So just passing this on in case anyone else runs into the same problem, a deformed original brake hard line nut that would not thread into the new flexible hose. I had this happen in the past with a front caliper hard line nut, in that case I had to replace the short hard brake line going to a front caliper.
I fought with this one (trying to get the nut threaded into the hose) for awhile before coming to a decision point, try to fix the deformed/flared nut or replace the hard line, so went with sanding the nut tip and flared hose tip with Emery cloth until it fit.
So someone might wonder if the flared tube will still seal after sanding the nut and tube?? Answer IMO is there are plenty more threads on the nut so it can be tightened further in a thousandth of an inch or so to squeeze everything back together again.
Long Story:
I decided to replace both rear calipers because the old ones were the originals, had likely been fully extended for years, the pistons were developing significant corrosion, and when they were first bled (new to me FZJ80 at the time), rusty sludge came out. Likely that the PO had never bled the brake system.
So when I went to install the flexible line on the right rear, something that should take maybe 15 minutes, I couldn't get the nut threaded into the hose.
Tried all the usual tricks, making sure the hose and nut were lined up, checked the threads of both the nut and the hose, etc,etc. all the while brake fluid is dripping on my newly painted dust shield so took some close-up photos of the flared tube end and the nut then studied them.
The photos tell the story:
This is how it started, the unthreaded tip of the original hard line nut was deformed (from being compressed) along with the tubing flare a bit squished. IMO it was the deformed nut tip that prevented the nut from seating properly into the hose union which then wouldn't allow the threads to line up.
Next shows both the hard line nut and hose fitting; note that the hose clip was removed when attempting to thread the nut into the hose. Not shown was a test fit of the hose while loose ie: not in the bracket, just to see if I could thread them together after sanding the nut tip
Click twice to magnify, note the tip of the nut is flared from compression:
I ran a M10 x 1mm cleaning tap/thread chaser (non-cutting) into the hose fitting to ensure the threads weren't buggered, they weren't:
Next photo shows the unthreaded tip of the nut after sanding around the flared lip for at least a few minutes with Emery cloth. Hard to tell at first glance but the flared edge or rim has been taken down a bit (compare to the first two photos above).
Trivia: the Q tip with some of the cotton removed was shoved into the tubing to stop the flow of brake fluid but still allowed me to sand the lip of the nut and the squished flared tube end.
Click twice to magnify for a closer look:
A couple of tips when replacing the caliper flexible brake lines (hoses):
Always use a second wrench on the old hose fitting when removing the hard line nut (use a 10mm flare nut wrench for the nut). This prevents you from putting too much strain on the hose bracket. For the rear brakes that bracket is spot welded to the dust cover. Penetrating oil can help break the nut loose, or even a few seconds of heat from a torch (carefully) as a last resort (protect rubber bits and wires). Everyone has their own tricks to get things unstuck, what I do is spray in quick succession penetrating oil after light heating ie: not red hot. Idea is to heat shock the fasteners a bit but also hoping to help pull some penetrating oil into the threads. IDK if that makes sense but it seems to work.
IME there are a couple of different methods (sequence of steps) to go about installing a new brake hose, but most include not installing the clip until the nut gets started into the line. This helps to line up the hard line nut and hose a bit easier.
Another method (what I did) while working on the rear calipers is to also not connect the banjo fitting end of the hose to the caliper until I got the hard line nut started into the hose fitting. Of course the hose has to be inserted into the hole in the bracket before you attach the hard line.
Then I connect the banjo bolt (torque to 22 ft lbs if you have a torque wrench and short 14mm socket that will fit) using two new copper gaskets.
You do have to ensure you don't twist the flexible hose when you install it, that's one reason there are "fingers" on the caliper to hold the caliper end in the correct orientation. But there's also a straight line of lettering printed on the hose to help visually check that it's not twisted during installation.
Last photo shows the right rear brake flexible hose being attached to the caliper.
Photo taken to ensure both copper gaskets ("Packing, Union") are still in place before tightening down the banjo bolt. I used a very slight smear of thin but tacky cavity wax to help hold them in place during assembly.
After the banjo bolt is tightened down I go back and finish tightening down the hard line nut (use a wrench on the hose fitting also), then last attach the clip by sliding it down over the hose fitting and tapping it in place while holding some downward pressure on the hose against the bracket.
