1981 Datsun 720 Diesel SD22 Project

[Hankford]

Looking for feedback/help. My truck does not have a front stabilizer bar. It has all the threaded holes in the frame. Is there any reason to not buy one and install it? The 1981 Datsun factory service manual shows one, so I'm guessing mine had one from the factory and it was removed at some point.

 

[datzenmike]

4x4 are different somehow. Possibly stiffer or perhaps they don't fit 2wd suspension.

[NC85ST]

I had an ‘82, gas engine, a long time ago and it didn’t have a front sway bar either. The handling was terrible. I don’t see why a later model wouldn’t work. Are there sway bar holes in the lower control arm?

[datzenmike]

My '78 620 didn't come with a sway bar but everything was there for one. I got one off an earlier truck. They aren't marked as optional.  

[Hankford]

Yes, there are sway bar holes in the lower control arms. Thank you both for the follow up. I think I will keep an eye out and put a sway bar on mine, it appears that everything is there for one.

[Hankford]

The sway bar information was perfect timing, thanks again everyone. A 720 was listed yesterday nearby getting parted out, they had the parts I needed, and I'll pick them up this weekend.

 

I needed to take the bed off to address a few things and get access to the back side of the cab to mount the speakers. I used a handful of cheap pulleys attached to the shop rafters to lift the bed off. There are 6 bolts holding the bed on. I couldn't use an impact socket on the rear two, as it was too large of a diameter to fit through the access hole. I figured I'd replace the square pads at each mounting bolt while I was here. I haven't found a source for those yet. If I can't find some by this weekend, I'll follow up and see if anyone has a link. While I was pulling out the spare tire holder to better clean that tube, I found out why it's been acting up. It looks like one of the pieces is bent, so I'll add that to the list.

 

 

Speaker Mount Plan

I am going to use the two rectangular holes which originally held the spare tire rod supports to hold the speakers in place. I'm doing this so I don't have loose speakers behind the seat and I don't want to drill any new holes. This will also plug up the opening in the back of the cab that let water in the last time I cleaned the truck. I pressure washed again to catch some stuff I missed last time and also test how watertight the new setup is. No leaks, so this is what I'll stick with. The green washers are cheap PLA plastic (does not stand up to long term water), I'll print the final setup in a black PETG HF to handle long term water.

 

Here's the first draft of the waterproof washers. The rectangular protrusion fits the opening in the truck, keeping a #8 machine screw centered in the opening. I recessed the groove for the o-ring too much, I'll shallow that up on the final print. The bolt will attach to the back of the speaker box on the inside of the cab.

 

Edited February 26 by Hankford

[BenzDatsun82]

Wow that frame looks amazing. Assuming a previous owner blasted it or had it undercoated a very long time ago? It looks so smooth... Also very clever with the speaker mounting holes.

[Hankford]

Cars do pretty well over here in general. My commuter car is an early 90's and just as rust free and clean as this one. I think it's a combination of no salt on the roads, no coastal influence, and not that bad of summer temps. This truck is in good shape though, I think it spent most of its life in a garage until the last few years parked under a fir tree.

Edited February 26 by Hankford

[Hankford]

There is some undercoating on the truck. That was not common for this area as far as I know. I'm pretty sure the frame paint is all factory. There's one spot near the rear driver wheel where you can see some runs in the paint. The frame was on its side when painted (driver side up) based on the runs.

[datzenmike]

 

Frames are painted by the company that made them. Runs aren't uncommon and it's just to protect it and many of the underside and suspension parts from rust before the new owner picks it up. Any undercoating is usually done at the dealer or for the dealer and is basically a scam to drain more money from the buyer. Usually by some uninterested minimum wage worker.

 

This was my 710 wagon driveshaft. Some idiot sprayed that crap all over one side for the full length. I scrapped it off.

 

 

 

[Hankford]

That looks like the stuff on my truck. It's horrible. I haven't scraped any off yet, but I've taken as much of the loose stuff off as I could with a pressure washer. 

[Hankford]

Here's the photo of the new eBay door lock pulls. No issues with the fit, but I did not use the opening trim. The original ones were in surprising poor condition despite the door cards being in good shape.

