splicing a brake line.....

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Hi forum members,My welding rig is an old German military army fire truck.  It is a 1969 Mercedes Unimog model TLF-8.  I converted it into a work truck about 14 years and have been using it every since  with only minor issues like clutch, brakes, etc.  I go out with it about two times a week.  It is equipped with an air booster for stopping power.  This was an optional device as these trucks do not normally have one installed.  This particular model did.  It stops Ok without the booster but I prefer to use it given the weight I carry on it.Anyway, the booster finally failed and took out my brakes altogether as the brake fluid goes through the booster even if I use it or not.  I can turn on the on-board air compressor and that feeds the booster.  For the past year I have not used it as it has started to make my brakes stick and not release so I put it on my things to do list and worked with it like that until now.Yesterday I pulled the booster out of the truck and planned on installing a by-pass brake line so that my braking system can work again.   I already ordered the parts needed from one of the Unimog dealers that provides service and parts for these trucks.I found that the two brake fittings that feed and exit the booster were frozen so tight that it took repeated torch and penetrating fluid cycles to break them free.  One came loose fine the other broke loose but did not free itself from the brake line which twisted from the torque and had to be cut loose so I could drop the booster from the truck.My question: Can I safely braze a piece of brake line to the one I cut so I can continue with the repair?  I have been brazing from my early days of welding and have repaired maybe several hundred cast iron and steel parts both large and small and have a lot of faith in the strength of the repairs using this process.  I already have a sleeve for the splice from a piece of 3/16" brake line which fits snugly over the 6mm brake line of my truck.  I have made many such splices over the years but not on a braking system.I would like some other opinions if you don't mind.  Is there a better material to choose other than the brass brazing rod?  I have seen fittings in the past especially on older foreign cars that have what appears to be silver soldered brake fittings.  Is silver solder a better solution?Attached is a mockup of the proposed type of splice.  Part of the reason for the splicing approach is because the working area is very tight and I don't think I could get a flaring tool up in there to make a flare and join it with fittings.  Also I am worried that I may create a nightmare trying to remove the entire length of brake line so I could replace it new line as the working area again is small and the fittings will be frozen solid as the first set were.Any thoughts would be greatly appreciated.Last edited by therrera; 08-21-2014 at 12:20 PM.Reason: to correct an error
Reply:You should be able to get straight metric brake line with fittings and bend new ones.  Any welding or heat can cause possible issues with contamination/particles in the system.GlenMiller Dynasty 200DX - Millermatic 350P - Hypertherm Powermax 45Want to sell!! - Hobart Handler 150
Reply:I'd be surprised if a brazed brake line would pass inspection. I haven't watched all this guys video but he starts off with the right connector. These guys should have most of what you need.---Meltedmetal http://www.cunifer.com/Last edited by Meltedmetal; 08-21-2014 at 12:34 PM.
Reply:Napa auto parts will have everything you need including the flare tool if you wanted to keep part of the existing line. Or you could go all out and order lines from goodridge normally between $50-100 bucks a pop.Napa will also make any kind of hydraulic line if you bring them the pieces as a measurement.Real welders know how to penetrate!(Equipment)Whatever can be used to beat my opponent into submission!
Reply:Splicing brake lines is ILLEAGAL!!!If you were to crash and there was a investigation/ inspection of the vehicle and they find that kiss your azz goodbye.Your Insurance company will be of NO Help to you....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:I wouldn't splice it. Now that that's out of the way. . We need pictures of the mog Airco Ac/Dc 300 HeliwelderMillerMatic 200 (stolen)Miller Maxstar 150STLMiller AEAD200LE (welding and generating power) Hobart MIG
Reply:Originally Posted by Dantheharleyman99Napa auto parts will have everything you need including the flare tool if you wanted to keep part of the existing line. Or you could go all out and order lines from goodridge normally between $50-100 bucks a pop.Napa will also make any kind of hydraulic line if you bring them the pieces as a measurement.
Reply:Hi all,Okay,  got the drift.  I will try and flare the line in place and add a piece to give me the total length needed to hook up my booster once its repaired.  For now I wont worry about connecting it back as I will need to drive it without the booster for now.  I will just cut my by-pass long enough to connect to where I cut it.  As long as I have the room, the splice should go OK.  If not, I will have to take the line out and believe me I am NOT looking forward to it!!!!Thanks,TonyPS: attached are shots of my rig for the curious.
Reply:That thing is pretty sweet! That would come in useful down here in the swamp!Real welders know how to penetrate!(Equipment)Whatever can be used to beat my opponent into submission!
