Hi Guys my rear hard brake line rusted out does anyone know if it is metric?
Are the fittings metric?
It looks to ne 10-12 feet long
Does anyone recommend me using 3/16 stainless steel line?
Any info can help.

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1984 W123 300CDT

The fuel lines may leak if you seriously disturb them. So if you can run the new line without involving them. You may save some effort.

A new standard brake line will probably be good enough for the remainder of the cars life. Some times the caliper bleed screws are pretty bad. Rather than risk breaking them off.

When bleeding that replacement line. On 123s. I have filled the master cylinder. Left that rear line fitting loose at the T if I remember. It has been a long time. Then gravity bled that line until pure fluid emerged. Then tightened the fitting back up. I got good pedal afterwards.

I live in a rustbelt and there have been times the bleeder screws on the calipers were unusable. Usually I heat them with a torch and cool them with water three times. At times here they are just rusted too much basically. Or have still broken off with even that approach. Usually it works though.

They are regular metric coupler nut 3/16 line - best material for brake line is the cunifer material line sold at parts store. Buy the one that says GM - its the same as mercedes. Dont buy the japanese one as its inverted flare rather than bubble flare which mercedes uses.

The cunifer line bends way more easier than steel, looks great and is rust proof. You can buy a 25ft roll of it at NAPA, the pricey bit is the bubble flare tool and that takes some practice.

an easy way out would be to buy the inverted flare tool from napa (the one that comes in a plastic bag) and some inverted flare nuts and union. Buy a premade bubble flare line at the length you require, till where the original line is still solid - splice the line in with the union you have.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

Yes, they're metric .

NAPA auto parts stores sell the metric brake pipes .

Remember to dig out our bigger sockets to use as mandrels when you're making the bends and use ONLY flare nut wrenches on the nuts ! .

Smacking the bleeder valves dead on with a ball peen hammer before you use a 6 point box wrench or socket to loosen them usually breaks them free .

If you snap the bleeder off when you hit it, you didn't hit it straight on .

I imagine a good used caliper can be sourced from a Western M-B enthusiast very cheaply if necessary .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better