Those are more like thin metal flex tubes with light paper wrap. . i've never heard of burning the tubes with welding. i think theres a decent airspace between the rail and the tubing.

 

Oh, I wasn't worried about burning them -- they're not in the car!
My concern was being able to put the HVAC back in in after the cage is in if the tubing goes all the way down to the frame rails.
See these renders on the 3d scan where the cage definitely gets in the way of reinstalling the air vents, the ducting that goes to them, and the frunk release mechanism:

 

You are clear with that design. I don't think a full cage is needed for a road vehicle. but I've never rolled one.

 

I have no plans of rolling one either!

 

When driving with windows down - you can put a finger between the top of the door frame and body and feel the constant movement/flex. Wild... to me at least...

Brandon
'91 Turbo

 

That's crazy, I'll have to try that on my NA 964 and then compare it to the RUF after full seam welding and integrated cage.

 

Nice work and amazing what todays technology does for us these days. I might be mistaken but I have always been told that the seam at the base of the rendering of the roll cage should be the point that the cage is mounted to. It is less than ideal for the driver to enter and exit but supposedly the best place for roll over protection. A plate should be welded over the seamed area and then the cage welded to that.

I am not a cage builder but this is what we did with my track car and was settled on after many arguments over safety vs accessibility. The cage is welded to the lower portion of the tub in 8 places along with A & B pilers and makes for a rather stiff tub. I will be putting 600 whp down so we will see what happens. It had no issues with 330 hp and tq to the rear wheels.

I would never drive this on the street. Even though it is technically street legal.

 

Thanks for the pic, that looks strong!
I keep going back and forth between building the IRC to the same specifications as RUF (they apparently terminate it at the dash top!) or trying to improve on the design.
My cage builder suggested these modifications to their plans for better rollover protection, but I don't think it's going to be possible to integrate them without making major street-ability compromises.
At the end of the day this is a road car and will not be used on track, so while the RUF design is definitely sub-optimal from a cage designers perspective it may be the right choice for a street car with full HVAC.

 

No doubt one of those things you hope never to test. These tubs are far sturdier than the G body cars. I had a friend flip his 964 coupe onto its roof at high speed and he walked away without an issue. These are pretty sturdy. I have also seen a head on collision with these tubs at 70mph and although there was extreme carnage both parties walked away with only minor nerve damage in one leg. I hope he doesn't mind me posting these. I don't think a full cage will be all that necessary for street duty 🤞So I would do what you feel most comfortable with. Although my days of driving fast on the street ended a while back and save it for the track.

Nice work but way to much alcantara or should i say Racetex for me. I am wondering where the water bed goes LOL Sorry.

 

Don't worry.. there will be zero alcantara/racetex in my build!

Those photos are very interesting because the 911 I've seen on it's roof had the A-pillars collapse but it was a G-body.
The occupants weren't badly hurt but mostly because there was a roll bar in the car that kept the rear of the roof from collapsing on them.
I guess every crash is different though!

 

Both mirrors survived?? crazy.

Brandon
'91 Turbo

 

The change in metallurgy and construction of the 964 was a significant improvement in strength all around. I stay away from G-body or earlier cars for that reason. I saw a very nice F body car pushed into a tool box at low speeds (under 10 MPH) by another car and cause more damage than the rollover I pictured. The tool box sustained less damage than the F-body. I personally like a half cage or roll bar for street use. Although they look the same they are very different overall. The added weight is looked at as a negative but it really was needed.

I don't mind racetex but it is a bit overdone sometimes. I used it on my headliner and dash of my track car. I hadn't planned on putting anything until management said she wouldn't drive it without a full interior and looking nice.

 

That is very interesting. I've been pretty adamant on the need for at least a roll bar and, in this case, opted to add the integrated cage because of what I saw in that accident. Though not especially high speed, it still totally crushed the A pillars. It makes sense that there would be metallurgical upgrades over time (and there continue to be -- I learned a lot from my fabricator about the advantages of a modern still like Docol over what I thought was the gold standard in 4130) that would improve safety in the car, but the 964 tub looks so much like a G body (or F body) tub that I had assumed they were identical.

I'm waiting for the photos, but apparently the car is now entirely seam welded and we're onto the last big steps of fabrication. Fingers crossed I can pick up the chassis in two weeks.

I also had a nice chat with Esteban at RUF North America today -- while he couldn't answer my specific esoteric question, he could not have been more helpful, friendly, or supportive. It's awesome that RUF is back in the US and now that they are starting to offer parts and service I expect that support is only going to get better and easier going forward.

 

Some seam welding progress:

 

Are you using the factory manuals to stitch weld the seams?