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Question Harness Questions

Hey guys- been lurking around this site for a while soaking up some great information. I posted a while ago regarding suspension console repair (thanks for the responses), and those problems have been rectified and my first 914 is finally coming home to me Friday!!
Anyway, the reason for this post is questions regarding seat belt harnesses. I intend to auto-x and de this car, and obviously would like to put harnesses in it, and was wondering what all of you have done: brands, 4 point or 5 or 6 (if even possible with stock seats), latch lock or cam lock, belt widths, is a harness bar necessary?
Thanks in advance
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Old 08-14-2002, 12:38 PM
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No harness bar

5 points

Cam lock if you can swing the cash outlay, otherwise the latch style work just fine.

6 is overkill

Use the latch in type that utilize a eye bolt. The eye bolts will screw into your existing lap belt holes.

Drill two holes in the firewall for 2 more eye bolts and double nut them. The belt manufacturer will tell you too mount the shoulders straps just below your shoulders behind the seat.





Mount the sub strap with the same eye bolt and jam nuts. This is all SCCA and PCA legal.

B
Old 08-14-2002, 04:05 PM
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Brad

How 'bout a reinforcing plate on the firewall so the bolts don't pull through on hard impact. Same on submarine belt (crotch killer).

Jus' thinklin'

Ron
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Old 08-14-2002, 04:34 PM
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Ron,

I use the large thick flat washers on both sides of the eye bolt that you see in the pics with the double nut. This is what SCCA requires.. or you can run a single Nylock.

I can put both feet on the firewall and yank on the straps and the wall just barely flexes. I dont see them pulling through the washers and then through the firewall.

Possible. But highly unlikey.

B
Old 08-14-2002, 04:40 PM
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Am in the middle of installing harnesses myself. Went with a Simpson 5-way cam lock, std 3" webbing (good prices at Jegs, Summit). Had to wade through a little confusion with "bolt in" (metal anchors sewn into all 5 strap ends, "wrap around" (no metal anchors, buckles for securing to a tube frame), and "floor mount" (snap clips on strap ends to hook up to eye bolts on chassis) flavors to consider. Mine is a universal bolt-in / wrap around; will bolt to existing lap belt mounts, have to sink a bolt in the floor for the sub strap, and two in the firewall for the shoulder belts.

Went with camlock not only for convenience, but on the theory that if you have been in an "incident", and you need to get out NOW, and your hands/arms have been injured, and / or you're upside down, you don't want to be trying to unthread those hoop thingies off the other thingies with your teeth.

Yes, you do need a harness bar. The shoulder straps must leave your shoulder and extend back AND UP by at least 10-15 degrees to prevent compression to your spine should you have an impact, and I'm told SCCA requires shoulder straps to be anchored to the chassis (a good standard to follow). Check out Stable Energies, their harness bar is a lot less expensive than Weltmeister's.

If you're going to a harness, consider a "race" seat to keep your backside from sliding around on hard corners. Holding onto a steering wheel for dear life in a hard turn does not help your steering precision. Also, if you're going to do a harness, consider a roll cage too; if you are held erect by two shoulder straps and the car rolls, do you really want to trust your neck to a 30 year old windshield hoop?
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Old 08-14-2002, 04:50 PM
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An FIA approved seat doesnt require a harness bar. Save your harness bar money and buy a real seat.

Camlock and such: If your belts are on you and tight, the latch type fly apart when you release the latch just like the camlock. There is no "unthreading". We run both.

I agree with the 10-15 deg. but it also depends on the heigth of the driver. My shoulders are way above the person who drives the car in pictures.

We reguarly build SCCA Improved Touring cars and all of them have to pass annual inspections. Lucky for us one of our friends (Basil Adams) sits on the BoD for SCCA and attends our local events (SF Region). So.. if I'm doing something wrong with regards to the install of belts... its the first thing they are going to see. I have never heard of the "anchoring to chassis". The GCR however, specifically points out the double nut and large flat washers when passing through sheet metal for at least the IT classes. GT classes may be different, but I also race a GT2 car that fits the rules very closely and dont recall seeing this (I will look)

B
Old 08-14-2002, 05:12 PM
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jdogg - First, before you do anything - Read and understand the rulebooks for the events you plan to attend - Rules for safety equipment vary from region to region and from one organization to the next.

In my '74 I'm using "G-Force" 5 point camlock belts with snap clips to eyebolts at all mounting points. Stock mount points on the lap belts, large washers on both sides of the sheetmetal on the floor and firewall mount points. The shoulder belts run over a Stable Energies bar which lets me retain the stock DOT approved belts needed to pass the annual state safety inspection. I think camlocks are the way to go, quicker to fasten and release, the latch mechanism is smaller and doesn't rattle around. Snap clip mounts let you remove the belts in seconds, handy if your car is a daily driver and your passenger prefers the stock seat belt.

I've also installed Corbeau Forza seats, they have "cutouts" to guide the belts. Again, check the rulebook, my region requires the use of this type of seat when using 5 point belts. Also, if you'll be running events with an instructor you will most likely need both seats equipped the same.

