Search



Go Back   Third Generation F-Body Message Boards > Tech Boards > Brakes
Register Forgot Password?

Brakes Looking to upgrade or get the most out of what you have stock? All brake discussions go here!

Welcome to ThirdGen.org!
Welcome to ThirdGen.org.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, join the ThirdGen.org community today!


Reply
 
Thread Tools Search this Thread
Old 04-28-2011, 12:15 PM   #1
Supreme Member
 
dennisbernal91z's Avatar
 
Join Date: Feb 2005
Location: Milford, postal code: 01757
Posts: 3,674
Car: F1, 390 powered Camaro Z28,building
Engine: 385, All forged, Trickflow Al heads
Transmission: T-56, SPEC STAGE 3, hurst shifter.
Axle/Gears: Moser/ 4.11

Classifieds Rating: (2)
Send a message via AIM to dennisbernal91z
Brake line size, why does GM use the 1/4" to the rear?

Like the title says, what is the point of the larger 1/4" to the rear? Inline tube says there is no point. Mopar has done 3/16 everywhere forever. Ford does on some things. Hot rods are almost all only 3/16 all over. I want to do it this way.

Thoughts?
__________________
here we go... again
http://www.cardomain.com/ride/782913/1
dennisbernal91z is offline vBGarage Page   Reply With Quote
Old 04-28-2011, 12:17 PM   #2
Supreme Member
 
BlackenedBird's Avatar
 
Join Date: Mar 2011
Location: Central Texas
Posts: 2,891
Car: GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: Aussie 9-bolt/3.27 posi

Classifieds Rating: (5)
Re: Brake line size, why does GM use the 1/4" to the rear?

Why redo something that obviously works already?
BlackenedBird is offline vBGarage Page   Reply With Quote
Old 04-28-2011, 02:27 PM   #3
Member
 
Gibson27's Avatar
 
Join Date: Mar 2004
Location: Nfld
Posts: 105
Car: 84 z28
Engine: 383 stroker
Transmission: th-350
Axle/Gears: 3:42

Classifieds Rating: (1)
Send a message via MSN to Gibson27
Re: Brake line size, why does GM use the 1/4" to the rear?

because if you have a all original 82 like me with SAE fittings, your gonna be in for a time looking for the "ghost" fitting that is the 9/16 for the 1/4 line to the master cylinder. I have 1/4 line here to do the replacement but i cannot find the fittings.
Gibson27 is offline vBGarage Page   Reply With Quote
Old 04-28-2011, 02:36 PM   #4
Supreme Member
 
BlackenedBird's Avatar
 
Join Date: Mar 2011
Location: Central Texas
Posts: 2,891
Car: GTA
Engine: 350 TPI
Transmission: 700R4
Axle/Gears: Aussie 9-bolt/3.27 posi

Classifieds Rating: (5)
Re: Brake line size, why does GM use the 1/4" to the rear?

I would think any place that makes custom hydraulic lines would have the fittings, if that is all your looking for. I have a place just up the road that does that.

But what he was asking about line size difference, not SAE vs Metric fittings.
BlackenedBird is offline vBGarage Page   Reply With Quote
Old 04-28-2011, 04:09 PM   #5
Supreme Member
 
//<86TA>\\'s Avatar
 
Join Date: Aug 2006
Location: Central NJ
Posts: 11,475
Car: 86 Trans Am, 92 Firebird
Engine: 408 sbc, 3.1L of raw power
Transmission: TKO600, T5
Axle/Gears: Moser 9", 3:70 trutac, 3:23 torsion

Classifieds Rating: (12)
Re: Brake line size, why does GM use the 1/4" to the rear?

