New Truck - '71 521

[andyZ00m]

Hey Mike, I do have front discs now! That was the whole impetus for this upgrade actually. 
 

I’ve looked into the booster thing and the trick is gunna be finding the pedestal/booster combo that will work without modifying the firewall and existing mounting hardware. 
 

I would like to do it. I’ve found the booster with the correct mounting plate for my

MS but I would probably need to fabricate the pedestal. 

 

[Slow Loris]

I dunno the big front wheel / little rear wheel look is pretty unique maybe you’re onto something. The hottest new trend in Datsun pickup builds???

[datzenmike]

 

You have the vertical mount MC the most common so  just about any Datsun with a booster will work other than z cars and 810/Maxima. My 15/16" early 280zx MC fit right to my 710 booster.

[andyZ00m]

2 hours ago, datzenmike said:

 

You have the vertical mount MC the most common so  just about any Datsun with a booster will work other than z cars and 810/Maxima. My 15/16" early 280zx MC fit right to my 710 booster.

But I’d still need the pedestal. That’s the tricky part! 

[ggzilla]

when you shop with Ratsun-preferred suppliers the pedestal comes with the booster, like this Datsun B210 booster

 

 

[Slow Loris]

14 hours ago, andyZ00m said:

far, the 1" MS while it does require more pedal force, its not unmanageable. We'll have to see after a month or so how I feel about it.

So I’ve just completed a disc swap as well, I used a 13/16” master (no booster) and I’m feeling like there is too much travel for my liking. Maybe 7/8” is the magic number. 
 

Relative to the force you used to use when it was all drums to stop quickly, how does the 1” compare? 

[andyZ00m]

1 hour ago, ggzilla said:

when you shop with Ratsun-preferred suppliers the pedestal comes with the booster, like this Datsun B210 booster

 

 

Are you, perhaps, one of the Ratsun preferred suppliers…?? Haha. 

[datzenmike]

10 minutes ago, Slow Loris said:

So I’ve just completed a disc swap as well, I used a 13/16” master (no booster) and I’m feeling like there is too much travel for my liking. Maybe 7/8” is the magic number. 
 

Relative to the force you used to use when it was all drums to stop quickly, how does the 1” compare? 

 

 Almost any caliper will be larger inside than the stock wheel cylinder so will need more fluid volume to move it. The pedal will travel farther to make up for this. Yeah a larger master will work but there are limits to how large as the effort also increases. This is where a booster really helps with the effort. What's the stock master, must be 3/4". If 13/16 is still too soft 7/8" or maybe 15/16"??? 1" might be too stiff. I guess it's trial and error till you get what you like. I had a 1/8" larger master in my wife's 710 and it was like stepping on a brick. Also automatic so you had to press and hold at lights.  

[ggzilla]

Nah, i meant a junkyard like pick-n-pull. Their parts often come more complete than the fancy-schmancy new part companies

 

18 minutes ago, andyZ00m said:

Are you, perhaps, one of the Ratsun preferred suppliers…?

[andyZ00m]

14 minutes ago, ggzilla said:

Nah, i meant a junkyard like pick-n-pull. Their parts often come more complete than the fancy-schmancy new part companies

 

The pick and pull in my area never has ANY Datsun stuff, but might be worth making another trek. 
 

Haven’t seen the one you linked a photo of but that actually looks like it would fit next to the clutch MS in the 521. 

[andyZ00m]

14 minutes ago, ggzilla said:

Nah, i meant a junkyard like pick-n-pull. Their parts often come more complete than the fancy-schmancy new part companies

 

The pick and pull in my area never has ANY Datsun stuff, but might be worth making another trek. 
 

Haven’t seen the one you linked a photo of but that actually looks like it would fit next to the clutch MS in the 521. 

[wayno]

You do what you have to do guy, make what you need, but first you have to buy what you are going to use, the booster and brake master you are going to use, I believe I would use the 1973/74 Datsun 620 booster, but you need the master brake mount plate also, you also need the shaft from the booster to the brake pedal that is the right length or longer so you can cut it too length, I recall I used a Ford Courrier brake master and remote reservoir.

You are starting with a 521, I started with a 520 and had to install a 521 brake pedal assembly first, check out this thread, I had to get the brake master away from the engine/intake first.

 

https://www.nwdatsuns.com/phpbb/viewtopic.php?p=61088#p61088

 

I made this pedestal to fit this booster(unsure what booster is), it was complicated, pedestals are easy to make if you can weld.

 

 

If you go down 5+ photos you can see the braces I made to stabilize the end of the brake master so it does not flex when stepping hard on the brake.

 

If you cannot weld, make the parts yourself and have/pay someone weld it for you, if you lived near me, I would weld it for you, if you go down to post 169 you can see the dual SU install, I even made my own gaskets, post 174 has it finished with filters installed.

 

It has been a long time since I did this, I had a heart attack the next day(May 9, 2016).

