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I'm finishing up my 700r-4 to T5 swap and am trying to figure out where the hole in the floor needs to go and how big these holes were cut originally without having to to a lot of trial and error. From another thread I found on here about this swap it looks like the hole is pretty much centered on the flat section an inch or two in back of where the auto trans cable hole is, and it looks like you have to remove the spot-welded on auto bracket(s). Is it just a matter of centering your shifter boot trim in this area and using it as a pattern to cut out the hole, or is there a more accurate way to do this? It looks like the hole is pretty generous in size.
I installed the transmission in the car without the shifter installed (cover the shifter cavity) and then used a transfer punch to mark the area in the tunnel where I need to cut. Lower the transmission again and cut out the floor. I left about half an inch clearance all the way around.
I don't know how far taken apart your car is; but the tunnel in that area is one piece between the floorboards & the firewall. Looks like the factory spot-welded in the right tunnel piece for whatever trans the car would come with. If you could get that whole piece out of a stick car, wouldn't be too hard to drill out the spot welds, cut the excess off towards the rear, and weld it in. Would then be EXACTLY right, with the right mounting and screw holes for the boot and everything.
I don't have the seats or carpet out of the car (yet). I have all the console and e-brake stuff out of the way and I pulled back the carpet to be able to remove the reverse light switch cable and add my hydraulic clutch stuff.
Looks like Benny K on this thread https://www.thirdgen.org/forums/tran...y-t5-swap.html took the approach I was going to take. It's hard to see with all the brackets in the way, but the flat space where the shifter boot screws to looks just big enough for the boot so it seems pretty self evident where it needs to go. (I wish I would have found this thread before I made this one.)
I didn't know if GM had separate floor panels for auto and stickshift 3rd gen unibodies or just one and the auto cars got the shifter brackets welded to them and the cable hole cut out, and the stickshift cars got the flat section cut out and the holes drilled for the boot in some super quick manner. All the older GM and Chrysler cars I've worked on that had the shifter mounted to the side of the trans extension housing just had a big hole torch cut into the side/top of the trans tunnel for the shfter and a separate shifter boot hump welded on so they could use one floor panel for both stickshift and auto cars.
I installed the transmission in the car without the shifter installed (cover the shifter cavity) and then used a transfer punch to mark the area in the tunnel where I need to cut. Lower the transmission again and cut out the floor. I left about half an inch clearance all the way around.
This is what I did as well and what I would recommend.
This is what I did as well and what I would recommend.
I thought about taking this approach but was concerned the back of the gearbox would just get in the way and I would end up having to take it back out and put it back in several times before I got the hole location exactly where I wanted it. I'm working by myself with the car on jackstands so I only want to install it once.
I thought about taking this approach but was concerned the back of the gearbox would just get in the way and I would end up having to take it back out and put it back in several times before I got the hole location exactly where I wanted it. I'm working by myself with the car on jackstands so I only want to install it once.
It wasn't in the way for me. I made the cuts from the top side with a jig saw. I removed the crossmember and lowered the transmission down and had plenty of room. Unless the marks you made from the underside were somehow way off I don't see how to mess it up.
The hole is 7" tall (front to back) x 5-3/4" wide (side to side). The rear of the hole is 5-3/4" up from the front of the e-brake bracket; 11-1/4" forward of the structural brace (that contains the rear bolts for the front seats), where the brace goes over the tunnel.
Once you cut the hole, then line up the rubber boot over it (that boot covers and "insulates" the hole; it's not the shift boot) and use it as a template to mark its bolt pattern.
Thanks, that's really helpful. Yes, I know the rubber boot isn't the actual finished boot, the outside boot seems to be made of leather or something. I got both when I pulled my T5 at the salvage yard.
The hole is 7" tall (front to back) x 5-3/4" wide (side to side). The rear of the hole is 5-3/4" up from the front of the e-brake bracket; 11-1/4" forward of the structural brace (that contains the rear bolts for the front seats), where the brace goes over the tunnel.
Once you cut the hole, then line up the rubber boot over it (that boot covers and "insulates" the hole; it's not the shift boot) and use it as a template to mark its bolt pattern.
Do you mean the front of the tab of the E-brake bracket that's spotwelded to the floor? Also I'm having trouble with the "11 3/4" forward of the structural brace" measurement ending up in the same place: where on the structural brace do you measure from?
Do you know how far from the back of the hole for the auto shift cable the front edge of the manual shifter hole needs to be to double check my measurements?
Here is my conversion. Unfortunately I don't have a pic of the bracket welded to the floor on my auto body but below is a factory 5 speed image. I did weld in a factory stiffener around the hole
The first two, blue and red, are the measurements I mentioned in the earlier post.
Blue: 11-1/4".
Red: 5-3/4" (the tacked bracket beneath, that you asked about, is about another inch farther back.
But simpler yet, there's a tacked bracket just below the edge of the rubber boot (yellow lines in the picture), and the boot is spaced about 1/8" from that point. Get the boot squared-up, trace it all the way around and mark the bolt holes. The boot's flange is about 7/8" wide, and the hole through the tunnel will match the inner edge of the flange, where my colored lines hit.
Nothing scientific, I know, but with all of those measurements to work with, you should be able to get the hole pretty close to factory.
05-18-2023, 03:05 PM
