How to Remove Dents from a Floor Pan?

[arbezc]

Thanks Rodney & 962, the links & comments are very useful.

I’d watch a few of the Garage Time clips but missed those two. Thankfully my floor pan is much less distorted. I hadn’t thought of a floor jack & sand bag with weights. I may copy a couple of his custom tools. I wondered about welding the pulling device to the outer seam. A clamp & pry bar would reduce the post weld repairs.

The videos raise a couple of questions:

Is the tunnel section of rear half of the pan essentially flat or should it have a slight bulge downward? The front section is clearly formed downward in the middle. My rear section looks flat but photos of replacement pans appear to have a slight bulge in the center.

In the last video, he uses Xylene to remove old carpet glue. I had planned to use Acetone or Lacquer Thinner. Is Xylene more effective or safer?

[Marwil]

The floorpan under the tunnel should have a slight bulge downwards all the way to the back.

[arbezc]

Thanks Marwil, I found a clear image on-line that confirms what you say. The rear half appears to protrude downwards about 1/2 the extent of the front section of the tunnel.

Does anyone know what the purpose of the 12 or so 2" round forms are for? I would guess drains holes used in manufacturing? Mine are sealed on both sides with sound deadening & undercoating.

[962porsche]

what Marwil said^
acetone thinner and xylene will all kill you! the vapors are all just as bad so taking care and wearing proper protective equipment is a 100% must. using this things in doors in high quantity even with proper PPE is not a good idea.
in most cases we just use our large eraser wheel to remove the old adhesive dent fix 700DX. it's a costly tool but it has the power to strip the old adhesive right off.
if your looking to just do the wet solvent strip removal of the adhesive soak down a rag or old smaller size towel lay it over the adhesive and let the solvent do it's work for 15 minutes or so then wipe the area clean of solvent. solvent will also eat away the paint from the floor.

[arbezc]

Thanks 962,
This forum is a great source of information for 1st timers. I wish it existed when I pulled my car apart. The DentFix kit is pretty expensive for one-off use. There's a 3M Eraser Wheel I may try but anything driven by a hand drill doesn't usually pan out.

I can do a fair amount of cleaning outside but that won't work for painting. The most I plan to spray is a panel or wheel well as I work my way around the car. I'm mainly using epoxies. I don't have a good mask, just N95 dust masks, can you recommend one?

[962porsche]

there are a number of good masks for spray painting in the 20 - 25 dollar range. the Gerson 8311 is a ok lower cost mask. because a mask will only filter out the bad crap for no more than 40 hours seal it back in the bags they come in. this is not the in use time this is the open to the air time.

your not going to like the drill type eraser wheels. the only thing they may be good for is to remove a taped strip down the side of a car and even then they are only so so.

[arbezc]

I'll check out the Gerson mask. Thanks for the tip on sealing the filters, makes sense.

Could you clarify something I came across in the 911 Workshop Manual on using the P836 Front End Gauge? It states, "Measurement and take-up points are welded in the floor plate since the 1975 models. This facilitates the damage diagnosis considerably." I think they're referring to the lateral Dimension 1200mm C on the Floor/Frame Assembly diagram below:



On my 73 tub there are 2 punched holes in roughly these locations. Do these holes coincide with the points welded to a 75 & later car? Can they also be used for dimension checks?

Thanks again for your help,
Charles

[962porsche]

not to sure what your asking?
but measurement C should measure out to be 1200MM.
remember that on a unibody car you have 5MM of play ( that will be 2.5MM plus or minus )
what I'm not seeing is if they are measuring from the center of the holes or from the edge of the holes opening.
I do not have the factory manual for this.
looking in my chassis measurement book it states that :
all bottom view dimensions are point to point.
holes are measured to closest edge.
bolts and studs are measured to center.
so check for notes in your book to see what and how they are measuring the chassis.
to get proper measurement you need to use a tram gauge things like a tape measure will give you a faults reading.
we use a Celette frame bench so measuring is not used as the measurement pickup points are done by the fixtures of the bench.

