Brake line size?

Fiolosm · November 6, 2013

I hope this isn't a stupid question but I have tried the search box for this but couldn't find an answer. So any help would be great. I have a 2002 1500 sierra, 4x4, 5.3, SLE. It came from up north so the brake lines are in need of replacement. The lines going to the rear wheels after they split are 3/16 tubing, but the lines that run to and from the ABS I think are 1/4. But I'm not sure cause while I've been looking for the line I also found some 5/16 line that according to the websites (Autozone, Napa, etc..) fit this truck also. I'm tring to get everything together because I really need to do this job this weekend. Thanks in advance.. I'm give'n myself about three days to tackle this, I've never done it but I believe I can.

Edited November 6, 2013 by Fiolosm

59ih340 · November 6, 2013

The lines are 1/4" I think (been a while since I've done one) but the fittings are a different size. You have a couple of options. They sell at NAPA and such an adapter with the right size fitting on a 6" line with a standard size fitting on the other end. Then you can use a regular union and attach it to a regular length of tubing. or due it the way I do buy a bunch of line (however many feet to go where it needs to). Snip off each line at the ABS module. use a 14mm 6pt. deep socket and remove the fitting. clean up any rough edges on the line and drive it out using a punch, check the fitting for cracks and reuse it if it's good. Then work back from the abs module to your termination points (calipers,master cylinder etc.). I recommend the second way for several reasons. The main one is the abs module is aluminum and the fittings are steel. If you try to use a regular wrench or line wrench you will probably strip the fittings. waste a ton of time and not get the fittings out. This will ruin your day and probably several more.If you cut the lines short at the abs,use a 6 point deep socket and ratchet you can get right in there with enough leverage and they will break free (fairly easy).The fittings can sometimes be VERY hard to break loose. Just so you know. don't be discouraged but you may need to use substantial elbow grease to get the lines to break free.Just take your time and plan each line from the abs to the caliper. Get a double flare tool for doing brake lines,a cheap tubing cutter and have it. bleed everything and check for leaks. also get yourself a gallon of brake fluid it's cheaper and you'll need at least 2 qts. try to do as long of runs as you can. less joints = less chances for leaks. I've done all the lines in trucks in under 3 hours. don't expect that your first time out. But allowing 3 days is more than enough time to do a nice job a account for any setbacks. Good Luck!

brucelimerick · November 6, 2013

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

brucelimerick · November 6, 2013

After reading the post by 59ih430, I remember the reason I used the brass adapters, the factory aluminum to steel connection is a corrosion nightmare. My steel fittings were toast and there was pitting on the threads of the ABS. I used 6 pt brake fitting wrenches to get them off, a conventional wrench would for sure have rounded them. The pressure I used was scary on a couple of them. I was a little worried as I knew what the ABS was worth if I screwed it up.

Bruce

Gone Again · November 6, 2013

This is a recent release from AC Delco that some might be interested in. This complete pre-made brake line kit could make this nasty job a lot easier.

http://www.shopownermag.com/Item/116710/acdelco_introduces_brake_pipe_kits_for_gm_trucks_suvs.aspx

Fiolosm · November 7, 2013

Thank You all for the great information. I am going to start on it Friday, and I will post how it went good or bad. Thanks again.

Fiolosm · November 14, 2013

Well I just want to say that every thing went well. I changed all the lines except the two that ran from mc to abs. The reason was mainly not enough time, we had a bonfire saturday so my wife found a bunch of stuff for me to do, but it's all good. I did do a bit of redneck engineering though, I used a garden hose to run my tube to the back on the inside of the frame instead of try'n take the bed off and run it along the old line. I left the tube inside of the garden hose the so it wouldn't rub a hole in the tube on the frame. The trickest part I would have to say was the bends I had to make at the abs, It was real tight and I bent them by hand. I used steel tubing, it was pretty easy to bend. I was able to reuse all but one of the fittings, the one on the back was rusted soild. I had to replace the rubber line that it was attached to. It took me about 13 hours over the span of three days, which was worth it. I got everything to do this for under $150. So Thanks again for the brain pickin's ya'll were alot of help. I hope I can return the favor some time. Peace Out..

brucelimerick · November 15, 2013

You are welcome and I'm glad your job went well. I like the garden hose trick. It does make things easier going in when you have an idea of the potential pitfalls. 13 hours and $150, hard to beat that.

