520 brake rebuild/upgrade options?

[hucklefish]

What are my options for rebuilding and eventually upgrading my 520 brakes?

My right rear bleeder somehow backed itself out while I was driving and I had to finish the drive with the hand brake. I put it back in against my better judgment and started bleeding, then messed everything up by forgetting to put the brake drum back on and pumping the brake pedal until the wheel cylinder popped its pistons out completely. Decided it's time to at least replace the wheel cylinder, and I have a new one in the parts bin that came with the truck. However, I've also drained the master cylinder several times, so I think I'm going to have to bench bleed it. Eventually I'd like to upgrade to disc brakes all around, and if  understand right that will require a new master cylinder. So I'm considering replacing the wheel cylinder with the one I've got, and upgrading the master cylinder now. Is there a bolt-on master cylinder that will work with my 4-wheel drum brakes and work later with front disc and rear drum brakes, and still work later with 4-wheel disc brakes?

I found this: https://www.silverminemotors.com/products/15-16-upgraded-master-cylinder-for-620-520-521-310

I've seen the name Wilwood a lot here too. They also sell this: https://www.silverminemotors.com/products/1964-1977-datsun-620-520-521-310-front-brake-upgrade-kit and https://www.silverminemotors.com/products/1964-1977-datsun-620-520-521-310-truck-rear-brake-upgrade-kit?variant=44444661350714

If I read the descriptions right, these require some modifications, but no swapping in parts from other trucks (machine hub down 1mm and get larger wheels for the front, modify e-brake cable and get long housing bolts for the rear). Are these kits good? Reputable? Anybody here used either of them? Are there better options out there?

EDIT: I should add I'm not opposed to swapping in parts from other trucks if that's a more cost-effective option or better for future maintenance or parts availability, but I want to keep the 1000kg payload rating in the rear.

Edited August 1, 2023 by hucklefish

[datzenmike]

 

 

You have an 11/16" master. Going to a 15/16" is almost 39% larger and without a brake booster it will be like stepping on a brick. Do this later if/when you upgrade the brakes.  Geez $800 for front disc???? The 520 has 10" drums and lots of stopping power. The only drawback is keeping them adjusted so they do stop.

 

Neglect or indifference caused this and once fixed and the lesson learned it's unlikely to happen again. These trucks need to be maintained. Check and adjust the four drums at least every 6 months. The 520 uses a single master and ANY leak and you loose all braking. If you feel this may happen again, (it's unlikely) get an early 620 dual 11/16" master and separate the front from the rear circuits. I did this on my '71 using the master from my 510 I scrapped. I think the 521 flair had to be cut off and changed to fit the 510 master. The earlier 520 may be the same as the '68 510 I had.

[Stoffregen Motorsports]

The easy bolt on front disc brake kit is not a bad option. There are guys here who have used kits and others who have mix/matched OEM parts to get it done.

 

Don't go for a cheap rear disc brake kit though. Too many pitfalls with crappy rear discs.

[hucklefish]

Thanks again, both of you.

For now I'll clean up the brakes and put everything back together, and maybe replace the wheel cylinder, maybe not. Then I'll start looking for an early 620 master cylinder, and later I'll think about upgrading the front brakes and probably keep the rear drums.Much earlier on this thread somebody said I shouldn't use this 520 as a work truck, and two of the reasons given were the drum brakes and the probably worn out king pins. Since I plan to go ahead and use it as a work truck and keeping fixing it up as I go, would either of you still advise sticking with the drum brakes all around? I'm a handyman, and I typically carry around probably 300-500 pounds of tools and mixed "just in case" materials and hardware. So far, in about 2 weeks of use, I've had no problems other than the brake bleeder screw popping out.

Somebody in a different thread said "NOT SILVERMINE CRAP" and Beebani agreed, but that was a thread on a 620. Is there a better option than Silvermine for 520s? I've been through the first 4 pages of the Brake threads and haven't found anyone talking about upgrading a 520.

EDIT: Found a positive review of Silvermine Motors products here, though it's for a 280Z: 

 

 

Edited August 2, 2023 by hucklefish

[Crashtd420]

I dont see anything wrong with the silvermine setup.....

What was the complaint?

 

Personally I'd just buy the bracket to use oem parts and the get the pads, calipers and rotors from the parts store... 

 

I think this is the only option left lately... bluehands and beebani are not making things anymore....

 

Also sometimes stock wheels dont fit.... not sure with the silvermine setup....

[Crashtd420]

And there is no reason you cant use it as a daily work truck as long as everything is in good working order... front disc with the dual circuit master cylinder will be safer..

 

Mikeklotz ( bluehands ) has king pin rebuild kits for a good price if you need to rebuild yours...

 

Plus a couple hundred pounds is nothing for these trucks.... 

 

[datzenmike]

The 520 was rated to carry 1,000 Kg or over 2,200 pounds. Drum brakes are fine they just need to be maintained/adjusted and that's the biggest advantage of disc brakes. You basically can forget them till the pads need changing, no adjustment. The single master has no back up but the emergency brake, that's scary but that's how they did it back then.

[wayno]

I made my 521 into a work truck, it has the same frame as the 520, it was a lot of work upgrading to front disc brakes, if I had not added power steering I would likely still have the 521 frame under it, but the power steering wasted the front frame section, at one point I had the 1990 V6 dual piston calipers on my work truck, it stopped great even when hauling huge loads of firewood.

 

This is not the largest load of firewood I have hauled, but it is the only one I have a photo of on my laptop.

 

 

I can tell you how I did my disc brake conversion(before Ratsun existed), but it has to be done right or it can be dangerous.

[hucklefish]

NOS brake adjusters from datsun-roadster-parts on eBay are twice the price of new ones from Thailand - are they that much better?

 

And new parts made in Thailand in general - reliable, crap, or good enough for the price?

Edited August 4, 2023 by hucklefish

[banzai510(hainz)]

remeber the 520 and 521 were sae threads(.then the 620 showed up and all metric set up body and the motor

 

 these new kits might be metric I dont know

 

the brake adjusters really dont go bad just clean them up.