Thanks.

I am adding ABS and want to have a larger combined reservoir if I can but need a smaller volume cylinder than some of the later boosted masters would have to keep a reasonable pedal pressure.

Plus disc front and rear.

https://www.ebay.com/itm/306039749770?fits=Model%3A521+Pickup|Make%3ADatsun&_skw=datsun521+rear+wheel+cylinders&itmmeta=01K0FGFQ6BJN9WJSRGB0QA7S3R&hash=item474163fc8a:g:Rg4AAOSwHdBnhfTo&itmprp=enc%3AAQAKAAABAFkggFvd1GGDu0w3yXCmi1ej40lf6ouO8zsWhc94RehnilHr7GNl1RaaQZnBfpxQRnr3jQ6QwMlb25z%2F7RwJtSOElxa3wKTfNxqFbyrELuVh9DXvbx7WiD5reIrHeW%2F6NutXzb53xVo3U0mitiqrPexCMXTUbzgFOCOmbNGrJEfI0sSYmqqDnUHPfUxX9a2e%2BS3Khr%2Bi3%2Fel07HrkAPKNLthpwBnHnHcPDbQ9KiJDYVvnfp5fKb56l9sXpd1f98QH%2FKlVNfSRZaUUPJF%2BMxtbYIs%2FGnpLbB7%2FCoj0d4QPzux9SqMqqutQBXxJ3q13YCOGWLhn%2FaA7fT1YTpOZCwgHGE%3D|tkp%3ABk9SR6jzvvCDZg

I'm trying to replace my original Nabco 7/8 brake master cylinder for my 1981 720 4x4 (May 1981 build date). I bought a new replacement from Centric (13042306), but noticed the front and rear ports are in the opposite position from the original. Otherwise the Centric looks fairly similar to the Nabco unit. I know from the factory there were also Tokico master cylinders, and perhaps there were changes to the brake system for the 1982 model year (I know they added self-adjusting brakes, so maybe there were other changes as well?).

Does anyone have any insight into the variations of the master cylinders of this era and possible differences between cars and trucks? 

Do the front and rear systems operate with different pressures? If I were to use this MC, would I necessarily need to reroute the hardlines to the new F and R positions? Or would I be better off locating a new MC with the correct ports? 

Thanks for your help.
 

CC on the caliper mount is approx 88-90mm.  

Below picture shows distance rotor and caliper mount.

1. Bench bled the master while installed (plugged brake lines and used the bleeders on the side), no air, perfect firm pedal. 

2. Take out the brake line plugs and connect the brake lines...pedal goes to floor.

3.  attach bleeder line and bottle to passenger rear, open bleeder and it dribbles out.

4.  pump brakes 5 times and very little comes out.

5.  pump some more and nothing.  this is the same on both passenger rear and drivers rear.

fronts are fine....no leaks in lines or cylinders.  Fronts are disc and the calipers are not leaking either.

Bummed.......

These two comparo pics aren't very impressive, they don't really show how significant the difference really is. But here they are anyway.

Stock 720

Pathfinder

These comparo pics show the differences better.

Pathfinder on the left

Pathfinder on the left

This swap is also larger than the d21 v6 upgrade I have heard of people doing, but never seen.

Parts needed:

From a 96-99 pathfinder

Brake caliper

Brake caliper bracket

Brake rotor (00-02 might be an even better option)

* Brake backing plate (or you can cut/bend your 720 backing plate

Everything else you can reuse from your 720. The hub, rotor to hub bolts, caliper mounting bolts, bracket mounting bolts, brake hose, and brake hose banjo bolt - all stock 720.

Additional parts

Heavy duty washers, a 2-3 mm thick (x4), 12mm or 1/2 inch hole, I suggest grade 8 or 10.9, suspension grade stuff.

The only modifications that need to be made are to the pathfinder caliper, and this can be done before ever starting the install.

This is the back of the pathfinder caliper. The brake hose area needs to be widened to accommodate the 720s brake hose head, which is large and oddly shaped. I ground away some metal from the top and bottom on the inside of the caliper bolt area. I also ground the notch a little wider so that the brake hose would fit in it.

Doing this will allow the brake hose to be mounted in the best position possible on the back of the caliper.

The caliper brackets bolt right to the knuckle, but the offset is different from the pathfinder, so the caliper doesn't sit quite right.

First off, when mounting the bracket you need to space it out so it won't bind on the rotor. That's where the heavy duty washers come in. Place a washer between the knuckle and the caliper on each bolt as you put it together.

You can see the washers between the caliper bracket and knuckle here. This was during test fitting when I was figuring out what would work. I removed these and replaced them with washers about 1.5 inches in diameter and higher grade.

