Metal brake lines

[CypherWulf]

so, I was looking at my brake system to see why I don't have any hydraulic pressure, and I found the leak, the metal brake line going to the left rear wheel has rusted out, and needs to be replaced. The haynes manual has some general information, but nothing specefic. As I've never done this job before, I'd appreciate any tips you guys have. In addition, I need to know how long to expect this job to take, IE weekend job or something I can do after work during the week.

[Eagle]

Was this the line on the axle, or the line from the front distribution block back to the rear of the chassis?

[Wildman]

Here's about the best write up on this subject.

 

If you found one broken line now.......you'll find more latter, so......replace all the hard lines now, and even the soft line (from the body to the axle) and save your self some grief latter on.

[Eagle]

Here's about the best write up on this subject.

 

If you found one broken line now.......you'll find more latter, so......replace all the hard lines now, and even the soft line (from the body to the axle) and save your self some grief latter on.

Agreed. And eliminate the rear height-sensing proportioning valve while you're doing it. Getting rid of that means about three things less to fail.

[CypherWulf]

yah, it's the one running from the block out to the back of the chassis, thanks for the link, I'll study it carefully.

[FxRacing282]

Here's about the best write up on this subject.

 

If you found one broken line now.......you'll find more latter, so......replace all the hard lines now, and even the soft line (from the body to the axle) and save your self some grief latter on.

Agreed. And eliminate the rear height-sensing proportioning valve while you're doing it. Getting rid of that means about three things less to fail.

 

I'm learning about these brake proportioning valves in class. and other than the amount of things that may or may not go wrong. i am curious why people are always complaing about them? i know how much fun brake lines are and all. but if your going to do something then why not do it all and do it the right way? not saying that taking it off is bad as it does make the system more simple. I'm just curious why yall always say take em off.

[Eagle]

Reasons to remove the rear proportioning valve:

 

1) It's an extra steel line running the full length of the chassis. In other words, twice the possibility of a rear brake failure due to corrosion. I patched a rusted section of the primary line, and then had the secndary line burst while bleeding.

 

2) The rear proportioning valve is now +/- 20 years old, and it has a diaphragm in it. The one in my '88 exploded when I made a panic stop to avoid a doofus octagenarian who cut me off. You can't buy new ones, and I wasn't about to install a 20-year old junkyard part to replace a 20-year old part that had just exploded, so I bypassed it.

 

3) If you chase down my photo of a cut-open front metering block, you'll see that the one I sliced and diced would NEVER have provided the by-pass, emergency function it is supposed to provide. I have no way of knowing what percentage of them out there may be similarly defective, but any that are would leave you with virtually no rear brakes if you lost the fronts.

 

That's three potentially serious problems. Too many risks for me. I can handle too much brakes in the rear a lot better than I can handle none. When I bit the bullet and replaced the hard line all the way from the front to the rear, I plugged the by-pass port in the metering block, removed the (exploded) proportioning valve, removed BOTH rusted out steel lines and ran a single hard line from the metering block directly to the rear flex hose. I now have decent rear brakes for the first time since I put the truck on the road about 5 or 6 years ago.

[CypherWulf]

well, I have a friend who was an army mechanic before he reclassed to HVAC, so hopefully he has experience with bending, flaring and installing brake lines. TBH, I don't know all that much about the complete workings of a brake system, like I've said, the mantra was always "if you can't do it with a gerber and a hammer, get a mechanic" (you'd be supprised what you can fix on a HMMWV with those two tools tho) I'm not looking forward to sinking too much money into tools that I wouldn't use more than once tho, I might look into using the Auto craft shop on post (Full maintainance bay, lift and tools, just have to sign a waiver and pay an hourly rent) I'll talk over the project with him, but something has to happen soon, I really don't like the brakes the way they are, but I don't have a choice, as I have to leave my wife with a car during the day. Hopefully my friend can help me understand more about what I'm getting myself into.

[mjdoa]

I now have decent rear brakes for the first time since I put the truck on the road about 5 or 6 years ago.

 

Eagle,do you think that that valve might be

a contributing factor to the all around crap

rear brakes from the get go?

Becaues mine's still there,and if it'll get me better rear

brakes I'll junk it asap.

[Eagle]

I now have decent rear brakes for the first time since I put the truck on the road about 5 or 6 years ago.

 

Eagle,do you think that that valve might be

a contributing factor to the all around crap

rear brakes from the get go?

