So I have a 77 240d and it failed inspection. One side of my rear brake lines is pretty rusty, so I'd like to just replace everything while I'm back there instead of doing the bare minimum.

Does anybody know what size hard line I need, and what size fittings I will need? I have new hydraulic hoses which I will be installing as well.

Do I need to drop a lot out of the rear end to replace the hard lines on the '77? I'm afraid I might end up not being ableIto put something back together if I have to take too much apart (old bushings, stripped threads, etc). Final exams are coming up and I am out of money. I'm pretty good about keeping the car safe to drive, but I'm out of money until my next round of finan cial aid comes in. Also know the PO and he took care of the car until he sold it to my mother who gave it to me after several years.

If I do need to drop lots of stuff, should I just do the fuel hard line now too? I had to put a rubber patch line from about the drivers seat to the filters on both the send/return lines. I'll replace them entirely if it makes sense to do this while the brake lines are being done. If it can wait until February, I really don't have any money left. Just spent 400-500 on this car (and I'm waiting for the replacement for my "new," two week old, faulty alternator to come in to my parts shop... had to borrow a jump pack from a university mechanic to get her to Autozone

Those pipes are available from the dealer and they are not too expensive. I looked up the brake pipes for my W111 220SEb sedan and they are replaced by W123 parts.

You will have to bend them with a tubing bender. Use a good penetrating oil on the pipe connections. Use flare nut wrenches as well.

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Regards

Warren

Currently 1965 220Sb, 2002 FORD Crown Vic Police Interceptor

Had 1965 220SEb, 1967 230S, 280SE 4.5, 300SE (W126), 420SEL

ENTER > = (HP RPN)

Not part of the in-crowd since 1952.

Thank you Warren for the helpful advice.

I'll check with a local dealer tomorrow (its Turkey Day). Time is of the essence right now, I'll need to get the car re-inspected by Tuesday.

Are the hard lines 5mm on the '77 240D? Some forum searching has led me to this number... I think VW might also use 5mm line and I could check with them if the MB dealer doesn't have the line readily available.

I'd rather stay stock, but I have heard of people going to 3/16 line with adapters. I could do this in a pinch and just replace the one section of line that has me failing inspection right now. I think I might go to Cunifer in the late winter/early spring if it is indeed as good as reported.

Thanks again, and happy Thanksgiving!
-Luca

The replacement lines are generic lengths like 300mm so you may end up having to be creative with how you route them and you may need to make a loop to take up excessive length.

Put PB Blaster on all the fittings and let it sit at least overnight. Don't be afraid to apply some heat with a propane torch if necessary. Do this before you round the fitting.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe

I'm not so concerned about the length of the line. I can cut it and flare it as I need. It's the outer diameter that I am concerned about...
I believe it is a 5mm outer diameter, but I was unsure. I could measure it, but was really just curious if anybody knew off-hand, mostly so that I buy the proper fittings if I don't get the line with the flares and fittings attached. I'd rather buy a big 25ft spool of line anyways, since I will eventually replace all of them and it will allow me to make a few mistakes.

So, 5mm outer diameter?

Thanks again for the help so far,
-Luca

after extended research on materials i replaced the lines on my 1972 220d last winter. there are now lines made from a nickel/copper alloy which can be bent by hand (no tool) and are highly resistant to corrosion. i paid between $2 and $3 per foot. the stuff cuts nicely, bends very easily, and flares with no trouble.
because i'd dropped the rear subframe assembly from the car there was no problem running the lines over the subframe. getting the hoses separated from the hard lines was tough. and i never did find replacement fittings of the same length... everything out there had universal threading which was about twice as long as the originals. the longer threading meant having to shim (with stainless washers) the difference at the bracket where hose and hard line meet.

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I have always recommended fedhill.com for Cunifer lines and fittings they are very nice to deal with, but I was at AutoZone a month or so ago and when talking to those folks found out they now carry Cunifer line both made up sections and 25 foot long rolls in two diameters. If I recall correctly a 25 ft. roll of 3/16" = 4.7 mm was around $45! $2.20 a foot is a great investment in long term corrosion resistance and an even better investment in ease of installation!

Your car is earlier than most but many MB brakes use Euro bubble flare fittings that are M10 X 1!

Thanks Billybob.

I just replaced the hardline. Only the rear left, short section "needed" to be replaced. I say "needed" because thats what the VW stealership told me when I went for an inspection. My brother and uncle, both automotively inclined, and my friend, who helped me with the brakes and is a certified Audi tech, all said there was no reason for the line to be replaced. Minor surface rust/corrosion, but no rot or flaking. The VW folks also told me that my front left upper ball joint was bad... but it's the wheel bearing (overtightening the center nut eliminates all play in the wheel and there was never any movement at the spindle). And the mechanic said that the little bit of oil on my exhaust manifold, which also failed me (though it doesn't even produce any smoke), looked like it could be an issue with a bad crank seal. It was obviously the valve cover gasket, which I just replaced the other day when I adjusted the valves. No more dripping...

Argh, I digress... the brakes are done and I appreciate all who provided useful input.
-Luca