Hard brake line repair/replace?
 

Folks,

I am in the midst of repairing rusted out fuel lines on the '85. While doing this I noticed the long rear hard brake line is badly rusted in small spots. It is not leaking, and the brakes work fine.

I am planning to POR-15 the small areas and put it back together.

OR

Can I put in a 6 inch hard line patch somehow with compression fittings? I dont want to replace the whole thing. Im already having too much fun with the fuel lines.

OR

Am I being a moron for not replacing the entire long length?

I think Im starting to go crazy with the rust related repairs. Never again will I buy a 123 from the rust belt.

dd

I think SAE requires flared fittings but personally from a technical standpoint, I would use stainless steel Swagelok fittings or similar.

I think they relaxed that requirement on rear brakes.

I would replace as much as seems like it is rusted. Check all the mounts for rust issues. Also, I would use flare fittings, no need for extra expense.

Don't use compression fittings! They probably won't burst on you, but they may squeeze the line enough to impede flow (ask me how I know).

Replacement Euro brake lines are available at AutoZone. If you want to patch, you can buy short lengths from AZ, the unions are available at Napa and the bubble flare tool is available from eBay.

They also sell the "Bubble" Flaring kits. I bought one several months ago it was about $24 from one of the Ebay Sellers and while a China Import is marketed by the too company OTC.

They may be available from the local autoparts but I did not look.

The best pic I could find on short notice:

Generic brake line from Autozone is very cheap. Potentially wrecking your car due to a half a$$ repair is expensive. Spend less than $10 and fix it right.

Scott

p.s. Autozone also rents the bending tool for free ($5 or so refundable deposit)

dieseldan,

i did the brake lines myself with a bending tool which I eventually did not use so much as well as the flaring tool. in the pictures posted above, i dont believe they are correctly labeled. its either single flare or double flare. possibly the hardest part is bending the lines that go outwards from the T-valve to the brake/hub area. might be different from your vehicle, but on my 300D Turbo, watch out, lots of bends on the road...

Best thing to bend them with the original taped side by side. And oh, practice like nobody's business. And probably the most key of all key tips: before you crimp the end, please make sure you put on the nut! because once you flare it and unless you cut it extra long, you're out of luck. You'll have to bend the whole thing again.

here are 2 links I collected along the way that helped:

http://www.pharmacy.arizona.edu/staff/wunz/NoABSTCS/DoubleFlare.html
http://www.carcraft.com/howto/50919/index.html

thanks guys. i should replace that line. i think i knew it all along.

trouble is that it's a nightmare to replace that 10' line back to the rear without a lift. i may limp this one over to the indy to do. id think with a lift and their skills they'd be able to patch it up very quickly and not cost too much.

dd

If they try and charge a lot find somewhere else. I had the lines replaced about a year ago and from what I remember the price was minor.

True enough. Lines are a PITA, but really not that time consuming on a lift.
But, if you can do the fuel lines, the brake line will seem easy, especially now that you've had practice....:D

DD,

I would replace the whole length. I tried patching in a piece with flare kit and could not get it so seal after many tries.

Paul

What if you DON'T have a lift? It looks like I'll need to replace mine. I do have jack stands, but even with those, it's not easy to manuever under the car and those rear brake lines don't look very easy to get to.

I don't think I'd want to try patching something like brake lines. I guess the hard lines run all the way from the master cylinder to where they attach to the hoses?

A Mercedes mechanic I spoke to last week told me that you have to drop the rear subframe assembly out to get to the brake lines. Is this true? If so, how does that work exactly? I see what he means because there is a joint from the main F-B line to the L-R lines which seems to be concealed by the subframe.

Unfortunately the pice does not show the Subframe.

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=123193&M=617%2E952&GA=722%2E120315&CT=F&cat=318&SID=42&SGR=090&SGN=05

This is to the whole site:
http://www.detali.ru/cat/oem_mb0.asp?TP=1

That's helpful for understanding what's involved. I had the CDs for that car, but haven't looked at them yet.

Thanks for the links.

Unfortunately the long line (Part 17) from the master cylinder to the "T" in back runs between the subframe and the body.

I replaced mine from the T up to midway on the car last winter. I had a time getting the new line fished up over the subframe, but it was way easier than removal of the subframe(and I have fairly new subframe mounts)

I spliced the old line where it was still good using a regular old AMERICAN double flare. ( the 3/16 line from Mcparts is very close to the 5mm.) I just used an adapter from 3/16 SAE to 5mm bubble at the T.

It sounds like you replaced the hardest part. Why not just do the whole thing? Mine is leaking somewhere close to the tee in the back. I'd rather just do the whole thing and not have any splices along the way.

Did you get them replaced, Dan? It looks like I'll have to have mine done. I don't have a lift available. I asked an indy mechanic in Vienna what it would cost and he estimeated $500-600. How does that compare with what yours cost?

