Brakes

[Standing Elk]

Ok, let me say right off that I am not disagreeing with the concept of proportionally setting up the brakes on the model A. However, I am the sort of guy who is not satisfied just being told something if I do not see the logic or fully understand why, so bare with me here. That being said I understand that you would not want your front brakes locking up before the rears and this is the reasoning or logic behind setting the rears up more than the fronts. But it seems to me, that since the front of the car has the added weight of the engine and will have even more added weight as soon as the breaks are applied, due to inertia, then there should not be an issue with all four breaks being set the same. So what am I missing here? Not saying I am right just trying to understand. Thanks

[Jacksonlll]

The model a was designed for rear skid. Modern cars are set up for front skid. Because of the weight, I don't think you could make the front wheels skid with the rear on a high friction surface.

[WHN]

I remember the first time I rode an English bike with front and rear brakes when I was a kid.

Coaster brakes were used on most bikes back in the day. “Rear brake only”.

For those of you that see where I’m going here. You know what happened if you gave it to much front brake.

Back brakes first, than front brakes. Most of the time, all you use is the rear brakes. Enjoy.

[SeaSlugs]

I cant explain why Henry had them setup that way but from a safety standpoint you DO want the fronts to lock before the rears so the rearend doesn't skid around and spin the car. If all 4 are set equally due to the inerta load the rears will lock up and skid.

When adjusting brakes ive been told and have done when you cannot turn the front wheels anymore the rears should still turn but be rather hard to turn with both hands.

Roads have a crown to them and if your rear wheels lock the rear of the car will go towards the ditch while the front goes into on-comming traffic. If the fronts skid you skid straight and eventually if skidding long enough into the ditch. If your on a curve good luck.

Modern cars are typically 70-30 split - meaning the front does 70% of your braking while the rear does 30%. Really modern cars all have ABS - the shortest distance you can stop a car is that moment right before the tire skids - abs pulses back and forth on either sid eof that moment so you still have control.

[Synchro909]

I'm not being critical in any way here but the way I see it, a driver will lose directional control over the car with the rear brakes locked no less than with the front ones locked. For maximum braking, front and back should reach the point of locking at the same time. Obviously once all 4 are locked, the driver is just there for the ride as he has gone past the point of maximum braking and has lost any ability to steer the car.
When the wheels lock depends on a few thing like load distribution, road surface tyres and more. Given that, we are kind of chasing our tails worrying too much about the details, IMHO. Whatever the case, Ford had too much bias towards the rear which was common practice in days when 4 wheel brakes were something comparatively new. It took a while to get things right.
I build my cars for driving and to do so as safely as I can in modern traffic and the idiots I am forced to share the road with. I move as much bias toward the front as I can but still haven't reached the ideal. I do that by improving the efficiency of the front brakes, not lessening the efficiency of the rear ones.
Let the debate begin! (politely)

[SeaSlugs]

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Originally Posted by Jacksonlll

The model a was designed for rear skid. Modern cars are set up for front skid. Because of the weight, I don't think you could make the front wheels skid with the rear on a high friction surface.

If you repeatedly kept driving on the identical patch of road (ie keeping friction the same) you could eventually find that sweet spot when adjusting the brakes to skid all 4 but in the real world with grit and ever changing road surfaces it would be pure luck.

[Bill G]

I am not sure I understand the question.

But, here is an answer any way.

The key part of the mechanical brake system that makes it so that the rears have more braking power than the fronts is the actuating levers at the ends of the brake rods. Front levers are noticeably shorter than the rear levers. About half as long. That gives the rear more leverage and more braking action.

You can always back off the back brake adjusters, thus biasing the power more to the front. Some folks have also put longer levers on the front to give more front bias.

I didn't want to mess with the original configuration because I am not ready to have the fronts lock up on me and loose steering. I had that happen in my Honda on the ice the other day. Not a fun feeling. Plus the Honda has ABS, but on pure Ice, that doesn't do much good.

