Brake Adjustment

dmaxweb

dmaxweb

Well-known member
How do I adjust for a 60/40 ratio? Reading Les Andrew's procedure seems like the result would be more like 40/60.

I have front floaters if that makes any difference.
 
Just reverse the procedure. adjust the front to lock up and the rear to be real hard to turn. Teds floaters require the front brakes to work first (60%).
 
Was reading your post with interest. Do you mean it should be 60/40 (Front/Rear) if you have Floaters on the front brakes?? I have Bratton's (don't know who made them) floaters on the front. Why does that make a difference on whether front or rear brakes lock up first? Thanks!
 
Why does that make a difference on whether front or rear brakes lock up first?

It makes a difference if the fronts lock up first, then you have just lost the ability to steer your car, do you really think that is the best way to go? I would rather have the rears lock first, at least then I can steer to avoid the situation and maybe miss it altogether!
 
Jim Parker Toronto said:
I would rather have the rears lock first, at least then I can steer to avoid the situation and maybe miss it altogether!
Click to expand...

You won't be able to steer either, but you will be able to do a good job of fishtailing. If your fronts have braking and your backs are locked, you have a lot less traction in the rear. Put any steering into that car, and you have oversteer (a famous race car driver said "understeer is where the front of the car hits the wall first and oversteet is where the back of the car hits the wall first").

I realize that Model A's aren't race cars, but race cars are set up so that the fronts lock first, that way the car stays in a straight line rather than spinning out.

Steve
 
The front brakes have more stopping power by shifting the weight of the car to the front when braking. The extra force on the tires onto the pavement create better braking action in the front.
 
i just talked to ted . he said the the rears should hit first . ........... steve
 
This has been discussed many times in the past. The original Ford Service Bulletins are still the best method of brake adjustment. The Model “A” service brakes are designed to lock in the rear first. Use the stick method to hold the pedal down at the two inch level and check for proper lock in the rear and heavy drag in the front. If anyone doubts it, just confirm the length of the rear levers in comparison to the front levers. The longer rear lever will naturally apply more torque to the rear wedges than the front levers can. IMO trying to change the original Ford design is asking for trouble.

Brake adjustment method.
http://www.vtmodelaford.org/repairtips.htm

Pete
 
why would you want to "lock the brakes up anyway" once you lock them up. you have just lost braking. now you are skidding. not a good idea.
 
cannon said:
why would you want to "lock the brakes up anyway" once you lock them up. you have just lost braking. now you are skidding. not a good idea.
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If you can NEVER lock them up, then you are giving up braking potential. You don't WANT to lock them up, but they need to work well enough that you CAN.

I still disagree with the rear lockup first concept. Remember that it wasn't much earlier that they thought that you shouldn't even HAVE front brakes, much less have them lock up first. The rears on a T lock up first because that's all they have.

Steve
 
Steve on a stock A the rears will hit first /or has more leverage but this is not ideal .All modern cars with disks bring the front on first As the weight pitches forward the rear become light ,so with the weight on the front you get maximum grip .You work the pedal just short of skidding.
to adjust the fronts back off the rears and get the fronts working good then bring up the rears .I dont sell to Brattons ,

the tires
steve norcal said:
i just talked to ted . he said the the rears should hit first . ........... steve
Click to expand...
 
A tremendous amount was learned about vehicle dynamics since the Model A era.

As previously said if the rear wheels lock first the car will be unstable and tend to spin. Then even if the driver gets off the brakes they will need to recover from the spin which takes space, time and a certain amount of skill.

If the front wheels lock first the car will just go straight. Get off the brakes and the drive can steer the car again.
 
Jim Parker Toronto said:
Why does that make a difference on whether front or rear brakes lock up first?

