Tech help: jackpoint damage question

[livetopedal]

Hello Pelicaners!
Longtime reader, first time posting. I have been shopping SC and Carreras for about a year. Today I inspected a nice '86. I am used to seeing the usual jackpoint bulges under the rear carpets but this car had four drill holes, equal-sized through each floor, mirror imaged on the opposite side. Is this from an attempt to fix the bulge or is this a sign of more extensive body work?
THX!

[rusnak]

jack point bulges? Those are not "usual" or common. They are a sign that someone is doing things on the cheap.

[Jack Stands]

previous Rollbar install?

[CCM911]

+1

If you see four holes on each side, your next step will be to check for some rear mounting holes, generally to the outside rear of the back seats.

[awdbandito]

I would say roll bar, or more likely, its bolts for harnesses.
Look in the center front of the driver seat for where a sub-belt would be mounted and one on each side for the lap belt.

[pksystems]

Sounds like it is reinforcing plates on each side of sheet metal for a bolt in rollcage. Maybe they took the cage out, and just slapped the carpet over the mounts when they decided to sell.

[KTL]

If they are large holes, approx. 1-1/2 to 1-3/4 diameter, look for some evidence of welding at areas further away from the holes. The reason for the holes is something like this:

- Bend cage halo, rear hoop, uprights, all designed to fit nice and tight against the roof, pillars
- Put the pieces in the car and tack them together, checking fitment
- Tweak alignment of bars accordingly, weld joints as much as is accessible
- Push cage down thru the floor via the holes that have been cut
- Now we have access to the top of the cage.
- Finish the hard to reach welds and pull cage back up into car
- Place plates on the floor (sometimes called "plinth boxes") over the holes to shim the cage upward and get it back up into position tight against the roof and pillars.

The dents in the floor are very common unfortunately. The floor is very easy to bend with a jack. Also easy to bend back. Use a heavy hammer, preferably a rubber dead blow hammer. On my racecar, I beat them back down with a sledgehammer. Ugly, but effective.

It always surprises me that it took Porsche until 1987 to put clearly visible jack/shop lift points on the 911 tub. Earlier cars have gotten dented really good w/out these things

[KTL]

The picture of the rear jack point also shows a good indication of a cage/rollbar installation. I don't like the floor as a support for the main hoop of the rollbar. If it's easy to dent with a jack, that tells me it's also easy for the rollbar foot to punch thru the floor when the car lands on its roof.

[livetopedal]

Great input! Thanks! That last picture showing the three bolts is exactly where this car had the silicone filled holes. I also noted the rear decklid had been replaced but didn't think twice about it. Guess this car had a roll bar at some point.
My search continues...... Thanks everyone.