School me on Roll Cages (SC/Carrera)

[porsche0nut]

As the title suggests, I am interested in learning more about roll cage options and people's experience putting them in SC/Carrera's for track use.

Interested in bolt-in, half cages and learning about harness mounting points.... I am interested in the specifics of how and what more than opening up a debate about their value/use. I also do not want to drill any holes if possible.

- what cage brands have people used and liked? features? dislikes?
- how difficult is the installation?
- where do you mount a harness to? (5 point)
- do the harness mounting points need load distribution or reinforcement (i.e. along the parcel shelf?)

If you have any pics of the installed bars/harnesses, that would be a bonus!

[regnihe]

If you don't want to drill any holes, how do you plan to secure the roll bar (cage) and the sub belt? I assume of you don't want to drill holes you don't want to weld either?

[porsche0nut]

Originally Posted by regnihe

If you don't want to drill any holes, how do you plan to secure the roll bar (cage) and the sub belt? I assume of you don't want to drill holes you don't want to weld either?

In part, that was the reason I started the thread - to find out how to do this and what products are out there. From my limited knowledge on the subject, there are roll cages designed to use existing factory mounting points (i.e. the strut tower or seat belt bolts?)... so I'm interested in learning from those who have done this themselves if that is true and their opinions on the setups that they have.

[Bill Verburg]

Originally Posted by porsche0nut

As the title suggests, I am interested in learning more about roll cage options and people's experience putting them in SC/Carrera's for track use.

Interested in bolt-in, half cages and learning about harness mounting points.... I am interested in the specifics of how and what more than opening up a debate about their value/use. I also do not want to drill any holes if possible.

- what cage brands have people used and liked? features? dislikes?
- how difficult is the installation?
- where do you mount a harness to? (5 point)
- do the harness mounting points need load distribution or reinforcement (i.e. along the parcel shelf?)

If you have any pics of the installed bars/harnesses, that would be a bonus!

While the bolt in cages are ok, I'd suggest a custom built weld in.

It sounds as if you want more of a roll bar or rear section, rather than a full cage which is problematic on the street anyway.

If you are going to race it the sanctioning body will have their say, if this is more for DE then work w/ the shop for a safe install

As to the harness you want a cross bar behind the seats, you want a few inches behind the rearmost seat position, the height should be at or just below the height of the Hans so that there is an unobstructed straight path from the Hans to the bar at a sleight downward angle(Schroth Installation checklist)

For the subs, again the sanctioning body will specify what they want, for DE the usual is a reinforced pad eye drilled through the floor(see the Schroth doc) or a GT3 bar that is sandwiched between the sliders and the seat mounts

If you are retaining the 3 point belt as well you will need to provide a provision for its attachment point on the B pillar if the bar obstructs the stock hard point.

[Quinlan]

I believe if all you want are 6 point harnesses, that you can install a harness bar using the existing upper seat belt mounts. If you are after a roll bar, there may be half cages that utilize the rear seat belt mounts, the lower front belt mounts and the upper front belt mounts to bolt in without requiring any holes to be drilled. I had a half cage like this in my 944.
Brey-Krause advertises a sub mount that bolts between the seat rails using existing bolts, but I don't know if they offer a specific model for the sc/carrera.

[Number1_dog]

I have a 1979 911SC and I have a DAS 964/993 Bolt in bar. I like the cross braces that this bar has. I will mount a harness on the cross bar behing the seats.

[Jack Stands]

I've always been told that roll cages are bad ideas in a car that's going to be street driven as the possibility of hitting a non-helmeted head into a bar are increased. If it's a dedicated track car, disregard this post.

I'd opt for a weld-in cage if it is going to be a track car along with NASCAR style door bars that protect the driver.

[Dantilla]

Lots of great info on proper cage fabrication in SCCA's GCR- General Competition Rules.

[porsche0nut]

Wow thanks for all of the responses so far!

I guess I should clarify, this is primarily a street car that sees moderate track use, at this point about 1 DE weekend per month between May and Oct. I'm interested for two reasons: 1) The added safety that having a harness and roll bar/cage structure provides in the unfortunate event of a collision, and 2) the improved restraint for cornering. I don't intend for this car to ever be raced, which is why I'm more interested in bolt-in roll bars/half cages that can be removed down the road (for example, when I have kids and want to take them in the back seat).

So I guess my new questions become:

- is there a reason against simply putting in a harness bar and mounting the harness to the seat belt points and rear shelf? This is certainly the most cost-effective and simplest solution (and lightest), but does the lack of a "cage" pose a danger to a strapped-in driver?