MikeInCtown · November 15, 2013

I have an 04 with 17x,000 miles and you guys are scaring me. I can see needing some new tubing here and there, but the fact that the lines would be so corroded, hard to replace, and hidden through and behind things scares the crap out of me. Looks like I'll need to start accumulating some tools here and there and prepare for the eventuality.

brucelimerick · November 16, 2013

It's not technically difficult. You really just need a flaring tool and a little hand bender. The problem is GM installed all the lines on a bare frame with no thought to future maintenance or corrosion. So to do it in your garage is a pain in the butt, but not hard, just frustrating sometimes. Just remember what GM would charge you to do it and have a beer. You will be able to fill the box to over flowing with the money you will save. I would recommend splurging and using the easy bend lines. They are corrosion proof not corrosion resistant, big difference, you can bend them with your fingers and they are almost kink proof.

woodmanyoel · December 30, 2013

I have a 2001 and just finished replacing all the brake lines...

Bruce

Thanks Bruce - your post helped me out qutie a bit earlier I was also having a hard time figuring out if it was 1/4 or 3/16..

I did this earlier today on my friends lift, I'm not a beginner but I'm not a fast expirenced mechanic either. I was able to do the RF, Both Master Lines - And the line running back to the splitter - it took me nearly 5 hours including a trip to the auto store. I messed a couple things up - and my biggest fudge was definitely on the last two lines of the night Is switched one of the lines going into the ABS module from the bottom to the top (so 5/16th fitting into the 1/4th fittings hole) - I didn't stripped the threads out - but I can't put the 1/4 fitting back in there anymore.. I was flaring the right front line and the rear master line at the same time and got the fittings mixed up - very dissapointed inmyself.

I'm going to go to the store tomorrow and see if I can get another 5/16 fitting and just run that in the front right's spot since I already reamed it out.. hoping it will seal up.. don't want to have to go to the JY and pull an abs module.

Wish me luck.

-J

klmcc67 · November 28, 2014

where do you get the 5/16 fittings i cant find them anywhere, I just go a truck given to me but the left front brake line is missing from the left rubber hose to the abs block. so i do not have old line to go by to find out what size fitting goes in the abs block.

beasticles · September 28, 2015

I know this is an old thread - but it is one worth digging up since it deals with the notorious brake line rust that troubles most GMT-800 body trucks.

About to tackle replacing the hard brake line that runs from the ABS module to the splitter at the rear of the truck feeding the two calipers. I joined this forum just to say thank you, particularly to brucelimerick, for all of the information posted about this job.

Basically, my background story is that I bought a higher mileage (163,XXX) Z71 Suburban (2003) on Craigslist for below market price - the guy was just trying to get out of his loan payment. The body was clean and the interior in decent shape, but it had clearly been neglected. The suspension was original (shocks and everything) from the factory, and the underside has significant surface rust (not frame damage though) as the vehicle started its life in Michigan (I am in Virginia).

I have been working through the vehicle, updating and replacing parts as needed, and it is shaping up to be a pretty decent car. I am still questioning whether or not I would buy another GM vehicle, as I have experienced now two inexcusable design failures - the transfer case pump rub issue (causes pin-sized holes in the t-case), and now the rusted to hell brake lines.

**End rant**

The other weekend I replaced all of my shocks and put new coil springs in the rear of the truck. Of course, after letting the axle droop I now have a brake line leak in the long line running from the ABS module to the rear splitter.

