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Got it to pass smog, the work begins now... 1986 Nissan 720 project


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well, my 720 passed smog. i have a lot of work ahead of me though. front suspension, tires, stereo, paint and body work, misc stuff, possibly rebuild transmission, at some point rebuild the engine but that's if i blow it up first. i have most the stuff to rebuilt the front suspension too.

Anyways, i started this thread instead of starting a whole bunch of others for various things so i keep it all in one place; basically a thread for my truck. one of the first things i need to address is my transmission. it will need a rebuild at some point, i can hear bearing rattle and also occasional whining depending on the gear, speed, or load. i'll touch more on this later.

 

But i noticed on my drive to the smog shop that i leaked gear oil out the tail shaft. i remember having this problem before when i used to drive it daily, and i replaced the tailshaft seal. i can't remember if it still leaked or not. i will replace that, but if it still leaks what do i do next?? It was enough it came up through he boot since it is worn out really bad. i also didn't go over 55 or 60mph since the tires have been on it since parking it in 2014, and shakes like a mf'er depending on the road. it legit was scary.

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1 hour ago, A guy named Rick said:

Anyways, i started this thread instead of starting a whole bunch of others for various things so i keep it all in one place; basically a thread for my truck. one of the first things i need to address is my transmission. it will need a rebuild at some point, i can hear bearing rattle and also occasional whining depending on the gear, speed, or load. i'll touch more on this later.

Welcome!

Smart man, easier to find information if not scattered in 50 different threads.

Edited by Charlie69
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Yeah those trans noises can't be ignored. A leaking seal is only another symptom. You can't seal a wobbly shaft. You can rebuild now while it is in one piece or shop for another one because if you wait until it grenades it probably won't be rebuildable.

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4 hours ago, bottomwatcher said:

Yeah those trans noises can't be ignored. A leaking seal is only another symptom. You can't seal a wobbly shaft. You can rebuild now while it is in one piece or shop for another one because if you wait until it grenades it probably won't be rebuildable.

 

LMAO well it's held up through a couple of quick burnouts 😛 Hey, had it running the best it's ran, even before it sitting there for 7 years, and tried a quick burnout. Then victory one for passing smog 🙂 I'm going to try replacing the seal again for now and use the truck for what it's meant to be, which is haul a bunch of shit out of my house.

I'm going to start with that, and do the upper and lower ball joints, front struts, tie-rods, sway bar links, and idler arms. I don't feel like doing the control arm bushings now, do you think i can get away with replacing those later on or am i asking for more work and risk of damaging my new parts by having to take it back apart again?

Also, i have a nasty rattle from the engine on start up. and yes it definitely is internal. I have my choke idle speed turned down for now otherwise it's worse. It honestly seems like it takes about 5 - 10 seconds to build oil pressure or get oil circulating. This is concerning me.

I think if i can get away with putting a new seal and it not leaking, i'll hold off on the tranny rebuild because i'd like to rebuild the engine and trans at the same time IF i don't decide to take on doing a KA swap.

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Rattle could be worn timing chain guides. The plastic comes off and it's chain against metal.

 

Make sure the transmission isn't over filled. Two liters is full. 80w90 oil or synthetic? I find synthetic tends to seep out easier.

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80w-90 Castrol. I cannot attest for a few months prior to that if I used a synthetic gear or not. I remember doing the clutch, then taking it apart again like 2 or 3 months later because the clutch fork came loose from the throw out bearing and wouldn't disengage all the way. Had to top up then and that's when I used the 80w-90.

 

So you're saying if over filled it'll leak out the rear?

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When you have the spindles off doing the ball joints, check the lower bushings by grabbing the end of the lower control arm and try to wiggle it front to back in several positions throught the normal travel of the lower control arm.  I there is movement then lower control arm bushings are bad.

 

this can only be done by backing off the torsin bars and pulling them.  This is parts of my front end rebuild process.  I pull, clean, and grease the torsion bar ends.

Edited by Charlie69
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5 hours ago, Charlie69 said:

When you have the spindles off doing the ball joints, check the lower bushings by grabbing the end of the lower control arm and try to wiggle it front to back in several positions throught the normal travel of the lower control arm.  I there is movement then lower control arm bushings are bad.

 

this can only be done by backing off the torsin bars and pulling them.  This is parts of my front end rebuild process.  I pull, clean, and grease the torsion bar ends.


maybe i misunderstood Charlie? idk. i thought he meant pulling them out and then wiggling the lower control arms. also says about pulling, cleaning, and greasing.

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Part of my front end rebuild is to remove the torsion bars and clean and regrease them and the sockets they go into. 

 

As far as checking the lower control arm bushings I remove the torsion bars from the sockets that are bolted to the back of the lower control arrms and then I test for play in the bushing.  If you do not remove the torsion bar prior to checking the bushings then you  cannot get the control arm to move front to back because the torsion bar being in place will prevent this movement by hand.

Edited by Charlie69
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Ok one thing I want to add is an oil pressure gauge. I only have the light. I'm looking into a tachometer too, based on a test ran on hotrod.com, the iEquus and the Sunpro  tachs were 2 of the most accurate across the board from idle up to 6K RPM (i know my redline isn't even that high). what are your thoughts on these?


I'm pretty good by tuning by ear (and smell for rich/lean), when i got the truck smogged i was at 830 RPM when i was shooting for about 800 so not bad off. i want to work on getting the Weber back on and tune it, but i want to really dial it in with a tachometer.
 

Also, how hard will it be to install an oil gauge. Equus also has the oil gauge sending units that can be screwed in place of the original for the light that i can use with one of their oil gauges. how difficult would this be to do?

https://www.hotrod.com/articles/hrdp-1201-rev-counters-tested-7-tachs-under-100/

 

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The '83 came with a tach option, get one and it fits into the blank your dash, plug 'n play. If you find a tach it will likely also come with the optional plug 'n play clock. The red line for the Z24 engine is 6,250 RPM

 

The 720 also came with an oil pressure gauge. All, 4x4s have a console with oil pressure and a volts gauge. Not bad looking either. You will need the special pressure sender. The wiring for these gauges are tucked and taped up in your dash harness.

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Well I got tires today. Road Hugger GTP 215/55/r16. I was actually able to really drive the truck now and WOW I don't remember it being as much fun. Why do so many people say these trucks are slow?? I believe it's slightly quick, for what it is at least. Only 103 hp (not anymore i bet) and like 134 lb-ft tq? But it feels like it scurries along nicely. 

 

Pic is when I was getting it smogged. Still had old tires. I'm going to ditch these wheels eventually. Any recommendations on wheels? I have 16's. 

 

20210626_150711.thumb.jpg.70df83902bd46a50fbf370fc2fe5d7e3.jpg

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I found a source once that said 130 @ 2,800 RPMs for a Z24. This means that the engine is only making just under 70 hp. In order to keep the 130 torque flat across the rev range the engine has to double it's HP as it doubles it's RPMs. Or 140 HP @ 5,600. A tall order.  Since 99.999% of the time you are just driving around town, low speed torque is very satisfying. 

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