DE Help

[JCF]

I will not be allowed to use my car for DE's any more (nor should I probably) unless I get a better seat/belt system.

I have Vintage R type seats and bad 3 point belts (from Andover Auto)

The car is a '67 911 , mostly original (interior is real nice) and I would like to keep it as close to that way as possible.
I have already relocated the mounting points and am reluctant to to drill lots of holes (unless I absolutely must).

I am pretty lean so the bolsters block a real tight fit with the lap belts. So I am guessing I prob will need to get new seats with 5 or 6 point openings.
This would be mostly a street car - maybe 9 track days a year.
Can anyone let me know what my options are ?

Thanks
John

[boyt911sc]

John,

Are your seat belts not working properly? Did they fail during tech inspection? What's the reason for the seat belts to be non-compliance with your club's regulation?

I was in similar situation and was able to remedy this problem. Contact me at ATD911@hotmail.com. Good luck.

Tony

[ttweed]

Unfortunately, the pre-'68 chassis doesn't offer many good options for 5 or 6-point harness mounting, and the lack of belt guide holes in your seats is problematic. I would consider getting a full race seat and dropping it in for DE events. If you have relocated the lap belt mounting points (they need to be lowered from the stock '67 position in order to get a 45-degree angle) and have guide slots on the seat, then another hole for the anti-sub attachment has to be drilled in the floor for an eyebolt with a big backing plate.

Then you have to deal with the shoulder harnesses, which is not easy, as the '67 has no easy harness bar solution, since there is no B-pillar shoulder belt lug. One option is to run the shoulder harness all the way to the rear deck and drill more holes there for more eyebolts, but that is sub-optimal due to the length of the belts. You can fab a custom harness bar using the existing shoulder belt holes in the rear quarter panels, with a vertical brace down to the rear seat belt holes, or you weld one in, or you can bite the bullet and install a rollbar with a harness crossbar welded to it, which you might want to do anyway if you are running a lot of DEs.

Good luck,
TT

[JCF]

Thanks Tom, I was hoping you would see this and give me your input.

I did lower the lap points.
The rest is kind of what I figured from what I have been reading and hearing. The roll cage is almost the only way out as a bar would make it less safe without a helmet (?)
I wouldn't hesitate except I am so damn conflicted. On the tech line at LRP I was told the car belonged in a museum not on a track. Not quite, but it is pretty nice.
But the look of terror as I told my instructor I wanted to go out again (and again) made me realize I would have to do something .
I guess I was kind of hoping for a magic bullet.

Tony;

The bolsters are as high as my belly so the belts don't really hold me in tight.
They also tend to come unclipped - nor do they hold the settings when I pull them tight by the loose ends. Otherwise they are fine.. ..
I had to put back in the originals .
Sent a pm.

Thanks;
John

[Grady Clay]

John,

I agree with Tom about a track only seat. Your choice should
bolt into the original 16 M6 mounting threaded holes. With the
correct (narrow) seat, you can fabricate an interface between
the seat and chassis to mount it appropriately low.

For the lap belt and the crotch strap(s), your only choice is
through the pan. The original mounting points are too high
and far back IMHO. The lap belt must go completely past
your hips to the mounting. It should NOT just go across
your lap.

Does your ’67 have shoulder belt mounting points on the
rear inner fender side bolsters? If so, you could make a
bolt-in seatbelt bar system.
"
"
© Dr. Ing. h.c. F. Porsche K.G.

(note; this image is a '68)

Of course the best solution is a bolt-in roll bar with integral
seatbelt mounts and seat back support.

Best,
Grady

[JCF]

Thanks Grady :

Here are some pics of the mounting points.
How would the bolt in system work ?

I appreciate the help;
John

[Grady Clay]

John,

Here is a diagram from the 2003 SCCA GCR.
"
"
© 2003 Sports Car Club of America
Here is the 2007 GCR

I prefer the floor mounting to be slightly farther back and the
crotch “anti-submarine” belt go straight down or only slightly
to the rear. The dual anti-submarine belts need to anchor
directly under or outboard of your legs.

Note that the shoulder belts have a slight down angel but not
more than 20° down. They should never go over your
shoulders and then to the floor.

One function of a shoulder belt guide is to prevent sideways
movement. The belts need to be captive as they pass over
the bar.

You could fabricate a small “cage” that becomes the shoulder
belt bar and is a seat back support by using all the pick-up
points in the rear of the cockpit. Those include the existing
shoulder belt mounts, the existing lap belt mounts, the new
floor lap belt mounts, rear seat lap belt mounts, the shoulder
belt mounts on the package tray and even the rear seat back
pivot bolts.

Sort of a bolt-in “birdcage.”

With the rear seat backs unbolted, you can mount new shoulder
belt anchors at the junction of the carpet and upholstery on the
firewall. You can do this by pulling some of the carpet from
under the upholstery. This way you don’t damage anything.


Your choice of seat and seat mounting is critical.

Best,
Grady

[JCF]

Would the birdcage be any less invasive than a roll cage ?

If a rollcage were to be removed would it be easier to replace the carpet areas removed to install it or would it be easier to restore all the areas that would be altered to attach the birdcage?

