Technical How much Trans tunnel clearance

I am doing the floor and trans tunel on my build. I am running a c4 auto. How much clearace do I need? I dont want to give up feet room that I dont have to.
Thanks

 

Enough to not rub, but enough to access bolts and cooler lines.

 

Fold up one of those blue Harbor Freight moving pads a few times and put it over the transmission to establish some clearance and build away.

 

I agree. There's no actual tolerance. It can be damn near touching, as long as there is some room for deflection. I'll be the first to admit, in my last build, I needed as much clearance as I could get, and wound up mashing the trans into the floor. I figured as the mounts wore in, gravity would help it clearance itself. I was right.

 

Depends entirely on you motor mount system. A stock system you may need up to an inch all round. A stiff aftermarket system with good control, probably half that.

 

I'm working on the custom firewall/floor, and trans tunnel of my '56 F100 with 5.3/4L80E as we speak. The tightest spot is about 3/4" gap between the bottom of the floor crossmember and the top of the flange of the tail housing. Everything else has 2"+ of space for access to bellhousing bolts, shifter lever, switches, cooler lines, etc.

Keep in mind building in some room to be able to move the transmission back off of the crankshaft/clutch to drop it down.

 

Cut up an old garden hose to use as spacers. Works great and is the perfect thickness.

 

Mine damn near touches, hope it doesn’t bite me in the butt

 

When I built my Austin gasser I wanted the tunnel as small as possible because the interior was already cramped! So I built it within less than 1/2" clearance everywhere. I also made accommodations for trans removal if needed, so I holesawed holes over the bellhousing to block bolts through the new trans tunnel metal. Drilled the holes 1 1/8th inch, and installed KO seals that could be removed once I peeled back the carpet. Glad I did as I had to change the flywheel once and it made removing the 3/8 bolts a snap.

 

Same! I put a bead in the floor pan to add a bit of clearance to the rib on the bellhousing. If it hits, 2 things are for sure: it will self clearance and something went very wrong with my rear mounts.

 

As long as it doesn't touch/rub your only issues are heat transfer and access. Removable panels help access.

 

Thanks for the replies.
I have around 1/2 to 3/4 inch clearance at the bell housing and the top of the trans. The trans tunnel and floor will be removable with a bit of work if It comes to that

 

I put enough room in my floor pan and trans tunnel so that I could just slide my fingers in the gap. I also made the trans tunnel removable so that any shifter or trans adjustments could be make from the top.

I went with the idea of "make it tight, make it removable" train of thought.


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700r modified to fit a 324 rocket

 

I have always tried to maintain an inch of clearance all around.

 

I put a little extra in the Henry J in anticipation that I go up to a th400, but now I'm fighting for a spot for a gas pedal, so keep those things in mind.

 

SBC & PG, 3" channel, 5" clearance oil pan to ground & air cleaners 1/2" below cowl. To get more foot room (albeit on the pass. side) and symmetry, I put a union in the cooler lines right behind the header because there would be no way to access them once the tunnel was in. It also required moving the dipstick tube to the pan. I've aimed for an inch of clearance with a little more on top for the floor mounted shifter.