As I've posted before, I've got a set of GT3 seats (from Suncoast Porsche) lined up to go into my Cayman S. I ordered a new set of Schroth restraints from HMS Motorsports this morning. When I called Jay at HMS, I thought I knew exactly what I needed. A half hour later I was thoroughly "edu-macated" and placed an order for something entirely different.

The Lap Belt
If you order a Porsche GT3 seat, you'll find it comes with a special mount point for harnesses. Schroth supplies the restraints for Porsche and makes a lap belt specifically designed for use with a GT3 seat. Note the funny looking mounting hardware on the end of the lap belt. ...not your usual spring clasp.


Sub Strap
I originally wanted a 5-point belt (a single sub-strap). The GT3 restraint kit that Schroth sells comes in a 6 point (dual sub-strap) configuration. When you order your GT3 seats you need to make sure that you also request the hardware for your sub-strap to mount to. ....it's not part of the "normal" hardware your dealer would order for you. You don't want to have to punch a hole in the floor of your Cayman now do you? The sub-strap bar is the same thing Porsche uses in their Cup Cars. I'll be removing the "clasp" buckle on the ends of the sub belts and just wrapping the sub-belts around the sub bar under the seat.


Shoulder Harnesses
Decisions time! Hans or No Hans? If you wear a HANS device, the "standard" 3 inch shoulder strap won't work. It will slip off your HANS. You need a 2" belt over the HANS device. Schroth has a shoulder restraint that is 3" at the camlock end and narrows to 2" as it goes over the shoulder. Kinda looks like this:

If you don't use a HANS device, this isn't a concern for you - the normal 3" shoulder straps should work just fine.

This belt configuration can be yours for about $400 a side - slightly more than many other kits. ....but you save a trip to Brey-Krause for a transmission tunnel mount kit and a rocker panel side eye-bolt.

Thanks. You just saved me enough time to wax the car, once I get it, one more time.
I also got the GT3 seats from Suncoast- good business. Been there once to check out the stable and talk racing- they know their stuff.

Wow, just found this. This is great stuff. My Cayman is not in yet, but I've already got a rollbar and now need to get some GT3 seats and a harness. Thanks very much for posting this. I bought my current Schroth 4-point harness from HMS and so will do the same with the

Can you give more details on why you will be removing the clasp buckles?

Thanks again!

objectuser what roll bar did you get?

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Is that 35mph corner 45, 55 or a ..... corner?

I bought mooty's.

[Objectuser - Can you give more details on why you will be removing the clasp buckles?]

FWIW in '07, PCA won't let you run their DE events with a 4 pt harnesses (even w/GT3 seat), you must use an anti sub belt either 5 or 6 point. 6 is better if you value your family jewels. The "clasp buckles" DRVREG refers to are on the sub straps. The sub straps wrap around the underseat bar using D-rings......... You can get substrap bars from Mantis Sport, Brey Krause and Porsche.

Cheers,

Morefun's right on the money. When you buy the Scroth harnesses the substrap comes with clasps on both ends of the sub strap. In many racing applications there would be eye-bolts through the floor of the vehicle or whatever you're mounting the sub-strap to. In the Cayman, I won't have eyebolts to clip the belt to. I'm going to remove the clasp from the end and just wrap the substrap around mounting hardware. It will be secured with a D-Ring just like the ones on the shoulder harness.

Glad to know this helps!

P.S. My travel schedule is finally going to lighten up a bit and I have a date in the next week to get into the shop to get the seats in. I should have some photos to share soon!

I thought it might be a good idea to provide a little more detail about the Scroth lap belt.
When you install most racing harnesses in a street car you use the stock seat belt attachment points and a little extra hardware to mount the lap belt. On the drivers side of the car you replace the bolt holding the seat belt to the side of the car with an eye bolt. Depending on the vehicle you may have a similar attachment point on the transmission tunnel side of the car. In the Cayman the lap belt attaches to the seat mounting hardware. If you were to attach a lap belt to that location you'd need to add a little fancy attachment hardware from Brey-Krause. It's a twisted piece of metal that sits between the seat rail and the stock seat belt. That's what you'd clip the "inside" lap belt to.

When you install a GT3 seat, your lap belt mounting options are little more simple. The seat has two "pegs" to accept the lap belt. (Think of the bolts sticking out the side of Frankenstiein's neck and you get the idea) You don't have to attach anything to the stock lap belt location on either side of the car. The Scroth lap belts attach to the seat, not the stock seatbelt mounting locations.

If you don't buy a Schroth harness with the funny looking lap belt attachment hardware for your GT3 seats, you won't be able to use the "Franken-pegs" on the side of the seat to attach your lap belt. You'll need extra hardware from Brey-Krause to mount your lap belts too.

Yup, understood. I saw that post a month or two ago. The 4-point is in my M3, but the Cayman should be here in another month (I hope) and I'll use a full harness (probably a 6-point due to this thread) at that time.

You don't talk about using a rollbar or harness bar. Does that come in to play for you?

A harness bar is necessary for the shoulder straps.....