NewKindOfClown Posted March 25, 2013 Share Posted March 25, 2013 Hey all, I've been trying to read up on this. I understand the line from the 'nose' is the line to the proportioning valve, the bottom front is the emergency line to the rear brakes in case of failure, and the line at the back is for the front brakes. My mechanic friend took a look at it while it was up on the lift, and he asked why I don't just put the two lines at the prop valve into a coupling and run the rear brake hose straight to the third line that's back there on the driver side of the axle. I didn't have a good answer for him besides, as Eagle has pointed out, that leaves more aging brake line waiting to rust out. Would this work? Also, I've seen a diagram mentioned, but I can't find it. Would someone mind posting that? Thanks, guys. Sorry for posting another one of these. Link to comment Share on other sites More sharing options...
skidoo_j Posted March 25, 2013 Share Posted March 25, 2013 Diagram: http://comancheclub.com/topic/19732-random-informative-picture-thread/?do=findComment&comment=216000 Link to comment Share on other sites More sharing options...
NewKindOfClown Posted March 25, 2013 Author Share Posted March 25, 2013 Thank you! That thread is now bookmarked. Much clearer with a picture. As for what my buddy suggested, I thought that would block off my rear brakes because only the failsafe would be connected. Can anyone confirm? Link to comment Share on other sites More sharing options...
Eagle Posted March 25, 2013 Share Posted March 25, 2013 Thank you! That thread is now bookmarked. Much clearer with a picture. As for what my buddy suggested, I thought that would block off my rear brakes because only the failsafe would be connected. Can anyone confirm? No, if you do it as the diagram indicates, it's the bypass (emergency) line that gets removed and the port for it gets blocked at the metering block in front. The "failsafe" circuit no longer exists, and the line to the rear operates the rear brakes normall (with no proportioning) -- just like the cars I grew up with. Link to comment Share on other sites More sharing options...
NewKindOfClown Posted March 25, 2013 Author Share Posted March 25, 2013 Eagle, I understand that, and it's what I want to do. He has the MJ, however, and he wants to leave all three and put a coupling on the two lines at the prop valve, then run the soft line to the single line on the driver side. I think that would eliminate my rear brakes UNLESS there is a failure in the main line. I'm asking for confirmation because he isn't inclined to do more work than necessary if he thinks the outcome will be the same. Link to comment Share on other sites More sharing options...
Eagle Posted March 25, 2013 Share Posted March 25, 2013 Eagle, I understand that, and it's what I want to do. He has the MJ, however, and he wants to leave all three and put a coupling on the two lines at the prop valve, then run the soft line to the single line on the driver side. I think that would eliminate my rear brakes UNLESS there is a failure in the main line. I'm asking for confirmation because he isn't inclined to do more work than necessary if he thinks the outcome will be the same. So he wants to retain both hard lines, eliminate the rear height sensing valve, and merge the two hard lines just upstream of the rear flex hose? The problem is going to be bleeding. If there's any air in the bypass (emergency fail-safe) hard line, stepping on the brake peddle will just allow the fluid in the primary line to back-feed and compress the air in the secondary line rather than actuate the brakes. It is possible that tripping a fail in the front brake circuit, per the factory procedure for bleeding the rears when you do have the height sensing valve, might do the job. But ... I don't know if the height sensing valve has a backflow preventer (I would guess it would have to), so I don't know if this would work. Overall, I think this sounds like a really foolish thing to do. Instead of exposing ten feet of steel line to rust and corrosion, let's expose twenty feet of steel line to rust and corrosion to get to the same place. What could possibly go wrong? Link to comment Share on other sites More sharing options...
Keyav8r Posted March 26, 2013 Share Posted March 26, 2013 Absolutely not trying to be a smart a$$, but since Eagle has been there, done that and your mechanic friend hasn't, i believe I would go with Eagle. And, since Skidoo_j has linked to a "how to" diagram and photo of the way to do it maybe your buddy can see how it will work. If I decide to eliminate my rear proportioning valve (and I may just because I hate bleeding brakes), that's the way I'll go. Link to comment Share on other sites More sharing options...
NewKindOfClown Posted March 26, 2013 Author Share Posted March 26, 2013 Okay, Eagle, that makes sense and should be a good enough reason for him to listen to me. That is the way I'd like to have it done, but I needed a reason for him as to why his idea is impracticle. I was also curious if it would function, despite not being the best method. I'll explain and show him the diagram when I talk to him tomorrow. Thanks again, guys. Link to comment Share on other sites More sharing options...
Eagle Posted March 26, 2013 Share Posted March 26, 2013 The thing is, once you eliminate the height sensing valve you have NOTHING to gain by keeping both hard lines to the rear, and potentially a lot to lose. If he's thinking that keeping the second line will retain the failsafe rear brake circuit, in fact it won't. Case 1: Either rear hard line ruptures. Doesn't matter which one, they are now fully interconnected, so a leak in one is a leak in the system. Result: no rear brakes. Case 2: Front brake line ruptures. This is the condition the failsafe is intended to address. If the front brakes fail, it ensures that the rears will get 100% (rather than proportioned) braking force. But ... with the height sensing valve bypassed, you already have 100% rear braking, all the time. There is no reason to retain the failsafe circuit, because it adds nothing. But it makes it exponentially more difficult to bleed the rear brakes, plus it doubles your exposure to corrosion of the rear hard lines. In deference to your mechanic, I'm sure he thinks his way is going to be better for you. The problem is that I don't think he has any idea how that system works. I have sawed an MJ front metering block in half (the photos are on this forum, somewhere), and I know exactly how it works. Keeping two hard lines to the rear with no proportioning valve is just NOT a good idea. Link to comment Share on other sites More sharing options...
chappy88 Posted October 12, 2013 Share Posted October 12, 2013 hey Guys Been following this and have elliminated the prop valve, it was pooched anyway! , just wondering about the plug @ the routing block. Is there such a part for this or did you just cut the line and seal it? Link to comment Share on other sites More sharing options...
Eagle Posted October 12, 2013 Share Posted October 12, 2013 hey Guys Been following this and have elliminated the prop valve, it was pooched anyway! , just wondering about the plug @ the routing block. Is there such a part for this or did you just cut the line and seal it? Go to Lowe's or Home Depot or a large Sears HARDWARE store and buy the shortest 1/2"x20 bolt you can find, and a 1/2" I.D. O-ring. Cut the bolt to a length that will barely allow the head of the bolt to seat on the valve body when the tip of the bolt contacts the seat inside the bore, then cut or grind it just a tad more -- not more than 1/16 of an inch. Put the O-ring on the bolt. Put a dab of silicone RTV on the end of the bolt and allow it to set up, then screw it in enough to slightly compress the O-ring. Done. I think the threaded portion of the bolt will need to be about 3/8" to 7/16" long, but it's been a few years since I last did one so I don't remember for sure. Might be as short as 5/16" but I don't think so. Link to comment Share on other sites More sharing options...
Jerry Posted October 13, 2013 Share Posted October 13, 2013 hey Guys Been following this and have elliminated the prop valve, it was pooched anyway! , just wondering about the plug @ the routing block. Is there such a part for this or did you just cut the line and seal it? You can buy the plugs at an auto parts shop and they are pennies. Ask for the size as mentioned already. Link to comment Share on other sites More sharing options...
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