Reply:On my 1996 GMC truck the line running along the frame has two unions in it, so that is how GM does it, these are brass ones.Just like what "meltedmetal" posted on that video
Reply:Originally Posted by GlenCYou should be able to get straight metric brake line with fittings and bend new ones.  Any welding or heat can cause possible issues with contamination/particles in the system.
Reply:Where do you get parts for that beast / I know case tractors was the US supplier for years  and supplied them to the Army in the 80"s  gxbxc
Reply:don't try to use a compression coupling. flared union would be fine.miller thunderbolt 250vlincoln square wave tig 175 prolincoln idealarc mig sp250everlast tig 210EXTeverlast power plasma 50chicago electric (hf) 130 tig/90 arcchicago electric 90 amp flux wire3 sets oxy/acet
Reply:Damn, that is the ultimate go anywhere welding rig.Awesome.
Reply:Hi again,I picked up a double flaring tool kit and am about to dive into the project.  I will most likely work into the night as I have some service calls that are waiting on me.  I am not sure if the flaring tool will fit in the space available, but we'll see.....   Thanks for the video, that was a nice touch as I have never done a double flare before.My rig is the most common of these vehicles to be imported from Europe as they are older NATO vehicles for the most part and go up for auction just like the DOD hardware here in the States.   Dealers from here go overseas and buy them and import them into the U.S. and supply a niche market of off road vehicles based on the Mercedes Unnimog.  Mine is a model 404.1, the most common available and in relatively large numbers.  The same dealers who supply the vehicles also buy up parts inventories and even whole vehicles for parts so practically any part is available short of some items that are scarce like the oem air compressors or air boosters like mine, military generators that power the radio truck versions and gas fired heaters that keep the engines warm in the harshest of winters.  These types of parts are almost non existent and most Mog owners improvise replacements as the situation requires.  The last air booster I saw for sale was gong for $1600!!!!For example I got a hold of an air booster off of an M35 deuce and a half (for $300) which is about the same size as my stock one and plan on adapting it.  Its a good thing I brought up the issue of how best to splice the brake lines because my initial plan was to braze the SAE lines that fed the M35 booster to the metric 6mm Unimog brake lines using some type of home made reducers.I adapted a Ford straight six to this one based on an adapter kit made by a fellow in Canada who had a business that come up with modifications for these vehicles and coming up with all type of adapter kits for them.  He even stuffed a V6 into one and was offering a kit for it.  He closed his shop though.I get my tires from a local tire dealer that keeps 9.00 x 20's non-directional military tires in stock.  They go for $150 each.  I will probably have to have a machine shop make up a set of double flare type adapters as I don't know if there is anything like that available on the market that can adapt SAE to metric.  Anyone know or have a lead?Mine is the only Unimog of this type that I have seen that is a work vehicle as most owners use them as off road or rock climbers.  Some are heavily modified and I've seen guys adapt the axles to other vehicles in order to get the offset centerline for the differential which gives the Unimog about and 18" clearance.  It uses portal axles consisting of a gear box at each wheel that drives the axle (and wheel) and allows this vehicle's axle to ride higher than a normal off road vehicle.They are very rugged and I have been on service calls where I've been up to my axles in mud and been able to churn my way free.  I know that various state and federal forestry services also use or have used this type of vehicle and are available now and then on their auction sites.  I had one client call me and he later told me the reason he picked me over others he found online was because my rig showed him "I meant business!!"  I thought that was "cute".Finally, I am preparing my rig for sale as I need to move to a more highway friendly version.  I get asked to travel at times and my rig is not a traveling vehicle.  It is too slow and cumbersome.  I have had the highway patrol tell me to get off the freeway as my top speed is 45mph.  I want to repair a list of items so that the new owner does not have to do any work to it and sell it complete with every tool currently on it as a turnkey operation.  I hope to be able to use that money to turn around and replace it with a more modern rig with cruise control, air conditioning, cd player and the amenities that an older guy appreciates more than a young fellow.  Also it will have to be an automatic as my wife likes to go out with me sometimes and this way she could share in the driving. Thanks for all the feedback and warnings.  I will take it to heart,Tony
Reply:Originally Posted by boatbuoydon't try to use a compression coupling. flared union would be fine.
Reply:buy a metric double flare kit.Miller thunderbolt 250Decastar 135ERecovering tool-o-holic ESAB OAI have been interested or involved in Electrical, Fire Alarm, Auto, Marine, Welding, Electronics ETC to name a just a few. So YES you can own too many tools.
