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I am replacing the complete floorpan on my 71 cutlass and was hoping for some guidance on getting it lined up correctly. The pan I am using does not include the braces or the rockers, I am butt welding it around the perimeter to the existing edges of the original pan just inside of the rocker flange. I would like the mounting lugs for the rear seat on the new pan to line up with the same location as the original and this is where I have questions. First off, the original lugs were not centered, being about a 1/4" off. With the new pan, the driver side lug is in the same position as the original but the passenger side is 3/16" off. My only option would be to cut the lug off of the new pan and move it. It would probably be easier to tweak the wire on the rear seat to fit up with the new location. Any input or am I overthinking this?
When i did my fronts there were some stamped in features, they didn't line up perfectly but i split the difference ( only a slight amount like 1/8” +-) and they came out fine. A whole floor may be harder to line up fr to rr and side.
Ok, a little help please! The new floor pan i have just does not line up straight and I'm curious what you guys would do. The best "fit" with the rear lined up between the tubs, the existing floor braces fitting in the pre-formed pan, and the front of the pan lined up with the firewall, leaves me with the seat bracket and belt holes way out of alignment(see pics). Should I just elongate the holes and weld in place? Plug the holes and redrill new holes? Either way this thing will not be straight unless I replace the floor braces as well.
Has anyone just elongated the holes this much to make it fit? I don't want to do a hack job but thats what seems to have been done from the factory...
Last edited by Natedawg; March 18th, 2021 at 06:39 AM.
I cant be much help here i only replaced my fronts, but are the holes off a little off fwd on one side and rearwd on the other? If yes maybe the floorpan needs to turn slightly clockwise or ccw to get the holes closer? I realize that may change the fr and rr alignments too, but maybe a trim at the fr and rr will help.
idk how the braces are attached is it possible they are sloghtly off fr to bck as well?
it looks like your pretty close i know cdrod did a floor replacement and has some pics maybe his thread can help.
when i did the fronts i only had some pinholes and smaller areas near the middle of each side of the pan i had the 2 front 1/2s for replacments so i screwed the replacment to the original and cut thru both w an airsaw. That worked great, i had to make a couple tweaks but for the most part i cut in front ofthe brace and in back ofthe front mount so ididnt need to ‘align’ much more than sheet metal.
I'm cdrod; I did a full pan replacement including the braces and the inner rockers so I didn't have the registration issues you are having as the seat belt holes were already drilled into the new braces. Do you still have the old pan that was removed? Maybe you could confirm your measurements on the old pan (if it's still around). I did have one minor problem with my replacement pan; the seat belt retractor mounts at the sill plates were on the wrong side of the brace. I had to cut off the lugs and drill new holes in the correct locations and reweld the lugs in place.
Is your car a hardtop or convertible? Did you install any cross bracing to prevent movement when the old floor was removed? Is the body still on the frame or is it on a rotisserie or body stand? Convertible bodies get much of their strength from the floor pan and braces because they don't have a soild roof like a hardtop. Do you think your body could have shifted a little after you removed the old pan?
My car is a coupe, and I have it bolted to the frame right now. I have the original floorpan but its in pieces. One of the seat belt holes is clearly off on the new pan while the original braces are not straight either. Its a mixed bag. Now that I've typed that out, I'm going to move the holes in the new pan and call it good enough. If I can get the interior back in then that's all I can hope for.
Yeah sometimes it helps just to bounce a few ideas around, i had my pans for a couple years before i started cutting, it was my first time. When i finished i was like i shoulda done that years ago!
what i have found on repo parts is the bends are not as crisp as the factory stampings.with the pan setting in there is it sitting tight on the braces underneath?
Yes and no. It depends on which side of the brace you are looking at! As stated above, the original braces and pan are flared out towards the passenger side, so the radii are different on each side of the braces. I think I can suck up the gaps with sheet metal screws, final trim, then plug weld. Here are some pics.
Nate:
Even on original cars the braces don't track the floor pan for a perfect fit; there will be open gaps in some places. My repop'd pan from AMD has gaps between the braces and floor at most of the bends. You can use small sheetmetal screws to pull the new floor pan down to the existing braces for spot welding. After you've welded everything together, remove the screws and plug weld the holes. I used this same approach when I welded my trans tunnel because the curves were not the same between the new pan and the firewall metal. The sheetmetal screws kept both panels aligned for welding. Just make sure the car is on a level surface and the body is sitting on the frame or evenly lifted at every body mount location otherwise you may weld in a twisted pan!
February 15th, 2021, 10:12 AM
