size of brake lines

Has anyone had a problem running 3/16 brake lines with 40 hyd brakes and a stock master cyl. Will there be enough volumn flow?
input appreciated.

 

it'll be fine.

 

I can only see it being a volume flow issue if the brakes are not kept adjusted up. JW

 

The brake line size will not overcome maladjusted brakes. The volume required is solely a function of the master cylinder, not the "tubes" that deliver the fluid.


Ray

 

Will we ever solve this idea. Bigger is not always best.

 

the fluid in a 3/16" brake line will get there faster, thus ensuring quicker stops, lol.

I was surprised to see 3/16" lines on a 67-68 Dodge rear-end.
Don't know why I was expecting bigger. As long as there's a good conduit to the MC, it doesn't matter.

 

Hnstray, i agree with that and i have 46 brakes on my T.My thoughts were of the returning fluid only due to the cylinder bore sizes and shoe return spring tentions.Cheers JW

 

The main reason to run the 1/4 inch lines is that you can use all stock connectors (assuming you are running a complete '40 system).

Charlie Stephens

 

less volume, but higher line pressure.

 

The size of the line does not effect the pressure the master cylinder delivers to the caliper/wheel cylinder.

 

It's about the only time that size doesn't matter .......

4TTRUK

 

This has been the subject of bench racing for years, but the short answer is it does not matter. 3/16 or 1/4 will make ZERO diffrence in the performance of your braking system.

I am a hydraulic technician for a living and can tell you about formulas you can use to calculate pressure and flow through lines, fittings etc as pressure and flow are inversely proportional and change with the presence of resistance. But in the end for the brakes on your hot rod, it just doesn't matter.

Good luck, -Abone.

 

some older drum systems used 1/4" rear and 3/16" front. Using a single fruit jar cylinder, I always understood that 3/16" offered increased line pressure to engage front brakes first, then rears??

 

I guess I am also a hydraulic tech as I am a fire sprinkler contractor. To push the same volume through a small pipe as a big pipe (or tube) you have to increase the velocity of the fluid. Basicly a funtion of cross sectional area. With higher velocity comes higher friction loss.

All that said. Probably no problem. I am using 1/4 inch on my 32 cus it is old school. Did they have 3/16 brake tubing in 1963.

Tim

 

my 55 chevy is set up as I described. Before proportioning valves, I assumed line size(pressure) was only way to change the braking system to allow for timing of braking front to rear? Anyway, good luck.

 

qmdv, my 39 Willys had 3/16 lines as standard. JW

 

And my '41 Ford had 1/4" from factory.

 

I have always used the 3/16 as it's easier to bend. The size is not important. What is important in a brake system is to change the fluid about every 3 years as brake fluid absorbs water from the air and will rust the system.

 

All good input I feel better about using the 3/16 SS lines - looks better and easier to bend.
Thanks all

 

Precisely: the principle to keep in mind here.

The bigger the diameter, the smaller the proportion of the cross-sectional area that is subject to laminar flow. But with the sorts of displacements and velocities we're talking about I think we're all agreed it's splitting hairs.

Of course the bigger the lines, the greater the total volume of fluid in the system. If any kind of contamination makes the fluid compressible, through cavitation or whatever, the greater the fluid volume, the greater the effect. In other words, if there are gas bubbles in the fluid it'll take more pedal travel to squash them to near-liquid if the total fluid volume is greater.

 

Why is everyone talking about flow volume? There is no recirculation of the hydraulic fluid in a brake system. There is a reason an application of the brakes should be instantaneous. All the way to the caliper piston the brake lines stay full of fluid assuming there are no leaks in the system. The size of the brake line will not make your system any more or less safe, and will not affect the systems performance.

 

Yep I'm thinkin that you could have 2 inch lines and the brake system would work the same as if it was 3/16. It's all about the volume of the master cylinder to the volume of the wheel cylinders. Or am I wrong?

 

270dodge you are correct.

 

That is a common belief. In a brake system, pressure is equal in in all parts of the system. Or in the case of a system with a stepped bore dual master cylinder, pressure delivery is equal in all parts of the system.