The other problem caused by the knuckle differences is that the pads overhang the rotor by about 1/4 off an inch.

I'm not overly concerned by this, but actually I think it's great news. In 2000, when pathfinders switched to VQ motors, they also increased the brake rotor size again, from 11.2 up to 11.8 inches. This bigger than 1/2 inch difference in diameter translates to a little over 1/4 of an inch per side of the rotor. I haven't tested this theory, but this would result in a perfect fit using 97 caliper/bracket and the largest rotor of this design that Nissan produced. Somebody try this and report back!

Here's a pic showing the diameter difference. The rotors are lined up at the top, so the difference is visible completely at the bottom. 00+ R50 pathfinder would be a full inch larger than stock. When I need new rotors I'm doing that.

The best news about this? The calipers clear a 15 inch rim, so even the largest rotor fits under my rims with no issues. I'm pretty sure 15 is the smallest rim it will clear though.

I haven't driven on this setup yet. I'm in the middle of redoing all the bushings in my front suspension, so it will be a couple days before I test it out.

Thanks!

Never had one do this. Is that…wrong or normal? 280z m/c so disc/drum residual valves internally (I think) if that’s part of this? 

Next up on the docket for my 720 is getting the parking brake in order. I have the correct rear cables, but I'm completely new to the set up. Any tips on the routing and installation, or anything I should know of or be prepared for before I jack up the truck?

no more vacuum assisted brakes! 

now have strong and consistent brake pedal feel

full write up/how to here: https://bratindustries.net/electric-brake-assist-for-the-electric-datsun-720/

Whats a electric brake booster?

It’s an electric motor that helps your foot push the brake pedal.

simple. 

they are in everything these days, ICE vehicles (being most are now direct injection) and EV's.

the most common one used is made by bosch, called the Ibooster.

The one i used is from a tesla model y, and has a dual port 1" bore master cylinder. A nice increases from the 14/15" MC on the 720. This plus with the additional assist power from the ibooster makes for stronger brakes effect. My truck now stops on a dime!

The tesla model y one also has a fluid reservoir that dosnt tilt down, so it works as is. The model 3 one has a funny shape and wont work very well.

Iboosters from different vehicles have different MC and fluid reservoirs. but the ibooster itself is the same. bolt pattern might be different.

Install:

To adapted the brake lines to the tesla MC i used  M10x1.0 inverter x M12x1.0 bubble brake line adapters

To mount the ibooster I made a new mounting bracket, and used a M10 male to M8 female coupling for the original pedal clevis to thread into the ibooster push rod. 

I still have the stock rear drums, so i needed to add a 10lbs residual valve on the rear line as the ibooster MC dose not have one built in like the 720 MC.

wiring is simple. permanent 12v lines (40amp fused) and a wire connected to the trucks ignition circuit via a 5amp fuse (this wakes the ibooster up).

• 1 = 12V+ permanent 40A fused
• 9 = GND
• 20 = 12V+ ignition 5A fused

thats it!

powerful, consistent, vacuum less brakes 🙂

I have a friend who is in his 80s and drives a 1978 Corolla that looks like shit but drives perfectly. He swears that he hasn't touched the brakes in 30 years and credits using silicone based Dot 5 and cupronickel lines when he ran the brake lines last. He's had to replace pads and such obviously but not had to touch the hydraulics at all. He did the same thing with his clutch as well. 

Is there any truth in what this old curmudgeon is telling me or is it overblown? I'm not asking for people who haven't done it necessarily, more so for people who have done it. 

I replaced the slave and clutch master, new fluid and the clutch still won't firm up.  I put a plastic tube on the Zerk of the slave and ran the tube into a cup of Brake Fluid, pumped the clutch, air bubbles came through the cup.  but that didn't work either.  I've never has this problem, I've replace a few slaves and I don't know what's going on.  Thanks for any comments, thoughts ... Best  I'm stumped,  the old brake fluid was black, now it's a clear yellow.

So here are my 2 questions for you:

1/ Since I have a 78620 that has disc brakes from the factory do I need the bracket to adapt different brakes.

2/ What rotors and calipers can I can I swap in to my 78 620 King Cab

3/ what do I need for the rears? is it the same as all lower years? or is it different?

Thanks for your help in advance. Love the community here at Ratsun very helpful keep it up!

Good thing is, I see no wetness on the right side.    But, did I put the shoes on correct the last time I worked on them?

Got the new drums checked for balance and true—all good. However on my left rear wheel, when I pop on the drum and pop on the wheel and tighten lug nuts, the brake starts rubbing something fierce. Adjuster is backed all the way off, and it slides well. As near as I can tell the inside face of the wheel is flush with the drum, and it’s same wheels, same drums on all other wheels and don’t have this problem.

Why would this be? What am I missing?