Quote:
Originally Posted by Gibson27 View Post
because if you have a all original 82 like me with SAE fittings, your gonna be in for a time looking for the "ghost" fitting that is the 9/16 for the 1/4 line to the master cylinder. I have 1/4 line here to do the replacement but i cannot find the fittings.
this fitting?
http://store.fedhillusa.com/a244.aspx
if it is, you can thank me later
//<86TA>\\ is offline vBGarage Page   Reply With Quote
Old 04-28-2011, 04:11 PM   #6
Supreme Member
 
//<86TA>\\'s Avatar
 
Join Date: Aug 2006
Location: Central NJ
Posts: 11,475
Car: 86 Trans Am, 92 Firebird
Engine: 408 sbc, 3.1L of raw power
Transmission: TKO600, T5
Axle/Gears: Moser 9", 3:70 trutac, 3:23 torsion

Classifieds Rating: (12)
Re: Brake line size, why does GM use the 1/4" to the rear?

but no, you will never find the proper fitting with the rear hard line if you use the smaller 3/16 4.75mm tubing.

whats so hard with using the 6mm or 1/4" line? fittings are available. Look in the link i posted to . FedHill has everything. why reinvent the wheel
__________________
"i thought the plan was fool proof?"
"fool proof, yes. idiot proof, no."
//<86TA>\\ is offline vBGarage Page   Reply With Quote
Old 04-29-2011, 06:39 AM   #7
Member
 
Gibson27's Avatar
 
Join Date: Mar 2004
Location: Nfld
Posts: 105
Car: 84 z28
Engine: 383 stroker
Transmission: th-350
Axle/Gears: 3:42

Classifieds Rating: (1)
Send a message via MSN to Gibson27
Re: Brake line size, why does GM use the 1/4" to the rear?

FTR... I thanks 86TA already lol.

Funny thing is that I scrapped a 84 i had and that master cylinder has bubble flares, I also bought stainless flex hoses off ebay for the 84. So to use these on my SAE 82 camaro I need to buy bubble to inverted flare adapters lol.

So much fun....
Gibson27 is offline vBGarage Page   Reply With Quote
Old 05-04-2011, 12:14 PM   #8
Supreme Member
 
dennisbernal91z's Avatar
 
Join Date: Feb 2005
Location: Milford, postal code: 01757
Posts: 3,674
Car: F1, 390 powered Camaro Z28,building
Engine: 385, All forged, Trickflow Al heads
Transmission: T-56, SPEC STAGE 3, hurst shifter.
Axle/Gears: Moser/ 4.11

Classifieds Rating: (2)
Send a message via AIM to dennisbernal91z
Re: Brake line size, why does GM use the 1/4" to the rear?

I am not trying to re-invent anything. I am a mechanical engineer and am wondering why they did that. Thats all. Well at least thats the first part. Second part is, I don't have a single brake like in my 700HP Procharged camaro right now. I want to route all my own lines from scratch, I don't have anything right now so I would like to buy a HOT ROD kit that someone sells, like Inline Tube does. This is what I did with wiring. I ripped all the GM stuff out and wired the car with a HOT ROD kit. Now I have easier access to my fuse pannel and all my wires are labeled with what they do.

Anyways, it doesn't look like anyone has any real engineering reason as to why GM used 1/4". Interesting that if it is "needed" then why hasn't everyone done it. Line size has nothing to do with pressure output. The line size at your calipers in the rear is still 3/16, just like the front.
dennisbernal91z is offline vBGarage Page   Reply With Quote
Old 05-04-2011, 03:06 PM   #9
Member
 
Gibson27's Avatar
 
Join Date: Mar 2004
Location: Nfld
Posts: 105
Car: 84 z28
Engine: 383 stroker
Transmission: th-350
Axle/Gears: 3:42

Classifieds Rating: (1)
Send a message via MSN to Gibson27
Re: Brake line size, why does GM use the 1/4" to the rear?

Not trying to cause a stir but I though line size could affect pressure output, or at least the amount of force you need to exert.

If Force=PressureXArea , then Pressure=Force/area so....

if 100lbs of force/ a area of of lets say 10 inches to make it easy then it creates 10lbs of pressure.

If we decrease the area by half then 100/5= 50lbs of pressure.