Thanks to this forum I have already purchased EasyBend brake line (copper nickel) and a double flare tool - I plan to cut out the old line at the ABS module and the splitter, but otherwise leave the old line in place and simply bend into place a replacement line which I will secure to the existing line.

I appreciate all of the information here - particularly on the fitting size/line sizes. I also have a Motive Speed Bleeder so hopefully that will help with the process. The only concerns I have about the job are creating my own flares, and tightening the new line to the ABS module where there is hardly any place to fit a wrench. Will post up how it goes for anyone else who might be up for tackling this job. After realizing how expensive it would be to have a shop do this job, I decided to tackle it myself even though I have never replaced a hard brake line before.

GreasyHands · September 29, 2015

Will post up how it goes for anyone else who might be up for tackling this job. After realizing how expensive it would be to have a shop do this job, I decided to tackle it myself even though I have never replaced a hard brake line before.

I for one will be anxious to see how your project goes. I have an 03 with rusted lines that bust and still in the process of gathering info. The truck is several miles from here so I need to take allot of stuff with me for the repair.

Just this am talked to the local GM dealer. He gave some additional info but I have no idea if it applies to your vehicle and I am not sure about mine until I tear into it. He told me NAPA 100X4 and 105X3 are all the fittings I need and they are the part numbers they use....I hope so they are allot cheaper than GM. I did check NAPA on line store, they look ok. He further said all the lines for the ABS, MC, proportioning valve and front brakes are 1/4 and inverted flare. Only 3/16 is across the axle at the rear. We will see. I am taking bubble and inverted flare sets with me and some fittings . After I tear into it if the flare is different off to NAPA for ISO.

I could go on and on about this GM truck. E-Brake bracket rubbing against the wiring harness causing an intermittent fault and parasitic drain, Roof lamps not connected, intermediate steering shaft knocking from day one, calipers and rotors shot.....10 year old truck with 30K miles. On the good side, the engine seems strong and it does have a nice ride.

There is several posts about the brakes and I am not trying to contradict their findings, just sharing what I found so far

Waiting to see your posts

Butch

beasticles · September 29, 2015

I for one will be anxious to see how your project goes. I have an 03 with rusted lines that bust and still in the process of gathering info. The truck is several miles from here so I need to take allot of stuff with me for the repair.

Just this am talked to the local GM dealer. He gave some additional info but I have no idea if it applies to your vehicle and I am not sure about mine until I tear into it. He told me NAPA 100X4 and 105X3 are all the fittings I need and they are the part numbers they use....I hope so they are allot cheaper than GM. I did check NAPA on line store, they look ok. He further said all the lines for the ABS, MC, proportioning valve and front brakes are 1/4 and inverted flare. Only 3/16 is across the axle at the rear. We will see. I am taking bubble and inverted flare sets with me and some fittings . After I tear into it if the flare is different off to NAPA for ISO.

Greasy - brucelimerick's longer post above is immensely helpful as he was kind enough to actually list out the sizes of each line along with the size of the fitting at each end:

"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."

Since I only plan to replace my ABS to rear-splitter line (which runs the length of the top of the driver's side frame rail), I went with 1/4" Easybend line from Amazon: https://www.amazon.com/gp/product/B0027ABNUC/ref=oh_aui_detailpage_o01_s01?ie=UTF8&psc=1

And plan to purchase a 1/4" x 1/4" fitting for the splitter end, and a 1/4" x 5/16" fitting for the end that ties into the ABS. I also purchased this https://www.amazon.com/gp/product/B007C6JZ6A/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1 flexing and ratcheting flare end wrench to hopefully help with the awkward angle of the fitting at the ABS pump (the one going to the rear splitter is the top right corner fitting). I will be making my own double flares on the Easybend line, and bending it into place by hand.

The only thing that is unusual is that some of the fittings are 5/16" with a 1/4" bore, but if you Google you'll find many parts stores carry such a fitting.

Will post up how things go.

Edited September 29, 2015 by beasticles