alternate to drilling through the floor pan for sub belt mounting?

[cgfen]

Hi
I realize that conventional wisdom dictates that most of us drill through the floor pan and install eye bolts for sub strap attachment points.

I am resisting that path purely because ii don't want to drill holes in the car.
I realize many of you think that's foolish, please try to put that aside.

I've seen two alternatives;
1. Around the thigh harnesses, similar to a parachute harness, that attaches twice to the existing lap belt attachment points. People here in So. Cal, frown on this because it is;
A. unconventional
B. perhaps not well suited for upright seats, local vendor SUBESPORT does not recommend this path for upright seats.
C. creates a busy attachment point

2. Fabricating a bar that runs under the seat pan to wrap the sub belt around.

I'd like to try # 2, but am getting conflicting information as to whether or not i can use the seat mounts to attach the bar to, or if i have to sandwich the bar between the seat mounts and the floor pan somehow.

I run in PCA and POC events.
The car is a 96 4S

Looking forward to your thoughts and or photo's if you've gone down this path.

thanks

Craig

[mistertate]

Puttin' holes in the car is the SH_T! In the words of Homer Simpson-

"Puttin' Speed Holes in the car!"

Seriously, OMP makes a 6-point harness that works pretty good. The sixth point is because it has two straps for the sub-belt, both mount to the lap belt points making a sort of vee under the seat. The two strap sub belt goes around your balls a little better too.

[barney911rs]

I would ask OMP if that is for an upright seat, as you heard before the 6 point is more for laid back formula cars. If you want t play, you need to pay, and in this case the cost is a hole in the floor. If you are careful, and put globs of silicon around things, you won't have any water intrusion. If you want to sell the car, patch the hole and put the carpet over it.

[Dixie]

The setup John describes will work for the subs. But there is much you may be leaving un-addressed. What seats are you using? PCA mandates your seats have holes for the shoulder belts (and sub if you're running a single sub.) Also, where are you mounting the inner lap belts?

And whatever you do, don't run the sub belt over the front of the seat bottom.

[Bill Verburg]

Originally Posted by cgfen

.......
2. Fabricating a bar that runs under the seat pan to wrap the sub belt around.

I'd like to try # 2, but am getting conflicting information as to whether or not i can use the seat mounts to attach the bar to, or if i have to sandwich the bar between the seat mounts and the floor pan somehow.

I run in PCA and POC events.
The car is a 96 4S

Looking forward to your thoughts and or photo's if you've gone down this path.

thanks

Craig

No need to fab, though you could. BK R-9031 should do you.

[cgfen]

Originally Posted by Capt. Carrera

The setup John describes will work for the subs. But there is much you may be leaving un-addressed. What seats are you using? PCA mandates your seats have holes for the shoulder belts (and sub if you're running a single sub.) Also, where are you mounting the inner lap belts?

And whatever you do, don't run the sub belt over the front of the seat bottom.

good questions

Seats = Cobra Imola's with shoulder harness holes and sub strap hole in seat pan.

inner lap belts = mounted to a BK type fitting that is "sandwiched" between the bottom of the seat mount and the top of the sliders. Also held in place by the bolt at that junction.
see http://www.livermoreperformance.com/porsche_harness_mounts.html R 9004 and R 9005 parts

thanks

Craig

[cgfen]

Originally Posted by Bill Verburg

No need to fab, though you could. BK R-9031 should do you.

this one?




if so, that looks like it will work.
I can sandwich it between the mounts and the sliders or the sliders and the floor pan depending upon clearancing.


hmm some rectangular tubing and a few endplates = not much $$$$$$$$$
time to stop putting off buying a starter boy MIG welder methinks.


thanks Bill.

Cheers

Craig

[barney911rs]

Double check the rules to make sure they will allow you to mount the sub like that for W2W racing. Better to make sure before doing the work. Should be fine for DE, but those rules keep changing as well.

[Dixie]

Double check the rules to make sure they will allow you to mount the sub like that for W2W racing.

Excellent point. The setup should be fine. The method is detailed in the SCCA GCR for W2W racing. And you know how anal the SCCA can get. But there's nothing like getting approval from the clubs you run with...

[Bill Verburg]

996/7 GT2/3 use a similar bar setup for the subs

Here is how the factory did seat installs on 964/993 RS/Cup

#22 the tunnel side harness mount and #18 spacing washers are placed between the slider rail and the sidemount. the sub bar would be similarly sandwiched.

But of course do check w/ the sponsoring organization.

The feedback that I have gotten varies from "crap" to "not ideal but it does satisfactorily solve a problem" This from scruts and pro race team engineers

some cars, like Corvette must do it this way.

I'm still considering it for mine.

[Bill Verburg]

Here's how they do it in a factory GT3

[NY91184]

In the same situation now, figured I would bring your post back and see which route you took. -Brian

[Bill Verburg]

Here's a GT3 sub bar under an SPG XL

[MysticLlama]

I'm looking at doing this on mine and have been reading a bunch of these threads.

I am particularly looking at the 964/993 Cup solution that Bill posted and have a couple of questions...

If it's okay to have the seat belt mounted to a point where it is sandwhiched between the seat rails and floor pan, shouldn't that be a safe enough solution for the sub belt also?

What is the purpose of a sub belt bar if you have a 6 point belt belt and can just go to either side with the sandwhich method? Can they just be bolted up to the sides?

