Sparco install in 72 911...PICS

[rennch]

Here's what I did on my summer vacation:

http://www.whirledmedia.com/seatinstall/seatinstall.html

Works really well so far!

mike

[88 Club Sport]

Looks good Mike. That's my next project after I get the oil cooler plumbed up front.

I noticed you have your harnesses attached to the harness bar. I always thought that was a no no as the harness bar is intended more as a guide, than a point of attachment. I just added harnesses prior to the Continental Divide DE 2 weeks ago but took them all the way to the rear seatbelt mounting holes in the tub.

[rennch]

I think that's correct. I'm just using the car for Autocross, so they are more there to just keep me in place.

I have to actually mount some later model seatbelts in there for regular street use.

[MotoSook]

Looks like he's got the early Weltmeister harness bar with the wide flange that goes over the B-pillar and bolts onto it using the stock seat belt bolt. I have the same and it is very sturdy. I too just use the harness bar for the shoulder belt w/o bolting the belt to the seat bolt. I don't feel it's a bad compromise.

[Wil Ferch]

I see a number of things that would bother me from a safety standpoint.
- ok..you're autocrosing..but for anything like DE or even street work, don't mount to the harness cross bar. Don't care how strong it looks, not strong enough.
- the side mounts look mounted backwards...causing the 5 hole height tang to be in back and the four hole height in front. The 5 hole tang partially covers the seat hole where the lap belts go through...high chafing potential ...looks dangerous.
- lap belts using one bolt behind the seat, and using narrow mounts that "bunch" the width of the belts. Very bad news....something like this killed Earnhardt.
- hope there is at least a VERY substantial backing plate behind the single bolt that holds both lap belts for one seat. Something like 8" on edge and about 3/16" thick...hope it isn't a fender washer.

Do some research and note that the required pull-through resistance forces should withstand something like 3-8000 lbs (!)

For starters, look at what a racing sanctioning body might allow, or look into a Simpson catalog.

Sorry for my not-too-normal abrasiveness here..but we're talking Safety.... and Emilly Post etiquette won't get people's attention.

Love ya like a brother....dontcha know

Wil Ferch

[Pat S]

Noted. Thanks for the input, all.

[}{arlequin]

spicing up the interior a bit? Matching your harness and door straps to your wheel stitching is a nice touch...

[Frostie]

Looks great Mike. I too have a set of Evo3’s too put in my 911. I’m defiantly going to make a note of what you fabed up for mounting your seat brackets. It’s too bad you lost a bit of head room. How tall are you? If you don’t mind me asking, as I’m 6’4” and may have to fab something up a little different to drop the seats

[Victor]

Originally posted by Wil Ferch

Sorry for my not-too-normal abrasiveness here..but we're talking Safety.... and Emilly Post etiquette won't get people's attention.


Wil Ferch

Man you almost made me put non-slip soles on before running to the fridge for another beer.

[MotoSook]

ok..you're autocrosing..but for anything like DE or even street work, don't mount to the harness cross bar. Don't care how strong it looks, not strong enough.

Not having made any statements about the other things in that car, I'll just address this one comment.

Let's look at what happens on a frontal impact. The body wants to go forward, right? The should belts should counter that. For the sake of this discussion, lets say the force between the body (top of shoulder) and bar is horizontal. With shoulder belts that are bolted to the seat bolts, then fed through a harness bar, the harness bar is just as likely to give, and probably worst (depending on the bar design). Why? Because the shoulder strap is loading it not only toward the front of the car, but also down. If that bar gives, how much slack are you going to see? Take a look at some of the set ups...if the harness bar were suddenly taken away, most of those cars would have a lot more slack then if my harness bar were to give.

If you have never seen the bar that I have (as as seen in the car linked to in this thread), you may have a hard time envisioning, but the round bar is welded onto flanges that have a forward and rearward lip to it that go over the b-pillar. It is then bolted down with the seatbelt bolt. There is far less flex or rotation in that design that some of the bars I have seen that are used with the belts bolted to the rear seat belt bolt.

I'm not saying that boltings belts to the rear seat bolts and feedign it through a well designed harness bar is not a good idea. But look at the whole picture....crap..everytime someone posts pictures on this forum at least one person has to jump on them to criticize their work, and that is good...SOMETIME! It's a good reality check most of the time. But more often than not, it's only to express a one sided view or thought. Not always one that has considered all the options and factors.