Reply:I have one in my hands right now.  The problem is that I am unable to make the flare for lack of room on the cut part.  I am unable to get the flaring tool in the space to use it.  Hence it is of no value.  My only recourse is to pull the line or go with a compression fitting repair.  Why not use the compression fitting? Thanks,Tony
Reply:That stuff is sold at any part store around here but you will FAIL a DOT inspection with that method of repair here no questions asked.When I first got the truck I have it needed a sticker and a physical so I had the boys give it a once over..They found that type of repair going to the rear brakes and called to tell me it had to be one piece or no sticker.That's the way it is here anyway.......zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.
Reply:Hi Zap,As long as the repair works, holds and is safe, I can live with it.  I have never been asked to submit my truck for inspection here in Arizona.  When I get my booster back rebuilt or if I have to adapt the m35 booster as described earlier, I will deal with replacing the line.  I think I don't have an inspection because this truck does not require a commercial drivers license in which case it would get inspected as part of the registration process.Thanks,Tony
Reply:A straight compression fitting is a NO NO , Your mechanic friend was either not trained properly or he has been cutting corners for years an d just been lucky no one was killed. Guy just do it right, take then line of and fix it .with the amount of time spent trying to get around doing the hard fix you could have been done by now . gxbxcLast edited by gxbxc; 08-22-2014 at 12:19 PM.
Reply:Using a compression fitting on brake lines is illegal just as brazing a brake line is. You will be responsibe even if you don't own the vehicle anymore if it can be proved you fixed it that way. I have seen compression fittings used before and it will work but it at some point will also fail. Take the time to do it right, it just may save someones life in the future. Your mechanic friend is dead wrong on this one.Quality work is never Cheap, and Cheap work is never Quality!!If it's broke, and you're not, we can fix it!!  Lincoln Idealarc sp200Century 230amp ac/dcSmith O/A TorchesHuth Hyd. Pipe Benderother misc "cool" tools
Reply:.with the amount of time spent trying to get around doing the hard fix you could have been done by now .
Reply:Unimogs are the shiznit.
Reply:I have a degree in Automotive Technology and have work on vehicles for over 20 years.  I would never use or recommend anyone use a compression fitting.  They have a use and in the automotive industry is not it.  The compression fitting will loosen under stress caused by vibration.  The correct way to fix the line is to replace it completely.  You also need to know what degree flair is required for the vehicle.  There are several different degrees that are used on older vehicles.  I dont know is the mog uses a 45 deg flair or not.  Please take the time to fix it the correct way.  Thank YouHooking up the ice maker on you frig is one of the uses
Reply:I agree that compression fittings are not a good idea. I used one on an old Toyota Camry, for a temporary fix. This was for a couple weeks, until I had the time to replace the lines. Under normal braking you might be fine. But under emergency braking, the line pressures can reach an excess of 2,000 psi. On a truck your size I wouldn't trust a 3$ fitting to stop in an emergency. It's a crap shoot, it may last for years or it could fail when you least expect it.Thermal arc 211iCk flex-loc 150 & 130Clamps, saws & grindersHarbor freight 80 amp inverter
Reply:Double flaring with a union is acceptable.  Make sure it's a double flare though.  It's not like hooking up a water line with a single flare.  Care has to be taken to do a double flare.  Make sure the tube is dressed properly after cutting (your kit will have instructions), and make sure it's absolutely square.  These work just fine"Any day above ground is a good day"http://www.farmersamm.com/
Reply:HF has them, but you can get better quality ones elsewhere http://www.harborfreight.com/double-...kit-66534.html"Any day above ground is a good day"http://www.farmersamm.com/
Reply:Hell, all your connections at the brake cylinders are nothing but double flared connections, nothing different with the proper union........same same"Any day above ground is a good day"http://www.farmersamm.com/
Reply:http://www.autozone.com/autozone/acc...ntifier=895706"Any day above ground is a good day"http://www.farmersamm.com/
Reply:I posted a picture of the repaired line using a double flare fitting and union.  I had a hell of a time getting the flaring tool in the area where the cut off line is.  I don't know why it didn't show up but I am posting it again.  Also when I went to bleed my brakes I found that one of the fittings was leaking.  I re-used one of the flare nuts that I grazed with the grinder when I cut the brake line at the fitting to remove the air booster.  I am going to take off the by-pass line I installed this morning and redo the leaking joint using a new flare nut.Thanks,Tony
Reply:If you ever need to splice tubing just remember Swagelok or Yor-Lok.  It's the best system and nobody will ever give you beef for using it.  For brake line sized stuff a coupler will run about $20 (in top grade stainless steel) and requires no special tools to install (you can do it with a combo wrench).  Most of their fittings in that size are good for 10,000 psi.