246 Underbelly Restoration

I've always wondered "What's above the belly pan -- between it and the cockpit floor?" That area has been sealed for about 36 years on my '74 GTS. The pan is actually two aluminum pieces, although I've heard that some of the early cars had one large piece. The largest piece on mine is rectangular, extending from several inches in front of the oil sump to a few inches behind the leading edge of the door. It's got four "stiffening ribs" running lengthwise. Mine was full of dings, scratches and scrapes - - road and track rash. Before going to Cavallino, I was determined to have that pan replaced even though the judges wouldn't be able to see it on a grass field. I wanted it correct. The other section of the aluminum pan is shaped like a truncated pyramid with the base overlapping the leading edge of the rectangular pan and ending at the rear of the spare tire compartment -- the area under the footwells. In front of this pan is a rectangular fiberglass piece directly under the spare compartment.

Because of the stiffening ribs, there was really no way for me to replicate the large rectangular piece at home, so I used DEW Motorcars, a highly regarded restoration shop in Sterling, VA, to take off the old piece and make a new one. That would take awhile, so I drove the car home without the pan and started the refresh of the area that was now fully exposed. Pix #1 shows what I found (you're looking at a small portion of the total area--toward the right rear corner of the car) - - a little scary but not nearly as bad as it looks. That's the fiberglass floor and fiberglass batting that keeps the center tunnel from getting too hot in the cockpit because of hot coolant hoses in the tunnel. The white and brownish residue is the product of 36 years of bi-metallic corrosion where the aluminum belly pan was touching the steel support structure. All of you have this on your Dinos, you just can't see it. The good news is that Ferrari (or should I say Scaglietti) was smart enough to tack weld a "sacrificial" metal strip on the support structure between the support and the Al pan. Luckily, it's fairly easy to treat the resultant corrosion. I did it in 3 steps:
1) Wire brush all the residue off, 2) Brush on Rust-Oleum Rust Reformer- -I did this on all the metal in the area, 3) Brush on a high quality rust primer - - I used Rust-Oleum Rusty Metal Primer (#7769). Pix #2 shows all the sacrificial metal and a couple other pieces fully coated. Where you see gray, I did step 1 & 2 only because the corrosion was very superficial and should go another 36 years without a problem. Pix #3 is a close-up of the finished opened area forward of the rt rear wheel. That's the reconditioned sacrificial strip on the left with the two rivet holes. It "Ts" into an oval shaped frame piece under the rocker panel which runs into an angled frame corner on the right. The frame members were in very good condition (heavier, harder steel), but wherever the belly pan was riveted directly to a heavy frame piece, like under the rocker panel, there was some corrosion around the hole. I did all 3 steps on each rivet hole and often painted the whole frame piece, as in Pix #3.

My next thought was . . . "now that I've got this area open, I should add some insulation in these open cavities to 1) decrease road noise, 2) decrease heat from the road (cooler cockpit) and 3) decrease air and moisture in those cavities." So, I found some Dow 1" closed cell styrofoam insulation (aka, Blue board) at Home Depot that was perfect. Pix#4 is all the custom cut insulation pieces on the garage floor with a yard stick to the right for comparison. Pix#5 is that same area in the earlier pix but with insulation in place.

The finished product in place in Pix #6 and 7 from front to rear--fiberglass panel under spare area, small Al piece (truncated pyramid shape) under footwell area and large Al rectangle with 4 stiffening ribs.

Whew! Sure glad that job is over,

Bill
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I agree with you completely - - quality was definitely not a high priority in 1974. Every time I do a project on the Dino I think, "How can I make this better using today's technologies without changing the original appearance."

Time? Good question, I didn't keep track of each project but here's a "Best Guess."
- 3 Step "Refresh" within the underbelly cavities ~25 hrs
- Insulation: find and buy a suitable material (DOW Blue Board), measure & custom cut each piece, glue in place ~20 hrs
- Prep & Paint rocker panels - the last step because it's best to wait until the new large rectangular pan is riveted in place then paint the rocker panels ~12 hrs
- 3 Trips to DEW Motorcars ~4 hrs

So that's ~61 hrs of my labor. I could do it again now in 40 hrs.

The work that DEW did--take off 2 old pans, replicate the large one, paint those two and the small fiberglass panel, reinstall all. That was about $1500. They also made the front bottom--the nose area below the fans, the small air dam, the battery protection shield--look too perfect for a 70,000+mile car. Also fixed a paint chip on a fender (everybody reading this, please put a foam cushion on your floor jack handle! NOW! I didn't until it fell on my fender after 32+ years of ownership). Beautiful work for another $1000.

Bill

 

mb, I couldn't resist taking off the underbelly just to see what was there. And, of course, one thing leads to another. Go figure! Besides, I really enjoyed all that time laying on my back under the car - - NOT!