[andyZ00m]

DAMNNNNN, The fact that you have the actual date marked means that you are not joking about having a heart attack... Glad youre still here brah!

 

I will need a booster eventually. Been driving around yesterday and today after some testing and validating the brakes are working and not leaking anywhere. I think Im going to keep the 1" MS from wilwood and find a booster that works with the mounting of this thing. I have a buddy that is a welder and he can help fabricate the pedestal and the longer pedal to booster shaft (could make this too).

 

Its totally fine to drive right now, but Mike was right that on longer rides especially in traffic, you do get leg fatigue.

 

The larger wheels are definitely a different look! It fucks with the proportions of the original body/wheel tire combo that I loved. Its such a small change but a big visual impact. Its growing on me for sure.

 

Edited March 24, 2025 by andyZ00m

[ggzilla]

So making a pedestal is not too difficult

 

Wayne, you only used that long pedestal to clear the dual-sidedraft carburetor setup?  The booster you had before on your 520 looks like a stock 4.5" Datsun Master-Vac but with shorter pedestal than the B210 version (or maybe it used no pedestal at all)

4 hours ago, wayno said:

Here is what it used to look like.

 

4 hours ago, wayno said:

made this pedestal to fit this booster(unsure what booster is), it was complicated, pedestals are easy to make if you can weld.

[andyZ00m]

On 3/23/2025 at 2:31 PM, Slow Loris said:

So I’ve just completed a disc swap as well, I used a 13/16” master (no booster) and I’m feeling like there is too much travel for my liking. Maybe 7/8” is the magic number. 
 

Relative to the force you used to use when it was all drums to stop quickly, how does the 1” compare? 

 

Its def more but not unmanageable. Its really easy at light braking but when you need to stop quickly or more than casual traffic, it takes some force. I'm 6"3 200lbs so maybe your leg mileage may vary haha. 

 

I think I will eventually go the booster route, especially since there is so much room right there in the engine compartment.

[wayno]

21 hours ago, ggzilla said:

So making a pedestal is not too difficult

 

Wayne, you only used that long pedestal to clear the dual-sidedraft carburetor setup?  The booster you had before on your 520 looks like a stock 4.5" Datsun Master-Vac but with shorter pedestal than the B210 version (or maybe it used no pedestal at all)

 

 

I had to do a lot to clearance the brake master for the dual SUs , keep in mind that this is an early 1966 Datsun 520, there was a lot of room between the brake master and the clutch master in that first 520 firewall photo you quoted, I had to remove the 520 brake/clutch pedal assembly and install a 521 brake/clutch pedal assembly, the 521 brake booster/master is installed in the 520 clutch assembly hole, I made a new hole next to the old clutch mount position to work with the 521 pedal assembly.

 

The pedestal I made was to clear the clutch master using the 521 pedal assembly.

 

I do not remember what that booster was from anymore, I think it was a 620 pedestal/booster, but I parted out a 1981 Datsun 310 at one time and it might have been from that, then I made a pedestal to fit that booster, it has been too long for me to remember everything.

Edited March 25, 2025 by wayno

[andyZ00m]

Reporting back after a year of driving with no booster! 

 

Spoiler, its fine. I think 15/16" or 7/8" would be also fine and less pressure, but I dont want to swap out the MS to try it at this point. I can stop so fricken fast with these giant brakes its awesome, even with a load. 

 

I did get a booster from a late 70s 620 from my neighbor but havent installed it as I would still need to fabricate the pedestal. 

 

Im now thinking about steering and swapping out for an l20b. A guy has one about an hour from me and its rebuilt. Thinking about doing the swap... is it worth it??

[datzenmike]

I had a '71 and put a '75-'77 L20B in it. I liked not having to rev it so much to get through the gears. The L20B had a lot more lower grunt and pulled harder and that meant not down shifting as much on grades. 

 

Steering??? not much you can do about an upgrade to the steering. Unless you mean swapping in an electric power steering.

[andyZ00m]

Yeah, Ive heard the swap to l20b is a pretty noticeable upgrade. 

 

Got the front suspension all dialed in, but haven't touched the steering (center link and tie rods). They look like they haven't been serviced in a long time. Might be fine underneath the grease.... 🙂

[Slow Loris]

Tie rods seem to disappear for 521s, especially the left ones. Currently available on rock auto but who knows for how long?? 
 

If you get the L20b you’ll likely need a large wing on the back, and maybe the front too, to create some downforce, otherwise your truck is liable to take flight what with all the power.

[banzai510(hainz)]

19 hours ago, Slow Loris said:

Tie rods seem to disappear for 521s, especially the left ones.

the show up back on rockauto then say low again. also the centersection

 

just recheack ever now and then when there is a set get them.

 

I got 2 sets AC Delco made in Korea. the center was vintage parts or someshit from Autozone of all places.

Be honest I dont think Ill wear out this set as I rarely drive the 521 now.