The purpose of a sub belt(s) in all of these excersizes is to keep the lap belts situated to where they can actually do the work of holding you in, correct? So they shouldn't be subject to quite the same loads as the bigger belts.

So here is how I'd like to set mine up:

Seats are Recaro Pole Positions w/ all slots

Lap belts bolted to factory points on door sill and tunnel.

Shoulder Belts wrapped to harness bar on roll bar, which I then also want to tie into the B pillars just for a bit extra reinforcement.

The sub belts came with very beefy bolt in tabs. I'd like to sandwhich these between the side mounts and the sliders, since the bolts there are actually stronger than the original seat mounting bolts, and have a lot of extra thread.

This also makes the sub belts move as the seat is adjusted forward and back which keeps them located correctly with different drivers since they don't have adjuster straps like the lap and shoulder belts do.

Thoughts?

[38D]

Originally Posted by MysticLlama

I am particularly looking at the 964/993 Cup solution that Bill posted and have a couple of questions..

The 964 cup is not mounted as described above. Each side has 2 small threaded inserts that are welded into the chassis for the 6 point subs.

[MysticLlama]

Sorry, I probably worded it poorly.

The way that it looks is that #22 is where the lap belt mount bolts, is that correct?

What I was referring to was that if that were the case, it would seem that mounting to the seat rails, as was done in Carreras and later was considered a strong enough point to mount the belts.

Does that make more sense?

[Bill Verburg]

Originally Posted by MysticLlama

I'm looking at doing this on mine and have been reading a bunch of these threads.

I am particularly looking at the 964/993 Cup solution that Bill posted and have a couple of questions...

If it's okay to have the seat belt mounted to a point where it is sandwhiched between the seat rails and floor pan, shouldn't that be a safe enough solution for the sub belt also?

What is the purpose of a sub belt bar if you have a 6 point belt belt and can just go to either side with the sandwhich method? Can they just be bolted up to the sides?

The purpose of a sub belt(s) in all of these excersizes is to keep the lap belts situated to where they can actually do the work of holding you in, correct? So they shouldn't be subject to quite the same loads as the bigger belts.

So here is how I'd like to set mine up:

Seats are Recaro Pole Positions w/ all slots

Lap belts bolted to factory points on door sill and tunnel.

Shoulder Belts wrapped to harness bar on roll bar, which I then also want to tie into the B pillars just for a bit extra reinforcement.

The sub belts came with very beefy bolt in tabs. I'd like to sandwhich these between the side mounts and the sliders, since the bolts there are actually stronger than the original seat mounting bolts, and have a lot of extra thread.

This also makes the sub belts move as the seat is adjusted forward and back which keeps them located correctly with different drivers since they don't have adjuster straps like the lap and shoulder belts do.

Thoughts?

The spacing of the subbelt on either side of the seat centerline needs to be such that going to the sides is not going to work.

w/ either a GT3 style bar or a pad eye bolted through the floor arrangement there is only a few inch displacement from center line.

the only issue w/ the GT3 style subbar is that it is not approved by most race organizations except where it came from the factory that way(simliar to the Matter aluminum cage regs).

Get a copy of the harness mounting instructions, Schroth has some of the most complete, read them carefully to understand the geometry neeeded for each of the belt components.

[38D]

Originally Posted by MysticLlama

it would seem that mounting to the seat rails, as was done in Carreras and later was considered a strong enough point to mount the belts.

Does that make more sense?

You'd be surprised. I've seen the front mounting points fail in a 964, and that was with the 964 cup style sub mounting to the floor. I wouldn't want to add any additional load to the seat mounting area.

[MysticLlama]

Okay, was just trying to figure out the geometry of this thing.

When compared to my stock, fraying, 3pt belts, I think anything is an improvement, but I don't want to skimp putting stuff in in a safe manner.

What I was going for with the seat rail/crossbar mounting was to hopefully find something that would be safe for multiple drivers.

I'm not so much trying to avoid holes in the floor, the car is way beyond stock anyhow. What I want to end up with is the option that is the best for different size drivers without being unsafe to either of them.

So I guess the best bet is aim for 0 degrees for the tallest driver that goes to 20 degrees for the shortest when the seat is pushed forward and hoping that is a single mounting point?

I'm still missing where the lack of safety is when the straps aren't straight down, but I'm sure the guys that built it put more math into it than I have. Looking at my setup, even with the belts attached to the side rails I can't really see where the additional load comes from, given that the belt fastener is already angled that way (mine if pulled straight out from the buckle split far apart vs. going straight down).

Seems like if the seat bolts snap, you're in way bigger trouble anyhow...

I just got concerned when I read the "pulling through the floor" bits on several other threads all over, and though the seat mounting points might be a better bet since the lap and shoulder belts are supposed to have most of the load and have separate chassis mounts anyway.

Besides some rules, are there any safety downsides from using a peice of barstock across the rails that falls into the correct angle of the sub belts? Similar to the BK mount, but a custom made one since I didn't see one that would work correctly for my app.

This car is intended for 90% street and an occasional DE now and then, for whatever that's worth.

[MysticLlama]

So was looking again tonight at possible mount points on the floor, where washers/backing plates would or wouldn't fit etc. and looking for pics and came across this...

http://www.teammiata.com/mall/Willans-harness.aspx

Talk about a lot of rules being broken on that top pic.

Scary.