Rear Brake Line Size

[dudeiwin86]

Sorry for the newbish question, but i did search, and all of the results i found were for a 14-bolt and im not sure if its the same as my 10-bolt.

i have steel hardlines from the distribution block (sitting ontop the diff) going to each brake drum in the rear.

the way they were routed (by the previous owner?) caused them to rub and i actually wore a HOLE into one of the rear steel brake lines (yes. a hole in a hard line... )

what is the thread size on the distribution block and brake drums?
does the steel line size really matter?
O'Reilys is showing 3/16" O.D. lines, 1/4" OD lines, and all sort of options for threading.

i dont know what to make of it and i was trying to avoid tearing it down until i had parts in hand to replace.

thank you!

 

[diesel4me]

On my '82 K2500,I just replaced all the hard lines,the one going from the combination valve on the front crossmember back to the rear end is a 1/4" line,I used 3 60" peices with unions to replace it,that is the perfect length (for a long bed truck!)..the only other 1/4" line is one of the master cylinder to combination valve lines,all the others are 3/16" lines...be aware you must re-use some of the original fittings,as GM decided to put "mongrel" fittings on some ends of the lines that dont have the standard sized thread the "ready made" lines come with--you'll need to save them for re-use by cutting the line close to the fittings and use a 6 pt. socket to remove them without boogering up the hex..or buy brass brake line adapters ($$$$ and somewhat hard to get) to put the new hard lines on,at the master cylinder & combination valve..

 

[496truck]

Typically they used standard thread on their flare fittings. IIRC it's a 45* double flare 3/16ths line.

 

[dudeiwin86]

thanks for the input!

im just replacing the lines from the rear distribution block to the drums.

so... 3/16 steel lines.... and flare them myself and re-use the fittings on the end?
(oreilys shows options of 3/8"-24 threading or 7/16"-24.... its neither of those?)
was hoping for something a quick(er) with pre-made fittings, but thats no big deal.

thanks again for the quick help, trying to get my daily back on the road safe. only front brakes is a little wild

 

[496truck]

My guess would be 7/16, but just a guess, could just be thinking of the wrench size. You can buy lines in lengths that will be close enough to what you need with the proper ends on them and preflared. Not sure what size flare nut?.. bring an old one with you. Or, check to see if they have a rear brake hose in stock (the hose is what has the dist block on it) and match it up using that. Then hand them back the hose and just buy the lines.

The mongrel fittings mentioned before are mainly used up front at the m/c and prop valve.

 

[dudeiwin86]

10/4.
was gonna try to get em on my way home, but its no sweat.
ill just tear em out when i get home then take the OL's car up to the parts store and match.

very much appreciate the help guys

 

[4X4HIGH]

Most lines are 3/16" diameter and a 3/16" line uses 3/8"-24 threaded fittings. A 1/4" line uses 7/16"-24 threaded fittings.

 

[dudeiwin86]

Most lines are 3/16" diameter and a 3/16" line uses 3/8"-24 threaded fittings. A 1/4" line uses 7/16"-24 threaded fittings.

that makes sense,
i just went and measured... mine are 3/16" with 3/8" fittings.

do they have to be equal distance on each line?
the ones on there now appear to be ~40" driver side and ~30" on passenger.

got me wondering if that's the culprit for the tug to one side on heavy braking.

 

[diesel4me]

I used a 30" 3/16" line with 3/8 x 24 threads on the passenger side rear,and a 51" on the drivers side--that one needed to be looped,as it was a bit too long,but the next size down,a 40",was too short..the ready made 3/16" lines & fittings will screw right in place of the originals..the "weird" fittings are on the master cyl and combination valve ,that you must re-use,but the ones going to the wheels and rear brake hose are "standard" sized fittings ..

 

[496truck]

got me wondering if that's the culprit for the tug to one side on heavy braking.

negative ghostrider. that's normal K5 operation.

there's another thread on that subject here somewhere.

 

[dudeiwin86]

doesnt bother me really.
my frames cracked at the steering box and im sure that doesnt help with the tugging either.

this toys a project, but its gonna be another fun one to build up. just gotta get my first one out of the garage before i can get to work on this one.