Thursday, August 19, 2021

Actually installing the transmission subframe

Previously, I had gotten prepared to tack the drop tabs to the transmission subframe. Then I did actually tack them on, and the moment of truth was that I had not goofed it up and it would still fit between the frame rails.

It did fit, and here it is clamped back into the frame. This is when it really started to feel good.

Here's my rinky-dink welding setup - an old 110V wirefeed welder, a Harbor Freight welding table, and some LED work lights dangling from the boom of my engine crane.

Full props to those lights, though. Two of them were so good I went and bought some more. They make it a lot easier to see the weld as I work, even once I strike the arc and the helmet goes dark. Amusingly, with five of these pointed at the welding table, it was so bright that my helmet triggered before I even turned the welder on - I had to turn down the sensitivity so I could see before I pulled the trigger.

Definitely a farmer-grade weld, but it's going nowhere. I need a lot more practice before I can dash off those perfect, beautiful beads I have been seeing in online tutorials.
Once I had the subframe fully welded out, I picked the engine and transmission again and started dropping them into the frame. Here, the forward engine mounts are in their slots, and I am just about to start dropping the tail end of the assembly, I want to get the tail pretty low, so I can actually bolt up the subframe from underneath and then pull it back up into the frame.
... Just like this. The transmission is lower here that it needs to be, by a couple of inches, and I have the subframe bolted up to the transmission mount. All new engine and transmission mounts, by the way - much more rigid than the stock units, and also just not worn out.
Then I used the crane to lift the tail end of the transmission into place, so that all the tabs lined up with the tops of the frame rails, and I started tacking it in.

That bead on the left-hand side of the frame makes me very happy.

At this point, I have not yet fully welded out the drop tabs - just the beads on the top. I still need to get the vertical beads and the ones underneath. But, as you can see, it bears my weight easily, and feels very very solid.

Once I finish out the welding, I'll hit the welded areas with some seam sealer and then rattlecan all the places I had to sand off the powdercoat.

Between the drop tabs and the new transmission mount, I should get right at three inches of drop at the tail of the transmission. Maybe even a touch more. And that's exactly what I needed to keep from burning up the gears.

Sunday, August 1, 2021

Fixturing jig

I'm still wrestling with getting the rear subframe welded to the drop tabs. I spent a log time with magnets and clamps, trying to get a stable assembly of the subframe and the tabs that I could tack up in the frame, then remove to complete welding. I had no luck, and even cursing at it didn't help, so I decide to regroup and find another way to fixture the tabs.

I need them to be the right distance apart, both side to side and fore/aft, and I need the top edges to be in the same plane. I decided to try 3D printing these little jigs, which I will position and screw to a piece of plywood.

The idea is that I will clamp the plywood to the frame and use the frame and the transmission subframe to position the drop tabs, then screw the 3D printed jigs to the plywood. This should give me a repeatable position for the tabs, which I can remove from the car and move to my welding table.

This is effectively upside-down in the frame of the car, but orientation doesn't matter right now - just the dimensions I mentioned.

The plywood board is clamped to the frame of the car. The blue plastic jigs hold the tabs. I've used the transmission subframe to get everything in position, with some clamps and spacers to help align everything.

And here's the finished fixture, with the tabs in their slots. This can be repeatably placed in the frame, so the width is right if nothing else.

I will next finish prepping the subframe and the tabs and get it all aligned, then tack it together and test-fit it in the car. I think it should work; then I can finish weld it, bolt it back to the bottom of the transmission, and tack it into the frame.