Becaues mine's still there,and if it'll get me better rear

brakes I'll junk it asap.

 

Absolutely. You do know what that rear valve does, right?

 

The theory is that pickups are light in the rear when empty, so without some "outside assistance" the rear brakes would tend to lock up prematurely under heavy braking (panic stops, and maybe even less than full panic mode). But -- when you're loaded, you need all the braking you can get. So, they put in this doohickie that reduces the amount of braking to the rear wheels when the truck is empty, and allows progressively more pressure to the rear as added weight lowers the bed closer to the axle. In fact, the default (unloaded) setting is essentially zero rear brakes, which is why Comanche rear brakes never seem to wear out.

 

I can't tell you how many Comanches I've looked under that had the push rod for the valve disconnected, missing, or installed in a way that clearly would render it unusable. Then there's the fact that the second line to the rear requires a special bleeding procedure that most independent shops probably aren't aware of and thus don't do. My best guess is that 2/3 of the MJs on the road, even if the doohickie is in the truck, don't have a functional rear proportioning valve. So what's the point of keeping it if it can't be serviced, can't be replaced, and nobody has the tools to adjust it? It MUST be adjusted if you lift (or lower) the truck, or it can't function as designed. How many people do that, as opposed to just unhooking the rod and zip tying the lever in a more-or-less horizontal position (thereby forever locking in zero rear brakes)?

 

Get rid of it. If you aren't comfortable with a vehicle that might lock up the rear brakes in a panic stop, go to Summit Racing, buy a Wilwood adjustable proportioning valve, and plumb that into the line leading to your rear wheels.

[FxRacing282]

well, thanks for the detailed response. :cheers:

[HOrnbrod]

[Absolutely. You do know what that rear valve does, right?

 

The theory is that pickups are light in the rear when empty, so without some "outside assistance" the rear brakes would tend to lock up prematurely under heavy braking (panic stops, and maybe even less than full panic mode). But -- when you're loaded, you need all the braking you can get. So, they put in this doohickie that reduces the amount of braking to the rear wheels when the truck is empty, and allows progressively more pressure to the rear as added weight lowers the bed closer to the axle. In fact, the default (unloaded) setting is essentially zero rear brakes, which is why Comanche rear brakes never seem to wear out.

 

I can't tell you how many Comanches I've looked under that had the push rod for the valve disconnected, missing, or installed in a way that clearly would render it unusable. Then there's the fact that the second line to the rear requires a special bleeding procedure that most independent shops probably aren't aware of and thus don't do. My best guess is that 2/3 of the MJs on the road, even if the doohickie is in the truck, don't have a functional rear proportioning valve. So what's the point of keeping it if it can't be serviced, can't be replaced, and nobody has the tools to adjust it? It MUST be adjusted if you lift (or lower) the truck, or it can't function as designed. How many people do that, as opposed to just unhooking the rod and zip tying the lever in a more-or-less horizontal position (thereby forever locking in zero rear brakes)?

 

Get rid of it. If you aren't comfortable with a vehicle that might lock up the rear brakes in a panic stop, go to Summit Racing, buy a Wilwood adjustable proportioning valve and plumb that into the line leading to your rear wheels.

 

Well, I must be one of Eagle's documented statistical (I'm sure) 1/3 who has a functional load leveling rear valve. I'm getting really sick and tired of hearing "dump the rear load leveling valve" in all cases. I've done the 96 booster upgrade, and converted to rear Explorer disks, and have retained the valve. The only mod I did was to extend the axle to valve arm rod to match the lift. I haul heavy loads all the time and the load leveling valve still does exactly as it should, biases the rear brakes exactly as it should. Should it ever fail due to an internal diaphram failure (which I've never heard of, most failures are caused by rotted out brake lines and the valve itself is sealed) I will then swap in a similar Toyota load leveling valve, because it works! With a Wilwood adjustable or similar, no bias compensation is provided to the rear wheels with a heavy load, it's constant. I suppose if you never haul anything, bypassing the valve is okay. I haul crap, so I'll be keeping it in the system as designed. Oh, and when bleeding the system after mods, following the recommended FSM procedure pertaining to the load leveling valve is definitely recommended. :cheers:

[CypherWulf]

okay, after a discussion of our finances, or lack thereof, the question came up, if I do go to a JY for my brake lines, will a newer Cherokee use the same ones? I'm thinking that a newer XJ might have some lines in decent shape, but I need to know how new would be too new.

