The rear brake lines on Hiro are shot. There are several rust-throughs along the underside of the body (all at the clamps). I've got the lines out, and, jeez, there are a lot of bends.

I've never done brake hard lines before, but it seems to me there are more bends than needed. I believe that some (most?) of these bends are there only because the brake lines were mounted very early in the manufacturing process, and were designed to be out of the way while other components were mounted to the shell. If I replicate the existing bends, I'll have to remove a lot of components to get them into place. My intent is to simplify the run when I recreate the lines, and that I should have full brake functionality when I'm done.

Does anyone see a flaw in this approach?

 

Follow my way, i have done both full lines on my car. Cut the old one out and match up to the new ones and tape/bend method. Slide the rear section in first then work towards the front.

The tool is king here.

https://www.northamericanmotoring.co...-the-same.html

 

@ECS Tuning is probably the best way.

I purchased a roll of nicop and bent everything by hand (and a beer bottle neck). Both rear lines were done in an evening, it wasn't terrible. Did all the exact same bends need to be made? Probably not exactly, but it would probably be faster to mirror what the factory did. Best of luck!

My supplies list:
25' of 3/16" ni-cop brake line
M10x1.0 bubble brake unions (to replace my trashed firewall unions)
M10x1 bubble steel tube nuts
Bubble flare forming kit
ATE TYP 200 fluid

Have a set of soft (or braided stainless) lines ready to install too. If your lines need replacing, chances are you won't be able to remove at the soft line connection. Or it will be far more frustrating than its worth.

 

I put in the right side tonight. I put on a nut and flared the end, then fed the line toward the back at the point where the lines leave the underside of the car and go into the fuel tank well. I ran it around the top of the fuel tank well, then down to the connection point to the brake line at the wheel. I then cut the front section about to the length of the junction at the bottom of the firewall, and fed it under the subframe from the back to the front. Another nut and flare, and it's ready to be screwed into the junctions and teased into its final position on the run. The nicop took the flares well and was very easy to work with and forgiving.

I need a 3/16 M12-1 line nut for the other side, which is delayed from Amazon. I think the local Autozone has them. If I get a chance tomorrow I'll finish the left side and post up some pictures.

 

They do need to be bent close to what you see - in cases, it needs to avoid suspension movement, and to prevent rubbing on other components. I did this - yes NiCop - nickel copper lines are good. Mini sells you steel lines that are difficult to bend well. AGS - American Grease Stick makes a good product. Also be aware - most fittings are 10mm. BMW/Mini use a 12mm fastener in some cases. I transferred over the 12mm in those cases - you will need to make flares to do that. If you are not skilled at this - get someone who is. It’s your life on the line, and possibly others.

 

The driver's side uses 12mm fittings at the bottom of the firewall and 10mm at the back. That line also uses 6mm tubing. None of that makes sense, since we're talking pressure, not volume. These are also the rear brakes, which provide a smaller percentage of the braking power. If 10mm 3/16" is good on the one side, then it's good on the other side. I'm going to use a 3/16" 12mm at the firewall junction and run 3/16" all the way back. I saw several posts that reported using 3/16" with no follow-up saying they died, so I think that will be fine.

I saw a post in another thread where someone was waxing ecstatic about a particular tube flaring tool, so I bought it. It is incredibly easy to use, pretty much fool proof, and it produces beautiful bubble flares (especially in that soft nicop).

 

I did our entire brake system on our Lemons track car with the generic split beam universal bubble flare tool. It took a LOT of practice to get right. Highly recommend skipping the autozone tool rental and go straight to the style linked above (trusting that it truly is foolproof). Save yourself a few hours of headaches and leaky joints.

 

We have this set on super sale. Schwaben Metric Bubble Flaring Tool Set , if you do your own.

I just used that tool above in our kit and did not have to flare anything.

But if you do need a flare kit down the road for anyone else.

https://www.ecstuning.com/b-schwaben.../006394sch01a/



The last post in that link above shows the step by step and what he ran into. https://www.northamericanmotoring.co...es-really.html

 

I got the left side line in last night. I had to cut off the forward flair and redo it twice. The first time because I forgot to put the nut on (of course) and the second because the flaring tool fell off the line while I was tightening it on, and I didn't notice that the nut slid off. But there was still enough line to get it reflared and to get to the junctions. It went together with a generous amount of anti-seize. I have M12 on the left and M10 on the right, both going into 3/16" tube to M10 nuts at the rear. I went to put the brake hoses onto the (new) calipers and I realized at some point I'd messed up and ordered the wrong brake hose kit (The one I ordered was for a 2005. Dummy.). It was nearly $200 and so long ago (January!) that I can't return it. Urg.

I ordered a basic pair of rear hoses and a metric crush washer kit from Amazon. It'll be here Friday.

I also ordered new plastic line clamps for the underside. They aren't BMW, but they look like they'll work. $12 for 40 of them.

 

I know this is an old thread, but it's a topic I know well. I haven't replaced lines on a Mini, (I don't have one yet, I'm shopping in the near future) but I have on 2 other cars, and about to do a 3rd one, when the weather dries out a little.

Nicopp is definitely the way to go on replacing metal brake lines. I don't know why they don't just make them with that, instead of steel that will eventually rust out. Maybe they do with newer cars, I always have older ones.

So all of you, can you tell me how old your Minis were when you had to replace the brake lines? Having had 3 cars (a Ford, a Saturn, and a Nissan) have rusty lines that broke, I'm a bit on the paranoid side about this.

Also, did you have to remove underside shielding to get to the lines? If so, how hard was it to remove, and were you able to reinstall it after? I've never seen the underside of a Mini.

Thanks for any info you can pass along!

 

I had to do one of the lines to the rear - left rear - mine is a Feb 2005 build - got it new. It was a NY car - now in semi retirement in San Diego. I did the line in 2020? And the master at the same time. Done in American Grease Stick NiCop from the junction under left floorboard to the flex line.

I did not have to move much to get to the line - if it was right rear, I would have to go around the gas tank.

 

Thanks, that's helpful. So the lines lasted about 15 years?

 

The original Steel - yes - if you live where they don’t use salt - much longer.

to be clear - we are just talking about the rigid lines. The rubber / flexible lines that go from the end of rigid to the calipers - they can last a long time. Mine are still original - this convo reminds me to check.

 

Circling back to the topic question : "Do the brake lines need this many bends?"
It has always been my understanding as with brake lines as well as headers, was - The reason being that the (both lines (e.g: rears) should be of equal length), which might be one reason for all the necessary bends (?).

Be it true or faulse...
Just something I remember from when I was a young adult building my first cars.

 

I don’t think so. Lines are filled with brake fluid. Your pressure on the pedal squeezes the pads. That is why we bleed - to get any air / space out. Length should not matter.

 

Headers are equal length to help scavenge exhaust gases from other cylinders to help engine performance.

In hydraulics, pressure is the same throughout the system, so the length of the tubing and number of bends is irrelevant. I think hard brake lines tend to have lots of bends so that they fit tightly and out of the way of most components.