IPSC

Would it be acceptable for a PCA, DE to route the Sub Belt of a 6 point harness in this manner?

Up from the mounting points through the bottom of the seat AROUND the bottom cushion?

Yes or No? If no why not?

IPSC

bruinbro

I would say no as the cushion would compress and allow way too much travel of the sub belt.

Bro

jester911

Here it is from the PCA website.


# Harness Systems: If the participant chooses to install a 5 or 6 point driving harness ( four point systems are not safe and therefore not allowed) several changes to the automobile must be made to create a safe occupant restraint system. Harnesses must include a antisubmarine strap and be mounted in an approved manner consistent the manufacturer’s instructions. The Harness system must be used in conjunction with a seat which has the supplied routing holes for the shoulder and anti-submarine belts. All pieces of the restraint system must be installed in accordance with the manufacturer’s instructions.

This means that a seat is required to have the proper routing holes for the harness as supplied by the seat manufacturer for the shoulder and anti-submarine straps. The shoulder straps should be mounted at 90 degrees to the axis of your spine or at most 40 degrees down from horizontal. Because the addition of the harness system means that the occupants are fastened upright in the vehicle, a properly padded roll bar or roll cage is strongly encouraged to complete the SYSTEM. The use of one without the other may result in an unsafe environment and is not a COMPLETE SYSTEM. Due to UV degradation and wear the harness webbing must be replaced every five years.

Go here for the rest. http://www.pca.org/drivers_ed/standards.html

Larry Herman

Based upon the fact that SCCA specifically approves this type of mounting method, where the sub-belt holds you like a cradle, it should be acceptable for PCA.

The way you have mounted the belt ends, and the way that the belts are routed through the seat would determine if it is safe or not.

chrisp

There's more to the story.

6-pt subs require that the mounting points are 100mm apart (center to center). The seats that pass FIA homologation don't have a sub hole wide enough to properly mount a 6-pt sub. So by definition the two rules conflict. This is a fundamental problem in the world of safety equipment right now.

You can route the sub under you hips as long as they continue to travel downward through their path to the floor. You also want a straight shot between where it leaves your body and the mounting point at the chassis. Compressing seat foam will create slack (as pointed out above) and compressing seat shell material can lead to a failure of the seat. Additionally you definitely should not run a cradle set up with a typical bucket race seat because the subs have to go under your butt, travel back up to the exit holes and then back down to the car. This set up will not restrict vertical movement.

Basically, you need to make custom holes in the bottom of your seat if you want to run letter-of-the-law 6-pt subs. Really the only seat material that promotes this is aluminum. Modifying a composite seat is a bad idea and is frowned upon by the manufacturers I've talked to (Sabelt, Sparco, Cobra, OMP). Plus any modification to your seat renders your FIA homologation null-and-void and automatically bumps you into the seat back support rule.

I am surprised at how little is checked by PCA (my only sanctioning body experience) because there's a lot of homemade stuff that isn't really scrutinized heavily. Don't get me wrong, there's a lot of good homemade stuff out there but there is a lot of junk too.

Larry Herman

Yeah, what he said.

IPSC

I am not opposed to having an upholstery shop put holes in the seat bottom, I just want to know where to put em?

IPSC

jester911

Your region may or may not enforce it but if the holes were not made by the seat manufacturer then it won't pass.

From the PCA National website:
This means that a seat is required to have the proper routing holes for the harness as supplied by the seat manufacturer for the shoulder and anti-submarine straps.

RedlineMan

Hey;

This is of course a compromise setup, but it IS recognized as one that is fairly effective. It is NOT NEARLY as effective as running the subs down through the seat base, but that is only true - in reality - when you have that type of routing mounted to something SOLID. That would NOT be a floor pan, in my estimation, even though that is the "accepted standard."

You are playing a lot of compromises against eachother, and VERY FEW people have a full view of all the parameters and permutations involved. On the one hand, a cradle type sub mounting like you are talking about does a lousy job of lap belt control, and does not restrict upward (toward the roof) motion, but neither does a "proper" mounting if the floor collapses upward. A cradle does an excellent job of hip control, where a sub that runs straight down or forward of the shoulder belt's path does not. Think about all of that. Which is better? Little bit of Column A, and a little bit of Column B?

For my money, a cradle type will keep you safer in more instances than a downward sub mount to a flimsy tin floor pan because you stand much more of a chance of hitting something in the horizontal plain than going on your lid. Percentages.

Here's the rub... literally. In order to get any sort of decent lap belt control, THE SUB STRAPS MUST BE ADJUSTED SO THAT THE CRADLE CUTS INTO YOUR THIGHS/GROIN, AND ARE RELATIVELY UNCOMFORTABLE. They have to be TIGHT to offer enough performance to come close to a "proper" vertical mounting style.

Simple stuff...eh?

IPSC... You may run afoul of someone saying that you can have no more than one belt per mount point. That is also dumb, given all the other compromises that are considered OK. You'd also do much better with that setup to remove the seat cushion when you are on track.

SCCA is "generally" pretty good on this stuff. PCA should keep their brains on idle, and follow like they always have. They don't know as much as they apparently think they do. Narional seems to have NO FREAKIN CLUE where the ball is anymore.

RedlineManPCA

Capt. Carrera

Would that pass PCA DE tech? Maybe... maybe not. Regardless it’s a crappy setup. In fact, If I was your instructor I would not use that set up. I’d use the stock belts instead.

So what set up would I suggest you use? One specifically mentioned in the SCCA GCR General Competition Rules). The GCR allows mounting them under the seat, and up between the legs. It also allows mounting the subs to the lap belt anchors, and running them over the sides of the seat. (While not quite optimal, this is a great set up for a street car that you don’t want to modify too much.)

The SCCA GCR does not approve running the subs from below the seat and over the sides. It does not allow mounting the subs below the seat and kind-of-sort-of through the seat.

As stated earlier, SCCA regulations are much more stringent and specific than the PCA’s. So it follows that if the SCCA approves a set up, then PCA will as well. You can view the SCCA GCR at www.scca.org

RedlineMan

Huh?

I'm curious as to how you are interpreting the SCCA procedures, and what IPSC has. Unless I am not seeing the pics correctly, he has the subs bolted to the lap belt mounts, and run through the lap belt holes in the sides of the seat bolsters. I can't claim to be an expert on SCCA scriptures, but how is what he has different than what you say they want?

Of course it is best to run them through the seat base, but If I am seeing his setup correctly, this is indeed a known and fairly effective method of doing it.

I'll have to go read.

Larry Herman

It is hard to see from the picture. Please remove the cushion & take another picture. That will remove any question as to how you have them mounted.

RedlineMan

OK;

This is from the 2008 GCR (see attached). This is all I see regarding double sub straps and their mounting. Please fill in the gaps I may have missed, because I don't see anything about where the belts have to be run, other than from the lap belt mounts (permissable), and up between the driver's legs. Where the belts go between those two points (the beginning and end termini) is not discussed anywhere that I could find.

Did I miss something?

sjanes

Sounds like they are mounted under the seat, and come up around the cushion:

"Up from the mounting points through the bottom of the seat AROUND the bottom cushion?"

95m3racer

One of, if not the best methods for attaching sub-belts are to mount them to a bar behind the base of the seat. This will put the sub belts in direct tension, which is what you want.

(This is a rally car that was built to demonstrate"optimal" innovative safety designs)





Also, since we're talking about belt tension and stretching, you also want your shoulder belts mounted as close to the seat as possible. Belts stretch a lot!