WahooSteeler Posted November 18, 2009 Share Posted November 18, 2009 This past weekend I finally got around to spending a little time with the MJ. I was installing my Edelbrock shocks on the rear when I got bit in the arse by the Jeep maintenance monster. I was installing the left rear shock and tapping the top mount on to the stud with a rubber mallet when I noticed a drip. Damn brake line(s) were leaking at the T-connector going to the height prop rod and regular line. This was not a discovery, this was new. I must have hit one of the lines with my arm or something as I was swinging at the shock mount. I haven't made a real close inspection of it all as I finished up on the shocks and then it was dark. There is no break in the line and it is hard to tell if they are rusted because there is a lot of road grit on them. I'll need to get back under there and clean them off to get a better look at it all. That being said, assuming the worst and that I have to replace some hard lines, I did some searches on brake topics. Of course the other part of the equation is whether or not to keep the height valve. Currently it is not hooked up but since I use the truck a lot for hauling heavy loads, I thought it would be a good idea to hook back up at some point. So I'm looking for input as to repairs and/or replacement of the line(s) and input on the height valve. I know most people say junk it. Also to note, I'm 90% sure I'll be taking this work to my mechanic since I don't want to mess with brakes and such. It's probably a little beyond my skill set as it is, and I definitely don't have the tools if I need to install and flare new hard lines etc. :dunno: On a positive note, a quick drive around the block (I still have front brakes) and the ride with the new Edelbrocks (I aimed for every bump in the road) was fantastic. :banana: Link to comment Share on other sites More sharing options...
maddzz1 Posted November 18, 2009 Share Posted November 18, 2009 I broke a line on the MJ 2 weeks ago when bleeding the brakes after a 95-96 double booster upgrade. Then 2 days ago found another broken one on the XJ (thought it was the wheel cylinder originally). The rear line are very easy to replace. They come with the correct size fittings and they are already flared. Flaring is not hard tho. Link to comment Share on other sites More sharing options...
Eagle Posted November 18, 2009 Share Posted November 18, 2009 I won't "recommend" this, because it's probably illegal, but if it were my truck I would remove the height-sensing valve and eliminate that second hard line from front to rear. One less line to rust, one less potential leak/rupture to worry about. Actually, TWO less ruptures to worry about. I base this on my own experience. The height-sensing valve on my '88 MJ blew out when I had to make a panic stop. They aren't available, so I just eliminated it. In the process, I also plugged the outlet for the bypass line on the bottom of the front metering block, and replaced the entire hard line from the metering valve to the flex hose at the rear axle. The effect of this is that I now have 100 percent (unproportioned) braking to the rear wheels all the time. I know this is not ideal when the back isn't loaded, because it can allow the rear wheels to lock up early (the reason they have that valve there), but I grew up before they had such things as proportioning valves, so it doesn't bother me. I'm happier knowing that I have all the brakes available to me, and I'll take responsibility for driving such that I hopefully don't swap ends due to too much brakes in the back. If you frequently drive with the back loaded, eliminating the rear height-sensing valve is probably a good idea. Just remember to take it easy when the back isn't loaded. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 19, 2009 Share Posted November 19, 2009 Hey Wahoo - if you decide to bypass the load sensing valve - I got first dibs on it. Never hurts to have a spare. :cheers: Link to comment Share on other sites More sharing options...
Wildman Posted November 19, 2009 Share Posted November 19, 2009 :agree: With "re-plumbing" the rear and all the hard lines at once, and replacing the soft line at the same time. Long time ago......well a few years back, I would replace this line, then 2 weeks later replace another line, so, theory being, if one line starts leaking from rust, the other lines are not far behind for leaks, and it's better to replace all the brake lines once, and bleed the system, Once. I've been running the one MJ for 5-1/2 year with the rear proportioning valve removed, and I've have several panic stops, and only a couple of time did the rear tires lock up with no load in the bed. Double flaring steel brake line is not hard, but, I'll agree, if your not "comfortable" with doing it, then let a pro do the brake lines. Nothing worst that not having brakes when you really need them :roll: Link to comment Share on other sites More sharing options...