I fought with this one (trying to get the nut threaded into the hose) for awhile before coming to a decision point, try to fix the deformed/flared nut or replace the hard line, so went with sanding the nut tip and flared hose tip with Emery cloth until it fit.
So someone might wonder if the flared tube will still seal after sanding the nut and tube?? Answer IMO is there are plenty more threads on the nut so it can be tightened further in a thousandth of an inch or so to squeeze everything back together again.
Long Story:
I decided to replace both rear calipers because the old ones were the originals, had likely been fully extended for years, the pistons were developing significant corrosion, and when they were first bled (new to me FZJ80 at the time), rusty sludge came out. Likely that the PO had never bled the brake system.
So when I went to install the flexible line on the right rear, something that should take maybe 15 minutes, I couldn't get the nut threaded into the hose.
Tried all the usual tricks, making sure the hose and nut were lined up, checked the threads of both the nut and the hose, etc,etc. all the while brake fluid is dripping on my newly painted dust shield so took some close-up photos of the flared tube end and the nut then studied them.
The photos tell the story:
This is how it started, the unthreaded tip of the original hard line nut was deformed (from being compressed) along with the tubing flare a bit squished. IMO it was the deformed nut tip that prevented the nut from seating properly into the hose union which then wouldn't allow the threads to line up.
Next shows both the hard line nut and hose fitting; note that the hose clip was removed when attempting to thread the nut into the hose. Not shown was a test fit of the hose while loose ie: not in the bracket, just to see if I could thread them together after sanding the nut tip
Click twice to magnify, note the tip of the nut is flared from compression:
I ran a M10 x 1mm cleaning tap/thread chaser (non-cutting) into the hose fitting to ensure the threads weren't buggered, they weren't:
Next photo shows the unthreaded tip of the nut after sanding around the flared lip for at least a few minutes with Emery cloth. Hard to tell at first glance but the flared edge or rim has been taken down a bit (compare to the first two photos above).
Trivia: the Q tip with some of the cotton removed was shoved into the tubing to stop the flow of brake fluid but still allowed me to sand the lip of the nut and the squished flared tube end.
Click twice to magnify for a closer look:
A couple of tips when replacing the caliper flexible brake lines (hoses):
Always use a second wrench on the old hose fitting when removing the hard line nut (use a 10mm flare nut wrench for the nut). This prevents you from putting too much strain on the hose bracket. For the rear brakes that bracket is spot welded to the dust cover. Penetrating oil can help break the nut loose, or even a few seconds of heat from a torch (carefully) as a last resort (protect rubber bits and wires). Everyone has their own tricks to get things unstuck, what I do is spray in quick succession penetrating oil after light heating ie: not red hot. Idea is to heat shock the fasteners a bit but also hoping to help pull some penetrating oil into the threads. IDK if that makes sense but it seems to work.
IME there are a couple of different methods (sequence of steps) to go about installing a new brake hose, but most include not installing the clip until the nut gets started into the line. This helps to line up the hard line nut and hose a bit easier.
Another method (what I did) while working on the rear calipers is to also not connect the banjo fitting end of the hose to the caliper until I got the hard line nut started into the hose fitting. Of course the hose has to be inserted into the hole in the bracket before you attach the hard line.
Then I connect the banjo bolt (torque to 22 ft lbs if you have a torque wrench and short 14mm socket that will fit) using two new copper gaskets.
You do have to ensure you don't twist the flexible hose when you install it, that's one reason there are "fingers" on the caliper to hold the caliper end in the correct orientation. But there's also a straight line of lettering printed on the hose to help visually check that it's not twisted during installation.
Last photo shows the right rear brake flexible hose being attached to the caliper.
Photo taken to ensure both copper gaskets ("Packing, Union") are still in place before tightening down the banjo bolt. I used a very slight smear of thin but tacky cavity wax to help hold them in place during assembly.
After the banjo bolt is tightened down I go back and finish tightening down the hard line nut (use a wrench on the hose fitting also), then last attach the clip by sliding it down over the hose fitting and tapping it in place while holding some downward pressure on the hose against the bracket.
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