flightline

I'm about to buy a harness for my 951, and I'm interested in the Schroth Hybrid II. The harness comes with clip-in ends on the lap belt, but I'd like to use the bolt-in style end (B24.15.13), and use a M12 bolt through it into the 1/8" steel seat bracket. The seat bracket attaches to the factory seat mounting points, with 2 8mm hex head cap screws into captive nuts at the rear.

Is this setup strong enough, or do I need to drill into the floor/torque tube tunnel with a backing plate? I'd like to avoid drilling as much as possible, if nothing else to help protect against corrosion.

I also noticed in the Schroth hardware guide the B.24.15.13 has this note on it: Cannot be used for a Lap Belt bolt-in bracket under SFI 16.5." Anyone know why this might be?

Thanks

MUSSBERGER

Corrosion? Really? I would rethink your priorities.

flightline

It's not that it's a high priority really, but I'm having trouble seeing a real negative to going through the seat bracket. Bolting to the seat mounting is simpler, more reversible if I decide I want to change the setup, and doesn't expose body metal to the atmosphere without the benefit of galvanisation or undercoating. Considering the factory lap belt attaches to the seat rather than the floor, I think I have to assume that the seat mounting is strong enough to take the load. Unless anyone has any cons that I need to know about, than I think this is what I'm going to do.

docwyte

I wouldn't do that if I were you. I'm using the stock outboard B pillar bolt for my harness, and have a plate welded inside the tunnel with an eyelet bolt going through it for the inner lap belt mount.

Going overboard here is the way to go.

flightline

Is there a reason to use an eyebolt rather than the bolt-in bracket? I don't have any plans to remove the belts. How much room is there inside the tunnel for the reinforcement plate? And finally, what size is the outboard thread for the lapbelt?

M758

Have you seen how small the bolt are on the seat? Don't bolt to seat frame. You probably won't pass tech with that.

Mahler9th

The 951 cars have been driven on the track since they first came out. I had three different ones... two were driven on the track. Back in 1995 or so, my friend the late Jim Pasha wrote a brief article on this very topic and included pics of my car. I still have it somewhere.

While we don't see these cars as much in track day and DE events as we used to, there are likely still folks around many areas that still have street/track 951s and/or have worked on them.

These forums are a good resource, but I suggest tapping into local PCA contacts with experience with these cars. Depending on where you live, there should be plenty of folks that can point you in the proper direction.

That strong suggestion notwithstanding, I do not believe that using the stock seat bracket is the best way to go. As I recall, on the outboard side I used the factory lap belt anchor point. On the inboard side, I drilled a hole and mounted an eye bolt with appropriate hardware. There was never any issue with water getting in or corrosion. All in all it was pretty straightforward.

What type of seat will you use? What type of harness bar, roll bar or roll cage?

I have been using the Schroth Hybrid II HANS harness in my 911 race car for more than 10 years and I still prefer it to other products. I admonish folks to read and follow the manufacturer's instructions for sub belt bolt placement so that the angles are correct. And I also strongly admonish folks to frequently check the condition of all belts, especially the sub belts as they can get wear from rubbing against the grommets in the seat bottoms. In my 911 race car, this wear is not insignificant as the subs rub against the grommet in my Recaro racing seat. I replace the subs separately far before the rest of the harness system is worn out or out of date.

flightline

I have a momo SuperCup seat in the car and a welded rollbar that I had done by a guy in my area. The seat in installed with custom steel brackets I had waterjet cut out of 1/8" A36. I may at some point go to a full cage but there's other things I'm looking to do first. Does anyone have any pics of their inboard lap belt attachment?

VaSteve

There is enough room in the tunnel for the reinforcement plates. There is a bracket to support the exhaust, you don't want to interfere with that (I think you need to be forward of that point). It will all fit.

Alternately, you can use those Brey Krause brackets that fit under the seat rails. They have a place to put the harnesses on and the factory seatbelt. They are spendy.

Both parts available from OG racing.

I would only worry about water getting up in that tunnel if you're crossing streams or something. I can't see how it could possibly get in there.

flightline

The Brey-Krause R-9005 thing looks pretty much identical to what I'm talking about doing, only it looks thinner and with a longer moment arm than my solution. It comes down to whether the floor is strong enough there, but is there really any reason to suspect that it's not? Do they rip out?

Eric_Oz_S2

The rules here in Oz (CAMS) state you can not use the existing seatbelt mount if modified in any way. This means you can use the outside mount, but as soon as you change the inboard you need to use an eye bolt with 3" x 3" backing plate - which is what I did. The bigger problem you will have is where to moun the sub bracket. I ended up drilling holes in the floor with backing plates. You could use a (strong) bar between the slides as an alternative. I couldn't find a suitable one that would work with my configuration.

disasterman

Never compromise with belt mounts. Use a made for the purpose eye mount with backing plates. Confirm (double check) your submarine anchor points for the correct angle when in driving position. Safety wire the clips closed on the your schroth hybrids.

Then go fast.

jerome951

Flightline, just put a bead of silicone or similar sealant on the backing plate when installing and you won't have to worry about corrosion.

Try to get the inner attachment point at a similar angle and height as the factory outboard point. As VaSteve said, as long as you miss the exhaust hanger you're OK.

Also check you're sanctioning body's requirements. They may require equal restraints for both driver and passenger (assuming you are still instructed).

Carrera51

Go through the floor using a proper eyebolt with backing plate like this one: http://www.ogracing.com/catalog/2-Ca...RNESS-MOUNTING

After installed, seal the area up with some silcone sealer. Did this on my own car and it never leaked.

Potomac-Greg

Two things: On the sub belt, I used the OG Racing plates, AND a secondary backing plate that was about 8" x 10". I didn't weld, just bolted and sealed with silicone. The floor on the 944 is paper thin and I can imagine that OG Racing plate punching through like a can opener. The inside lap belt is best done through the tunnel. There is a heavy steel channel or rib in the tunnel (visible underneath the car) a little behind the seat that gives a good solid anchor point for a harness mount. I drilled through and made a "saddle" plate on the other side (next to the exhaust) and used a fat eye bolt. As noted, if you're going to put in harnesses, why take any chances.