zKars

The gap is to pass the bare little cable once you’ve pushed the main metal body back through the big hole. Whack the end until it dislodges from the bracket, moving to the left in your picture.

No. The length of the rod and shape of the end of it are different. The oil seal is completely different as well. Pity. If you were brave enough or clever enough, you might be able to grind off the rivet in the center and steal the diaphragm. Just have to figure out some way to re-rivet on to the old stem. Bit tough I think.

Well, learning is SUCH a complicated business, Trial, error, more trial, more error. So, it turns out that the U shaped arms are not changing shape and growing wider magically. It is the outer aluminum cast case that is changing shape, ie getting narrower, causing the arm to rub and stick. And it twas “I” that was causing the squeeze. In my vise. I was holding it as you see in a couple of pics above, very gently squeezing the case just enough to hold it. Well, the wall thickness of the sides of that GMB case is SO THIN that I was actually distorting the case inward, not just momentarily reducing the clearance when its in the vise. When it failed, and I brought it in to diagnose, I put it in the vise, THEN noticed the arm was binding. No surprise now. I then assumed that was the issue and the above couple of posts resulted. Note that I cannot cause the same distortion and tight arm motion when clamping an OEM pump body. Much thicker stuff. Big surprise. Thus we are back to square one. I have reassembled this pump with all its original parts and it sucks and blows just marvelously. It is not clear again what caused it to quit after my initial 30 minutes of use. Now I’m down to the diaphragm plunger getting mis-aligned in the arm hook, or the spring having fallen out of position causing poor return action. Hard to believe at cranking RPM’s that that would be an issue. Not check valves, I had the OEM cap with their check valves in place during the on-car failure. Has to be something mechanical. The search continues. Another lesson in forensics.

More to add. I have taken apart the GMB pump to see why the arm became sticky. I also inspected the other new GMB pumps I have and they are both free moving of course. Further, if I remove the spring, the diaphragm spring action is sufficient to return the arm after each stroke. Now clearly you need enough spring force to ensure the arm returns when the engine is running at 7000 RPM. Point is, if the spring falls off its perch, the pump may still “work” at the lower end of the RPM range. So my spring off its perch isn’t the main failure So what happened is that the arm rubs the inside body of the pump near the pin, causing enough friction to make it sticky. I hacked off the housing where the sealing balls are located to get the balls out. Zip zip gone. Then the pin through the arm just fell out. Loose. The arm came out with a tiny tug. The pin is just placed through two holes in the arm, and sits and rotates in the body of the pump. No bushings. Steel pin rotating in aluminum body. Oil is the only thing keeping it from wearing quickly. Now to the issue. The U shape of the arm is simply a bit wide and is rubbing the body, just above and into the body near the pin. I went to put the arm back in and put the pin through it to start seeing what’s going on, but I couldn’t quite push the arm in far enough to get the pin started, then saw that it was rubbing the body. I can easily push a bit, put the pin back through and have the same stiff rotating arm that hangs up. In one picture below you can see the shiny spot where it rubs the AL body on the front side. Now the mystery is that it was loose to start with. How did that fairly thick, pressed into a U shape, arm “expand a little” and “become tight” with a bit of use? I do not have an answer for that yet. I can see in the other two pumps that there is room on either side, not much, but clearly enough. The U shaped arm is not particularly symmetrical and the hole through it is different on one side, as the sides are not perfectly parallel. When I put the pin through and attempt to hold the arm “vertical” relative to a square, the pin is not sitting quite straight through it. So I thought it was going to be a dragging pin in the body that was causing the friction due to oil not getting in there,, but nope, the arm expanded like a noddle when it got wet with oil I guess. Maybe it “Relaxed” from its obviously press formed shape when it got hot? I’m reaching here..... metallurgists out there? I do know that if I just take a BFH to that arm and make it the “right” width again (or grind a bit off, or widen the inside of the body a bit), that I will have a wonderfully performing pump. Until the pin works it way out of the body..... Anyone have any 6mm ball bearings I can put back in there? Oh dang, I’ve ground off the place where it sits. Thread it and put a very short bolt in? Silicon? Bit of epoxy? Shiny spot above the hole. Bit of black Sharpy above that where I applied some to the body to see where the arm touches. You call that square?

