to write this yesterday morning but was pulled away. Since then some have thought through the concept.

What Chris did was increase the leverage to the fronts which were technically under leveraged compared to later cars when Ford finally understood the reality of front versus rear needs. Yes, this does slow the actuation of the front brakes. That is normal and unavoidable. Look at the ratios of any block and tackle. The lift capacity is not determined by the size of the cable or rope (although it must be suitably sized), but the the capacity is determined by the ratio or number of wraps of the cable. The more wraps, the slower it lifts but the more it lifts with the same applied force.

Everyone assumes the Model A front brakes actuate or engage at the same rate as the rears. This is not the case. The topic came up about ten years ago regarding an article written suggesting the brakes could be adjusted 50-50 or 60-40 front-rear. I explained at that time it was simply a fallacy. In doing so you are simply reducing the function of the rear brakes and FORCING the much stiffer (less leverage) front brakes to do more of the work. Think of it this way, shortening the front brake rods to make the front brakes come on earlier is the same as lengthening the rear rods to come on later (reducing rear brake function) except the latter lowers the functional height of the brake pedal. I further explained that to even equalize the braking force at the drum (front to rear) you must actually equalize the leverage. This essentially also means making the brakes actuate at the same rate.

Now it's important to note that the simpler linkage of the rear brakes DOES provide a slight mechanical advantage due to efficiency but not nearly to the extent that the the added leverage (and slower actuation) does. Adding leverage to the fronts will similarly slow the actuation which can then be adjusted to engage at the proper time. Wear will not cause any future adjustment issues assuming the modification is not too extreme.

Marco,

Thanks for your input.

I tend to write like an Engineer and you have the ability to explain things in a very clear and easily understood manner.

Your comments are always valued and appreciated.

Chris

[Bob C]

Here is a picture of a vacuum setup
.

[Special Coupe Frank]

Originally Posted by MikeK

Thanks Chris for a thread about a totally new mod that stirs controversy. That's been missing here for a while. Now someone needs to start one about how they adapted a modern vacuum booster to the cross-shaft for mechanicals.

It's been did. Vacuum-boosted mechanical brakes were around in the early to mid 1930's... some of the big Lincolns used them, among others.

Maybe not "modern", but they existed.

[MikeK]

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Originally Posted by Special Coupe Frank

It's been did. Vacuum-boosted mechanical brakes were around in the early to mid 1930's... some of the big Lincolns used them, among others.

Maybe not "modern", but they existed.

Originally Posted by Bob C

Here is a picture of a vacuum setup
.

I never said there were no vacuum assists on mechanicals!
I pondered the idea of using a modern vacuum assist. THAT has never been done to my knowlwdge on an A. Brackets/ linkage/ leverage, etc. It would be a design challenge, as modern boosters are basically "push" operation, and mechanical brake systems are based on all "pull" rods.

It would be interesting if was worked out with a new available booster and parts. That would make a leverage change like Chris did to shift the front/rear bias a toe-tappin' delight.

[hardtimes]

chris,
i didnt say that YOU said that 'ford got it wrong'...reread the thread! it was said by other. impressive resume, indeed! 'homebrew' may have been a condensed description, certainly not meant to be derrogatory, which is apparenyly how you took it..and i now can see why knowing some of your history! i can appreciate your applying your expertise to improve the A mechanicals...and would be right in line to purchase any real improvement thereto!
mabe said wrong, and certainly not directed towards YOU, but i read over/over the same past imput to 'leave them there stock mechanicals alone as ford made them'. then some new /differing change idea comes along.....and out the window goes the leave them alone crowd!

btw chris,
i do not have as great a background as you , in this field. however, i see/understand your method/application! i also have 50 years of driving cars with mechanical and hydraulic brake systems, including fords...practical application! good luck with your efforts !
i'd be interested to hear from an engineer with your background, why a model A with bendix hydraulics and modern materials, i.e.- stainless line, synthetic fluids and PROPER installation/maintenance...why you think it wouldnt last?

[Special Coupe Frank]

I pondered the idea of using a modern vacuum assist. THAT has never been done to my knowlwdge on an A. Brackets/ linkage/ leverage, etc. It would be a design challenge, as modern boosters are basically "push" operation, and mechanical brake systems are based on all "pull" rods.

It would be interesting if was worked out with a new available booster and parts. That would make a leverage change like Chris did to shift the front/rear bias a toe-tappin' delight.

Whether it's a modern "co-axial" booster or a 1930's "pull-can", the effect is the same: a vacuum-assisted device, adding to the operators pedal effort to apply the brakes.

Adding a vacuum servo to the main pull rod of an otherwise-stock Model A braking system would not change any leverage or alter the front-rear brake bias; it would simply reduce the amount of pedal effort required on the part of the driver.

I guess it could be done; the tricky part would be setting-up the reaction valving.

The 1956-'62 MoPars did have a similar vacuum pedal-assist power brake: it was a big oval can or bellows mounted above the stock MC, and an operating rod that went through the firewall, acting on a lever attached to the brake pedal arm. Have them on my '60 Windsor... they work pretty well, but it's a real Rube Goldberg-looking set-up.
PITA to check the brake fluid in the MC too.

By 1963, MoPar came to its senses and adopted Bendix brakes, and coaxial power-brakes,like the rest of the industry.

