Time for another photo dump.
With the driver’s side crossmember recess completed, it’s straight onto the transmission tunnel. I had fabricated and tack welded one in some years back to clear the T56 when I originally put it in the car, but after calculating the driveshaft U-joint angles and raising the crossmember accordingly, it was no longer adequate, nor tall enough.
Good thing I had only tacked it in at the time.
The tacks got cut and the first version removed once it was clear it wasn’t tall enough, and that’s why the car hasn’t had one for some time now.
Looking closer, you can easily see the interference issues even with the relief cuts I had made.
So the new tunnel would have to get bigger. I started chasing it forward cutting out small sections at a time, I’m ideally looking for about a finger’s width gap all around. I was close here until I noticed the area circled, this was an “outie” obviously caused by something. Further investigation revealed that it was indeed the transmission. More needed to be removed yet.
Alright, up to within 1/2” of the floor pan to firewall pinchweld now, about where I figured it would end up. Now it’s plain to see what was causing the “outie”:
I completely understand why F body transmission tunnels look the way they do now. The T56 isn’t a particularly big transmission, but it definitely is quite tall. Good news was, I now had all the clearance I needed. So I just rounded off the corners and ended up with this:
A look down the sides of the bigger opening reveals that there’s tons of clearance down the driver’s side…
…while the passenger’s side is a bit closer but still good. If you look close, you can see I marked two unnecessary castings that I’m going to remove next time the trans comes out, just to avoid any potential contact.
Then it was arts and crafts time in The Skunkworks. Figured out my length, center lines of the tunnel and shifter, then mocked it in place to determine the height and side profiles. Should look something like this:
Just to verify fitment, I dug out the new F body T56 tunnel boot I had bought from GM, and test fit it on there as well.
Better have a look down the inside of the tunnel to see if there’s going to be any surprise interference issues next.
Other than the reverse lockout solenoid (which I already knew was going to be close), everything looked good. I’ll probably go back once it’s fully welded in and cut the opening around the shifter a little larger so I can remove the shifter without dropping the transmission. This’ll simplify servicing and buy me a little more room around the shifter base. Time to transfer the template to steel.
I do not possess a slip roller nor do I know of anyone that has one, so I knew this was going to have to be hand formed. I initially tried bending it over my Argon welding bottle, but the metallurgy of this sheetmetal must be different than what I used before. It’s not very malleable, and didn’t want to take a form.
I ended up having to take it into work and ratchet strapping it to a post while heating it up with a big rosebud tip on the oxy-acetylene torch. Crude, but it more or less accomplished what was needed.
Here’s the new piece formed with the curve next to the first version. It’s quite a bit bigger now.
After cleaning it up a bit, I clamped it in place for a test fit and visual. Not bad for the first swing at it:
Remember that reverse lockout solenoid I mentioned? I didn’t forget that it needed a little additional clearance. I pulled out the sand sack and my new Eastwood mallet, and after marking the area that needed the clearance, I went to town stretching the metal in the area.
The pointier end of the mallet moves the metal very quickly, while the more blunt end worked well for smoothing it all out. It’s lightweight, which is nice when you’re swinging it a couple hundred times. When I was done, the inside looked like this:
The outside now has a nice little bulge to it, and only in the area that needs it. If I had an English wheel, I would wheel this area a little just to smooth it out more, but this will suffice for what I have to work with.
I’m out of room for any more pictures, but I’ve since done another test fit and there’s plenty of clearance around the solenoid now.
Tonight I started doing the final fitment and tacking it in, but that’s for the next update. Thanks for checking in on the progress friends.
D.
