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Tips
Tips

Floorpan replacement

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Jedi Trainee
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Hi guys and gals. I'd appreciate any and all help with my question.
I'm doing some much needed work to my 67 Sprite The floorpans are pretty much non-existent but the inner sills and the crossmember seem to be in good shape.

I'm pretty good at welding and have a consumer-grade MIG welder using 75/25 argon C02 shielding gas as well as an inexpensive (Northern Tool & Hydraulics) Oxy/Acc. rig

I've done a lot of cosmetic body patching in the past - even replaced the floors in my 70 GT6 - but it has a frame under it. All the talk I hear about door gaps closing up and the entire tub shifting out of square frankly scares me - But the floorpans have been rotten for a while because TPO had tried to get by with chopped strand fiberglass cloth and snot-ball resin right over the rot and the doors seem to function fine.(You should have seen what was entailed in removing the seats)
If done carefully ( that is one side at a time )can the spot welds along the center tunnel and crossmember be cut out and the new floorpan panels (purchased from Moss) offered up from below and welded in place?
I hope somebody out ther has done this and can shed some light on this subject as opinions I have read so far vary widely and run the gamut from just dropping a piece of 18 guage sheet metal in the seat well and one in the footwell and welding it in ( I don't buy that - even a dummy like me knows that the complete panned in floor provides the rigidity for the body ) to the necessity of building a rotisseire to roll the shell over to just rolling the body on it's side ( I don't buy that either - seems like walking all the way around the mountain to take a leak in your neighbor's yard)
But anyway - Thanks in advance for any tips on this subject.

Bob M.
 
Hi Bob, I saw your "teaser" in the post about bleeding brakes and looked this up.......here is what I remember, having read up on this procedure. Firstly, if the inner sills are in good shape then you are lucky, but remember, if the floorpans are rotten then the inner sills may be too. Check very carefully! If the sills have to be removed, they should be done one at a time, so following the same advice with the floorpans is sound reasoning. To prevent distortion when replacing the sill, the accepted method is to brace across the door aperture with a piece of angle iron, bolted in to the holes for the door hinges. If the inner sills are sound, and you have the door closed, I think that you should be fine. I agree with using the proper floor pans, as they do indeed aid in the rigidity of the tub. Try drilling out the welds if you can. That way you can use a plug weld when attaching the new floor pan. Cutting sounds a wee bit drastic to me. I am not too familiar with the Midget, but I would have thought that dropping the floorpan in from the inside would have been easier than welding it in from underneath. But anyway, I have seen the "roll the car on its side" method of easy access performed, and it really did work a treat! The trick is to place an old mattress under where the car will go, and remove the door mirror. Make sure that you have plenty of muscle to help in this! I hope that this will help a little, and in the meantime, I shall try to find that article!
 
I do not have alot experience in this matter, but it won't stop me from giving my opinion. /ubbthreads/images/graemlins/smile.gif
If this car is just a weekend fun car and not a "show" car, then I suspect you do not want to tear it down to the shell to replace the floor pan. If it is only a small section of the floor that is rusted then do a patch repair with some 18 guage steel and keep driving. When you decide to restore the car, then you can do it with proper panels. However, if it is a major portion of the floorpan, then you might want to spring for new pans and replace over to the original seams doing the best you can while the car is on stable jack stands. If the sills are solid, then I would suspect the only bracing needed would be from the top of one a-post to the other a-post, and like wise for the b post. (a to b bracing shouldn't be required, but probably wouldn't hurt)

BTW, I removed a 6 by 8 inch portion from my floor pan and patched with 18 guage steel. The rust hole was about 3 by 4.5 inches. The rest of the pan was so solid, that I couldn't justify spending the time and money on a "proper" repair.
 
Thanks for the information guys - Trevor, I regret to say that both sides, seat area and footwells are completely gone at the sills graduating to solid next to the tranny tunnel. so I think replacing the entire pan is the only option. While this isn't going to be a concourse car by any stretch I dont want to be doing a "Fred Flintstone" one day during a downshift.

Steve - I took a body hammer with a pick shaped end on it and went over both sills pretty well with the tap method and incredible as it may seem the inner sills appear to be solid - The outer sill(rocker panels) are bad right behind the front wheels for about 4" - then they appear to be good steel - I went over them with a grinder and the only rot or bondo in them was where I mentioned.


