Written in January 2020
This little mini-article documents the repairs that I made to my 70 Z's ashtray. Pictures follow at the end.
Like many of these ashtrays, the hinge pieces had failed, causing the lid to come adrift. The ashtray isn't much good in that shape. In fact, it doesn't even look good cosmetically. If this is the case for your ashtray, your options are pretty straightforward: Repair or Replace. I think most owners take the 'replace' route, but NOS ashtrays are pretty $pendy (US$1,200 new or $1,000 refurbished from JDM-Car-Parts.com, as of January 2020)). If you don't have the budget, you do what you have to do. No one wants a gaping hole in the console of their otherwise-perfect Series 1 interior.
I chose the 'repair' strategy partly because I was trying to keep my project budget under control, but equally because I get a lot of satisfaction out of restoring things. Before I discuss the details of what I did, I think it would be worthwhile to briefly discuss why these ashtrays fail in the first place. There seem to be a few culprits at work:
The little helical spring is too strong. This not only overloads the plastic hinge bosses as the lid opens and closes, but also creates an high shock load in those parts when the lid is allowed to snap open (as is usually the case).
The type of plastic used to create the main ashtray molding is really brittle (it seems like a 'bakelite'-type material, presumably chosen for its ability to withstand cigarette and cigar burns). That means that it's extra susceptible to stress cracking where high loads exist -- and that seems to describe the situation for the loads that the molded-in bosses take from the tray lid's hinge pins.
The tray lid's pivot arms (or 'ears') are molded with sharp interior angles where they meet the underside of the lid. More stress risers. More cracking.
In the case of my ashtray, all three problems were on display. 1) The hinge-pin bosses were cracked on one side. On the other side, the top of the boss was missing altogether. As an added nuisance factor, a PO had attempted to repair the one of the bosses using what appeared to be contact cement (now there's an optimist!). 2) The tray lid's RHS pivot arm had snapped off at its root. 3) Both of the threaded hinge pins were missing. These are parts that don't show up on eBay. In fact, I couldn't even find a picture to let me know what they looked like. All I knew was that they threaded into the bosses (presumably to allow the lid to be assembled to the tray).
The little hairpin spring has a required 'relaxed' configuration to make it operate with the right over-centre action when the lid reaches the half-open position in its travel. Too much tension and the lid will slam against its stops (see above). Too little tension and the lid action will feel 'floppy'.
Also, there are little 90-degree tangs at the ends of the arms that fit into holes in the tray wall and the lid arm. I didn't expect to find anything suitable in my little box of oddball springs. I also didn't expect to see a replacement OE spring up for sale on eBay. And it isn't exactly an over-the-counter item you can order from a hardware jobber. The only way forward was to make my own.
This isn't as hard as it sounds. Regular, untempered steel wire works fine for little springs like this. With limited travel, the spring material never gets taken past its elastic limit, meaning that it never takes a stretched set and always stays 'springy' (note: in cases where the required extent travel is more extreme, it's easy to put a bit of temper into the spring after you've formed it by heating it red-hot with a torch and then quenching it in an oil bath).
As mentioned earlier, evidence suggests that the Nissan OE spring is too strong (tempered wire, and also too thick), so there was no point in trying to slavishly copy that part of its design. After some trial and error, I ended up using 0.044" wire (that's a bit under 1/16" and roughly equates to AWG 18 or ~ 1mm).
I wanted my new spring to have about the same coil diameter as the OE spring -- that is, an OD of ~ 3/8" or 14mm. As a forming mandrel, a 1/4" drill bit looked about right. I clamped the bit in my bench vise so that the shank (smooth part) projected horizontally out one side of the jaws. Then, holding a 12" length of wire in my hands, I wrapped a double* coil around the drill shank and then examined the relaxed shape. The legs had to form a 90-degree angle a. The coil had to have a reasonably accurate OD and have a tight 'stack'. It took several tries to get this to come out right, but in the end I was happy with my result.
(* My first try duplicated the OE spring by having only a single-wrap coil, but it was too stiff -- I eventually found that a double coil worked better.)
