Cut Out Full Length Floor Pans Twist Warp

gregski · Apr 7, 2012

Got the front of my 68 coupe on jack stands the rear on it's wheels. A slight angle but not level for sure. I am about to cut out one full length floor pan at a time (passenger side first then when done do the same on the driver side) and weld in a new one.

The question is will cutting out a floor section that big weaken the structure to where it can twist or warp the vehicle? Am I better off making the car level, only lazyness prevents me from doing so, LOL. Is any temporary bracing required?

Apologies for yet another floor repair thread, but I like to ask specific questions, they may help others out as well in the future and may be easier to search / find.

Thanks in advance,
California Greg

Bullitt347 · Apr 7, 2012

Being a uni-body platform then I would think that cutting out part of the supporting structure of the car as it now sits could and will cause a miss-alignment issue. At best there should be temporary support bracing installed to prevent chassis flex along with the vehicle being level. If up on jack stands, then the vehicle should be supported at the front control arms and rear differential as close to the tires as possible. Ideally the vehicle will be supported by the wheel hub as this provides the same load on the chassis as if the car is sitting on the ground. You cannot take to many "before" measurements. The finished product quality is directly proportional to the effort put into the project. Cutting corners now will create an inferior finished product. It is much harder to fix a misalignment issue after your done, than to get it aligned properly when you are performing the repair.

bikefreak600 · Apr 8, 2012

i gutted my car down to the shell. support the car by the ends of the rockers if they are solid. make the car as level of possible by using various thickness boards/ sheetmetal stacked up under each jackstand. i made a make shift frame jig this way with extra jack stands on the ends of each frame rail also leveled just to verify nothing important moved. was very cheap to make and worked perfectly. take measurements of the heights of several points of the frames/rockers for reference. remember if your car does not have front torque boxes, once you remove the floor your front frame looses alot of rigidity. because of this i would never keep weight on the suspension with the floor cut out. it could bow the rear of the frame towards the ground/ push the cowl/firewall in. installing front torque boxes first will help prevent this aswell. also with a bare body shell, there is no extra weight load to support, eliminating any stress on the unibody

horse sence · Apr 8, 2012

you have to remember these cars are over 40 years old now they have seen a lot of rough roads, lead feet and just down right abuse, i would use as many jack stands
in several locations as possible it is likly some twisting has already occurred just do
to age deffinatly level it first to remove any possibility of twisting. being a unibody
each and every piece adds to the structure. 65-66s are the worst ,no torque boxes
up front its amazing the front ends dont fold up, this i have seen. inspect the torque boxes as well they add a lot to the structure. just to note, 67 only have one box 68
has two, they can easily be added to 65-66

2+2GT · Apr 9, 2012

As long as the car is evenly supported and level, you'll be fine. I would reconsider the two long pans, though. I did mine this way, 20 years ago, but now that the one-piece OEM style floor is available, that's the best way to do this. It's actually less work than the two long pans, and the results are far better.

bikefreak600 · Apr 9, 2012

2+2GT said:
As long as the car is evenly supported and level, you'll be fine. I would reconsider the two long pans, though. I did mine this way, 20 years ago, but now that the one-piece OEM style floor is available, that's the best way to do this. It's actually less work than the two long pans, and the results are far better.

well said. i wish i had used a one piece floor. it would have saved me tons of time !

gregski · Oct 3, 2012

you gotta know when to fold 'em

well after practicing MIG welding some sheet metal and failing big time, I decided it is best for the pros to handle this task, so I had the car towed ($65 bucks) on a flat bed truck to a local shop that specializes in classic mustangs, I really wanted a car guy to weld in the new floors and not just a good welder, know what I mean

let me tell you how the costs break down before I give you the bottom line, as they did more than just the floors

first of all this does not include the sheet metal, I bought the sheet metal on my own from a local mustang store and this shop was totally cool with that

so to weld in two full length floor pans (driver side and passenger side) plus two seat risers (you guessed it driver side and passenger side) it was $650 bucks, not bad

this included sealing the seams and painting the work inside the car and underneath the vehicle with POR15 plus coating it with this undercoating spray (I forgot the name so I will take a picture of the empty spray can they gave me to do the rest of the inside with)

take a look at the pictures I think it turned out great

horse sence · Oct 4, 2012

now you will have to make sure you have good brakes.you wont be able to drag your feet to stop any more

Couped Up · Oct 4, 2012

horseballz · Oct 6, 2012

Gregski,
Nice to see you back on the horse, so to speak, and posting again! You've been missed. Nice progress and congrats on knowing when to bite the bullet on letting other folks do things when needed/practical. Looking good.
Gene

5.0Droptop · Oct 6, 2012

Last set I did i left the car setting on all four wheels and cut them out and welded them back in.
I charged 900 and that included a trunk pan as well as subframe connectors.

Cut Out Full Length Floor Pans Twist Warp

gregski

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Bullitt347

I have been doing it wrong this whole time

bikefreak600

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horse sence

2+2GT

bikefreak600

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gregski

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horse sence

Couped Up

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horseballz

5.0Droptop

...all those nights we shared, and you're a dude??

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Cut Out Full Length Floor Pans Twist Warp

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I have been doing it wrong this whole time

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...all those nights we shared, and you're a dude??

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