Replace brake lines?

Discussion in 'Heavy Duty Diesel Truck Mechanics Forum' started by Dino soar, Sep 20, 2019.

  1. Dino soar

    Dino soar Road Train Member

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    I'm wondering if I should replace the brake lines on my truck.

    The ones that run to the Rears I can't say that I see any cracks in them or any of that, but they feel like really soft and super flexible almost like spongy.

    On the steer axle the lines seem like regular Airlines would feel, but there's only two of them and they're not that large and I have them out to put the brake cans on.

    I have the fifth wheel off still so it's a little easier to get to the back ones now.

    Everything else involving the brakes is new, except for the valves themselves. The truck sat for about 5 years. The guys that had the truck before me only replaced the bare minimum of anything that was needed. I could believe those lines have a lot of time on them, but like I said visually they seem okay except that the back ones seem very soft.

    Is it worth it to spend a couple hundred dollars and replace them now?
     
    Last edited: Sep 20, 2019
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  2. AModelCat

    AModelCat Road Train Member

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    If you're questioning their integrity, I'd change them. Especially if the 5th wheel's off. Never going to be easier to get it done than right now.
     
  3. Dino soar

    Dino soar Road Train Member

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    The thing that really has me questioning it is the softness of the lines.

    I thought Airlines were the same as fuel lines in that they have braided wire with a protective fabric over them.

    These feel like they are 100% pure rubber with no reinforcement. Like a thicker heater hose.

    I guess I better just replace them and be done with it I'll feel better.
     
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  4. AModelCat

    AModelCat Road Train Member

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    Usually just fiber braid I think. Steel braid is a high end option.
     
  5. Working2party

    Working2party Medium Load Member

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    If your worried about them test them. If they can hold 150psi shop air then they’ll hold anything your truck will put at them.

    There are multiple types of DOT approved air lines. Then less expensive version is just rubber inner and outer layer and an internal nylon braided. The best ones I call strati-flex (I or II) have the rubber core, a steel braided layer, and a nylon/fabric outer layer and usually have reusable fittings and are much stiffer to work with.

    Your rear lines could have been changed out with the cheaper version. You should make sure they didn’t go really cheap and put 3/8 hose (I see on trailers) on instead of the 1/2” that I see on trucks. I’m not sure if it’s a DOT thing or not.

    Either way, If your not sure about them, cap them and test them at a 30% higher psi than you plan to put at them on the road. Make sure there tied up to not rub on anything and you’ll be more than fine!!!
     
  6. Dino soar

    Dino soar Road Train Member

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    Well the guys I got the truck from I think just were not good on maintenance at all. They had different brake Chambers on each side I think they had different slack adjusters and none of the pushrods were cut at the right length and each one was different side to side, and I'm sure that those lines have been on there forever.

    So I had some other lines I was going to have made up so I took the brake lines off. When I got them off I saw they were all different lengths. I'm thinking what the hell? The valve is in the center, at least they should have pairs that are the same length.

    And then exactly as you said. I looked at one of those lines and it was a little effing line. So I went over to the old brake can and sure as Shinola they had a little tiny fitting on it. I don't know what the hell those guys were thinking.

    As much as I hate to spend any more money before I get started, I'm going to replace every one of those lines. Then everything will be new except for the valves.

    It just amazes me what some people do. And they were a small Fleet and they've had trucks for many years. You would think they would know better.
     
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  7. Dino soar

    Dino soar Road Train Member

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    Is there a standard size brake fitting for the 30-30 Maxie's and the type 30 service Chambers?

    Or do I just bring the old fittings to the hydraulic hose place and they'll get me the right size for the half inch lines?
     
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  8. spsauerland

    spsauerland Road Train Member

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    Typically see on a tractor -6 on emergency and -8 for service.
     
  9. Rideandrepair

    Rideandrepair Road Train Member

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    Definitely, the steers right away. I’ve had them last only a year. Current ones are 3 yrs old. They’re prone to leaking, as they move when turning. On both my Freightliner’s, I use longer hoses than original, and cut the inner wheel wells, just enough to avoid chafing, another common problem on the steers, ( especially with a longer hose). Longer hose seems to last a lot longer, less stress on the ends. I’d replace all the others. Get them made up, using the steel outer braiding type. I plan on replacing all of mine soon. They’re all original, 19 yrs old. except fronts, changed 3 times in the 11 yrs. I’ve owned the Truck.
     
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  10. Working2party

    Working2party Medium Load Member

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    3/8 NPT (National Pipe Thread) both the Chambers and Valves . If your redoing the lines, it Might not hurt to get som DOT Male to female 45deg brass fittings. A lot of times the little bend can make the hose lay natural.

    The hose fittings them selves will depend on the hose you go with. If you do spend the money for strato-flex make sure the fittings they give you match the hose. Both are marked with 1 or 2 but he parts guys have still messed it up.
     
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