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View Full Version : Brake Line Lengths - Balance b/w Left/Right



MWood
03-20-2012, 08:45 AM
Hey everyone,
I am part of an FSAE team in which most, if not all, of our members are new to this competition, with the exception of our team leader. Part of my senior design project is developing the braking system for the car. I have a pretty simply question that I was not able to find an answer to in researching on my own.

In running the brake lines, we plan to use soft lines from MC to a spot on the inside of the frame, run hard lines to the rear and then split to the left and right calipers, soft lines to the calipers.
Question: Is it important to have the lengths of the soft lines going to each caliper equal after the split? At first, our thinking was that under pressure it should not matter, but we do not want to make rookie mistakes and not have the car able to brake in a straight line. Any advice is much appreciated.

MWood
03-20-2012, 08:45 AM
Hey everyone,
I am part of an FSAE team in which most, if not all, of our members are new to this competition, with the exception of our team leader. Part of my senior design project is developing the braking system for the car. I have a pretty simply question that I was not able to find an answer to in researching on my own.

In running the brake lines, we plan to use soft lines from MC to a spot on the inside of the frame, run hard lines to the rear and then split to the left and right calipers, soft lines to the calipers.
Question: Is it important to have the lengths of the soft lines going to each caliper equal after the split? At first, our thinking was that under pressure it should not matter, but we do not want to make rookie mistakes and not have the car able to brake in a straight line. Any advice is much appreciated.

Kealan O Carroll
03-20-2012, 08:58 AM
Think of pressure drop difference with a difference in the pipe lengths http://fsae.com/groupee_common/emoticons/icon_wink.gif

Rex Chan
03-20-2012, 10:34 AM
I don't think there should be much/any flow in your brake lines. Thus, the lines act as a pressure vessel, with all the fluid under the same pressure. As long as your front calipers are on the same circuit (and all other parts/setup being the same), it won't matter. That being said, we (Melbourne) do get slight/moderate pulls to one side sometimes, due mainly to poor bleeding on one side.

Drew Price
03-20-2012, 12:19 PM
As long as you're using quality racing flex brake lines, and lines that are not way too small inner diameter it shouldn't matter.

Jon Burford
03-20-2012, 01:36 PM
Imperfections with bleeding the system will cause you many more problems than with the line lengths.
Don't worry too much! Just get them bled right!

Adambomb
03-20-2012, 04:13 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jon Burford:
Imperfections with bleeding the system will cause you many more problems than with the line lengths.
Don't worry too much! Just get them bled right! </div></BLOCKQUOTE>

+1, I've seen more problems with bleeding in FSAE than anything else with regards to braking. The fundamental problem is that FSAE students often aren't nearly as good of mechanics as they would like to believe. http://fsae.com/groupee_common/emoticons/icon_wink.gif I've seen some horrendous bleeding practices. I've seen cars where the team drove them for two years with brakes that weren't properly bled, and they just lived with the brakes pulling. Got a competent mechanic on it and in about 10 minutes they had a car that finally braked the way it should (albeit nearly two years after it competed...).

Jon Burford
03-20-2012, 05:44 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Adambomb:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Jon Burford:
Imperfections with bleeding the system will cause you many more problems than with the line lengths.
Don't worry too much! Just get them bled right! </div></BLOCKQUOTE>

+1, I've seen more problems with bleeding in FSAE than anything else with regards to braking. The fundamental problem is that FSAE students often aren't nearly as good of mechanics as they would like to believe. http://fsae.com/groupee_common/emoticons/icon_wink.gif I've seen some horrendous bleeding practices. I've seen cars where the team drove them for two years with brakes that weren't properly bled, and they just lived with the brakes pulling. Got a competent mechanic on it and in about 10 minutes they had a car that finally braked the way it should (albeit nearly two years after it competed...). </div></BLOCKQUOTE>



Thanks for that,
It is true, obviously make sure that you avoid kinks etc with your solid lines and make sure you have assembled your flex correctly if you are using "build yourself" lines.

K

Crispy
03-20-2012, 08:24 PM
Doesn't have much to do with length, but you might check out Hardlines vs Flexlines. (http://fsae.com/eve/forums/a/tpc/f/125607348/m/83320919841?) if you haven't already.