Back to this
 

Guys,

Its been through a year and I now have time to address the brake lines.

I have access to a lift now and a mechanic who suggested I splice in at the part of the car where the rear line goes back from the firewall. I dont have any rust until this point.

The mechanic is renting me the lift for cheap, and he has the double flaring tool. I just need to do the bends, he will do the seals and falres. He assured me they do this all the time (he's a full time tech at a Volvo dealership). He's been very detail oriented thus far on other consultations, so I trust him.

What size line do I need? 5mm? I can I order the right size in generic lengths from somewhere like CarQuest? I didnt see them on PP and Id assume shipping would be huge.


dd

The brake lines have an outer diameter of 5 mm. The fuel lines have an outer diameter of 8 mm.

I actually got my brake lines from the dealer - it worked out cheaper than buying a flaring kit.

Make sure thats actually legal in MA if you have an inspection coming up. Just a word or warning. Bought a car in VT where brake line unions are legal, and tried to register it in RI, where I discovered that they are specifically illegal for the safety inspection.

Junction blocks were fine, but a line to line union was a big no no. Had to replace the whole brake line from junction block to junction block.

have no idea what the MA rules are, but it would be worth knowing before you do something that you might have to undo later.

Wrong you don't have to drop anything..contact fedhill brake lines and make up new lines with cufner lines very easy to work with and will not rust, you can use your old fittings if there not damaged..just a thought done this many times. just remember to bubble double flare your new lines and put the fittings on before you flare, lol, Federal Hill Trading Company

Per the suggestion of other forum members I have ordered the lines from the dealer and will be installing them today. No lift, just high up on jackstands.

I'm going to do all 5 lines and 4 rubber hoses.

$150 from the dealer for all 5 brake lines, with fittings and flares already, just not shaped.

Good luck - I did mine about a month ago now with the same pipes from the dealer... I didn't come up against any real problems other than a little bit of a lack of space under the car when it is only on jack stands!

The OTC kit is decent. I own one, and it produces good bubble flares.

I had to replace the high-pressure SLS line last fall on my wagon, which required dropping the front of the subframe, not full removal. That's not so big a deal -- just pull the big bolts at the mounts and let it hang.

I spliced in a piece of line and would have used bubble flares but I couldn't find any unions that would fit them (this is for bigger line than the brakes -- 1/4 or 6 mm. maybe). So I had to put double flares at the union. It sealed just fine, and it handles constant high pressure when in operation.

it is a pita to replace the long line, but it can be done w/out dropping the subframe. it requires patience and careful bending of the line. i did it on my td. it was a dirty irritating job, but it works, the line is not rubbing anything that will wear a hole in it. i would never use compression fittings on brake lines btw. they may leak at some point, just not safe. factory long line isn't that expensive anyway.

Just did the same on my 87 300D. I ended up bending part of the line, wrapping it over the subframe (a maddening task:P), then using a small handheld bending tool to finish it in situ. Took a long time because I was extra careful not to kink anything ... would be easy to make that slip. I replaced both rear lines and the one that goes up to the front, plus the t connection, all from the dealer.
Good luck dieseldan ... I did mine on jacks too, not the easiest thing but you can do it.:) If you need it Harbor Freight carries a little tubing bender that worked very well for me do make bends while under the car ... can't find it online but it's basically just a handle with a round end that you wrap the tube around and a hook for leverage.

Finished the rears yesterday no problem. Took me 4 hours going slowwww and taking pictures.

Army: Why not drop the subframe?? Its 4 bolts and it makes the job so so so so much easier?

Some of the Mercedes OE replacement lines are slightly longer than the originals, in some cases had to figure out how to toss in a couple more bends to get the length right.

As I said earlier, drop the subframe at the rear diff. Support the rear diff with a jack before undoing the 4 13mm bolts. Youll need loctite to put them back (blue)...tighten to 30nm.

The long line wasn't that bad. Run the line down through the engine bay, then work back to front, fastening it along the way and mirroring the existing line. When I was satisfied with how similar the shape the new line was, I cut the old line out of the way. All hand bending, didn't even use the bending tool.

Inspect your fuel lines, if they look bad now is the time to just replace them. I replaced mine with 5/16" aircraft aluminum lines from McMaster-Carr.

Fronts and bleeding today.

Oh yes that I did! (I also did the fuel lines too - also dealer sourced as I can only get copper as an alternative here and that is bloody expensive)

Got distracted today and only ran the passenger front brake line. What a pain that was! Much worse than the long rear line!

Doesn't help that I have a few extra Frybrid components somewhat in the way.

Last short line tomorrow, then bleed, then hopefully all done.

Im pondering rebuilding the rear suspension now...hmmmm. The front was done 20k ago...

Army i think it was your pics i saw of a totally painted subframe!! That must have taken a long time to do...