It makes a difference if the fronts lock up first, then you have just lost the ability to steer your car, do you really think that is the best way to go? I would rather have the rears lock first, at least then I can steer to avoid the situation and maybe miss it altogether!
Click to expand...
My physics instructor would disagree with you. He demonstrated this with model cars. If the fronts lock up and the rears are turning and still have traction, the vehicle stops straight ahead with no rotation around the car's vertical axis (Skid). If the rears are locked and the front wheels are still turning, the car immediately begins a rotation around its vertical axis (skid) until it is headed in reverse. If you don't believe me lock up the front wheels of a toy car and slide it along the floor. Then lock up the rear wheels and free up the front ones and try the experiment again. If that doesn't prove it to you, take your car out in a big empty parking lot, get going 30 or 40 mph and lock up the emergency brake (rear wheels).
 
Paul from Maine said:
If that doesn't prove it to you, take your car out in a big empty parking lot, get going 30 or 40 mph and lock up the emergency brake (rear wheels).
Click to expand...

While locking up the rears, apply some footbrake to apply braking force to the front wheels. That will give you a good simulation.

Oh, and tell the officer that it's a scientific test.

Steve
 
Here we go again.:eek: I am not going to discuss the merits of front brakes locking before rears. We are discussing the Model "A" Fords here. Unless someone can show me a specific Model "A" Ford Service bulletin that supersedes the 1928 and through 1931 issues with a major change in brake adjustment method then, any modifications beyond that is not recommended and can have all sorts of ramifications as pointed out earlier. If one is going to adjust brakes in an un-recommended method, then why not just put in hydraulics?:rolleyes:

Pete
 
"If you don't believe me lock up the front wheels of a toy car and slide it along the floor. Then lock up the rear wheels and free up the front ones and try the experiment again. If that doesn't prove it to you, take your car out in a big empty parking lot, get going 30 or 40 mph and lock up the emergency brake (rear wheels)."

Paul, I don't think a toy car braking comparison is the way a 2140 lb car would react. I agree with Henry and his design of the brakes for the A, and I can't go test your theroy in a parking lot because I have original 4 wheel parking brakes, not 2!
 
I made the adjusting board per the Mechanics Manual and carry it with me in the trunk. I set the brakes per the notches in the board and have no problems.

Dennis L Oberer
Green Bay WI
 
Jim Parker Toronto said:
"If you don't believe me lock up the front wheels of a toy car and slide it along the floor. Then lock up the rear wheels and free up the front ones and try the experiment again. If that doesn't prove it to you, take your car out in a big empty parking lot, get going 30 or 40 mph and lock up the emergency brake (rear wheels)."

Paul, I don't think a toy car braking comparison is the way a 2140 lb car would react. I agree with Henry and his design of the brakes for the A, and I can't go test your theroy in a parking lot because I have original 4 wheel parking brakes, not 2!
Click to expand...

What are 'original 4 wheel parking brakes'?
 
modelaer said:
Unless someone can show me a specific Model "A" Ford Service bulletin that supersedes the 1928 and through 1931 issues with a major change in brake adjustment method...
Click to expand...

Show me where there is a bulletin that supersedes the owner's manual requirement to put only "clean fresh water" in the radiator :-)

The point that some of us are trying to make is that in the last 80 or so years, we have learned something more about braking. Between the T and the A, we learned that you can actually HAVE front brakes. Since then, we have learned that setting the fronts to lock first is better and safer.

Here's what Carrol Smith said about brake bias:

"The harder the vehicle is braked, the more load is transferred from the rear tires to the fronts and, since the tires' tractive capability is a direct function of vertical load, the less braking torque the rear tires can accept without locking. If the rear tires lock while the fronts are still rolling, we must reduce the rate of decelleration or spin."

"On the other hand, if the fronts lock first, we will merely slide onward in the direction of original travel (unfortunately this will be at a tangent to any curved path which we may have been attempting to follow) until the driver eases off the pedal enough to unlock the tires and regain steering control".

"The optimum available adjustment, at the present state of the art, is to arrange things so that the front tires will lock just before the rears under heavy straight line braking".

The "present state of the art" at that writing was 1978. I consider that that supersedes any service bulletins.

And, yes, I understand that Carrol Smith was working on race cars, but the physics is the same.

Steve
 
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