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Replacing my third cracked hard brake line

2K views 34 replies 12 participants last post by  jeepwhore 
#1 ·
I'm on my third hard brakeline on the passenger side rear axle. While driving today, I felt the soft pedal and had barely any brakes by the time I got home. I found brake fluid all over the rear passenger tub and axle again.
The last two had a very small crack under the nut that goes into the "Y" on the axle. That hard brake line comes off that "Y" and its not at a sharp angle by any means, but the last two were cracked right at the nut. I haven't been able to pull this line off, and won't until the end of the weekend, but I'm sure its cracked in the same spot. With the line installed, you can't see any cracks, but when you take the line off and slide the nut down, the crack is there.
The "Y" connection is secured with the bolt on the axle, and the hard line goes up to a bracket on the frame. I pushed on the hard brakeline, and its secure and didn't move, so it's not like the lines are moving around.
You can't see the crack in the pics, again due to it probably being under the nut, but the problem is circled in red.
Any suggestions?
 

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#3 ·
Matt, I see what you're saying by looking at the pic. When I got home, I tried tightening the line at the connection and it did move forward, (turning it towards the drivers side), on the axle as you see it. Its hard to get a better pic, but the hard line came off that connection straight and not at any sharp angle that would cause it to break.
 
#6 ·
Could the rubber line be pulling the block around, and flexing the steel lines? (as in kind of turning the block back and forth on it's mounting bolt)
Plenty of slack in the rubber line? Bolt that holds the block to the axle tight?

Seems weird that it has happened a few times at the same spot.
 
#8 ·
the fitting that's leaking seems to be too long for the application. Not sure what that would do, just an observation when looking at the other side's fitting.
Maybe have someone operate the brakes on/off while you observe the brakes lines at the 'T' to see if there's any observable flexing in the line/s. This is probably a long shot, but what the hey...
 
#9 ·
If the fitting isn't bolted real solid to the axle, it can work back and forth as the axle moves up and down pulling on the flex hose causing a stress crack in the steel line. The fitting does look crooked on the axle.
A friend had his CJ ordered off the road in a roadside inspection because that fitting wasn't bolted down. They forced him to get a new safety inspection before he could drive it again.
 
#10 ·
I appreciate the replies. I believe I figured out why the hard lines are breaking, but the solution may not be real easy. I didn't mention that I have rear discs on mine, so the hard line comes off that "Y", and goes up to a bracket on the frame. The soft line then comes off the other side of that bracket and goes to the caliper.
So when I installed this, I have a fixed position on the axle, (the Y connection), going to a fixed bracket on the frame. That means when the axle moves up and down the hard line has to flex somewhere, and eventually that nut probably cuts into the line.
When building the Jeep I started with YJ rear springs which had a bunch of flex in them, but I ended up putting brand new CJ springs on it, which are very stiff and don't have much flex. I bet if I had kept those YJ springs on this would have been a constant issue with the axle moving up and down farther.
So really what I need is a rubber line from the Y connection up to the bracket so that it can flex. If I can't find that long of a rubber line, I'll have to figure out how to let that pass side brake line hang free so it can move with the axle. I would probably need to keep the connection at the frame bracket in place so its secure, and maybe let the Y connection on the axle hang free?
 
#11 ·
I appreciate the replies. I believe I figured out why the hard lines are breaking, but the solution may not be real easy. I didn't mention that I have rear discs on mine, so the hard line comes off that "Y", and goes up to a bracket on the frame. The soft line then comes off the other side of that bracket and goes to the caliper.
So when I installed this, I have a fixed position on the axle, (the Y connection), going to a fixed bracket on the frame. That means when the axle moves up and down the hard line has to flex somewhere, and eventually that nut probably cuts into the line.
When building the Jeep I started with YJ rear springs which had a bunch of flex in them, but I ended up putting brand new CJ springs on it, which are very stiff and don't have much flex. I bet if I had kept those YJ springs on this would have been a constant issue with the axle moving up and down farther.
So really what I need is a rubber line from the Y connection up to the bracket so that it can flex. If I can't find that long of a rubber line, I'll have to figure out how to let that pass side brake line hang free so it can move with the axle. I would probably need to keep the connection at the frame bracket in place so its secure, and maybe let the Y connection on the axle hang free?
Ouch, yup you for sure have it figured. Why go down to the axle then back up? I think I would just T the hard lines over to where the two flex lines drop to the callipers.
 
