Brake line size?

GreasyHands · September 30, 2015

beasticles

Yes, brucelimerick post is a good source, no doubt. I am just a little cautious until I see what GM actually did under the truck. Right now it is a rusty mess, and it has been undercoated three times. My mother is a retired GM employee who worked with harnesses and she was not surprised when I told her about the parasitic drain with the e-brake bracket. She had the same issue when she had the truck but evidently the more miles I put on it the worse the issue became.

What really bothers me is GM will not step to the table. I do not believe there is little doubt inferior metal is the bulk of these issues. I have been a small block chevy and GM fan for many long years, but lately have drifted some. Dunno what to say, enough venting.

anyway waiting to hear how you do and wishing you well and safety. I wont be on mine for a few more weeks. Oh, I have a craftsman line set, but am purchasing another set similar to yours.

waiting to hear an update

Greasy

beasticles · October 5, 2015

beasticles

anyway waiting to hear how you do and wishing you well and safety. I wont be on mine for a few more weeks. Oh, I have a craftsman line set, but am purchasing another set similar to yours.

waiting to hear an update

Greasy

Greasy - quick update for you -

I installed the new rear brake line (that runs from the top right port on the ABS to the splitter above the rear diff in the back). Another forum member posted in this thread: http://www.gm-trucks.com/forums/topic/177718-best-way-to-remove-rear-brake-line-from-abs/page-2#entry1691258 thatthese AGS tube nuts are a perfect replacement for the ABS fittings - and he was correct: http://shop.advanceautoparts.com/p/american-grease-stick-co.-steel-tube-nut-5-per-card-1-4-in.-1-2-20-inverted-blf-44c-5/22190121-P . I actually could have salvaged my old fitting, but the new ones were a perfect fit (and at $2.50 for six nuts - why not!). I used a standard 1/4" tube and nut for the rear splitter - which I was able to source from Advance Auto as well.

As I mentioned in my prior post - I used EasyBend brake line from Amazon.com https://www.amazon.com/gp/product/B0027ABNUC/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1which worked great for my application - no issues with simply bending by hand. Having never flared brake line before - I practiced on short pieces of line Saturday night before tackling the job Sunday. I was able to get decent double flares on both ends of the line (obviously don't forget to have your tube nuts already on the line and facing the correct direction before flaring).

I had multiple flare nut wrench sets on hand - but in the end - due to the cramped space, I ended up using a small Craftsman 9/16" open-ended wrench to crack the ABS nut loose and remove (it was slow going as I had to turn it little by little due to the lack of clearance - damn you GM), and for the rear splitter I used a pipe cutter to snip the old line and was able to get a 1/2" (?) socket over the fitting to remove. The ABS fitting was on very tight as others have mentioned - and due to the lack of clearance I really had a heck of a time getting it to crack loose. It took all my strength with the small open-ended wrench to crack it loose - but once it is cracked - it will come off relatively easily.

I left the old line in place (it was rusted to hell and I didn't want to deal with removing it), and simply threaded the new EasyBend line along the top of the frame rail. I connected the line to the rear splitter first - then slowly threaded the line all the way up to where the ABS unit is. It's a little trick to get the tube nuts initially threaded into the ABS and the splitter, because the brake line is fighting you from "squaring" it up, but once you have the first thread in it snugs right up.

I still need to bleed my brakes tonight (was ready to retire for the night after getting the new line in) and check for leaks, but the hard part is now done! Timing wise I started around 5pm and finished around 7:30pm - just for removing the old line and getting the new line installed. Let me know if you have any questions. When my rear brake line started to weep I was doubting my ability to tackle this job, but it is certainly doable for the average shade tree.

Another tip - removing my spare tire made it much easier to move around the rear, deal with the rear splitter fitting, and feed the line up the frame rail from the back. It's not necessary but gives you a bit more space.

Jonathan Kirkpatrick · September 4, 2018

Gonna revive this thread once again since I just tackled this project this past weekend on my 2003 Suburban 1500. I bought a pre-bent and flared kit of SS lines. I was able to fish the rear line through the rear driver side wheel well.. it was actually not the hardest line to run. I found a youtube video of a guy who showed how its done:

https://www.youtube.com/watch?v=KHwIEwTZjnI&t=8s

I had several slow leaks at the flares when I was done, which I was able to remedy with copper flare gaskets.

Hope this helps.

Darcy Rivers · September 27, 2020

On 11/5/2013 at 9:38 PM, brucelimerick said:

I have a 2001 and just finished replacing all the brake lines. I think they are the same, sure sounds like it. According to my thinking GM really did a poor job of engineering this whole mess. I am a little jaded as I have been dealing with the rear discs since the truck hit 21,000 miles. Rears eat pads, passenger side has to have new pads every 6 months. Pads and rotors once a year. Dealer suggested I shouldn't drive it on gravel roads, lol. A Gucci city boy truck? Stupid designers as far as I'm concerned. The only other complaint I have is no locking rear differential. Should be standard, this truck gets stuck in a flat parking lot in the snow.

