Hot Rods Not comfortable with this.

My 1927 model T sedan has Lincoln drum brakes on the front and 11" drums on the rear.It is a lite weight car{fenderless}For normal driving the brakes work pretty well.But when I try to lock them up as in Skid,it wont.Its seems to stop quickly and does not feel like glazed lining .It stops.But Im not use to a car that wont skid the tires.I put the car up on jack stands and spun the front wheels.As soon as I hit the pedal the lock up.You cant move them by hand.With the car in gear and spinning the rear tires,hit the brake they lock up.This is with no momentum.The master cylinder is new and the rod has the correct stroke I believe.Is it possible that a lite weight car with big brakes and large tires just does not need to skid to stop quickly.I have a hard time believing that but .......Im lost.

 

IMHO, I would rather stop than skid. HRP

 

New cars don't skid either? Anti-lock brakes I believe they are called.

 

I new someone would anti lock me


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What are you using for a master cylinder?

Charlie Stephens

 

Early mustang drum disc.


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You may need to downsize master cylinder bore by 1/8" for more hydraulic advantage. It will cause a little bit longer stroke at the pedal, but with a set pressure at the pedal, you will have more pressure at the shoes because of the smaller master cylinder bore.
Just an idea.

 

What will thee additional pressure do?Are you thinking the lining is not expanding enough or not holding?


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Yet you have drum/drums? Seer ****er shorts with paisley shirt, it won't work.

 

Not according to the supplier.Why do you say that?


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Is it taking too long to stop? Why do you want the brakes to lock?

When the brakes are locked you don't have control over the ch***is, you have left it up to the vicissitudes of the Laws of Physics. You might not like that outcome.

When the brakes are working properly, you will be at a full stop, before any of them lock up.

 

On an early car without anti-lock brakes I expect to be able to lock my brakes. Not locking them is something I do to decrease stopping distance, sort of self applied anti-lock brakes.

Charlie Stephens

 

Are you capable of controlling a two wheel skid? How about a four wheel skid?

If skidding is so helpful, why is every single vehicle sold in the US, in recent history, equipped with a device specifically designed to prevent it? I wonder if automobile accident fatality rates dropping have anything to do with that....

If only we knew an engineer we could ask....

 

The master cylinder application appears to be 1" bore. What do you think Gimpsy? Asking seriously, not other.

 

I still want to know if the vehicle is taking too long to stop. From the OP's comments: "Its seems to stop quickly...", it would seem that it does not, so I am not sure what we are discussing here.

If I build a car, and it stops quickly, without locking up any wheels (aka: losing control of the vehicle), I call those properly functioning brakes.

 

Of course I am not capable of controlling a skid, that is the reason I said I don't lock them. Who said skidding is helpful? If you got that from my post you are reading something into it that wasn't intended.

Charlie Stephens

 

A disc / drum master will have a built in residual pressure valve on the rear only. So it will cause the rears to come on before the fronts as the fronts can easily **** in air by not having the RPV in the system. But most of your stopping power is in the front, so that is the Opposite of what you want.

 

You don't give the wheel cylinder bore sizes. That would really help.

 

Not skidding, ain't a problem, not stopping is a problem.

 

I'm uncomfortable because after 50 or so years of driving a lot of old cars it just feels odd.


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1 inch


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I agree...skidding ain't stopping,just wasting rubber and maybe endangering someone's health.

 

First car with really good brakes, in 50-years, might feel odd, but that does not mean that there is a problem with those particular brakes.

 

Maybe your on to something here.


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Could be.That was my speculation.


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FWIW, I went to a site and found that as an example, 1955 Ford car has 1" master and wheel cylinder bores. It's a heavier car too.
What kind of brake pedal is in the car? Just for info.
Food for thought.

 

Don't know them.


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In post #21, you said 1".

 

That's the master cylinder bore size.Not the wheel cylinder bore size.


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Do you understand "pedal ratio"? for non-power applications it should be about 7to1 power set-ups more like 4to1.