I missed your engine at DEW, but I've seen mine "in the nude" and they are the same. or damn close. Are you going to be a featured "Scaglietti Car" at the Reading Concours?

Bill

 

Dave, wish I had taken a picture but I didn't. The small panel (truncated pyramid shape with a small rectangular "door" in it held on by 4 small machine screw) was very good . . . just needed to be cleaned, sanded and painted. The large rectangular panel had normal dings and scratches and one 6" long dent and well scraped area which is why I replaced the whole piece.
Bill

 

It was a combination of 1/8" and 5/32" diameter aluminum pop-rivets for the Dino underbelly area. The trick is getting the correct lengths since sometimes you're going into thick chassis tubes at an angle that is not perpendicular to the metal thickness (long rivets) . . . you'll see what I mean once you're into it. Other times you're into light weight rectangular or square non-structural tubes (short rivets). I used Craftsman and Arrow brand rivets. Have fun!

It's part of the "mystique."

Bill

 

Scott, thanks for the compliment and for opening this subject again. Would I do anything different? Probably not, since what I did should last for a very long time and it's pretty much unnoticeable unless the car is on a lift. Is there an update? Glad you asked and sorry to say I didn't think of this sooner. I helped a fellow Dino owner in CA with detailed drawings and instructions on how to make the belly pans for a GTS from scratch. I'd like to pass that info to you all.

Following this paragraph is my narrative to him talking about the two drawings and, then, the pix of my Dino underbelly as finished. Sorry about the drawings--I drew them by hand and they are much too crowded with notes. My mechanical engineering drawing instructor in 1961 would not have been happy! So here we go:

PLEASE NOTE THAT ALL DRAWINGS ARE DONE FROM A VIEW ABOVE THE BELLY PAN, AS THOUGH YOU ARE SITTING IN THE CAR. The pictures are taken mostly from below - - this can be confusing when comparing the two.

The pix are also attached and below are the words to go with them. Have your mechanic/fabricator call if they have questions. I don't know if you have the fiberglass piece for below the battery/spare area or the 9 1/2" x 9 1/2" (approx.) non-aluminum piece that is on the driver's side just in front of the engine oil sump. It covers the throttle cable pulley. If not and you want drawings, I can easily sketch them.

Pix #1: All 4 belly pan panels taken from directly below. This is the "finished" side, although ALL panels are painted on both sides. The lift is blocking the view of the outer portions of the pan. The engine compartment begins at the bottom of the pix. The largest piece I've named P/N 1, the small access panel (lower left, 5 3/4" x 10 5/16") is P/N 1A, the second largest part (trapezoidal shape at the top) is P/N 2 and it has an access panel somewhat in the center, which I've named P/N 2A. P/N 1A and 2A are exactly the same size.

Pix #2: Looking rearward - - the rear portion of P/N 1 and the access panel, P/N 1A. That's the fuel pump and filter on the right and various coolant pipes on the left. The darker black square is the non-aluminum panel mentioned in para. 2 above. It's held on with machine screws. P/N 1A is flush with P/N 1 and held in place with sheet metal screws (details in Pix #6).

Pix#3: Looking forward - - close-up of the P/N 2 (the trapezoid shape) with P/N 2A laying flush, same as P/N 1A. At the bottom of the pix is the beginning of the black fiberglass panel mentioned previously (details in Pix #7).

Pix #5 (#4 deleted-redundant): Looking rearward with access panel P/N 1A removed so you can see how P/N 1 is "embossed" inward to allow for P/N 1A to lay flush with P/N 1. Note the sheet metal "screw-in U clips" for attaching P/N 1A. The white stuff inside the belly pan is closed cell 3" DOW insulating foam I put in in 2009 when I had my belly pan off, hoping it would reduce road noise and heat in the cockpit. Maybe it did, maybe it didn't!

Pix #6: Close-up of typical P/N 1A or 2A holes and screw ( #10 x 1/2" pan head, Phillips) which goes in the big hole x 4. I have no idea what the smaller holes are for - - just one of those Italian things - - why change the drawing! Let's go get an expresso!

Pix #7: Downward-facing (finished) side of the fiberglass piece mentioned earlier. It's roughly made but serves it's purpose nicely. The larger hole is for the A/C condensation hose to vent to ground. No A/C, no hole needed. The panel is held on with hex head machine screws and washers. If you don't have the panel you still will have the "female" receptacles for the screws.
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Tony, here's how Dow describes the insulation:
"Super TUFF-R™ Insulation is one of the most durable - and thermally efficient – insulation products offered for residential applications today. Three-ply poly/aluminum foil facers laminated to the high-performance polyisocyanurate foam core enable exceptional durability and water vapor resistance. One facer is blue while the other facer is reflective foil."

They can't say "waterproof" because someone will contest that in a lawsuit someday.

Bill