[Standing Elk]

Ok, so now Magic's answer brings up another question. If Ford's intention was to bias the braking effect toward the rear by making the rear brake actuating rods longer, more leverage, then why is at least one "excepted way" of setting the brakes up also advocate setting the fronts looser than the rears, referring to the "notched brake stick" method?

[Keith True]

The bias is engineered into the brake system.If you adjust the brakes according to the service bulletins it will act the way it is supposed to.If you try to change the bias by adjusting you are going to be under adjusted on one end and over adjusted on the other.If you try to use the arbitrary system of the board the brakes can do wonky things.That board does not allow for a few thousandths wear here and there,or a few thousandths of bends in the parts.That board idea was a gadget invented by a tinkerer in the 50's,and some try to hold it up as the holy grail.All that board is meant to do is to show you where things should be at different levels of the pedal.The trouble comes when people try to adjust things to fit the board.If you adjust according to the service bulletins the adjustment will be right on.If it still doesn't stop right you have other problems.

[Bill G]

I think that the notched board is just a way to make sure everything is equal. If you start with the adjusters on all four wheels just shy of applying any braking when the brakes are at rest and the clevis pins are adjusted to also be just shy of applying any braking pressure, all four brakes are in theory exactly equal and just shy of braking with no brakes applied. The key point is that all are exactly equal (more or less)

You could stop adjusting right there. You are in theory all set. The rear bias is built into the mechanics.

When you use the board and go through the notches, all you are doing is confirming that all the whees are doing what they should be doing at any of those settings. I.E. Rears applied hard and fronts are applied lighter, or rears are locked and fronts are firm but not locked. My thinking is that these steps with the notched board are just fine tuning the biases that are already built into the mechanics of the system itself.

I think some here have said that they don't even use the board.

[Bill G]

Looks like I posted at the same time Keith True was posting. I think we are saying the same thing.

[1931 flamingo]

The adjustment process has been the same for 87+ years...........why try to re-invent it??
Paul in CT

[michael a]

Let me throw this in the game where do floaters come into play

Sent from my SM-J700T using Tapatalk

[Synchro909]

Originally Posted by 1931 flamingo

The adjustment process has been the same for 87+ years...........why try to re-invent it??
Paul in CT

Maybe because there have been improvements made in the mean time as understanding of the dynamics involved improved?

[1930-Pickup]

In those days many cars were driven mostly on dirt roads. Today not so much. Was the original adjusting procedure set up more for (slippery) dirt roads, or hard roads, or a compromise?

[NCRebel]

I have enjoyed reading the posts here. I think adjusting the "brake adjustment board" with a shorter first notch will give equal braking tension on all four wheels at once. I like the rear slowing before the front on my A because of the steering control in a quicker distance.

I crashed an early model motorcycle by pulling the front wheel brake before the rear. It was no fun for the machine either.

[Bill G]

Originally Posted by michael a

Let me throw this in the game where do floaters come into play

Sent from my SM-J700T using Tapatalk

Interesting question. I am sure many others know the answer to this better than me. The purpose of the floaters is to make brakes operate more efficiently, and I think they are more often installed on the fronts, because the stock rears actually do float. Seems to me that more efficient braking, particularly from the front, will probably add a little more front bias. Just my opinion.

[jb-ob]

A point always over looked in the discussion of why Model A brake design is the fact most of American roads were unpaved dirt when the car was new. Era road maps show pavement ending just outside of town.

The era design seems to support the idea that dragging dead weight from behind while steering from the front was most efficient.

Was this a 'carry-over' idea from two wheel rear Model T brakes and how far into the V8 years did the design exist ?

[Patrick L.]

Ford was just learning about 4 wheel brakes with these monsters and we've come a long since. There is a big difference between wedge brakes and self-energizing brakes.

The last I want with these monsters is for the fronts to lock before the rears. When these brakes are working and adjusted properly they stop quite well at the speeds these cars were designed to run at.

[glenn in camino]

I've been driving my Model As for 40 years, and I always adjust the brakes tighter on the rear and so I can just turn the wheels on the front. It's always worked fine for me.