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73-87 Chevy _ GMC Trucks => Brakes, Frame, Steering & Suspension => Brakes and Braking Systems => Topic started by: 1967KaiserM715 on November 24, 2015, 05:12:44 pm

Title: Brake tube size
Post by: 1967KaiserM715 on November 24, 2015, 05:12:44 pm
Working on my 1985 GMC longbed. I ordered up a 25' roll of each 1/4 and 3/16 tube, Cunifer/copper-nickel. I stupidly apparently threw out the lines from the master to the prop. and I think both front lines. but anyways, can someone confirm that 1/4" and 3/16" is all I need for the brake lines. I will be getting 3/8" and 5/16" later for fuel lines. So if needed to be factory correct I will get more of the right size,

I believe it is 3/16 MC to PV for front brakes, 1/4 MC to PV for rear, 1/4 for the main rear line, and 3/16 for all four corners, can a couple people confirm this?

Oh I will be converting to Hydro-boost(diesel) from original Vacuum booster if that ends up playing a part in line size

Thanks all
Title: Re: Brake tube size
Post by: enaberif on November 24, 2015, 05:58:45 pm
1/4 from master to prop
3/16 for everything else
Title: Re: Brake tube size
Post by: 1967KaiserM715 on November 25, 2015, 04:28:56 pm
I'll have to check tomorrow, But I am sure the main line to the rear was 1/4"
Title: Re: Brake tube size
Post by: enaberif on November 25, 2015, 05:50:39 pm
Oh yes you are right! I forgot about that one.

1/4" with 9/16" and 1/2" fittings at the master cylinder and prop
3/16 from prop to front brakes
1/4" from prop to rear connector

Soft brake line from 1/4 line to axle then 3/16 from there to wheel cylinders.

Just did this myself.
Title: Re: Brake tube size
Post by: 1967KaiserM715 on November 25, 2015, 06:11:34 pm
Cool, thanks.

did you have to get a new prop/combo valve? I think I do, and need the right part number, I found a couple different numbers, but don't know?

1/2 ton, will be getting a 1-ton master and hydro-boost-although I may need a new master too-depends on how it looks when I pull it, so I assume the 1/2 ton hydro master will mount up fine to the 1 ton hydro-booster

I believe 11-15/32 brakes as well, need to double check
Title: Re: Brake tube size
Post by: enaberif on November 25, 2015, 07:34:53 pm
Yeah I needed a new combo unit. Got a CPP unit.