Now it was time to bend the tangs onto the ends of wire extending from the freshly formed coil. This easily done in your bench vise, but first you need to know how long to make the legs. It turns out that this doesn't have to be precise. In my case, I made the bend point for the tangs so that the finished length of each leg was 1/2" (measured along the leg, from the tang back to the point where the leg starts as a tangent off of the coil). Make sure that you bend the tangs in the right direction (they should both point outboard relative to the spring coil's centreline). Otherwise, you get to start all over again.
Once you form the bends for the tangs, you complete the spring by snipping the excess wire off each tang. The tangs should be at least 1/8" long.
Replacement Hinge Pins
With the OE pins MIA, I had to make my own. I started with a pan-head 1/8" machine screw, about 1" long.
I chucked about 1/2" of the threaded length in my drill press and then used a mill file to reduced the OD of the screw head to about ~ 1/8".
With the screw still mounted in the drill press, I then used the file to take the height of the screw head down to ~ 1/8". I now had a cylindrical screw head with a flat top, but with very little slot depth left to accept a screwdriver.
I now clamped the screw in my bench vise (using plastic jaw inserts to protect the screw thread) with the screw head sticking out and used a thin hacksaw blade to deepen the slot.
Then I reversed the orientation of the screw in the vise jaws so that I could cut off the excess threaded length. The finished length of the resulting hinge pin needs to be ~ 5/8". Get these too long and the heads will stick out of the side of the tray too much and you won't be able to insert the tray into the receiver hole in the console . Get them too short and the pins won't project far enough into the tray to engage the lid's pivot arms.
Repairs to the Lid 'Ear'
As noted earlier, the ear on one side of the lid (RHS) was had snapped off. I wasn't overly optimistic about just gluing it back in place. It was going to need some structural reinforcement. To achieve this, I marked and drilled 2 sets of opposing 1/16" diameter holes in the ear and the underside of the lid. Short plastic pins were then cut to length and glued in place as part of the overall joining of the ear to the lid.
Since the time when I did this repair, Steve Nix at 240Zrubberparts.com has begun offering a replacement lid*. That's probably a safer route to take (January 2020 price is US$100 plus shipping), but my results show that with a little attention to detail these lids can be repaired successfully. (* To the best of my knowledge, no one at this time is offering a replacement tray (tub) as a standalone item. Nor am I aware of any sources for the threaded hinge pins and the little hairpin spring.)
Repairs to the Hinge Pin Mounting Bosses
As noted earlier, the boss on one side (LHS) was intact but cracked. On the other side, the top of the boss was missing. Although I've always been suspicious of the ability of epoxy-type glues to take much in the way of side loads, they've improved over the years (the JB Weld product lineup is impressive) and I decided to give it a try. Of course, each repair needed to include a threaded hole for the pivot pins. I didn't like my chances for drilling and tapping in epoxy, so I instead did the epoxy repairs with the lid and the pivot pins (but not the spring) in place. The idea was to let the epoxy flow around the pins and their threads. To keep the pins from being glued stationary, I wrapped them with a turn-and-a-half of plumber's teflon tape.
After the glue set up, I was pleased to find that - with a little careful coaxing - the pins could be freed up and then screwed in and out within their new epoxy-reinforced homes. That allowed me to adjust the slop out of lid mounting.
Installing the New Spring
This was a little fiddly. The tray lid needs to be slid over to the right to get enough space to fit the spring tab into the its hole in the lid ear. Then the tab on the other leg of the spring needs to be inserted into its hole in the wall of the tray. This means putting some tension on the spring while also guarding against letting the sharp end of the spring tab scratch the inside wall of the tray. Just takes patience.
Unfortunately, I didn't take any in-progress pictures while I was doing these repairs. Hopefully, the finished-result pictures below will provide adequate details. As I write this, the repair was actually done four years ago. I'm pleased to report that all of the epoxy repairs have held up well and the lid still flips open and shut very nicely. The work took me a couple of workshop days and let me direct over $1,000 towards other costs and purchases.
If I had the job to do again, I would add a pair of soft-rubber snubbers to the places where the front edge of the lid contacts the inside walls of the tray when it snaps open. I think this is where the parts experience undesirable shock loads and it would be really nice to damp them out. I may just try to insert a couple of strips of adhesive-backed sponge-neoprene sheet in there to make that happen (wish I'd thought of this before I final-assembled the ashtray).