Another brake line question

Hello everyone, in the coming week I will be installing the brake lines on my jeep. A 1970 CJ5 with the V6. It has the 10" brakes front and rear with a 27 and 44. I have been searching and haven't found a definitive answer, I am a rookie so bare with me.

My question is I have a new dual master cylinder and throughout research have learned why they are more safe. But why on the factory setup do both lines go forward to a distribution block? This one:

Wouldn't the rear line just go straight to the back from the M/C? It goes forward via 1 line to this block and then back via 1 line. Forgive my ignorance but why it it necessary? I don't think it's a proportioning valve, as I have read they were not factory until mid 70's? I'm not sure if the line kit I purchased comes with the lines to go forward to the block. I'll have to double-check but I would like to go into battle prepared. Thanks in advance for any help!



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Mine looks like yours, also. sept built 1970 cj5
came like that when i got it, but the PO put 11 inch brakes on the front.

My top one, the one cut in your pic... goes to a brake switch, then to the front brakes.

 

I believe it was for a brake light switch, as said.

 

Gotcha, the front line which I cut when breaking everything down did go to the brake light switch from that block. Like this:

Also the rear line had a second, I was curious about what this blocks function is. It seems that it's not needed... Where the front brake light switch is, has the T for the front lines. I don't understand this block...


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I'm kinda/sort of a rookie too & anything I say is purely speculation as to WHY both lines go forward...It looks as though both lines might be the same length & they may have had a bunch of lines already pre made but not bent...maybe same for the rear line? (cost saving???) I just did R&P's Wilwood kit & routed the rear straight to the rear. I used a new 60" straight line from Napa & made bends to fit the new cylinder. My guess is that unless you're trying to do an actual (correct) restoration, it doesn't matter...

 

Thanks! That's what I was wondering. I won't plan on using that block then.


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If that is what it is then I would keep it. But in my research, others have said that they were not used pre 1972. Any way to know if that's what it is?

http://www.earlycj5.net/forums/showthread.php?t=102709

Post #9 by McRuff, I have seen it other places too.


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Hmmm...Napa lists the front wheel cylinders as 1" bore & the rears as 13/16"...I'm quite interested in knowing too.

How & why some things are engineered the way they are sometimes escapes me... IF that block IS some kind of flow control, I don't understand why they would use two different size bores in front/back cylinders. With a 13/16" bore in the rear & a 1" in the front, the rears would lock up before the front, which is what you'd want...right?

ETA: FWIW, my brakes have never worked better, BUT if that block will make them work even better, I'll gladly install a couple more lines.

 

So I'm still not 100% clear on this thing. So from what I understand this block does not incorporate a proportioning valve since it's from a 1970. It has a pressure differential switch though for the brake light? Is there some kind of wire hookup on this to allow this to throw the brake light on that I'm not seeing?


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There should be a round threaded thing screwed directly into the master cylinder. On the back of that, the end facing the engine it should have a plug, there are two types. On that plug you should have a wire attached - green I think

 

You know where it is....back in post #4 of this thread it's right above your front axle...two wires, a hot one in & IIRC, the other to your turn signal switch.

ETA: If I were you, I'd run a line from the master cylinder directly to that block where the switch is & route another new line (if needed) from the master to the block back above the rear axle, & call it good. Napa has lengths of pre made lines for just a little more than the cost of fittings alone. They're straight, but a little tube bender will get the job done quick. IIRC, they have lengths of 5"-60". I replaced all of my lines except one, because the fittings were boogered. If you don't have a 3/8" flare nut wrench, do yourself a favor & pick one up before you go any further with the lines.

 

Yea, for the brake lights. I meant the brake light on the dash that was mentioned in the post before that, my bad for not being more clear.


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Great info! Thank you!

So is this block really just a distribution hub? Seems pointless. I think my question is answered, It's not necessary to re-install this one, as it seems to have no purpose, although others may go in place of it which had a purpose, which is why it exists. Did that make sense? It's late here. Anyways, thanks again for all the replies everyone.


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Just my opinion. If the block is just to throw a dash light to let you know that one brake circuit is out, I would not reuse it. You don't need a dash light to tell you your brakes aren't working well. I also have a 70 but I don't have this block. I once lost a rear brake line and it was very obvious that the brakes weren't working at full power. Getting rid of the block is a step towards making things more simple and less complicated.

 

Thank you! Great advice, will probably do the same then. Especially since this block does not even make a light on the dash come on.


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