So if i am right, which is not all the time at all, then the smaller the diameter of the line (line size) the more pressure is applied to the brake cylinders and caliper pistons when the same amount of pedal force is applied.

Now it's been a while since I did any hydraulic calculations so if anyone wanna confirm that the formula is correct?
Gibson27 is offline vBGarage Page   Reply With Quote
Old 05-04-2011, 07:41 PM   #10
Moderator
 
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 14,152
Car: check
Engine: check
Transmission: check

Classifieds Rating: (1)

Re: Brake line size, why does GM use the 1/4" to the rear?

Quote:
Originally Posted by Gibson27 View Post
Not trying to cause a stir but I though line size could affect pressure output, or at least the amount of force you need to exert.

If Force=PressureXArea , then Pressure=Force/area so....

if 100lbs of force/ a area of of lets say 10 inches to make it easy then it creates 10lbs of pressure.

If we decrease the area by half then 100/5= 50lbs of pressure.

So if i am right, which is not all the time at all, then the smaller the diameter of the line (line size) the more pressure is applied to the brake cylinders and caliper pistons when the same amount of pedal force is applied.

Now it's been a while since I did any hydraulic calculations so if anyone wanna confirm that the formula is correct?
The formula is correct. However it doesn't appply to lines. Just the M/C bore to caliper/wheel cylinder bore.

Line diameter doesn't affect the pressure out versus the pressure in, of the line, end to end.

What it does affect is frictional losses and volume displacement.

99% of our 3rd gens have rear drum brakes. They require more fluid to operate, hence the larger diameter lines. Which ties into the frictional losses to operate the rear brakes. Have to move more fluid to operate them.

The down side of larger diameter lines is expansion. With pressure the expansion of the line creates the need for more fluid. A larger diameter line requires more fluid, which makes the brake pedal travel greater.

When using 4-wheel disc brakes with modern calipers, a 3/16" line to the rear is better then a 1/4" line.

RBob.
__________________

www.DynamicEFI.com

'92 Camaro in Dark Green Gray Metallic
RBob is offline vBGarage Page   Reply With Quote
Old 05-06-2011, 07:14 AM   #11
Supreme Member
 
dennisbernal91z's Avatar
 
Join Date: Feb 2005
Location: Milford, postal code: 01757
Posts: 3,674
Car: F1, 390 powered Camaro Z28,building
Engine: 385, All forged, Trickflow Al heads
Transmission: T-56, SPEC STAGE 3, hurst shifter.
Axle/Gears: Moser/ 4.11

Classifieds Rating: (2)
Send a message via AIM to dennisbernal91z
Re: Brake line size, why does GM use the 1/4" to the rear?

RBob: I couldn't have said it any better myself. This is why I asked the question in the first place.

You opened my eyes to the rear drum brake point. Thank you.

I feel much better running my lines the way I wanted to now.

New CPP master, Bindo line lock, C5 ZO6 fronts and stock disk rears, all plumbed with 3/16" double flare line.
dennisbernal91z is offline vBGarage Page   Reply With Quote
Old 05-06-2011, 07:14 AM
ThirdGen
1992 Camaro




Paid Advertisement


Reply

Go Back   Third Generation F-Body Message Boards > Tech Boards > Brakes

Tags
14, 18, 89, 91, 916, brake, brakes, camaro, disc, gen, line, lines, rear, size, stock, z28
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 


1982 Camaro '82 || 1983 Camaro '83 || 1984 Camaro '84 || 1985 Camaro '85 || 1986 Camaro '86 || 1987 Camaro '87 || 1988 Camaro '88 || 1989 Camaro '89 || 1990 Camaro '90 || 1991 Camaro '91 || 1992 Camaro '92


All times are GMT -5. The time now is 08:40 PM.


Powered by vBulletin® Version 3.7.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.5.2
All content copyright 1997 - 2014 ThirdGen.org. All rights reserved. No part of this website may be reproduced without the expressed, documented, and written consent of ThirdGen.org's Administrators.

Emails & Contact Details