I have addition news on the topic. This week I had reason to replace a stock pump on a very old and neglected 71 that i was trying to resurrect. I was just doing a quick job to try to get it running, so I grabbed one the new GMB’s I had laying around that i was previously investigating, Anyway, took them both apart, and slapped the top of the old Nikki (look fine) on the bottom of the new GMB and stuck it on the car. My prior guess about the GMB check valves being bad made me do that. It sucked fuel and I got the car started (another thread about Doing it for the first time in 40 years).... That was Tuesday afternoon/evening. Maybe ran the car for 30 minutes on and off. This morning I cleaned the carbs more and tried to start the car again. Guess what. No sucky, no pumpy. You have GOT to be kidding me. So long story short. The failure mode on this pump is no mystery. The pivot point on the mechanical arm seized up preventing the arm from being able to oscillate. It didn’t seize up solid, you can move it easily, but it was stiff for lack of a better term. The spring is not strong enough to push it back when it is in the up position. I have video of me moving the arm and having it stick/stay in the min and max position. The spring, when compared to an OEM spring is about 1/3 the compressive strength. This is a rough feel test, but it is MUCH weaker. I also found the spring laying loose in the arm, dislodged from its end points. It might be weak enough that it falls out after a bit of use, and the pump stops working as the arm has no ability to return to the “out” position. No amount of lube sprayed at the pivot point changed the friction one iota. The friction is smooth, is just much too high to allow the pump to operate what that wimp of a spring. I did put the stronger OEM spring in for a test, it was not strong enough to return it. An OEM pump arm is totally loose, nearly floppy on the pivot point. I have yet to check two other new GMB pumps I have to check if the rotation friction at the pivot is less or the same. I did initially put the pump in the vise and manually actuate it when I swamped the tops, and it felt normal and returned itself with the spring pressure. I’m also thinking that you are also actuating the diaphragm, stretching it up and down, as the arm moves which provides some additional spring pressure to the system. Is this enough to overcome the friction I have in this pump? No. Clearly without the spring in place, in this pump, it cannot and does not operate with the diaphragm spring effect alone. It worked initially, then quickly failed. 59DCDAF7-8D95-4CBB-BB6F-CDF83CDCDBBA.MOV OEM top, GMB bottom Little tab at the end holding spring The other spring perch is just a little bump. In its defense, the OEM pump uses more or less the same way to capture the spring. There is a geometric difference, as with the GMB spring, when you actuate the arm, the spring just BENDS as much as compresses. The OEM pump does more or less the same thing, just less bend, more compression. This contributes to the willingness to dislodge I believe.

Final chapter for now. Had to clean the carbs more thoroughly than I initially hoped. The jet tubes were not moving on their own, so couldn’t set richness or chokes. It was massively lean, would bog terribly just blipping the throttle, so I took them off last night and cleaned them up. One jet tube had to be pin punched with a ball peen hammer to move it. No damage, after cleaning and lubing, they now work just fine. I drove it quite nicely into its parking spot in my yard under its own power. Clutch felt perfectly fine. Would have loved to take it around the block and get it in second, but with no brakes, no way. The master has a layer of probably the stickiest black goo in the reservoirs I have ever seen. Will have to soak for ever. It has the nice early “Front in the front” master, would like to keep it. The clutch slave soft line was plugged with crud. Couldn’t bleed the clutch initially, so I suspect the rest of the brake system needs more cleaning and work than I’m prepared to do this round. I have “peachy” to get ready by Christmas and there’s a storm-a-comin’ this weekend that will snow in the fleet for the winter. Thanks to Jitensha (Kevin) for helping with the car rodeo today and doing a great job of wheel chock placing when needed.

Clutch master and slave are new. Wouldn’t push fluid to the slave. Turns out the soft line was plugged with crud. Fixed that, and now the clutch works. Can technically make it move under its own power. SU’s need to be dismantled and cleaned, the jet tubes are frozen and it’s tough to get the mix rich enough. Runs but way too lean. Will take care of that this evening. It has to move into my yard for winter. Don’t feel like pushing it uphill, so it will get itself there, even if I use the starter motor to do it.

Here is how nice the engine looks inside. Runs without a puff of anything white or blue out the tail pipe. Heater valve leaks. Good thing there are holes in the floor to let it out on the ground.

I cannot claim to be its first owner, just the second. It just arrived in my care last week. Apparently the rear brakes failed in 81, then never got fixed. Now if I can change the clutch hydraulics, I might take it for a spin. Who needs brakes anyway

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Well it took two days, about 8 hours of work, and a lot of sweat (it’s actually a heat wave here right now, +23C yesterday) but I did it. Boy is my right arm sore. I got this thing started. Was last running in 1981. Yup

Works fine on 7th gen ipad running IOS13.7 with Chrome browser. The layout and HTML that is in use on that site is almost as “vintage” as the Z it describes. It is no surprise users with various combinations of hardware and software will have any combination of issues you can imagine.

