Rear brake line corrosion (again) *Guide on how to fix*

[steve_naive]

Edit: Scroll down for DIY guide.

Just had an MOT fail on a rear brake line. Pretty sure the tester mentioned something about the hoses, so I'm guessing it will be the short bit of pipe I've been reading about.

Previous owner claimed he'd replaced all the steel lines with copper, years ago, so maybe he had neglected to do this part.

I've seen the advice to delete the short piece of hard line with a longer length of braided hose, my question is do I go with one long piece each side or two lengthened pieces? I'll contact the seller but I think the two piece per side solution would look like this:

https://www.ebay.co.uk/itm/283597603638?fits=Car+Make%3ABMW%7CPlat_Gen%3AE85%7CModel%3AZ4&hash=item4207bc0336:g:xMAAAOxyVLNSwuEt&amdata=enc%3AAQAIAAAA8C6ITQBclo5a4Vk9zYRDHvX1%2BCl3%2Bki9%2FyK5oMYZbi%2B56EJhBNrcfOQzVZ7IHthCPuaoyzIfactMorU9RXpTm%2F1sa5OHV4CGE%2FG3JTTx6X8Wg%2FPI%2FIbIzEP7%2BIkYd2%2BSSzvoypIgIEIrh704cOAvk1qW3FO3KYl4F84geS9a%2F9K4m%2BX6SFGJ1k%2Bd7vOMQwUlaB3g3mP0az%2BjQnH19kBKI5d%2BqDGSgmEPJLNHlt50lb4En456yOu2q1QBz7ue7o%2BHhj8SaLoB%2F%2F1BJxPluzKGVcJlPRJAHgmdmhWmWi8rfIJVjHNtNCWDWk0ES3vRwvT3CQ%3D%3D%7Ctkp%3ABk9SR-Ld3-DlYg

Any extra bits I should order? I'm reading that the brackets and nuts could be an issue. TIA.

 

[Zedebee]

Before you do anything else, get the wheel off and see what’s actually corroded. Sometimes the lines are just covered in crud which you can clean off, but usually the corrosion is on the main line where it disappears under the plastic undertray. No point in spending money unless it’s actually going to fix the problem.

 

[steve_naive]

Before you do anything else, get the wheel off and see what’s actually corroded. Sometimes the lines are just covered in crud which you can clean off, but usually the corrosion is on the main line where it disappears under the plastic undertray. No point in spending money unless it’s actually going to fix the problem.

Yes, just thinking ahead.

 

[enuff_zed]

What was the actual detail of the fail?
You say corrosion, but then you say the tester said hoses, which are the flexible rubber sections.
Definitely check first before you dive straight in.

 

[deltasierra]

I always watch the test being done if there is a problem I ask the tester to show me what he wants done.
Those long rear brake pipes must be a pig to replace.

 

[deltasierra]

I always watch the test being done if there is a problem I ask the tester to show me what he wants done.
Those long rear brake pipes must be a pig to replace.

 

[colb]

I changed my flex hoses for a two piece stainless set for the rear and single ones on the front you can get 1piece sets for the rears but you will need to secure them halfway with a zip tie, I managed to use the stock midway securing clip with the two piece set. Do check out if the hard pipes have been changed for copper by previous owner. Pay particular attention to where the pipes emerge from the plastic underbody channel in the nearside rear wheel arch for corrosion, they get blasted by the rear wheel. Replacement pipes are usually spliced into the long run under the plastic cover. Mine were cleaned and then smooth Hammerite paint applied as they were not corroded. Once dry I put plastic split conduit over the pipes to give added protection to them.

 

[steve_naive]

What was the actual detail of the fail?
You say corrosion, but then you say the tester said hoses, which are the flexible rubber sections.
Definitely check first before you dive straight in.

No, I said that there's a hard line in between two hoses at the rear, and he mentioned something about the hoses when explaining the corrosion so I'm assuming he meant that piece. Maybe not, I'll know when I check.

@deltasierra I couldn't watch what he was doing because in Northern Ireland the tests are done in a massive hanger and they had closed the door. I didn't see the car until they'd driven it back out to me.

@colb cheers. I'll give the two piece set a whirl if it turns out to be the bit I'm thinking it is.

 

[Darkangelv2]

What was the actual detail of the fail?
You say corrosion, but then you say the tester said hoses, which are the flexible rubber sections.
Definitely check first before you dive straight in.

No, I said that there's a hard line in between two hoses at the rear, and he mentioned something about the hoses when explaining the corrosion so I'm assuming he meant that piece. Maybe not, I'll know when I check.

@deltasierra I couldn't watch what he was doing because in Northern Ireland the tests are done in a massive hanger and they had closed the door. I didn't see the car until they'd driven it back out to me.

@colb cheers. I'll give the two piece set a whirl if it turns out to be the bit I'm thinking it is.

Have you completed this work as yet?

I’ve had an MOT failure (finally) and am struggling to find a garage that can complete the work until JANUARY!

I did however find you can get full length braided stainless replacements which I am mighty tempted by…..

https://www.prolinebraidedlines.com/products/bmw-e46-inc-m3-abs-retain-replacment-brake-line-kits?variant=31311172239441

 

[bigwinn]

What was the actual detail of the fail?
You say corrosion, but then you say the tester said hoses, which are the flexible rubber sections.
Definitely check first before you dive straight in.

No, I said that there's a hard line in between two hoses at the rear, and he mentioned something about the hoses when explaining the corrosion so I'm assuming he meant that piece. Maybe not, I'll know when I check.

@deltasierra I couldn't watch what he was doing because in Northern Ireland the tests are done in a massive hanger and they had closed the door. I didn't see the car until they'd driven it back out to me.

