Early 720 to D21 brakes, passenger brake line question

[1001001SOS]

I am researching and collecting parts for my brake system, with the goal of running Pathfinder dual-piston calipers on D21 spindles. My truck is an '82 720, build date 11/81.

 

My passenger side brake line has a distribution block between the MC and caliper as seen in this parts fiche:

 

 

I have read a bunch of threads about this upgrade, from people doing it on a lot of different gen trucks, and no one seems to mention this passenger side brake line. Everyone mentions using the D21 brake lines, but my OEM passenger side line has this block built-in (I think), so I'm not sure how to mate the female m10-1 fitting from the D21 rubber line to the male hard line from the MC, and still retain the third line to the rear. 

 

Is that ^ block REALLY all-in-one or can I separate the line and figure something out?

 

Do I need a new distribution block and a custom line?

https://www.nissanpartsdeal.com/parts/nissan-con-brake-tube~02463-13100.html

 

 

Seems like it would work, just wondering if this something I missed while doing research so far. 

[datzenmike]

Front and rear brakes systems are separate so a failure in one doesn't cause a total system failure. The 720 also has a  NLSV (Nissan Load Sensing Valve) which allows more line pressure to the rear brakes as load weight increases.

 

Up until Nov. '81 the NLSV used a brake pressure line from the front circuit as well as the rear line. I don't know why, but from Dec. '81 the NSLV got rid of this front line to the NLSV and only ran the rear line and this method was continued into the D21 Hardbody also.

 

Can you not use this part with the D21 Hardbody lines???

 

 

If not then make up what ever you like so that there is a line to the NLSV in the rear.

 

 

[1001001SOS]

1 minute ago, datzenmike said:

Can you not use this part with the D21 Hardbody lines???

 

This is the main problem, yeah. 

 

OEM:

 

MC > Hard Line > Block/Soft Line > Female M10 > Male M10 > Hard Line > Caliper

 

Swapping out D21 stuff gives me:

 

MC > Hard Line> Block/Soft Line > Female M10 > Female M10 > Banjo > Caliper

 

[1001001SOS]

This is making me wonder if I could swap out just the NLSV for the newer setup. Delete the second line to the rear altogether. I would much prefer to keep parts OEM, and not having to have a custom line made is a big plus. D21 NLSV is readily available so that seems like the best option.

 

 

[datzenmike]

I guess so. Different trucks and weights and tires.

 

The NLSV is mounted with an up angle at the front and a ball inside. During reasonably hard  braking the ball rolls up hill and blocks line pressure to the rear brakes preventing lock up. As cargo weight is added the rear squats and the incline angle increases making it more difficult for the ball to roll up and block pressure to the rear brakes. Effectively more brake can be applied because of the increased rear wheel traction from the cargo weight.

[Stoffregen Motorsports]

I would ditch the NLSV and install and adjustable proportioning valve like this -

 

 

Note - they come in 3/8 inverted flare and 10x1.0 BUBBLE flare. I hate bubble flares, so I will install them with the 3/8 tube nuts, even on a metric vehicle.

[1001001SOS]

Well it's looking like a bust either way. There is a second distribution block before the NLSV, so even the line to the rear on my truck is different than the late-720. Wouldn't matter anyway because that late-720 valve is NLA it seems, and the D21 valve I was eyeing is totally different.

 

So, back to either 1) custom front line and keeping the stock NLSV, 2) sourcing the whole late-model line and NLSV to the rear, or 3) getting rid of the NLSV entirely and using a proportioning valve.