Well I had some time on my hands so decided to try to fix this speedo pinion; as RRR opines, it is worth a try.
I took Oldkimmer's suggestions and looked into Q-Bond; it's glue is a cyanoacrylate glue (super glue) which was what I figured would be good for rebonding the original break since the surfaces are clean breaks with a tight, flush fit. Cyanoacrylates are very strong but are only good for very small gaps, .002" max in their basic form. The positive thing about them for this use is that they are resistant to gasoline, kerosene, and motor oils (and so hopefully is OK for trannie fluids too unless there is some additive that attacks it).
The interesting thing about Q bond is the powder that comes with it; from what I can tell, the powder is inert. But it is a very fine powder that comes in 2 types in their kit: one type for plastic and the other for metal. The powder is sprinkled on the area to repair and then is flooded by the glue (which is very watery). The fine powder fits closely together, forming thousands of very tiny gaps; the watery glue flows into these tiny gaps and forms thousands of very strong bonds. So you end up with a matrix of thousands of powder particles and glue bonds.
The parts prep was to clean in isopropyl alcohol several days ago and seal it into a baggie; when it was opened, I smelled immediately for any ATF odor in the bag and found none, so the gear plastic does not appear to have absorbed any ATF; that would indeed have been problematic as suggested. A final cleaning with denatured alcohol was done. Then dozens of tiny scores in the area of the plastic to be glued were made with an Exacto knife in a cross hatch pattern to give a rough surface for the bond to 'bite' into.
The original break was bonded with just the glue, and then the powder + glue was applied along the sides where the slots do not extend. I could stress it just minutes afterwards with no bond cracking even to the point of slightly flexing the surrounding plastic. It was left to set up overnight, as cyanoacrylate glues typicaly have a cure time to max strength of 24 hours or so. Some trimming of the slot end for the clip spring is done and it is ready to go in! Time will tell if there is any thing weak about this, but I have bent and pressed on it close to what I think would have been the breaking point of the original plastic with no adverse effects.
But just watch; after all this build up, it will just fall into pieces when I slip it on the speedo gear holder... or 1 mile down the road... LOL. I have tried plenty of repairs that have failed....but you sometimes learn a new trick.
With the metal powder included in the kit, this Q-bond might be some pretty good stuff for general repairs and has some advantages over JBWeld, in that there is none of the variability of hardness that seems to occur with 2 part epoxies I got this at NAPA for a bit over $15, and have seen it on the net for about half of that.
Thanks for the good ideas all, 'specially Oldkimmer!
Sorry but that seems to be the way it usually goes.
