Forgive this newbie question, but I'm getting ready to replace my cracked rear brake hoses and I am stumped. On the new brake hose, I noticed that the metal ends do not swivel against the rubber part of the hose so it is not readily apparent to me how I will get the ends screwed into both the caliper and the hard brake line at the same time. I'm hoping that I don't need to remove the caliper to perform this repair.

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Rob
'84 300SD 258K
'85 300D (sold)

I think the hard line coming from the car screws over the hose and swivels but I could be wrong.

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1985 300D Turbo ~225k
2000 F350 (Powerstroke) 4X4, SWB, CC, SRW, 6spd ~148k
1999 International 4900, DT466e (250hp/660 ft/lbs), Allison MD3060 ~73k

gasman,

The end of the brake line has a flare fitting on it. This flare fitting screws into the metal end of the brake hose.

If the flare fitting is rusted into the brake hose, use heat, preferably an acetylene torch, so you don't break off the metal brake line. Don't worry about burning the hose, you are replacing it anyway.

P E H

Okay, thanks for the tip and info, but I'm going to need some more hand-holding here (I'm a novice mechanic). I had the rear tires off this morning to replace the sway bar links (easy repair thanks to info on this forum), and looked more closely at the brake line to brake hose interface. The brake line ends at a 11mm flare fitting nut and then disappears behind the retaining clip/bracket holding everything to the frame of the car. The clip/bracket is more like a cage that is about 3/8" thick. On the other side of the cage is the brake hose. Should the 11mm flare fitting nut rotate against the hard brake line when turned. If so then I assume that I should put a wrench on the brake hose fitting and turn the 11 flare fitting nut. Is this right? Or is there a way to disconnect the clip from the frame of the car?

There is no rust on the fitting. The car has been garaged since new here in Texas. How difficult should it be to break apart the flare fitting from the brake hose? I don't want to screw up the hard brake line or flare fitting and then crawl into my indy's garage with my tail between my legs .

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Rob
'84 300SD 258K
'85 300D (sold)

gasman,

I'm going to revert to my motto: If it ain't broke, don't fix it.

There is probably nothing wrong with your brake hoses. But here is a easy test: With the engine running long enough to have a full vacuum, stomp on the brake pedal as hard as you can.

If none of the hoses rupture, your brake system has just passed with flying colors. I would bet you nothing ruptures and you don't need to replace anything.

You can do this test as often as needed to convince yourself that nothing needs to be replaced.

P E H

What about the internal diameter of the hoses decreasing as they deteriorate and cause the break pressure to be applied unevenly resulting in the vehicle pulling to one side when breaking?

- Peter.

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2021 Chevrolet Spark
Formerly...
2000 GMC Sonoma
1981 240D 4spd stick. 347000 miles. Deceased Feb 14 2021
2002 Kia Rio. Worst crap on four wheels
1981 240D 4spd stick. 389000 miles.
1984 123 200
1979 116 280S
1972 Cadillac Sedan DeVille
1971 108 280S

Gasman.......Use a 14mm wrench to steady the hose while you undo the 11mm flare fitting nut........make sure you use a good quality 11mm wrench or one of the special brake ones that look like a ring with a cut-out section for the line

They are usually quite tight and open with a 'crack'........if you are careful to hold the 14mm wrench steady nothing should break.............the hose sits in a hole in the bracket and is free to turn......... the flare nut holds everything together when tightened against the spring bracket .......the key is to ensure you hold the hose from turning with the 14mm wrench..............at least this is how it is on my 1978 280CE w123 front hoses that I have just replaced.........came undone without a problem on mine after 25yrs! ...................most of the braking is done by the front discs so make sure you check/replace the front hoses as well

When you remove your hoses.....cut one ...you will see several layers.....small inner line about the size of the copper lines........cracking on the outside is alarming, but probably a long way from dangerous

I didn't hesitate to replace the hoses on my 25 yr old Benz when I got it going again after being not used for 5yrs (see Vintage Forum)

Good luck....I would replace any cracked brake hose....how much is your life worth!!

Peter,

Yes, I saw that happen once in about 50 years. But there is a test for that too.

Just crack open a bleed screw and observe if brake fluid comes out when someone steps on the brake pedal. There is very little brake fluid flow, especially with disk brakes. Therefore little flow equals little pressure difference and no pressure difference when there is no flow when pads meet the disc.

So as long as you get a flow of brake fluid from the bleed screw, the brake lines and hoses are passing brake fluid sufficiently. QED

P E H