Biggs

Willwood 2 psi inline residual valves are on order though I did see a video with a Willwood tech stating residual valves on disc brakes should only be needed if the m/c is located at a lower elevation than the calipers. I figure it’s better to be safe than sorry and I like experimenting, anyway.

Please help me out with this comment. Why would I want to remove the front circuit's residual valve and move it to the back? BTW, I just see one place for one residual valve on the m/c. Thanks!

Wow! You guys are AWESOME!! I appreciate the enlightenment and showing me the error of my ways. I hadn't thought enough about it but using a disc/drum dual circuit M/C on a disc/disc dual circuit setup is asking for problems, especially when not done correctly. It's a no brainer to require the addition of a residual valve on the new back half of the equation. It worked great when I'd just done the front and still had the drums on the back, so why not go ahead and do the back, too? Sometimes you can't see the forest for the trees. I like the idea that I've over master cylindered the setup, too. I knew pedal force would need to increase (F=PA) but thought I'd need the extra volume due to the size of the dual piston 300ZX non-turbo front calipers and the Isuzu Tropper single piston rears. As stated above though, extra volume should not be needed if the correct residual valve is added to the back circuit. There may also be other issues with the setup. With the truck fully elevated and tested with the wheels on, the fronts spun manually stopped hard when braked but the rears seemed to stop much less abruptly. I bled the brakes using the pressure pot on the m/c which works great when everything fits correctly and makes an incredible mess when fit is less than perfect. Good thing paint is planned! It did find a blockage in the old splitter mounted on the H190 axle. Given this, it's likely the rear drums never worked as I don't recall having tested them prior to removal. I'll test again in the coming days with the old vacuum pump and install the needed residual valve. Thanks again!

Brakes have been bled and re-bled. The fronts will brake. The rears less so. I guess I could try different residual valves, but not sure that will help since pedal goes all the way. I’ve looked at 1” Willwood and thought that seemed a logical next step but wanted to check to see what others have done.

Hoping the participants of this thread are still involved with the site. I’m a glutton for punishment as I have followed through on modifications to my 72 521 including an L-18 (it was rebuilt and available), Weber carb (planning to go to dual SUs), GM one-wire (wouldn’t repeat) and 4-wheel disc brake conversion. I did the front brakes first and liked them so decided to move on to the rears. It was much more of a job than the fronts, but in always up for a challenge. My issue with this work, though, is I don’t seem to have enough volume of brake fluid in my 7/8” bore 280 Z master cylinder. I’d hoped the Z’s m/c would do the trick, but it does not. Any suggestions on what to try for a master cylinder? I’d like to keep it all Datsun/Nissan, if possible.

If you’re keeping factory ride height and need to replace your factory rear bump stops, the Daystar KU09016BK fit. I got mine from Amazon used (?) for $40. I figured the only reason they could be used was someone bought them and they didn’t fit. Sure enough, they were brand new. They fit into the two bolt holes on the frame rail itself, leaving the third offset bolt hole unused. The end of the pad fits perfectly onto the plate mounted on the factory axle of my ‘72 521. Their mounting plate is flat and does not exactly match the curvature of the original figure 8 pad, but they may after a few energetic rebounds.

Please tell us more about how you restored your dash. It looks great and mine needs some love.

I'm fairly new to Ratsun and have yet to get 100% into rebuilding my 521. I am in the planning stage as I set up and wire my new shop. I am curious as to whether or not I should plan to upgrade the front suspension to ball joints. Coil-overs, I've leanred, are also a possibility. Overall, I have learned a great deal from this website about my truck and what is possible, but, other than in the interest of bagging, I have not found a reason to upgrade from kingpins and torsion bars as I plan to maintain the factory height in the the front. My MG's have (and had) king pin front suspensions. I rebuilt the current car and it seems to be a good suspension (lever arm shocks not included in that statement). My 944 has torsion bars in the back and, again, I have no reason to complain. In addition, I see that king pin kits are still available on eBay. So why change? Thanks!

DanielC - I don't get the link you reference to open and I believe I need to take up the slack in my steering gear. Do you have another reference?

I'll take a set!