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Author Topic: Brake Line Size  (Read 4049 times)

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Offline fabr

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Brake Line Size
« on: July 14, 2014, 06:23:39 PM »
What size lines are you guys running for hard lines from master cylinder/s to calipers? Reason I ask is because on this buggy with 4 piston calipers front and rear using separate m/c's for front and rear and 1/8 inch lines the brakes have always felt"sluggish" both on apply and release. I can't describe it any better than that. I'm thinking the 1/8" lines between the m/c and the T to each caliper are the issue. Any opinions?
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Offline fastcorvairs

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Re: Brake Line Size
« Reply #1 on: July 14, 2014, 06:47:47 PM »
Quote from: fabr on July 14, 2014, 06:23:39 PM
What size lines are you guys running for hard lines from master cylinder/s to calipers? Reason I ask is because on this buggy with 4 piston calipers front and rear using separate m/c's for front and rear and 1/8 inch lines the brakes have always felt"sluggish" both on apply and release. I can't describe it any better than that. I'm thinking the 1/8" lines between the m/c and the T to each caliper are the issue. Any opinions?

I'v never got a firm turn brake handle using -3 braided line.  I get a good firm foot brake but never the turn brakes.  I power bled vacuum bled and foot pumped and still can't get a firm turn brake.  No air in lines.  Even put die in it one time to be sure there was no air.   
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Offline BDKW1

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Re: Brake Line Size
« Reply #2 on: July 15, 2014, 12:14:17 PM »
1/8" hard line and -3 braided line on everything including 6 piston CNC calipers. Have someone step on the brakes and watch the calipers for movement. Not having them perfectly lined up with the rotor is the #1 cause of crappy brake feel.
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Offline fabr

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Re: Brake Line Size
« Reply #3 on: July 15, 2014, 07:05:14 PM »
Yep,checked that a long time ago.  1/8" lines and -3 braided just as you.   Wilwood cylinders with balance bar.   It's not crappy pedal. It's a sluggish response I feel. Like a time delay of application.    Never had this on anything before.
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Offline fabr

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Re: Brake Line Size
« Reply #4 on: July 15, 2014, 07:31:07 PM »
Gear One brakes.
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Offline BDKW1

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Re: Brake Line Size
« Reply #5 on: July 15, 2014, 09:09:59 PM »
I would not run Gear Ones if they were paying Me. Wiwood or Brakeman. Or Brembo if you have the money.
 
Also, Tilton MC's work by far the best of any I have used. Wilwoods are second and CNC's are garbage.
 
 
What pads are you running?
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Offline fabr

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Re: Brake Line Size
« Reply #6 on: July 15, 2014, 09:41:55 PM »
I agree. No more G1 ever again.  I think they were the green pads.
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Offline Dunebound69

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Re: Brake Line Size
« Reply #7 on: July 17, 2014, 06:53:33 AM »
Try a larger master cylinder.  Do you have a residual pressure valve in the system?
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Offline Carlriddle

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Re: Brake Line Size
« Reply #8 on: July 17, 2014, 08:22:20 AM »
I'm running 3/4" mc(i think bought from DS) and 1/8" hard line all way to single 4 piston wildwood caliper.   I had less than 1" pedal movement before lockup, so I put air into line so I had a little more pedal play.  Crazy but work well.  Got an eye on a steal on front brake setup for car then mc will be sized proper, I hope. 

But brakes may have to wait as I've made offer on new love pad for mistress.  Then all my girls will be back under one roof?   rofl rofl
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Offline fabr

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Re: Brake Line Size
« Reply #9 on: July 17, 2014, 11:43:41 AM »
Quote from: Carlriddle on July 17, 2014, 08:22:20 AM
I'm running 3/4" mc(i think bought from DS) and 1/8" hard line all way to single 4 piston wildwood caliper.   I had less than 1" pedal movement before lockup, so I put air into line so I had a little more pedal play. Crazy but work well.  Got an eye on a steal on front brake setup for car then mc will be sized proper, I hope. 

But brakes may have to wait as I've made offer on new love pad for mistress.  Then all my girls will be back under one roof?   rofl rofl
WHAT??????????????????????? ??? ??? ??? ???
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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Offline Carlriddle

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Re: Brake Line Size
« Reply #10 on: July 17, 2014, 12:21:24 PM »
Brake pedal moved maybe 1" before lockup.  So I cracked the bleeder and now its perfect.  Mc was too big for single caliper system.

This is no way correct I guess.   nono
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Offline dsrace

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Re: Brake Line Size
« Reply #11 on: July 17, 2014, 01:47:06 PM »
if you only had to throw the pedal 1" and it would lock up the rear while moving with little effort in the 1" then you had it pretty much right on, if you felt that was too touchy then you actually need the next largest bore master cyl. if the pedal goes rock hard in 1" but doesn't lock up or apply the brakes solid then you have 1 bore size master cyl to large. this is the way i have always judged it, all of course if your close to begin with.
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Offline fabr

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Re: Brake Line Size
« Reply #12 on: July 17, 2014, 08:03:13 PM »
Quote from: Carlriddle on July 17, 2014, 12:21:24 PM
Brake pedal moved maybe 1" before lockup.  So I cracked the bleeder and now its perfect.  Mc was too big for single caliper system.

This is no way correct I guess.   nono
I guess I'm missing something. Cracking the bleeder would do nothing for pedal travel.  ??? ??? ???
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

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Offline Carlriddle

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Re: Brake Line Size
« Reply #13 on: July 18, 2014, 05:47:59 AM »
Quote from: fabr on July 17, 2014, 08:03:13 PM
I guess I'm missing something. Cracking the bleeder would do nothing for pedal travel.  ??? ??? ???

Its the opposite reason most bleed brakes I'd guess?  I also wrapped brake line where it passes exhaust.  Heat worked like parking brake Enemy is looking to use.  That seemed to help a lot too.  Whatever I did fixed the issue in my eye.
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Offline fabr

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Re: Brake Line Size
« Reply #14 on: July 18, 2014, 06:05:54 AM »
You should not have but 2 PSI residual pressure in the brake line with disc brakes. Not enough to apply brakes or even move the caliper pistons but enough to keep air out of system. If you were holding enough pressure to have exhaust heat expand the brake fluid and cause issues,your MC was not traveling to fully retracted position between brake applications or you have a MC for drum brakes that hold 10-20 psi line pressure. Fully retracted pressure in the MC is zero for either disc or drums. The residual valve is holding line pressure at approx 2 psi but the MC itself will have zero pressure till reapplication of brakes. 
« Last Edit: July 18, 2014, 06:13:04 AM by fabr »
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"There can be no divided allegiance here.  Any man who says he is an American,
but something else also, isn't an American at all.  We have room for but one
flag, the American flag... We have room for but one language here, and that is
the English language... and we have room for but one sole loyalty and that is a
loyalty to the American people."
Theodore Roosevelt 1907

-----------------------------------------------------------
 " You have all the right in the world to believe any damn thing you'd like, but you don't have the right to demand that I agree with your fantasy"
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