W140 - M119.980 Brake lines

[guyonabuffalo]

Hi folks, I wanted to get some insight on how to go about replacing the factory brake lines - specifically the metal lines that run along the length of the car underneath. On my 94 S420, there are 4 lines that run the entire length of the car, 2 of which are brake lines and the other 2 being fuel. There are rubber (or maybe plastic) grommets that secure them to the underside of the car. Unfortunately, road salt and 30 years of being exposed to the elements means that the portion of the lines that were specifically inside this rubber grommet have deteriorated dramatically.

I was recently working on the rear lower control arms bushings, when I accidentally broke off a piece of this grommet, which revealed the rotted out lines. I did a hasty repair on one of the brake lines that had also broken, by adding 2 threaded couplings (high pressure) to replace the section of line that broke. Its holding and my brakes work perfectly fine.

However; this is not cool! I would love to know how to replace the whole line or at least a sizeable section, without messing up the braking system completely.

I dont have photos yet because while this was happening, I was panicking and did not have the mental capacity to even consider taking photos. I will however add some photos later once I have had a chance to look at the hack job I did.

Your help and suggestions would be greatly appreciated.

 

[gsxr]

See if the hard lines are available new - you might get lucky. However, they may be 5-6 foot long... check each end to make sure you can replace them without pulling the engine or rear subframe. I've heard of the dealer supplying a perfectly-bent long tube, and also heard of the dealer supplying a tube that was rolled into a coil for easy shipping.

Otherwise, you can patch the line by splicing in a section of aftermarket metric hard pipe, along with metric bubble flare fittings and unions. This isn't easy nor fun, and requires the proper tools for the bubble flares. If any hard pipes have complex bends, look into buying Cunifer pipe which is easier to form / bend.

 

[JC220]

I am not certain if MB would supply the brake lines in the correct shape! Sometimes you get a steel coil.

It's better to remake the entire line in each case with Kunifer pipe as mentioned above. (Also known as Cupro Nickel) I find it useful to remove the original lines as complete as possible and use them as a pattern to make the replacement lines as close as possible.

Some pics from my W140 where I was making new Kunifer brake and fuel lines.