Anyway I digress. The rear lines are conventional 3/16" after the splitter on the rear axle. The line running to the splitter is 1/4" line and a 1/4" fitting going into the splitter. Where this line goes into the ABS it is a 5/16" fitting taking a 1/4" line. The 2 lines coming from the master cylinder to the abs are 1/4" line with 5/16" fittings drilled out for 1/4" line. The 2 lines to the front cylinders are 1/4 " line with 1/4" fittings at the calipers and 5/16" fittings with 1/4" line at the ABS. You can't buy these lines. All the mechanics I talked to after making the assumption that the 1/4" line would have 1/4" fittings could buy the 5/16" fitting with the 1/4" bore and they made their own lines. I ended up getting 1/4" to 5/16" adapters for the connections to the ABS and ran 1/4" lines. The adapters are a problem, they have to have the small end on the 5/16" side. The big ended ones can be used on the master cylinder. The 5 on the ABS required me to phone and visit every automotive part store in 200 miles. Special orders resulted in the large wrench ends. You just can't fit 5 of them on the ABS and get your wrench on them to tighten them. I have the part number in my truck of the company that still makes the small ones. If you need it let me know. To replace the main line from the ABS to the rear splitter will require you to either drop the gas tank or remove the box. GM hides this line between the gas tank and the top of the frame rail. To remove the gas tank it is also recommended you remove the box first as well. Only 8 bolts and 2 torx screws holding the filler hose to the box. Basically it was a horror show. If your engine light is on it is also the time to replace the solenoid valve vent for the charcoal canister and the ring which holds your fuel pump in the tank should also be replaced.

In hindsight I would buy the 1/4 x 5/16 fittings and buy 1/4" Easybend line and make my own flares. The steel lines are junk, even with the "corrosion" coating on them. By the time you get finished bending and routing it there are scratches all over it. The lines at the ABS are a mess. It is jammed between the charcoal filter and the fuel filter. 5 lines have that have 4 to 5 bends in 6" and fit into a 1/2" by 4" space going over the frame and then come together to run up the outside of the frame. You can buy a pre-bent set of lines for about $280 but after doing the job I would think you would have to remove the box, cab and most of the front end to get them in.

The Easybend is real cool line. Copper nickel, truely corrosion resistant and bendable by hand. You can almost knot it and not kink it. Unfortunately I found out about it about half way through my job and it was too late to switch. You could run 3/16" steel line from the rear splitter to the rear calipers, plain Jane runs which can be redone easily to have to avoid buying a 25' coil of the easybend. The Easybend seemed to be about $50 for 25'. Cheap believe me. I have abs of steel crawling out from under my truck about 500 times fine tuning the bends on the steel lines. I ended up buying straight steel line with the fittings on them. You pretty much need fittings and joints on the steel lines. Pretty much impossible to run a full line the way GM routes them. And every joint is a potential leak point. The easybend will allow you to run the lines with no joints and just bend as you go by hand. I will NEVER run another steel line, ever!

If you want to really know if I'm bullshiting just crawl under the drivers door and have a look at the mess around the ABS on the inside of the frame. Also look at the line that heads to the rear, you can see about 18" and it is gone. The lines are run in the factory with the frame fully exposed and no body parts on. Every mechanic I talked to cursed this truck and most would want $1,000+ to do the job. I expect with a dealer you would be well on your way to $2k. Our dealer shop rate up here in Canada is $115/hr. The only one who was reasonable was the one who showed me the Easybend, he was still $75/hr but had the secret. Too bad I didn't visit him earlier. It would have saved me a week of cursing. I have pics start to finish if you need them. My brakes are great, well as great as GM made them, they have always required more effort than any other vehicle I ever owned.

Bruce

Tks Bruce, great info very detailed! I recently replaced some of my lines going to the front end as well and it was quite a chore, I hadn’t done it before but I’m a quick learner. I did gave to use the coated steel lines and bend as I go to make the routing with only one joint where it turns down to connect to the wheel caliper. Luckily for me, the connections at the ABS valve broke free pretty easily, I had to cut/re-flare line and reuse the 5/16 fittings tho as new ones were not available.
Found some leaks, at first was very concerned but some of the joints just needed more tightening luckily. It can become quite challenging especially around the ABS valve where space is very limited. On completion, I bled the system and got the brakes working decently however, my Brake System Needs Servicing light won’t go away. Is it just a computer reset issue or what? Would appreciate any feedback on this. Tks.

Dillon St · January 24, 2021

On 11/5/2013 at 8:38 PM, brucelimerick said:

Where this line goes into the ABS it is a 5/16" fitting taking a 1/4" line. The 2 lines coming from the master cylinder to the abs are 1/4" line with 5/16" fittings drilled out for 1/4" line.

Thank you for the information. Do you know what the thread pitch size is?