Also; Are GTS seats (like the ST type with slots for 6 points) safe or am I better off looking for maybe a used modern racing seat

Thanks again Grady

John

[Grady Clay]

John,

My proposed “birdcage” would not be invasive at all as it only attaches with existing or necessary holes. It only serves as a shoulder belt and seat back support.

A “bolt-in” roll bar is more invasive in that it needs threaded mounting plates welded to the chassis.

The advantage of the roll bar is the additional function of improved rollover protection. Your 911 has been re-carpeted and it should be easy to install a roll bar where it is not apparent when removed.

The roll bar normally consists of four main components; the main hoop, two rear braces, a diagonal brace (from upper left to lower right) and a horizontal shoulder belt support. Depending on the seat, I like to see a (1 or 2) tube that supports the seat back. A seat is normally only mounted at its base. The center of mass of the seat and driver/passenger is considerably higher. Additionally, you don’t want the seat to be able to be forced back under the shoulder belt support in an upset. I think it wise to support the seat back with part of the roll bar.

Any roll bar design must meet the specifications of the sanctioning bodies. SCCA is the most significant as most others use them as the “gold standard.”

One difficulty is the lack of a seat belt mount on the “B-pillar” starting in ’69. There isn’t any good non-invasive solution.

Driver safety is paramount. You never know what may happen. Our wonderful old 911s are not particularly crash worthy compared to later 911s. Add 40 years of use (and some rust) … you get the idea.

Best,
Grady

[Jim Richards]

Anyone know if these seats (with sub belt) will be allowed with 5 pt harnesses? Shoulder belts are run inside the posts of the headrest.




JCF, I apologize for my highjack of your thread.

[Chilling in VT]

Originally posted by Jim Richards
Anyone know if these seats (with sub belt) will be allowed with 5 pt harnesses? Shoulder belts are run inside the posts of the headrest.




JCF, I apologize for my highjack of your thread.

Jim to continue with the highjack (sorry JCF), I was had the same question. I believe that the PCA has just changed the rules for seats and harness's. I was told that if I wanted to use 5 or 6 point belts, I needed to upgrade my seats to highback ones with holes for the shouolder belts. I specifically asked about the GTS seats and was told they did not fit the bill. There was an "exemption" for the older, square shoulderd seats that seems to have gone away. I am not sure how other regions are handling this but you shouold check with your club. I made the mistake of buying seats that I now can not use. Better safe than sorry.
Joe

[Jim Richards]

Thanks Joe!

[Grady Clay]

Jim,

Look at the SCCA diagram I posted above. The shoulder belts
need to be positioned close to what is in the diagram. If the
headrest supports interfere with that positioning then the
answer is no.

The seat needs holes to allow the lap belt (better called a “hip
belt”) to support your pelvis. If the belt goes over the bolster
side of this seat you can be seriously injured.

There needs to be an opening for the anti-submarine belt. The
function of this is to prevent the forces of the shoulder belts
from pulling the hip belt up onto you abdomen causing internal
organ injuries. It also prevents you from sliding forward under
the hip belt.




You will be better served buying a seat manufactured with these
holes. If you cut them it will probably compromise the strength
of the seat.

I agree with Joe. Read the rules first.

Best,
Grady

Reposted;I forgot the image.

[Jim Richards]

Thanks Grady. I have sub-belt holes, but the lap belts go over the bolsters. I'm not sure of the spacing for the shoulder belts, but think they are likely within spec. I'm checking with my local region to get them to weigh in on this. Oh well, if I must I guess I'll get a set of track seats and just use these seats on the street.

[Grady Clay]

Jim,

With all the incompetent drivers, you are more likely to have an
accident on the street. The problem with that seat is the hip
belt becomes a “tummy” belt. Look at a diagram of the human
skeleton.
"
"
© 1978 The John Hopkins University Press

You can see how important it is to keep the hip belt on the hips
(green line). By the time the belt gets to the yellow line, you risk
internal injury. Internal injury death is a close second after
closed head injury in any accident. With a good helmet it
probably becomes #1. Your and my old bods don’t like any
abuse.

Best,
Grady

[Jim Richards]

Grady, if I let my stomach get nice and big, maybe that would hold down the lap belts.

Thanks again, Grady. Oh well, I guess I need to start doing some track seat shopping.

[javadog]

Jim,

Here's a link I usually trot out whenever someone asks about harness, seats, roll bars/cages, etc. There is a lot of good information included, much of it generic to all installations. Go here, from the HMS Motorsport web site:

http://www.hmsmotorsport.com/docs/Competition_Instructions.pdf

If you have any doubts or questions, call Joe Marko at HMS Motorsport. He has quite a bit to say about driver safety.

Be safe,
JR

[Jim Richards]

Thanks JR. I'll spend some time studying it carefully.

[jittsl]

Jim,

If those are the same seats I have in my 71 then you are wrong in thinking the only way to run the lap belts is over the bolster. My GTS classic Nurburgring seats do have sufficient room to squeeze the lap belts between the bottom cushion and the bolster and to route them past the support strapping at the bottom of the seat and then on to a bolt mounted through the floor. As long as you have a sub strap hole and you route the shoulder straps between the head restraint posts and then over a harness bar or to a roll bar they should be acceptable for DE purposes. At least you would be for my region -- NER (which I happen to be track chair of).

Laurence

[Jim Richards]

Hmmm, I need to look at this. Thanks Laurence!