A seat belt bolt in the rear is jsut as likely to pull out as anything..there are multiple failures waiting to happen. Until soemone performs a scientific test on any one setup..it's all opinion..

OK Wil..lets have fun

[Noel]

Many PCA regions will not let a car on the track with 5/6 point harnesses without a rollbar. The reason for this is in the event of a rollover, you will be crushed as you are held so firmly in place. Something to consider even if your region allows a setup like this.

[}{arlequin]

now that I look at it again, I'm pretty sure your shoulder straps' loose ends (hanging down) have to be threaded through the metal "buckle" (the one between the harness bar and the back of the seats) one more time. Maybe you weren't finished yet in the pic..... this is the moment in the install when I'm still adjusting the "average" length for the belts.

As far as the strength of the bar... I think for autocross it would be fine, maybe even for a nice and easy rollover (on an auto-x course) as well, but as far as a regular accident with any sort of frontal impact, I think the bar MAY give. (It's a moot point if you ARE getting the street seat belts, though.)

[Eric Mckenna]

Hey,
I think that you have your seat brackets on backwrds......other than that great looking set up/


Eric

[Wil Ferch]

Souk:
You're certainly entitled to your opinion, and even with what you say, you've only addressd one of my many concerns of what I saw in the install. As I also noted, there is level of "concern" ...not so much "criticism" that I'd like to leave the reader with. If you've seen the many posts of mine I would hope you'd agree that this is my motive.
I take exception to the statement that I may have posted this just to provide a one sided view. With everyone else saying wow, great, etc...perhaps my views presented a balance to that...nothing more. As to the horizontal vs the combined horizontal and downward deflection of the resulting crash forces on a cross bar...I see your point, but still stand by my statements. If my premise was that wrong, then sanctioning bodies as those that check DE's or club racing wouldn't dis-allow mounting directly to the harness bar...but often they do if it's only a harness bar and not part of a full roll cage. As to the possibility of the rear seat bolt mounts being*equally* liable to pull out, I would think not since they had to be certified as real-world anchorage points as part of the car's original design to hold a person in-place, and the car would not pass Federal or other regulations for original sale. And this is for completely holding-in a body ( being used originally as lap belts)..not the partial load that holds a person's upper torso in-place ( as when used as anchors for front seat shoulder harnesses).
We can likely debate this until the cows come home...but I would rather not and would prefer to keep this friendly. Why not let both of our statements ride..at least others who do this can compare 'n contrast as they themselves go forward doing this.
They then would have some thought -provoking choices to make.
--Wil

[MotoSook]

Fair enough Wil, and the "one-side" comment thing was perhaps a global critique. I know you have a lot more sense then some posters (perhaps more than I do), and it's likely the reason for my response. I wanted the readers to think a bit. A lot of comments from the senior posters tend to carrier a lot of weight, so... as you stated...let the comments ride and give the reader some food for thought.

Dang...and I was hoping for a volley...of good thoughts

[Wil Ferch]

Why ask for a volley of good thoughts....when they're already there for all to see from both of our posts?.....
( groan ...)

In all seriousness, I will say this.... these kinds of modifications should be treated with the utmost respect and should be researched a great deal. The Simpson catalogue I mentioned is a good resource as are a number of technical articles that are available from SAE, and even from roundy-track type racing magazines.

--Wil

[nostatic]

I have to go with Wil on this. Everything I've read indicates that mounting the harness to the harness bar is a no-no. In addition, you need to also not mount at too sharp of an angle. So mounting to the rear belts points is OK, but NOT to the rear floor, as the forces in a crash would tend to collapse the seat.

[rennch]

I agree. This car is not a DE car. It never sees the track. It is a competitive SCCA autocross car. I just need to keep myself in the seat.

By the way...why a harness bar is less safe than the factory belts when using the same mounting point is beyond me. If it was ok for Porsche, why wouldn't it be ok for a harness bar? Do tell.

[nostatic]

You mean why is it OK to mount the seat belt right to the b-pillar, and not OK to mount the harness to the middle of the harness bar?

leverage I believe...

[}{arlequin]

the bar will bend... you don't know how much but it may be just enough for your head to reach the windshield