@colb cheers. I'll give the two piece set a whirl if it turns out to be the bit I'm thinking it is.

That’s correct each side goes from the hard line under the car to a flexi on the trailing arm to a hard line (which are sided so get the right one) to the final flexi that goes to the calliper

You could replace the flexi/hard/flexi with single braided hoses which will probably be the same price as the other components

 

[Darkangelv2]

Just as an FYI - after being told i would need to wait until JANUARY to book my car in for the hard lines/pipes to be replaced, i went ahead and ordered the complete braided setup from Proline.

I'll let you (and anyone else who gets hit with this dreaded corrosion fail) how i get on and whether these are a decent alternative solution.

 

[bigwinn]

I’ve never been let down with them- good luck!

 

[chanlon1]

No, I said that there's a hard line in between two hoses at the rear, and he mentioned something about the hoses when explaining the corrosion so I'm assuming he meant that piece. Maybe not, I'll know when I check.

@deltasierra I couldn't watch what he was doing because in Northern Ireland the tests are done in a massive hanger and they had closed the door. I didn't see the car until they'd driven it back out to me.

@colb cheers. I'll give the two piece set a whirl if it turns out to be the bit I'm thinking it is.

Mine failed at the Ards MOT centre back in Feb/March with corroded rear pipes.
I had a place in Bangor replace them, think it was £130 I paid.

 

[steve_naive]

Just as an FYI - after being told i would need to wait until JANUARY to book my car in for the hard lines/pipes to be replaced, i went ahead and ordered the complete braided setup from Proline.

I'll let you (and anyone else who gets hit with this dreaded corrosion fail) how i get on and whether these are a decent alternative solution.

IMG_2644.jpg

I used Wezmoto because that’s what I already had fitted on the fronts. Also went for the single line solution in the end, it worked like a charm.

This is what you need to remove:

The rubber lines can be snipped if it makes it any easier but be sure you’ve ‘cracked’ all the bolts first because some of them may be rusted on hard!

The top nut (to the right in this pic) is connected to a short, threaded metal tube that goes through a bracket, one of mine was fused into the bracket hole so I had to remove the hard line that’s on the other side of the bracket, put it to one side, hold a bolster chisel behind the bracket to avoid snapping it off while I hammered the stuck nut/tube out.

Lower down there is a plastic bracket held on by an Allen bolt (I think).

Then there’s another bracket, I would advise removing the 10mm mounting bolt and taking the bracket off with the brake line because it will likely be rusted tight and you might want to reuse it. Once off the vehicle, I had to Dremel the old brake line off.
In the end I didn’t reuse this bracket because the wezmoto lines have pre installed plastic washers that wouldn’t pass through. You could leave it off and just use a cable tie if you feel it’s even necessary.

Finally, there’s one last bolt to remove that feeds straight into the calliper, easy.


Buy one of these 9/11 flare spanners (cheap!) and pre apply wd40 to any rusty bits.

https://www.halfords.com/tools/hand-tools/spanners-and-wrenches/halfords-professional-flare-spanner-470112.html?cm_mmc=Google+PLA-_-Motoring%3ETools%3EHand+Tools%3ESpanners+and+Wrenches-_-Motoring%3ETools%3EHand+Tools%3ESpanners+&+Wrenches-_-470112&_$ja=tsid:%7Ccid:17363835999%7Cagid:%7Ctid:%7Ccrid:%7Cnw:x%7Crnd:11877500569102401689%7Cdvc:t%7Cadp:%7Cmt:%7Cloc:1007270&gad_source=1&gclid=CjwKCAjwnOipBhBQEiwACyGLusEljnxDerS1IImX_GOdhhVFb9ri51n1cnfESTPLy0QTHROBr5fV8xoClosQAvD_BwE

Can also be used on the calliper nipples. ^

You’ll need to bleed the brakes afterwards. I used this Vizibleed Brake and Clutch Bleeding Kit (cheap!) and it worked fine.
https://www.halfords.com/tools/hand-tools/automotive-tools/europat-vizibleed-brake-and-clutch-bleeding-kit-321141.html?_gl=1*qvtlcc*_up*MQ..*_ga*MTk5MzE0MDM4Ny4xNjk5Nzk2MDc5*_ga_VK44BRER97*MTY5OTc5NjA4MC4xLjEuMTY5OTc5NjExMi4wLjAuMA..

There’s YouTube videos on how to use it.

Before you start cracking brake lines, put some cling film under the brake cap and then tighten the cap back on to minimise fluid loss.

Oh and don’t forget to use a rag to catch any brake fluid - it will eat everything!

All in all it’s an easy job that’s made a faff with rust!

 

[Darkangelv2]

Ah, so it WAS the short piece that had failed the MOT.

Apologies, I was referring to the entire line (ABS to both rear). Didn’t mean to hijack.

Good job

 

[steve_naive]

Ah, so it WAS the short piece that had failed the MOT.

Apologies, I was referring to the entire line (ABS to both rear). Didn’t mean to hijack.

Good job

Oh so you’re replacing the lines under the plastic as well??
It hadn’t crossed my mind that you could do that.
A how to guide could come in very useful considering the amount of corrosion failures that crop up.

I know the previous owner replaced everything (except the short pipe I replaced) with copper pipes and said it was an absolute ballache of a job. Your solution (if I’ve read it right) seems much simpler.

 

[Darkangelv2]

Exactly this.

My theory being i can feed everything through all the tricky routes given the flexibility, right next to the existing hard-lines, before disconnecting & removing the old then securing & connecting the new.

I'll try and throw up some pics on here too - may make this thread helpful for both issues going forwards.