1/4" or 3/16" Brake Line?

[epix1718]

Bought the Kanter kit to completely replace my brake system.. new wheel cylinders, master cylinder, etc...  While at it going to replace the brake lines and they appear to be 1/4" originally and know that 3/16" is the modern standard.  Thinking about picking up this kit on Amazon that is 25' of NiCu 3/16" with all all the normal SAE fittings.  

 

Would this work?  (I've never replaced brake lines before so it's a learning opportunity)

 

https://www.amazon.com/gp/product/B01801G45A/

[Branded]

Whatever  size  your wheel cylinders and master cylinder accept. That what I would use. 

[Plymouthy Adams]

stock should be 3/16

 

[thebeebe5]

The lines on my '37 were all 1/4".  I bought a 50' roll and separate fittings at my local NAPA.  Ended up with a bit left over.   The price on that Amazon listing is really good especially if it's 1/4".    I paid a bit under $1/foot for the line only. 

Edited May 3, 2018 by thebeebe5

[rhelm1953]

From the standpoint of brake performance the size of the line makes no difference.  Use what ever was stock if you are restoring the brakes to stock, that will make finding the correct fittings easier.

[DJ194950]

Many cars and trucks I have worked on had 3/16" lines from the master (or the proportioning  valve-newer vehicles) to brake cylinders and the rear lines were 1/4" diameter.

 

Why? Do not know.

I am not any kind of hydraulic engineer, must be some reason? 

Any engineers out there with a answer??

DJ

[Frank Elder]

3 minutes ago, DJ194950 said:

Many cars and trucks I have worked on had 3/16" lines from the master (or the proportioning  valve-newer vehicles) to brake cylinders and the rear lines were 1/4" diameter.

 

Why? Do not know.

I am not any kind of hydraulic engineer, must be some reason? 

Any engineers out there with a answer??

DJ

I am not a hydraulic engineer but I did service Uncle Sam's Naval Air for over 12 years as a hydraulic specialist.....but I do know that line diameter doesn't matter with hyd pressure, all that does is dictate how much fluid needs to be in the system to operate properly. All I can think of is savings on the smaller line weight and monetary........Are all M/C s 3/16 standard issue? Who knows....lol.

[Plymouthy Adams]

the 1/4 line was a work around instead of going with a proportioning valve..you get a delay with the 1/4 line plus the expansion rate of the tube itself (yes it does expand)  Pascal is a theory, not an absolute science...as the components of the system work within their own mechanical limits...

[Ricky Luke]

Also has to to do with fluid volume. Larger wheel cylinder pistons that need a lot fluid to move the shoes need the larger line to deliver the volume of fluid required for the same push of the pedal.

 

Rick

[maok]

The volume of fluid that moves is based on the displacement in the master cylinder, nothing to do with the lines. The lines, regardless of the size will always be full of fluid. Unless there is air in there IMO.

[Dodgeb4ya]

I'm pretty sure  factory line size was 1/4" up through 42 then 1946 on was 3/16".

[Plymouthy Adams]

yes but was not that special thick wall copper line and not steel......

[Dodgeb4ya]

I worked on both a 1936 P2 Plymouth and a 42 S10 DeSoto that had original 1/4" steel lines.

now a 31 CD 8 Chrysler I did had the factory Copper 1/4" lines on it.

[Ricky Luke]

On 5/4/2018 at 10:18 AM, maok said:

The volume of fluid that moves is based on the displacement in the master cylinder, nothing to do with the lines. The lines, regardless of the size will always be full of fluid. Unless there is air in there IMO.

Yes and no. In theory with the right master cylinder you could push the right amount of fluid through a hypodermic needle, or use a 1/2" tube. It's an engineered solution based on cost, ease of manufacture, material availability, and at the time probably common sense.

 

Rick

[MackTheFinger]

No idea if your car is 1/4 or 3/16 but I'd order some of this, too...  Good stuff..

 

https://www.amazon.com/Stainless-Brake-Protector-Gravel-Spring/dp/B01IRQXJDS/ref=pd_sim_263_4?_encoding=UTF8&pd_rd_i=B01IRQXJDS&pd_rd_r=GER4PZ2TJZSWHF61XBG3&pd_rd_w=IXn6b&pd_rd_wg=91PAT&psc=1&refRID=GER4PZ2TJZSWHF61XBG3

[plymouthcranbrook]

3 hours ago, MackTheFinger said:

No idea if your car is 1/4 or 3/16 but I'd order some of this, too...  Good stuff..

 

https://www.amazon.com/Stainless-Brake-Protector-Gravel-Spring/dp/B01IRQXJDS/ref=pd_sim_263_4?_encoding=UTF8&pd_rd_i=B01IRQXJDS&pd_rd_r=GER4PZ2TJZSWHF61XBG3&pd_rd_w=IXn6b&pd_rd_wg=91PAT&psc=1&refRID=GER4PZ2TJZSWHF61XBG3

This stuff really works to prevent rust. i have had to repair lines on several cars over the years and have always found good metal under the armor