I cut the hole for my shifter today and am using the Chevelle tunnel many here have recommended. My question is how big is the hole I cut supposed to be? I cut it large enough to accommodate the shifter, but no more. When I put the hump in place, there is a large "pocket" under it on the driver's side. I see this as a potential problem for water infiltration when driving in rain (which I avoid, but can't always). Should I cut more, say follow the perimeter of the hump less a half inch or so? See pictures that follow.
Since I'm doing the same project I also had considered that problem. What I'm going to do is to get a nice heavy undercoating and put it all in the area where moisture could end up. I will be screwing my floor hump to the floor pan with sheet metal screws but before I lay it down I will run some silicone around its perimeter to keep moisture from running onto the rug. Then i guess every once in a blue moon I will take up the floor hump to check for rust damage and if I need to por 15 it and lay down more undercoating. Allen allioop108@aol.com
Ok. That sounds like a plan. I thought I would seal the hump up also with silicone and after it cures, put a small amount of water in there to find the low spot and drill a small drain hole. Then prime the raw edge of the hole to prevent rust.
Can you trim the new hump to fit on the inside of the car and then weld it from the underside of the car? You may want to test fit the trans and shifter before final trimming, welding and assembly.
Welding just isn't in the cards for me on this. Interesting idea, though. I would have to cut a lot more of the floor which I'm hesitant on doing (hence the reason for this thread). However, if I went that way, I could still use screws and silicone instead of welding. Just wonder about the strength of the floor after cutting all that out and not welding. I have test fit the transmission. This is how I determined where to cut the hole. Interestingly, people here have asked where to cut the hole. I mounted the tranny and marked where the bracket for the shifter was. Some have asked if the floor was dimpled for this. I actually did find a dimple exactly in line with my mark, but about 1/2" or so forward of mine. Don't know if this was to locate the hole or not, but sure seemed awfully coincidental if it's not. I will test fit the tranny again for a final fit, but the hump pretty much fits right to the contour of the floor. Thanks for your thoughts. Tom
Can anyone post pics of a previous conversion or maybe their stock original 4speed from underneath? I too am interested in whether I should weld or not.
