ryanabab

Well to give this thread an ending I took the car as far as I was able to. I finished the brakes, suspension, and got it looking the way I wanted but it started to run like crud right as I was leaving for school. Carburetor and gas tank needed to be gone through. I didn't have a good place to store it and work on it anymore after my parents were getting ready to move so I decided the best course of action was to sell it, instead of it just sitting for an unknown period of time until I could work on it (maybe several months to a year or more). Tried to sell locally and some jokers kept lowballing me, some of the Datsun crowd in AZ are morons. Popped it on eBay and ended up getting almost every penny back out of it that I put into it, so that was nice. People really loved that it was an almost ZERO rust 240z. Some kid and his dad bought it for what I'm guessing was his first car, so that will be cool that it will have new life being one of the coolest cars at his school. Till next project fellas

After some consideration of what I wanted to do with the motor/carbs I was introduced to someone who rebuilds the SU for a decent price. The $700ish price tag on some of the popular rebuilding sites made me look into completely different motors. I researched the Ka24de like a lot of the 510 guys do and man it is a simple swap. Even the wiring doesn't seem too bad. However, I am moving the car to the lot close by my house (was at storage at my parents house) and without any electricity in the lot I think that swap would get annoying fairly quickly, especially if I need to weld or use power tools for extended periods of time. Keeping the motor seems like the only sensible option at this time. It is running so poorly I don't know if I'll be able to tell if the throttle shafts are worn (the rebuilder does not do the throttle shaft fixes and it used to idle quite well before I gunked everything up from sitting so I think it is good enough to get it on the road with a good cleaning and rebuild. Getting the carbs clean and gas tank cleaned should put me on the road. Brakes are finally done (what a nightmare) and it of course started running bad soon after from possible debris in the tank. Hoping to get this started on sunday and get the old stuff out for cleaning!

I ordered a T Fitting for the front lines and the line going from the master and then I used a the proportioning valve as the union for the rear lines. I can take a picture of it tomorrow. Another member here had done this and I liked the simplicity and getting rid of older parts that could have caused the problems. I ordered 2 of the T fittings the lines go into. The wire is now being unused because the pressure differential switch is deleted.

Progress with the brakes! Fitting a Wilwood Prop valve, deleting the block under the MC the brake lines feed into with the power wire, and bleeding with a handheld mighty vac seemed to make the car bleed correctly for the time being. Pedal has held pressure for a week now, with no leaks I can see, and when driving I hit the brakes hard and locked up the front wheels so its looking like I might have finally fixed the brakes for the most part. Small tweaking with uneven pad wear on the right rear but other than that I'm hoping I will be in the clear. Its been a long semester at school and a few weeks off to work on this and also my Dad's Model A is going to be a fun time. Paid a shop to fix the brakes while I was at school, only to have them work just as bad and thats what made me put the other parts in and do it myself. Lost all faith in shops now.. but its finally coming together. On the last drive back I hit a bump and all my gauges except speedo and tach (which never worked) went out. So I'll be searching for a loose ground or blown fuse possibly tomorrow. Ordering in a 4in 1 tach gauge 5 inch as well soon so I have all my gauges with newer senders in a very simple little place for reliability and ease of getting it on the road faster.

Hello, so after a semester at school I wasn't able to continue working on my car like I had wanted to, but I think I have made good progress with my brakes not wanting to act like they should. I added an adjustable wilwood proportioning valve, deleted the block under the master cylinder that the front and rear lines go into that has the 1 wire going into it(which was an uncommon size I had to order from eBay coming from Latvia(I ordered 2 so I have a spare if anyone is interested), and then rebled everything including the master using a handheld mighty vac brand pressure bleeder (partly because I'm running out of friends that want to help rebleed the brakes for the 10th time and I was able to get some air out I believe. I test drove the car just down the street and locked up the front tires (which are new 225s). I just wanted to update this thread because I hate unfinished threads that never post the result. I will be adjusting the bracket I made for the rear because the one pad is biting uneven and then possibly bleeding a little more and adjusting the prop valve for more rearward pressure. That, as well as the inner rod in the booster may or may not be within spec but so far she is braking MUCH better than she was, there is hope for her just yet!

I will try all this tonight I have a friend coming over to help as well. Hopefully this fixes it because my daily just decided that it would rather prefer to dump all the coolant out from the front of the engine instead of keeping it inside. Ah the life of driving a $500 miata... hey its got AC though and in Arizona that means a lot! Will post back here if this fixed my car hopefully tonight.

So after using the same master that oriellys gave me with the shallower bore (both ones I got from there were identical) and a little longer pushrod from the original booster it is starting to look like my problem has been solved. I took out the residual pressure valves, got pushrod length to about where I believe it should be, and put in the new booster. The pedal was rock solid after just bleeding the master. I don't want to get too excited because there still is a brake fluid leak but even turning on the car and pressing the brake pedal felt much better. I will hopefully be fixing the leak tonight and seeing if I can get the brakes bled (if I have enough friends at this point haha 3rd times the charm). I'll update this if this fixed the problem once the brakes are bled so in the future people won't just be left hanging like so many other threads I read. As of now the reservoir is cracked.. in all my wisdom I overtightened it and it split on the bottom. Also the bottom fitting that holds in the residual pressure valve is leaking and I need to pull the master to tighten it without stripping the bolt. I am very excited to be finally driving it.. knock on wood..