[1931 flamingo]

On the idea of vac assisted mech brakes, It seems that many people are having enough trouble getting the vac w/shield wiper to work with the available vacuum, how big is the vac resevoir going to have to be to get anny vac assist to work?
Paul in CT

[Glenn of northport]

30 years ago i bought longer arms used them for many years last year i redid my brakes took off the arms,i just checked them and they are 5 inches long .I was happy with them and also with orginal ones,

[MikeK]

Originally Posted by 1931 flamingo

On the idea of vac assisted mech brakes, It seems that many people are having enough trouble getting the vac w/shield wiper to work with the available vacuum, how big is the vac resevoir going to have to be to get anny vac assist to work?
Paul in CT

The reservoir is built into the modern assist units, and generally holds sufficient vacuum for 2 complete applications. An A will produce plenty of vacuum to "charge" the unit while driving, more than many modern cars. Vacuum wipers suffer during acceleration, and speed up during deceleration, exactly the time an assist unit will get it's vacuum topped off. What will be needed is a larger fitting and hose to the intake manifold, something like 3/8" I.D.

This is a small diameter (about 6") dual diaphragm unit.

[1931 flamingo]

Thanks Mike!!! Love this place, so much info right at our finger tips.
Paul in CT

[Special Coupe Frank]

Originally Posted by MikeK

This is a small diameter (about 6") dual diaphragm unit.

Could it be as simple "inserting" this booster into the middle of the main pedal to cross-shaft rod ? ( Conceptually, at least? )

The stock battery location would cause some issues...

Someone could make it work...

[CWPASADENA]

Originally Posted by hardtimes

chris,
i didnt say that YOU said that 'ford got it wrong'...reread the thread! it was said by other. impressive resume, indeed! 'homebrew' may have been a condensed description, certainly not meant to be derrogatory, which is apparenyly how you took it..and i now can see why knowing some of your history! i can appreciate your applying your expertise to improve the A mechanicals...and would be right in line to purchase any real improvement thereto!
mabe said wrong, and certainly not directed towards YOU, but i read over/over the same past imput to 'leave them there stock mechanicals alone as ford made them'. then some new /differing change idea comes along.....and out the window goes the leave them alone crowd!

btw chris,
i do not have as great a background as you , in this field. however, i see/understand your method/application! i also have 50 years of driving cars with mechanical and hydraulic brake systems, including fords...practical application! good luck with your efforts !
i'd be interested to hear from an engineer with your background, why a model A with bendix hydraulics and modern materials, i.e.- stainless line, synthetic fluids and PROPER installation/maintenance...why you think it wouldnt last?

Thanks for your comments,

I am not looking for everyone to agree with me, or anyone for that manner. I am open to a constructive discussion. If I came down on you a little hard, I appologize. I try to be very careful about labling people or ideas. Certainly no body knows everything, all of us have some area of expertise and we can all learn.

As far as re-working the model A Brakes as Self energizing Hydraulics, I think someone is selling a kit to do this. There is nothing wrong with converting a Model A to Hydraulics but for this car, my personal preference was to leave the mechanicals and see if I can make them a little better.

I also understand there is a kit that converts the mechanicals to self energizing. I built this chassis about 6 years ago and this kit was not available or prehaps I would have considered that approach. I also have read on The Barn where some are very satisfied with this modification while others could not get the adjustment right and went back to the original configuration. I am not familiar with this modification so I would not have an opinion.

What I did is just a little different approach. This modification is simple, easy to install and adjust. Personally, I like how it works.

Again, I am not suggesting anyone else does this, this is just what I did.

Chris

[Bob C]

Probably need to find a booster like these.
http://www.pbr.com.au/products/heavy...erChambers.pdf

Bob

[CWPASADENA]

Originally Posted by Glenn of northport

30 years ago i bought longer arms used them for many years last year i redid my brakes took off the arms,i just checked them and they are 5 inches long .I was happy with them and also with orginal ones,

I was not aware that longer arms were made and sold 30 years ago but I am not supprised. There is really not much that is actually new.

Somewhere, I have an old kit that re-works the internals of the Model A front brakes. I think the idea was along the lines of making the fronts self energizing. This is an old kit that was sold back '30s or '40s. I will have to dig it out and see what it is all about.

Chris

[BCCHOPIT]

Originally Posted by 1931 flamingo

On the idea of vac assisted mech brakes, It seems that many people are having enough trouble getting the vac w/shield wiper to work with the available vacuum, how big is the vac resevoir going to have to be to get anny vac assist to work?
Paul in CT

You don't need brakes going up hill

[fiftyv8]

I have this question about an after market brake boosting product I've seen mentioned on the HAMB but at that time did not need to know about.

Who makes or sells this item that attachs to the main brake rod bar under the center crossmember and provides braking assistance to mechanical rod brakes.

I believe they are made especially for Model A Fords.

I've done a search here but come up with nothing.
It could have been they were mentioned in a thread about something else.

Any help or links would be much appreciated.

I am wondering if it is related to the folks in CA doing hydraulic brake conversions for Model A's.

Does anybody know where to start looking???

[PetesPonies]

I like what you did. It is basic mechanical advantage engineering and to me seems to be a good change. I assume you all are familar with this change that is available too ?

https://www.youtube.com/watch?v=2EjRe411l3M

[BILL WILLIAMSON]

Very good thread! Lots of info to ponder.
I once fabricated a new diaphragm for the vacuum booster on a '36 Lincoln Model "K." Car weighed 5,990 lbs, 16 inch brakes, built like a ton and a half TRUCK! Stopping was only a FANTASY without the booster!! The booster was gigantic! WAY too big for a light car. Bill W.