 

 

[datzenmike]

Dodge/Plymouth door lock pulls were all the same late '60s early 70s. My '70 Dart had plain jane black. A few minutes in a wrecking yard with a Chrysler Newport and I had chrome ones.

[Hankford]

I'm almost done with the stereo situation, which is good since I have a lot of suspension work to get to.

 

Updates to the speaker mount

I beefed up the 3d printed washer/o-ring setup and printed a final version in PETG HF. I also shallowed up the groove for the o-ring, so I get a little better seal. Finally, I couldn't find a fender washer with the same diameter as the 3d print, so I cut up some brass sheet I had into a large washer to fully support the 3d printed part. Hopefully that lasts long term.

 

Updates to the speaker boxes

I had to cut down the amazon speaker boxes to get them to fit behind the seat. Walmart had 8.5"x11" felt pieces for I think around $0.32. It was the exact size I needed, but they didn't end up centered and some plywood is visible. I used some 3/8 plywood that I had for the new back piece, with an overall front to back dimension of 3 15/16". I chose this dimension as the shallowest I could make the box with the speaker not hitting the back. There's a little space between the speaker and the back of the seat. I don't feel too great about a single #8 machine screw holding the speaker by itself, especially being offset to not interfere with the speaker. I'm going to make some rubber bumpers and put them at the 9 o'clock and 3 o'clock positions on the speaker box, so they take up the space between the seat and speaker and pin the speaker in place.

 

I also switched the connectors on the outside of the speaker box to a banana plug style.

 

Updates to the fuse box

The add a circuit I got from O'Rielly's worked, but the fuse cover no longer fits. I needed something taller with a slot for the add a circuit wire leaving the top. The random 18/2 wire running off to the left in the photo is what I'm going to use to relocate the fuse at the back of the stereo, so I don't have to take the dash off if that fuse ever goes out. The other end of that wire is soldered in where the fuse would normally go. That's next on my list to clean up.

 

Here's what I settled on, a 3d printed new cover. It fits good and hopefully looks sort of stock. 

[NC85ST]

I like that fuse panel cover. Nice job!

[Hankford]

Looking for some advice. I'm in the process of replacing all the worn-out bushings and cracked rubber boots on the truck. Pretty much everything is shot, so new upper lower ball joints, tie rods, cross rod, cab mount bushings, etc. I've done a lot of this stuff before. I'm not the quickest, but I can eventually get things done.

 

Anyways, I have zero experience with the front suspension torsion rods. I've read through the manual section on them, and I am still having second thoughts on the right way to do this. Is it best to throw caution to the wind and disassemble and use torque specs to reassemble, or should I mark the spline timing/alignment and measure the rear adjustment screw location and match all that going back?

[datzenmike]

Torsion bars or torsion rods. Torsion rods are part of the front suspension and have no rear adjustment.

 

These are the torsion bars and rear adjusters...

 

 

There's no need to remove unless replacing them. They don't wear out. If removing, mark front spline and adjusting bolt location so it goes back in the same position.

[Hankford]

Thanks for the clarification, I didn't realize torsion bars and rods were two different items. Your photo of the torsion bars and rear adjusters were the rear adjustments I was talking about; I just explained it poorly.

 

Here's what I was thinking, and I could be way off on this: given the low miles on this truck (just under 100k), I'm wanting to fix it up as much as I can as opposed to doing just what is needed to get it on the road. Considering the condition of the rest of the bushings (I've thrown a few photos below), I'd bet the lower control arm bushing should be replaced. I haven't checked the lower control arm bushing yet, but the upper control arm bushing rubber is bad and the tension strut rod bushings and cab bushings are bad/gone as well. So, I thought I'd replace the missing dust cover on the torsion rod and replace the lower control bushing while I had the torsion rod out. I'll probably take this opportunity to paint the lower control arms while I have them out.

 

Photos of the torsion rod dust covers (passenger side is missing)

I found an old forum post that backs up what I'm seeing myself, these dust covers are no longer available. I do think I've found a substitute and want to install it if possible.

 

Nearly gone body bushing on the front passenger side

 

Front passenger upper control arm

I'm going to bead blast and repaint this and replace the bushings.

Edited yesterday at 04:02 AM by Hankford