- with a roll structure in the rear (such as pictured in Number1_dog's post) is it ok to mount the harness directly to the steel tubing of the cage instead of the chassis? (I don't see why not... but worth asking)

Thanks!

[porsche0nut]

Originally Posted by Bill Verburg

As to the harness you want a cross bar behind the seats, you want a few inches behind the rearmost seat position, the height should be at or just below the height of the Hans so that there is an unobstructed straight path from the Hans to the bar at a sleight downward angle(Schroth Installation checklist)

This is excellent info - thank-you!

[JeremyD]

Look at the DAS Sport rollbars - I used one for years that I would bolt in, bolt out - in my 1987 Cabriolet - worked well -

[KTL]

Do a search for yourself. This subject has been discussed many times here over the years.

IMO for casual HPDE style track use TRE Motorsports makes one of the best roll bars. Note that it is a roll bar (behind the seats) and not an actual cage. It attaches to the frame rails and the rear seat belt mount points. Both of which are very solid parts of the chassis.

However TRE's bar install requires you weld in plates to the frame rails at the bottom of the window pillars and then bolt the bar to the plates. I think this style is the best setup because it puts the bar on the most solid part of the chassis- the frame rails. Other bar designs bolt to the floor (Autopower for instance) or some DAS styles use a platform that mounts to the lower seatbelt mounting point. The floor is VERY flimsy and the lower seatbelt mount point restricts rearward seat travel.

You do NOT want to secure your harnesses to the rear parcel shelf. That too is flimsy sheetmetal. A good bar design will allow you to wrap your harnesses around the roll hoop's crossbar, or you can guide belts to the rear seat belt mount points. But keep in mind the longer you run the harnesses, the more stretch they can allow in an impact. Harness material is designed to allow a certain amount of elongation when heavily loaded. The longer the run of harness, the more elongation can occur

The car's steel doors have some very sturdy flanged C-section beams in them. Not saying they're more effective than a dedicated cage's door bars. Just pointing out that the steel doors have considerable side- impact protection built into them.

[Bill Verburg]

Originally Posted by porsche0nut

...
So I guess my new questions become:

- is there a reason against simply putting in a harness bar and mounting the harness to the seat belt points and rear shelf? This is certainly the most cost-effective and simplest solution (and lightest), but does the lack of a "cage" pose a danger to a strapped-in driver?

- with a roll structure in the rear (such as pictured in Number1_dog's post) is it ok to mount the harness directly to the steel tubing of the cage instead of the chassis?

Thanks!

You want the fetch from the shoulder to the mount to be as short as possible, a few inches behind the rearmost seat position is the goal, w/ a slight inward angle
Like this


The lap belts are fastened to the chassis, doubling w/ the 3 points at the sills and at a new hard point at the tunnel side

The subs go to the floor or a GT3 bar

[Dueller]

The only true bolt in BAR that I'm aware of (no welding in mounting plates to bolt it to) is the Das Sport.

There are no true bolt in CAGES (that require no drilling or mounting plates welded in.

Harnesses can generally be attached to the bar/cage support in the main hoop.

Generally harness bars are guide bars not to be used as harness mounts
Exception: Brey Krause harness TRUSS

Most sanctioning bodies do not allow harnesses to be use with stock seats

Most sanctioning bodies require same restraint systems to be same for driver and passenger/instructor.

Check sanctioning body rule book.

YMMV

[Dueller]

Brey Krause harness truss

[tips]

Hiego, they make them all, full, half, welds, and no welds. high quality and not cheap


their club sport one doesn't need welding plates I was told.

[HorstP]

Company name is actually Heigo.
I have the club sport roll bar and it attaches to the existing seat belt points. No drilling or welding required. It fits very well. While it is bolt in, forget the idea of removing it when you want to carry somebody in the rear seats. Either or.

[saxen]

Im a big fan of weld in cages
1- the cage makes the car a bit stiffer than bolt in
2-if you ever want to go back to stock its easy to cut/grind out a 4 point cage.

i used the patrick motorsports cage, what i like about it is it came pre painted, the fit is amazing and it welds to the thick part of the car (not the floor like other cages) it topok me between 2-3 hours to clean the paint off the weld points and weld the cage in- i think it came out pretty well.

[porsche0nut]

^ Wow, that is clean!

[si Banker]

I have a bolt in roll bar with Porsche part number and it bolts into rhe car unsung the stock seat belt mounts front and rear. It is made out of stainless steal

It is for sale Price is $1200