Now make one that has material only where the thickness of the lip of the transmission touches the engine block, around the perimeter, and of course the area around the starter and under the block where it “sticks out”. All the rest of the material is doing nothing. You could even punch the lower area below the block full of small holes and claim that the air circulation created with the spinning fly wheel helps with engine cooling. Especially when water gets in there from the road and gets splashed around inside the clutch area. Ok, maybe that’s not a great idea..... Other than that, cool!

aha! Just not something I’ve seen very often. I only have two 280 hvac control setups, neither were AC unfortunately, so no vacuum switches....

ZX part I believe. I have pretty much nothing ZX, just 70-78 Z

If the other leads don’t pan out I have some block breather tubes, valve cover breather elbows, and maybe a S1 heat shield. All used, but all restorable. PM me.

I have a drawer full of jigs and things I’ve made over the years to make things “better” but I made one today that I’ve been wanting to build for some time. When installing new stock T/C bushings, you have to compress the rubber quite a bit to get the end of the rod threads to stick out far enough to allow you start the nut. I had previously modified a special welding vice grip, but it was a struggle at best. It is now in the metal recycle bin. Here is what I built. Some 5/8 threaded rod, few nuts, some 1/4 plate steel, piece of 5/8 ID pipe (garage door spring tubing). M6 threaded rod to keep the two halves aligned. Added that after using it to do the first one. This is the vice grip tool I modified before. The jaws are always in a V shape, never parallel.

Here is another way to share your knowledge. Post a couple of well posts, of cool tools you’ve made or bought that made your Datsun day go better. I’ll go first.

After you cut through the spindle pin (both sides) to remove the control arm from the strut, you can only push (either end) on the cut off surface of the pin that still remains in the strut. I drill a little 3/16 hole in the center, then apply the tip of the pointy tool on the air chisel and pull trigger. (maybe I cut the end off of a chisel and ground a point on the shaft, can’t remember)....

Other than pin lubricant, and insuring the pin slides in easily before attempting the re-install, the secret is a way to rotate the pin easily back and forth while you gently push the lock pin into place. It only fits correctly with the pin rotated "just so" making it very tempting to use too much hammer to get that pin to seat. I use a pair of thin M12x1.25 nuts that I lock together back to back on one end of the pin. Then I can put a vise grip on one of them and wiggle/rotate to my hearts content with one hand as I push the lock pin home. I find the pin is never "loose" by any stretch so it takes a bit of force to rotate and push/pull so having a firm nut/pair and vice grip gives you the torque to move it to just the right spot. Here is the result of the last pin pull last week. Yanked the threads right off of both ends of one pin, cut it off then used the air chisel on the middle bit. Popped right out. After that, didn't bother with the other (both of my spindle pin threaded rods now have pin threads stuck in them, humph....) just cut and air chiseled. Both pins where rusted solid into the steel bushings inside the stupid fancy poly bushings that were installed years ago without lube.... All the pin ends are still nicely bonded to the bushing tubes. All four. The lock pin area was clean as a whistle.

Thought I’d give you more paint chip anxiety Have you put the drip rail above the door openings back on yet? Maybe it wasn’t taken off for paint. If there is more than a thin amount of paint on the lip that the drip rail sits on, you will making gouges and chips when you pound that drip rail over that lip to put it back on. Just do it.

Great idea! And just what size heat gun did you use to shrink the shrink wrap?

Let me confuse this further. The picture I showed was of my spare dizzy, which is not identical identical apparently to the one from the car. I was not aware of all the little differences, but the one I can share right now is the numbers on the “original” one are painted on the side, not stamped on the body, and are hard to read. It is likely the same as what 606-52, though it is very hard to read. The “60” part is more less there. See the picture. This car is a UN Canadian car for sure, no air pump or injection tubing, clean balance tube, no evap tank, gas tank with single vent tube etc. I will see what number is punched on the sloted bar and let you know. But the overall issue is resolved I believe, it should have the single spring it has.

Thanks for posting the FSM description. Who knows why both springs. Most important part is as I paraphrase “weight with spring engages with long slot, no spring weight with short slot” so I put it back together again correctly.

Aha! un-balanced slots! Of course. One spring for sure. Dan, that third example clinches it. One spring!