So, I believe I'll employ both your advice and brace the door openings and drill the spot welds ijn an effort to replace the entire pan - The replacement panels weren't too bad - I think both of them were about $250. total

So thanks again, and I look forward to posting with both of you along with all the other members.

Bob M
 
Having done both sill and floor replacements several times, I will suggest a very handy tool I use for the removal of rusted members. It is a length of old rear leaf spring about 18 inches long. Use the tapered leaf and sharpen the tapered end with a grinder. This can be used to slice through metal and to separate spot welds. The length comes in very handy getting at difficult corners etc. Wear heavy gloves and use a 2 or 3 pound hand sledge. Safety glasses always!
This works much better than a much thicker chisel in areas like the sill and castle rail in front of the doors. A bit of grinding on any spot weld metal reamining and the new panel goes right in!
 
Thanks for the "keen" tip Tom ( Pardon the pun ) It happens I have an old set of leaf springs in my stash so one of them is about to be modified - I have been using a tool I bought from Eastwood company for separating spot welded sheets but it's sorta wimpy - just a piece of sharpened steel with a handle, similar to about any kitchen knife, upon the back of which you beat with the aforementioned 3lb. sledge - It works good when new but after a while the edge dulls and the back of the blade gets peened over - I imagine I can make quite a few of your design with one set of defunct springs...

In your experience have you seen a lot of "tub shifting" when doing this transplant? If so, how do you prevent disastrous results? Trevor and Steve both offered excellent tips in two previous posts - But I want all the knowlege I can gather.

Thanks again for your tool tip..Looking forward to posting with you in the future.

Bob Marsh
"K-Vegas", NC
 
Screenprinter, just bolt or weld a cross member in the door opening before you start cutting and do one side at a time. Last one I did I took some 1 inck conduit and flattened the ends and spot welded these in the door opening.
I have a file somewhere showing a device a fellow LBC owner made up which is an adjustable brace which can be used to jack open or closed the door opening on a badly rusted or wrecked car. Make sure you put the doors back on the car while working to check gaps etc. Do this BEFORE you do any more welding than a couple of spots to secure your pieces. Don't ask how I know!
 
Tom,

Maybe I'm going at this wrong, but I haven't removed either of the doors up to this point. I didn't see it as necessary but then again I,ve not done this on a Sprite before. Would the doors not act as a brace to maintain clearances in the door openings or is this something which shouldn't be done?

At this point even with the floorpans in their non-existant state the doors open and close pretty much like normal - Is this lulling me into a false sense of security?
 
No problem leaving the doors on and if they shut and the gaps are good use them as a guide. The bracing can be spotwelded on the flange inside the door onto which the door seal is pushed. Remove all the trim and anything flammable before welding anyway. Good Luck!
The doors will only act as a brace while they are closed and you will have to open them to get access to the castle areas if the inner sills are replaced. You said the inners looked solid so you may very well be able to keep the doors shut. Me,I like to be able to open them if necessary and welding on a cross brace takes but a couple of minutes?
If the door bottoms are rusty you may want them off to sandblast that area also.
I have seen MGB's with rotten sills that would twist and bend all sorts of strange ways when jacked up. One was so bad the passenger door would jam shut if jacked at the rear spring perch. If your sills are sound other than right behind the front wheel on the outer then it shouldn't see the tub shift.
It is going to be an absolute b*tch to weld those floors in from underneath. I never did master overhead welding.
 
Tom,

Thanks for the additional info - I guess I'll take everybody's advice and brace the door opening regardless of the doors being installed - As for overhead welding - It's not my favorite thing either, but with a good helmet and a carbon fiber welding blanket you can reduce the overall bi#@*iness of the operation - Actually I planned on shoving the new pan up from underneath, placing a few pop rivets to hold it in place and then welding as much from the top as is practical - such as plug welding along the transmission tunnel and the crossmember where the spotwelds are drilled out, along the sill where the pan meets it and wherever else I can reach - Some overhead welding will surely be necessary but I'll try to be fatalistic about it.

Thanks to all again for the info, after I get it all welded in and I get out of the Shriner's Burn Hospital I'll let you know how it went! /ubbthreads/images/graemlins/cheers.gif
 
screenprinter,
I know this is an old post. I'm getting ready to do the same to a 65 AH Sprite. I'm curious to know how it went. What gotchas you ran into.
The pans from Moss are about 2" short in width. I guess you cut the existing pan and weld to it? Or did I get shorted in the pan. Bad pun!
Thanks in advance

John Goss
 
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