Because of reasons, I have a Ford Ranger transfer case mounted in my project to do PTO things with. This has resulted in one point of trickiness - how do you get a transmission-mounted case turned into a standalone unit?
The electric version Borg Warner 1354 transfer case: tough, light (<55lb when you ditch the low-range planetary and the harmonic damper), works well in either direction and most orientations if handled properly (displacement circulating pump, chain drive with no tensioner), and has electric drive which can also be converted to manual, as it just moves the internal selector with a screw. It has one integral 1310 U-joint yoke, and a standard Ford size plate on the other output. However, there is a spline on the input, a spline that must be matched to make a slip-yoke.
Happily, output shafts for an automatic 4r44E are pretty cheap, in the $30 range. However, these shafts are hardened to a very high degree. How do you make something attach to that?
Typically, you’d be working with something like the below: a Spicer PTO yoke, available keyed or unkeyed for press fit.
Obviously, if you could install a keyway in the shaft or weld on the yoke, it would be ideal. Let’s discount a press fit for now, because the shaft diameter is a couple thousandths of an inch loose, and would never transmit sufficient torque. So, after you’ve cut the end off the Ranger output shaft with a suitable abrasive wheel, you’d want to set up for welding or cutting a keyway. That’s where some trouble sets in.
Welding is all well and good, but we’re talking trying to weld high carbon treated steel to malleable iron. Not good at the best of times, and requires the whole thing to be heated up while welding, welded with more power than I have available, cooled, and re-heat treated. Then it would need to be balanced, and even then it might (would) develop cracks. On the other hand, cutting high carbon tool-hard steel, and accurately, is difficult even with a carbide bit, and it’s way harder if you don’t have a mill. Okay, send it to a machine shop... and maybe get it right? Worse, even if you get the keyway right, there are some issues that present from using a keyway in pre-hardened steel, and some upper limits on torque. Not so good.
As it turns out, Loctite 660, which is designed for filling gaps in things that are supposed to be press fit and aren’t, is absolutely positively ideal for this. The existing several thousandths loose slip fit is perfect, because this stuff will fill up to a .020" gap. But wait, you say - how can it possibly be strong enough? Well, as it turns out, the shear strength of 660 is upward of 3300psi. That ends up in this application translating to well over a thousand ft-lb of torque. If it breaks loose despite that, it will slip safely in place rather that fracture. If I need to disassemble, I just have to heat it significantly (~500F), and it breaks down.
So there you have it - the story of how I decided to just glue something together.