WahooSteeler Posted November 19, 2009 Author Share Posted November 19, 2009 Don, do you still have your load sensing valve? I know you've hauled your share of heavy loads too, do you notice a difference in braking? If I do get rid of it, I'll wrap it up in that tailgate mat I still need to send you. :oops: Wildman, ironically when I drive it last weekend before this happened, it locked up a couple of times when I first needed to brake, but stopped doing it after that. Although, I did brake with a lighter foot. That was one of the first times it had ever locked up. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 19, 2009 Share Posted November 19, 2009 Don, do you still have your load sensing valve? I know you've hauled your share of heavy loads too, do you notice a difference in braking? If I do get rid of it, I'll wrap it up in that tailgate mat I still need to send you. :oops: Yep. But there are some subtle differences between the D35 and D44 load sensing valve bracketology, except for the valve body itself, and if you bypass it I'd very much like to have it all since I'm swapping in a D44 pretty soon. But it'll need to happen in this decade Wahoo. :cheers: Link to comment Share on other sites More sharing options...
A-man930 Posted November 19, 2009 Share Posted November 19, 2009 I just purchased two 25' spools of poly coated 3/16" brake line, an adjustable prop. valve, and all the necessary tube nuts/tees to replace all my 19 year old potential truck-crashers. I don't believe any other light trucks have used a height sensing valve and they work just fine. I'll just set up my prop valve on a gravel road somewhere to get the brakes to lock up together. Plus when I'm wheeling I can re adjust them to nearly the same as the fronts. oh and I got a double flaring tool kit for $30... who loves employee discounts?! :D Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 19, 2009 Share Posted November 19, 2009 I don't believe any other light trucks have used a height sensing valve and they work just fine. What? Toy pickups use them as well as a number of minivans. And probably many more that I don't know about. Don't understand what you are trying to say? Link to comment Share on other sites More sharing options...
Eagle Posted November 19, 2009 Share Posted November 19, 2009 He was trying to say that he didn't know Toyota uses a height-sensing proportioning valve. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 19, 2009 Share Posted November 19, 2009 He was? Okay. :cheers: Link to comment Share on other sites More sharing options...
A-man930 Posted November 22, 2009 Share Posted November 22, 2009 Well I definately could be wrong on that. My point was aren't there many many pickup trucks out there that didn't use this type of system? Link to comment Share on other sites More sharing options...
A-man930 Posted November 22, 2009 Share Posted November 22, 2009 wow, I'm just now realizing how much of a can of worms this height sensing valve issue really is... Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 22, 2009 Share Posted November 22, 2009 It's not a can of worms. It either works or doesn't. Since our trucks are so old and they are not available anymore, and there is a lack of expertise on how to adjust them, or even how the linkage works, most people bypass them. Or tiewrap the arm up. :nuts: Or -the most common reason- they flat don't work any more. Mine works fine, and I carry loads, I like the load sensing brake bias function. It still functions as it should, so I see no reason to dump it. If and when it fails, then I will replumb in another load sensing valve probably from a Toy P/U as this looks like the easiest option. And there are many other options, like plumbing in an adj. aftermarket valve in series with the rear brake supply line. Then you would be crawling under the truck fiddling with it when you're rig is hauling. Just do what you think is best for your own rig mate. Link to comment Share on other sites More sharing options...
Wildman Posted November 22, 2009 Share Posted November 22, 2009 wow, I'm just now realizing how much of a can of worms this height sensing valve issue really is... :typing: Your not new here.........are you??? :rotfl2: :popcorn: Link to comment Share on other sites More sharing options...
A-man930 Posted November 23, 2009 Share Posted November 23, 2009 wow, I'm just now realizing how much of a can of worms this height sensing valve issue really is... :typing: Your not new here.........are you??? :rotfl2: :popcorn: no not new, just not being very observant I guess! :rotf: Link to comment Share on other sites More sharing options...
JeepcoMJ Posted November 23, 2009 Share Posted November 23, 2009 lose the prop valve. hornbrod, I'm cleaning out all my parts...IIRC there are two load valves here. I'll save them and at some point in time they'll probably make it your way. I don't have a single MJ that still has a load valve. they're a PITA to bleed, prone to leaking/failing/falling apart, and I see them as nothing but a detriment. did not notice any changes in breaking power, but I did swap in xj proportioning valves. Link to comment Share on other sites More sharing options...
HOrnbrod Posted November 23, 2009 Share Posted November 23, 2009 No thanks............ Link to comment Share on other sites More sharing options...
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