 

Additionally, can someone please run me through the procedure for removing the brakelines, ie what tools I'll need, things to look out for etc. That would be much appreciated.

 

Also, in revewing the inventory of the local JY, they have a 89 Manche out there, I'll make sure to take lots of pics. (I might have my donor truck)

[Wildman]

Re-reading your original post........I assume your asking if a "newer" Cherokee, like what, '91-'96 or '97-02 would have the 'same' rear brake lines as a '86 MJ (as in your sign)

 

NO......even the Renix era rear brake lines are different, except the axle lines them selfs.

 

BUT!!!! :eek: ...........This is one item {Brakes in general} that You, me, or anyone should Never use, Used part on :eek:

 

Serious..........If your finances are holding you back, to buy some brake lines, even off the shelf stock lines, with the hollow nuts attached, then maybe you should park the MJ until the funds are available to at least replace the rotted out line, or do the proper 'front to rear' line replacement, and replace what ever else is needed, IE: wheel cyl's, shoes, hardware, soft lines.

 

I know, once you start replacing one line, on a '86, that's 23 years old, you will find other problems, and that's what I've said before, just plan on replacing everything at once, in other words......'re-built' the entire existing brake system.

 

It's one thing to get the truck running, and going down the road, like you need fuel, spark, and air for the thing to run........and once it's running, and clipping along the highway............how do you stop it????

 

If your drivers floor is rotted out, you'll be fine, cause that's how Fred Flintstone stopped his car :D

 

I think others will agree, that Used brake parts are out, used brake fluid is out, used brake lines are out.

 

I mean........if your started went, and you re-placed it with a used one, that's one thing.......but used brake lines??? No, and I'm wondering if the JY would even sell them to you??? :hmm:

 

If you think I'm harsh or off the wall on this, fine, but, I really don't want to read your next post in the Pub on how you when flying down the CO Mountain at 80 mph with no brakes, and you finally stopped rolling when you hit the fence at the Mexico border :roll:

 

I live far from you, so the chance that you'll plow in to my rear end is slim, I just have to deal with the other idiot's on the road around here :roll:

 

You should use "flair" wrenches on the hollow nuts, and fittings, cause the standard open end wrenches only 'hold' two sides, and the chance of rounding off the fitting heads is very high.

 

As far as cost for this........a complete brake job, lines and all from the front to the rear should be under $200 for all the parts, including drums if you need, and maybe under $125 if your drums are usable now.

 

That would be less that the bus ticket to get you back from where ever you stopped coasting from........or less that what your insurance rates would increase next year :brows:

 

Just replacing the rotted out line now........maybe what......$25???

 

Stopping where you want to stop..........Almost Priceless.

[mvusse]

Metal brake lines in fixed lengths with the nuts already attached would cost less at any auto parts stores than the gas to drive to the JY. You just have to bend them yourself. If you want to cut them down to exact length you need, a small tubing cutter is like $5 and Lowe's has a $10 flare tool that will work for brake lines, available in the plumbing section, not the tool section.

 

When I replaced a busted line that had been fixed by the PO by pinching it shut (so I had no rear brakes at all) I was limited on funds and replaced just that section. Afterwards I found the next section had also rotted through. Then when bleeding the brakes I blew out the next section. I then found one wheel cylinder was shot and the self adjuster parts had been turned into rust dust on the other wheel. I now have new hard lines all the way from the front distribution block (under the master cylinder) all the way back to both rear wheels. A new wheel cylinder and new self adjuster mechanisms. Bad thing is, between 7 trips to Advance, 8 miles away, I probably spent more money in gas than I did on parts. 112 miles to and from the parts store!

[Wildman]

 

That's what I found the hard way too......it's just better to get everything at once, and replace it all, bleed it one time.....and your done, and hopefully done right.

 

Watch that flare tool from Lowe's, that's only for a single flair, water lines, not the Double flair that's needed and legal for brake lines.

[Eagle]

On both my XJ and my MJ I have tried replacing rusted-out sections of brake line, only to have another section explode while trying to bleed the brakes after the repair.

 

Do NOT try to save pennies by using junkyard brake line.

[Tomahawked]

Harbor Freight has a double flare tool that was less than $8. It works great. Done many brake lines so far with no regrets. If you are up in the rust belt, might as well go ahead and replace everything thats steel on truck, not just the brake lines. With 20+ years of use, can't last forever. Just had to replace the brake lines on my `55 F100. Over 50 years and completely original something had to finally give up.