Brake Line Advise...

Clois Harlan · #1 (**permalink**) 07-13-2003, 06:40 AM

I have been looking at my brakes and making upgrades when necessary. When I built my kit I was given two different sizes of steel brake lines 3/32 for the front and 1/8 for the rears. I have disc brakes front and back (11" GM metric on the front and Thunderbird 9" on the rear). My kit came with no porportioning valve but I am installing one this weekend. That is when I got to looking at my brake lines a little closer and was wondering if I should replace my larger rear brake lines with the smaller 3/32" brake lines like I have on the front. I have read that drum brakes require 10 lbs of pressure and disc only require 2 or 3 pounds of pressure to work properly.

I don't have the pedal feel that I want yet, however the car does stop pretty good. I cannot lock up my brakes at speeds under 60 or 70 mph and just barely get some squeel when they do lock up. Any ideas on the brake lines being the same size? By the way I am running a stock late model Mustang master cylinder.

Clois

Clois Harlan · #2 (**permalink**) 07-14-2003, 05:12 AM

Bob/Roscoe/Fixit/ et al

Any ideas on brake line size?

kdavies3 · #3 (**permalink**) 07-14-2003, 06:02 AM

The normal way to go would be 3/16" OD for both front and rear.
I'd also use Kunifer (copper) as it doesn't corrode.

Clois Harlan · #4 (**permalink**) 07-14-2003, 06:17 AM

Thanks Kev,

Glad someone responded to this thread?

Clois

trularin · #5 (**permalink**) 07-14-2003, 07:36 AM

Clois,

It is not considered a good idea to use any copper lines for fuel or brake in the United States.

May I suggest 3/16" Stainless Steel. It is expensive but it will not feel the effects of age like traditional steel.

There is a place in MI, 'Inline Tube' that sells great quantities of this.

I used 3/16 for both front and rear.

I Hope this helps.

Roscoe · #6 (**permalink**) 07-14-2003, 07:42 AM

I also used 3/16" stainless from Inline. However, I really cannot comment with any knowledge about the drums and Mustang master cylinder setup. There is a good book out on brake systems that may help.

http://search.barnesandnoble.com/boo...sbn=1557882819

Roscoe

rdorman · #7 (**permalink**) 07-14-2003, 10:13 AM

Clois, when you get Freds book it will all be so clear. Sound like a broken record don't I?

The line size has nothing to do with travel, feel, efficiency..... he!!, I can't think of a thing it has to do with! The bigger the line, the more fluid it will hold

IF I recall correctly the concencious for brake line was 3/16 OD SEEMLESS tubing, steel (I have heard bad things on copper and aluminum), stainless or otherwise (although I would spring for the stainless), all AN fittings with appropriate hoses (I buy mine from Earls already made up).

The 10 and 2 or 3 thing is referring to residual pressure valves. Generally not considered required unless the master cylinders are lower that the calipers. 10 for drums and 2 or 3 for discs. They keep the pads in light contact with the rotors/drums. The actual hydrualic pressure required to stop is in the hundreds and even over 1000 PSI.

This may seem like a stupid comment but just in case, don't forget to put the proportioning valve in the rear line. If it is adjustable, if not exchange it

, it is nice to have it some place you can reach it from the cockpit. I have seen tranny tunnel (don't run your line there, think about a drive line failure and not having brakes on top of it!), next to the seat, etc.

What is it about the 'feel' that you do not like?

Rick

Clois Harlan · #8 (**permalink**) 07-14-2003, 12:53 PM

Just got back from Borders with the Brake Systems book that Roscoe recommended (they were either out of or didn't stock Freds book on brakes) but I picked up a book by Fred Puhn called "How to make your Car Handle".

I have just read the section on porportioning valves and will be installing mine on the rear brake line up close to the master cylinder so I can get to it under the hood fairly easy. I bought the screw type for $40 instead of the dash mount type for $80.

I wanted to make any adjustments before I changed out my brake fluid ($14/pint for DOT 4 is kind of expensive to me).

Thanks,

Clois

Edit insert: Rick the brakes feel extremely soft and require too much travel to stop the car fast. I briefly read about pedal travel and the formula to calculate the line pressure as well as several other calculations. Like you said the brake line pressure is anywhere between 350 psi and over a 1000psi. So I have some reading to do before I make any firm decisions.

rdorman · #9 (**permalink**) 07-14-2003, 01:00 PM

I think Fred's brake book is out of print. I got it off amazon. Let me know what you think of the other book.

14 a pint it a lot! I use wilwood 570 at about $9 with good luck. I also know people that use valvoline synthetic with out a problem for track use at the bargain price of about $3. Check your fluid temperatures next time you are out and buy only what you need!

Have fun!

Rick