#13 ·
Why go back up at all? There are thousands of models that have the flexible break line from the axle to caliper. One of those should work.
I just converted my KJ from a one piece ($$$$) solid to crimped rubber line to a two piece hard line to generic rubber line to the caliper. (¢¢¢)

I was thinking of doing something on similar on my front axle. One flexible line from the center out to the calipers. Less strain on the hoses from the frame to each caliper.
Ford does this all the time on the 4X4 Trucks.
 
#14 ·
solid to crimped rubber line to a two piece hard line to generic rubber line to the caliper
I think I have an idea of what you're saying. I've seen the two piece brake lines that have a hard line connected to a rubber line. I need to keep the Y secure to the axle and the line connected at the frame bracket, so I could come off that bracket with a short hard line, connect a rubber line to that and run it down to the Y. That would basically be the same setup. Then I'd have all the lines secure and the rubber line would allow for movement.
 
#16 ·
I'm getting confused....:confused::confused:

Come down from the frame in the center of the crossmember with the rubber line from this piece.


Go out each axle tube with a piece of steel line.


Then a short piece of rubber, or braided line from the steel line, to the calipers. This is needed to allow the calipers to move.


It should look just like Speig posted. Here's mine.
 
#17 ·
Ok, the way you're showing it is basically how I was thinking except I was coming off the center brake line with a rubber line. Then run a hard line off that up to the rubber line already on the caliper. Your way eliminates a couple unions that could leak. I can't tell by either pic, but is there a bracket or something to support the lines up by the caliper?
 
#21 ·
I'm hoping to ressurect this thread as, somehow, I've got to get 'Black Betty' back to being a DD. I'm hoping I'm on top of those issues I've posted elsewhere here, and just as I was getting her ready to go I got a brake light. Checking the Master Cylinder the rear reservoir was down to zilch. I inspected the Proportioning Valve and no sign of leaks there but my left rear backing plate was caked with crud and the rear differential seemed to be covered with brake fluid.
The brake lines are rubber all the way from a crossmember in front of the fuel tank, I don't know if this is stock from 1978 or an old repair.

I'm hoping for a little guidance and this is the first time I've dealt with brake lines. Any strategems to help me repair this I would be most grateful for. I'll post pics as soon as I am able, I'm thinking I may have to hose off the whole works with Brakekleen before I proceed.
 
#32 ·
I'm hoping to ressurect this thread as, somehow, I've got to get 'Black Betty' back to being a DD. I'm hoping I'm on top of those issues I've posted elsewhere here, and just as I was getting her ready to go I got a brake light. Checking the Master Cylinder the rear reservoir was down to zilch. .......
Wait. The "rear reservoir" or " the reservoir for the rear"

if it was the "rear reservoir" that's for the front brakes.....
 
#24 ·
They are rubber all the way from the crossmember to the back plate?

It should be rubber from cross member to vent on axle tube. Then hard steel line to brake cylinder.
Yep! That's what I saw last night John. Going to jack 'er up and take a couple of pics to post for tomorrow. I noticed that the rubber lines from the crossmember were held loosely with a zip tie and it looks as though the right line was abraded by the spinning u-joint at the differential. I've seen a few setups where the flexible line is only at the wheel hub, otherwise steel over the top of the differential and axles, but I still don't know if this is correct or an improved setup for my old CJ.
 
#23 ·
I would clean everything off really well as you said you were going to do. Even with all my lines being clean, the break I had in the line was so small, I still couldn't find it easily. If you see brake fluid on the diff, you'll know the general area, but mine was squirting so hard, the spray ended up pretty far from the cut.
Clean everything, fill the reservoir, then have someone pump the brakes while you are under the rear, and you'll then see exactly where the problem is. Just make sure and wear safety glasses....
 
#27 ·
I jacked up 'BB' last night (lost one of my damm jackstands) and took a few pics before I begin.


from under the differential


...another closer up


to the left of the differential


close up near the right hub


backing plate right side


and left side, there seems to be a loose washer on this line at the backing plate.

To be honest I don't know what I'm looking at, over the course of the last month I've been in an accident that totalled my van, had a stuck intake valve on the jeep, the carb on the jeep was subbed out to a carb "expert" that botched the rebuild 3 times, bought another truck, motor went bad in it (being replaced by the shop) so as you all can imagine I'm more than a little dizzy (still working 7 days per week),
 
#30 ·
Yep....and judging from how dry it is I don't think that's the source of your leak. Follow that line on each side from the backing plate to the junction by the diff. If there is no moisture follow the line up to the cross member and towards the proportioning valve until you find a wet area.
 
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