Sorry to hear about your troubles with the long front one... good luck with the bleed tomorrow. I'd re-built my calipers and had a nightmare on my bleed... litres and litres of brake fluid and because the front left hand caliper allows air in but doesn't let fluid out - 'even changed the master cylinder before I worked out what was going on...

As for the subframe - well I've answered your question you left on that thread - so all in a weekend's work if you're lucky!

Flaring & Fittings
 

I'm embarrassed to admit that I completely destroyed my steel line-to-rubber hose connections while attempting to replace the rear brake hoses on my 85 wagon. Needless to say, I'm pretty sure I'll need to replace both of the steel lines that go from the rear T-joint to each wheel. It's a shame, too, because the lines appear to be in pretty rust-free.

Anyway, in this thread and others, I've read about the various options for sourcing replacement hard brake lines. Pardon my ignorance, but I have a few questions before I go ahead and buy replacements.

-- What are the double and bubble flares? From what I've gathered from post #6 of this thread, are these the tapered, nozzle-like fittings on the ends of the brake line? For example, where the line narrows down as it enters the T-joint? Does it matter if the replacement line has double vs. bubble? Do replacement lines from Autozone or the dealer already have these fittings?

-- Does generic replacement line from Autozone come with all of the necessary fittings? I'm especially concerned about the proper nut, large washer, and male fitting that's on the end where the metal line meets the female rubber line.

It's my understanding that both Autozone and the dealer line will come unbent. If all else is equal (both come complete with all the proper fittings on both ends), I'll likely go with AZ so I can get the wagon back on the road ASAP.

Thanks,
Ted

dealer lines will be long enough. autozoo lines are only available in lengths from 6" to 3' so if you are replacing a long one, you will have to install a union in to match lengths.

Almost always when replacing the fuel lines this far north. If they are run in a group and usually they are. The brake line back to the tee at the rear end will have to be dealt with. Almost as much as I do not like it I use a pre made line from the rear tee to get me by that area.

Then a bubble flare union to connect me to the bulk brake line that I cut to length and bubble flair. This line is then one piece to the master cylinder.

If there is any chance of a brake line rubbing in the rear. I put a lot of grease on the line and slide a piece of hose over the portion that might be an issue. Sealing both ends of the hose to the brake line with more grease.

I have been fortunatly able to bleed the long rear brake line after installation. Simply by restoring fluid to the master and opening the line a little at the rear tee. Air is pushed out by gravity. You do not have to wait long for brake fluid to appear.

I had a good hard pedal so did not bleed further. To be absolutly sure you got all the air out though after the gravity feed do the rear calipers. Doing the line in one piece as many have done looks a litle awkward with the rear end in place. Obviously possible though apparently. At 150..00 for straight lines with the bubbles and fittings is more than buying a roll of brake line and reasonable bubble flairing tool plus doing your own bubbles.

I see no issue with re using the brake fittings nuts again if they are in reasonable shape. You will probably at some point in your life use the flaring tool again anyways or sell it at some point.

keep in mind, a BUBBLE flare is a simple double flare, formed on the flat side of the tube vise, and without the final double flare step.
Making a bubble flare with a double flare tool - YouTube

Should hard brake line rubbing against the underbody really be avoided? I can't imagine that steel lines would be that vulnerable to damage from the chassis. I feel like some SLS lines sit tightly against the underbody....?

I still don't see the difference in double vs. bubble flare tips. Do they differ in the relative hydraulic pressure they provide? Is it simply a difference in the ease of making unions?

I grabbed the old lines, and decided to just walk into Advance Auto. They guy was extremely helpful, and knew they were European lines before I even told him they were for a MB. They carried AGS steel lines, European version, 3/16". Bubble flare / metric fittings. I took in the replacement Pex soft hose to make sure the threads matched, and they were a perfect fit. The AGS line fittings had a slightly longer hardware, most likely to accommodate a larger spectrum of applications. Total for both lines was about $11.

The guy gave me some longer line than I would like, especially for the shorter driver's side. I bent by hand, and had to get creative about using up a lot of length. For future reference, I was happy to see that, apparently unlike Autozone, Advance carried lengths longer than 3', as the passenger side length was one whole line -- no union needed.

I'll finish the rear brake job tomorrow, and will report if there are any leaks in the fittings. I also plan to test the full range of motion of the SLS, to make sure that the rear axles do not come close to the hard lines at any point during their range.

brake lines or fuel... REPAIR
 

If they are rusted out replace them all not that hard to do order 25 ft of cunifer brake line from fedhill.com this line has been used for years on european cars is a nickle copper alloy mix will not rust or burst, bends easily and flares the easiest best bubble flares ever, I have used this stuff for years and it comes highly recomended by me and hundreds of others. replace the whole line don't do patches. fix it right the first time.:D