Are there braking upgrades? ...your significant other refuse to ride with you? Read on... While these trucks are pretty cool looking, fun to drive, and easy to maintain, nobody would ever accuse them of having the world's best brakes. We are currently in dire need of a confirmed braking upgrade. Theoretically speaking, there are four areas to consider: Front disk brakes The 521s and most 620s used kingpin front suspension. As such, they are incompatible with the balljoints and spindles more commonly used. This means that any disk brake swap on a kingpin truck will require pretty fancy fabrication, either to put disk brake rotors and calipers on the stock king pins, or swapping in completely different A-arms, mounts, spindles, etc. Although the 77-79 620s had disk brakes on the front, the mounts for the suspension arms are quite different, ruling out a simple bolt-on swap. For your perusal, the following images were scanned from the Haynes 620 Repair Manual: How the disk brake front end is put together 134K Disk brakes in cross section 89K Drum brakes in cross section 63K Drum brake A-arm specs 17K Rear disk brakes It seems a bit odd to contemplate a set of disks on the rear before ironing out a front disk swap:-) But hey, we're Datsun people, we're supposed to be a bit odd! Swapping a rear solid axle is pretty straightforward; you need a donor (likely a late model Pathfinder?) and some fabrication time - gotta hook up the emergency brake, wheel cylinders, springs and shocks, etc. Keep in mind the Datsun trucks are pretty narrow, so you may run into track width problems. Personally, I don't see a need for rear disk brakes on other classic cars, so I'm really skeptical of rear disks on a truck.... but that's just my opinion. Dual-reservior master cylinder Nowhere near as sexy as disk brakes, the single-well master cylinder is a potential safety hazard; if one wheel is compromised, you can lose all braking, no fun! Contributed by list member Nathan Marshall: I now have dual circuit brakes on a 521, wow what a pleasure. When I push on the brake pedal the truck stops in a straight line. I went out on my street in the rain tonight and I let go of the wheel at 25mph, slammed on the brakes, stopped in a straight line. How it's done........................... 1. purchase a new brake master for a 1976-620pu (don't need booster) 2. purchase one brake line plug (male), one line union (female), and a 36 or 40 inch length of line with end fittings 3. at the junction block on the fire wall remove the rear brake line and plug its hole 4. install union and new line to extend the rear brake line over to the master cylinder area 5. to install the new master cylinder you will need to make some modifications you will need to slot the mounting holes on the master cylinder about 1/16" per side bringing them closer together next you will need to neck down the "pilot" diameter on the mater cylinder by just over 1/8" all of the way around (or put a bigger hole in the fire wall) * I used a lathe to turn the master down, if you use a die grinder, don't over heat your new master cylinder and cook the seals 6. on the new master install an adjustable push rod (I used one from an old 510 clutch slave) the 521 push rod is about 1/2" too short 7. bend and install front and rear lines, bleed brakes, drive. This conversion took me about three hours total. After I have driven on it for a while and am sure I am happy with it I will offer help to anyone who wants it. Enjoy the Ride Nathan 510's R US er I mean 521's Power brakes Power brakes would be nice! Unfortunately, it has been suggested that the spacing of the master cylinder versus the clutch master may make it impossible to install a bulky master vac unit.