I pulled the new 15/16 master cylinder apart and noticed that there were the springs with a plastic underneath the flare where the lines go in, I believe for drum brakes? Should those be removed before reassembly? I believe they are referred to as residual pressure valves. They were in both of the lines and I think somewhere I read about removing them for disc brake applications. 10.jpg I took this picture from a write up here done by z car nut and could this be my pressure problem?

I have made sure the reaction disk is in place and thoroughly glued on, pulled it last night to check and make sure. It will not be going anywhere for the next 40 years or so. I remember seeing your posts in a few of the threads I have been reading. Thank you for helping all of us!

Now that you mention it the bleeders on the rear are facing about 3 o clock and 9 respectively. I will remove, block the piston, and then face them fully upright and re bleed the system with the new master and update everyone. Didn't realize that would make that big of a difference with them not 100% upright but still facing up most of the way. I will update this soon with the results. It is still well over 100 with the heat of the day and the sun on me hahah. Thank you for your help I appreciate it so much!

My thinking behind the pads are that one side of the pistons looks like they are almost bottomed out and if they can't expand enough could there be air pockets that are unable to be released? I am saying that because during some research one member mentioned he did this because as he said certain "racers" would do this for a more complete bleed. I have a new master coming in today and hopefully is the correct one. Otherwise where do you recommend I buy it from? The one I have now is a reman and I have heard from a few members that those are absolute junk. I personally have had good luck in the past with them.

The front calipers looks like the pistons have barely any room to move with the brand new big pads. Should I remove one pad and let the piston come out more so or would this not be an issue? I would put a spacer between the piston and the rotor so it would over extend. The calipers are on the correct sides as well. I'm thinking it has to be a mad master, booster, or an error in the pushrod length. I did have it set very close to where I believe it should be but no difference

I did do a brake upgrade, my rear drums were trashed so I put on 1985 maxima rear calipers with new rotors and a custom bracket I made, lines up good and all the pad is being used, I also did the toyota 4x4 fronts. I am using new rubber lines on all the calipers as well. Hoping this will make it a fun little track rat with the l24 and n47 head and a few other bolt ons. I can have the pressure I want with the car off but with it on the pedal goes to the floor. I am researching which brake booster I want to go with, right now for whatever reason it has the 6 inch booster even though the car is a 72. I have not removed it but it looks like it is original (or at least no other holes drilled in the firewall looking from under the dash) The pushrod actuating the master cylinder I believe is adjusted too far out right now because the pedal moves down a little and then feels like it bottoms out (unless thats just how firm its supposed to feel but I think its bottoming out) Brakes work marginally right now, barely slowing the car down. I plan to bleed again with the next master I have coming in today and readjust the pushrod. Also there seems to be no difference in the fluid when the pedal is depressed. I will let you guys know how the new master looks today. I think I also am planning to get a new booster and just stick with the 6 inch as it should be bolt in. Oh as a side not I did pull the pushrod to make sure that the reaction disk is in place and glued it on to make sure it doesn't go anywhere. I get the very audible hissing noise from the booster and seems like its leaking from that. The air check valve in the line is also facing the correct way, zero leaks anywhere in the system. I really need to type shorter... sorry

I have seen the pictures you posted here in an older thread and basically think of a third master cylinder, the one on the left for the zx was 1.02 inches, then the one for the 240z was .8 inches, now imagine mine being .5 inches. I did the on car bleed where you crack the bleeders and let the fluid go back into the master quite a few times and saw zero air bubbles after the first bleed. Same goes for all brakes around the car, I am getting a syringe for that method and also another master from a different supplier to make sure what I have is what I need. I just have never heard of anyone getting one and it ends up being much shallower instead of deeper like your picture shows.. would a poorly adjusted pushrod make for a soft pedal as well? I adjusted the pushrod so I could just barely install the master without feeling any resistance of the pushrod.

So I have very thoroughly researched this before posting here and I hope I don't catch any heat for this. I understand for the 15/16 master cylinder conversion onto my 1972 240z you are normally going to lengthen the pushrod that actuates the master so that it can reach and do its job. Well I bought this cylinder from Oriellys and it had no markings whatsoever on it. No Nabco or 15/16 forged on. I saw on the listing for it that it had a .9375 ratio 15/16=.9375. It did have the brake ports in the same position as the original and bolted on great. I am having issues building brake pressure and this may be a possible reason. The back part of the 15/16 master cylinder where the pushrod pushes is actually much more shallow than the same part of the 7/8. This would mean I have to shorten my pushrod instead of lengthening it like EVERY single person that I have come across and read about. Is this normal and I have just been confused the whole time or is this abnormal for a 15/16 master and I should try another one? This may be the reason I can't build any pressure in the lines because this cylinder is wrong. Any input would be appreciated!!