docwyte

Personally I'd remove that rollbar ASAP and go with a properly designed one that welds into structural steel. Having something like that being held in place with 1 bolt that's in shear doesn't make me comfortable at all. My weld in bar attaches to the frame rails of the car as well as the rear subframe.

I'm local to Hanksville Hotrods, he does alot of the Spec 944 cages and made my rollbar. I'm sure he could send one to you that you could then install/weld into place...

Carrera51

My father did DEs for years in his 964 using a Brey Krause R1010 harness guide bar in conjunction with a race seat and 6 point harness. Wanted to keep the car usable on the street. The DAS Sport roll bar is one of the best true bolt in solutions for the 964. You can occasionally find them for sale used here on RL when guys are deciding to install a full roll cage.

That said, if you are only doing two events a year, make sure your 964 is mechanically sound, put some good brake pads and fresh brake fluid suited for track use and go have fun. You might want to consider starting with a good sport seat with thicker side bolsters, like factory sport seats and those found in an RSA. Using those with your 3 point may end up working for you just fine in a stock car if you are just out there to have a good time and not trying to set a track record.

As far as the R3 working with a stock 3pt seat belt, I have never seen the sled test data to support this.

white924s

Thanks for the info, that's about what I thought it would be.

With respect to the bolts issue, I'm not sure if thinking about the load being applied vertically is necessarily the right approach - instead, if the car rolls, I think that it is far more likely that the impact would be on the side or at an angle on the top (i.e. you roll x degrees, where 90 < x < 180). In that instance, the main hoop would transfer the load to the frame rails, and the other pieces would primarily be to support. They would face loads both axial (good) and shear (less good), but the force wouldn't be just in shear, so I would be surprised if shearing of those supports was common.

I could be overlooking something, am somewhat removed from my solid mechanics engineering class, and haven't done any crash testing myself to support this, so I could be wrong. But just thinking out loud, it seems like bolting the bar to a structural hardpoint like the seatbelt mount is a decent solution.

JPS

Subscribed.

I have DAS in my 993, but considering switching to Heigo due to PITA factor with a dual use car in Manhattan...

HalV

Can you go into more detail here? I'm considering one of these roll bars for my 964. Why is the Heigo less of a PITA than the DAS?

Thanks!

JPS

I'm in a unique situation. I live in Manhattan, park in Queens, and truly dual-use my car. It is my only family car and will remain that way. It is my only track car and will remain that way. Therefore everything I do for track days needs to be undoable. I swap wheels and tires for DOT R compounds, switch to Pagid, clip in my harnesses (I do use the same seats, but that's a different saga), and take the rollbar in and out.

I used to have a cab...that was easy to put the bar in and out as one could just open the top and drop it in. I've switched to a coupe and bought the DAS. If it was a one time install, it isn't bad at all. For taking in and out, however, it requires removal of the side panels and heater ducts, rear seat backs (just the backs), and installation of a rather bulky bit of kit in terms of the 2-piece bar. Compared to weld in and such, it is pretty simple, but still.

The Heigo seems to have many more bolt points. Now, this is clearly easier to install, as it seems that nothing needs to be removed except perhaps the rear seat belt receptacles. However, obviously a bolt isn't as sturdy as a weld.

I'm obviously already taking a step towards riskier with a bolt in on seat belt mounts as opposed to weld in or even bolt in on shock tower and frame rails, but remember dual use. So the Q is, is the Heigo step backward in safety worth the step forward in ease of installation in my particular instance. Not sure yet.

docwyte

Hard situation, but I'd always err on the side of safety vs convenience.

HalV

Thanks for the info. My car is dual use as well, although I could leave the bar in since I only use the rear seats for a storage area. My boys (17&14) are now much too big to fit in the seats.

996_C4S

That progression of mods is dead-on in my experience. One other bolt-in rollbar option is the GMG World Challenge bar, which I've had for a couple of years and love. Haven't "tested" it; don't plan to.

Oddjob

To help put to rest the 140mph claim: I have GPS data logs of hitting 149 mph down the front straight in a slightly modified 944T (speedo indicating over 160). A 964, even in near stock trim should have no problem getting near an actual 140, at least close enough that its irrelevant to a safety equipment thread.

When Donahue and Holbert ran their Can-Am 917-10s at BIR (then called Donnybrooke) in '72, they claimed being near 200mph. Its a relatively fast track.