[arbezc]

Thanks 962, What I meant to ask was,

Do the two outer holes in my 73 floorpan match the take-up points welded to the pan on a post 75 tub? The two holes I’m referring to are just behind the wheel well on either side. Here’s a shot of the RH one:



I checked the hole spacing in my car & get very close to 1215mm center to center. The 75on diagram states 1200mm ±2 (Dimension C). I’m wondering if these weldments are visible on a 1975 chassis.

I’d say these floor pan holes in the older cars is in the same general location as the take-up points on a 75on chassis but not meant to be points for taking measurements. Perhaps they are only drain holes?

Here’s a copy of the page that talks about Front End Gauges P863 & 863a from the 75on supplement. They mention the use of a tram gauge to check points to the rear of the car.

Charles

The older pre 72 Workshop Manual has a couple of pages & a diagram referring to Celette measurements but no layout with dimensions. I hope I haven’t confused things further & welcome any comments or corrections,

[962porsche]

I believe the two holes your talking about are measured from there edges not to center to center. only bolt holes tend to get measured from center to center.
when measuring open holes you will need to clean the openings of all undercoats so your getting a true measurement to the edges of the metal and not any undercoatings that maybe hanging over the holes edges.

[arbezc]

Thanks 962,
I'll buy or make a Tram Gauge to check the above Dimension C from the inside edges.
That said, my 72 on Workshop Manual says "All dimensions are from centerline of hole & measured horizontally" in a couple of places. I presume they're meaning horizontal to the ground (level).

It would be useful if these floorpan holes on a 72-73 chassis matched the1200mm Dimension C on the 1975 floorpan drawing but I don't think they do. They aren't shown on any of the earlier "Check Dimensions" foldout drawings.

Would anyone know if there are welded take-up points for location C above on the 1975 & later 911 chassis?

[962porsche]

like I stated before I don't have the factory book to see what it gives for how they are measuring from point to point.
my book reads as I stated so if your book it telling you all measurements are from center to center than that's what you need to go by.

[arbezc]

Greetings,
I'm finally into removing the dents in my 911's floor pan. Unfortunately several are under the sills & are inaccessible form the inside of the car. Here's a shot of the worst dent in the right rear corner.


I'm considering using a Stud Welder & Slide Hammer to pull the dents out from the outside. For a little more $$ there are Dent Puller Welders such as the one below where the weld is made directly on the end of the slide hammer tool.


I don't have experience with either. I'm thinking Studs & a Slide Hammer may be better for deep dents but a Dent Puller would allow many smaller pulls without as much damage. Does anyone have advice on how useful either device may be for the floor pan?

Thanks,
Charles

[Cloggie]

I had a bunch of those in my '89 restomod....all it took was some care, a few hardwood blocks and a 2 lb hammer.

If you work the dent to release the stressed areas and gradually work the material they do go away, and that undercoating is tough stuff. All my hammering and whacking at most just flattened a few of the bumpy bits, not at all noticeable after refinishing.

Now to be fair, I had the car plastic bead blasted all over and put Raptor on as undercoating, so it really did not matter.

962 and the video are far better at describing the process than I ever could be, just want to let you know that mere mortals can do it given some time, patience and thought.

D.

[Dpmulvan]

I used a cheap HF stud welder and slide hammer think it was $100. Does what it’s suppose to do. Some of those dents will not pull all the way out with just a slide hammer there’s just not enough force especially in curved areas and corners. I just finished what your tackling and I don’t envy you. I ended up stripping off all the chip guard down to bare metal. Learn to use a dolly and hammer properly simple tools can get a lot done in a short amount of time. I don’t think spending $300 or more on a stud welder is going to give you an advantage over the cheaper HF $100 one. The HF worked fine for me essentially all your doing is welding on a copper coated stud.

[arbezc]

Thanks for your advice guys,
962 was very helpful a while back. I've ordered a clamp to try his suggestion of using a long bar to pry the worst area down. The car is inverted right now so it’s a bit difficult to hammer the dents out. I'll flip it shortly & give it a shot.
It’s looking more & more that the undercoating will need to be fully removed. I was hoping to save the interior sound deadening therefore a puller approach over a lot of hammer & dolly. Most of the car including the floor pan is very rust free. From what you are saying it may not be possible to save the sound deadening where there’s dents.
I can pick up a cheap stud gun for a bit over $200 Canadian. I likely try one along with hammer & dolly.
Thanks again