Blowing brake lines after 8.8 swap

Brakes worked fine before swap and now after I have blown the back right line twice in 2 days. I drove maybe 40 miles on the first one before it blew then this second one blew within 5 miles of driving. It seems like most of the pressure is going to that one corner based on the amount of heat I felt when I pulled over. The rear with the 8.8 is now disks versus the old drums with the 8.25 and nothing else in the brake system was changed. Both lines were brand new rubber hoses. When I bled the brakes fluid flowed perfectly from all four corners, as in there isn’t anything stuck in the lines preventing the other brakes from receiving fluid but the one that blew was the only corner that felt hot when I stopped.


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They call it a coincidence, other than that there is no reason. Did you buy new lines when you installed it?

Yeah the rear is all new lines the first set is from rock auto and the new one today that blew was from oreillys.


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One of the news stories a few months back was about a shortage of rubber. I wonder if that led to some poor choices in someone's supply chain. You may be the guinea pig who is serving as quality control.

At this point I would be inclined to go to a junkyard and look for a decent brake hose there. I doubt it would be any worse than what you have already tried.

Then go back to O'Reilly's & get a refund - probably be more trouble than it's worth trying to get any satisfaction out of RA.

Replace them with SS and be done forever!

Unless the problem is excessive pressure, rather than very poor quality brake lines, 'cos then the next weakest part is going to fail.

I ordered a brake pressure gauge from Amazon and I’ll try to measure the psi at all four corners tomorrow to see if it was a giant coincidence of two failing or if something happened and now I have excessive pressure in one place.


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The MC isn't capable of excessive pressure, you might find a line with decreased pressure because of restrictions, but......

So after a swap to stainless braided, zj proportioning valve guts installed, and a full system bleed, I measured 50 kg/cm^2 or 711psi on the driver side and 43kg/cm^2 or 600psi passenger side. No reason for the new lines to break like the last two, but the pressure seams pretty low to me.




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