So John, when's the cage going in?
Old 08-14-2002, 05:51 PM
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Brad

Wasn't doubting what you do, but I didn't think you mentioned the large double washers in your first reply. To prevent a "newbie" from just drilling holes and putting nuts on, I thought I would post so they could see the proper method.

Years ago a "newbie" was killed at Riverside. He had located the battery to the passenger compartment and bolted the hold down frame thru the floor sheet metal without washers or plates. In a roll over the battery came loose (bolts pulled thru floor pan), hit him in the head and snapped his neck.

Driver safety was always my concern; the car can be replaced.
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Old 08-14-2002, 05:52 PM
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Yee haw.

Ron,

I forget how "newbie" some of these guy's can be. I automatically assume they have been around race cars and have spent time at track events crewing and the such before jumping into their own car.

EJM,

100% check the rules for your region and what events you want to attend. As a general rule of thumb, I have found that the PCA uses a similar set of rules that SCCA mandates for safety devices. In other words: you cant go wrong with the SCCA rules if you plan to run PCA events. I build the cars legal for both sanctioning bodies so my customers can run whatever they want and not be pidgeon holed into one group or class.

About the only thing PCA is still up in arms about (I havent checked this week) is the FIA approved seat not needing a seat back brace. SCCA passed this this year. The seat back brace in a 914 can be a real pain to install and adjust....so FIA approved seats for ALL of our cars so I dont have to fab/buy a brace

B
Old 08-14-2002, 06:02 PM
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The way I read jdogg's original post, sounded like he was asking about adding harnesses only, not new seats.

"Anchoring to the chassis" is not a GCR quote, it was a vendor quote, referring to what is shown in Brad's picture. The vendor was trying to politely tell me not to use the the harness bar as an anchor point for the "wrap-around" harness ends. Thought I'd pass that wisdom on to my fellow "newbies".
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Old 08-14-2002, 07:37 PM
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I see said the blind man...lol

I thought you meant chassis chassis like the frame rails or something.

I cant count how many times I have seen the belts attached to the harness bar instead of over them and to the tub itself.

B
Old 08-14-2002, 07:41 PM
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jdogg, I'd recommend contacting the SCCA main office in CO and getting a copy of the GCRs, general competition rules. They are about the strictest as far as safety goes in the US and as I have found it is a time and $$$$ saver to build a competition car to the strictest safety standards you can find and it is best for you! I'd also recommend the race seat as noted and if you decide to get one, sit in it first to make sure the slots for the shoulder belts are the right height and will go over the shoulders correctly. It is not advisable to run them around the top of the seat and use a chest strap as they will slid upon impact. Good luck.
Old 08-14-2002, 07:56 PM
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I don't have too much to add to all the good stuff above...

I am fond of the Schroth Profi 5-point camlock -- it is very spendy but is possibly the highest quality setup out there. Any good FIA approved 5-point harness will do the job, however.

For the 914, pull-up style lap belts are way easier to deal with IMHO than pull-down; the adjuster mechanism lives outside of your race seat, plus you can get a lot better leverage (for tightening) pulling up.

The Schroth belts come with big welded backing plates with built-in nuts; I use those and then big SS fender washers (2" x 1/2" I think) on the inside, with the Schroth-supplied hardened eye-bolts.

The main benefit of using eye-bolts and clip-in belts, is obviously they are removable easily....among other reasons to help prevent them from getting stolen, to get them out of the way while working on the car, to get the passenger stuff (if any) out of the car to cut weight when you're driving alone, and so forth.

Another big tip..dumb-ass lesson I learned lately...be sure to either use a short enough bolt, or a jam-nut (like shown in B's lower pic above) on the tunnel side lap belt. Otherwise you can jam/displace the shift rod and you will have major shifting probs!!! Don't ask me how I know, just trust me on this...

Last thing, also mentioned above, IMHO a 5-point harness is just about worthless unless coupled with a real race seat. And, hopefully a cage and fire system as well. There is no such thing as being "too prepared".

LOL, scratch that first sentence, now that I wrote about a 4" post.
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Old 08-14-2002, 07:57 PM
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Oh man.

Chris,

I thought I taught you better than that.

That is exactly why that drivers side eye bolt is not flush tight to the center tunnel. I learned that the first time I pulled the factory bolt and noticed it was much shorter than the other harness bolts.


B
Old 08-14-2002, 08:06 PM
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A couple of further points--

1) DO NOT use regular hardware-store "bent around" eyebolts. Use only forged one-piece eyebolts. The bent ones can come unbent when stressed (say, in an impact) and then your belts are useless. Most rules do say this, so if you do as advised above and RTFR (yes, the SCCA tends to be the strictest and therefore the best to follow) you will see that.

2) I think that it is a very poor idea indeed to run a sub strap around the front of a regular seat. If you have a sub strap at all (and they are required by quite a few sanctioning bodies) then it must go through the seat. Either that, or you get six-point belts and sit on the dual sub straps. (That is my setup, I did not want to cut my stock seats.) This is not a rules requirement, but I still believe strongly in it.

(Hint--you don't want the buckle twisted around and pointing into your gut. When you loop a belt around the front of the seat and tighten it, guess what happens to the buckle??)

3) The stock seat is not that bad a seat if you are a large-ish person. Just take out the bottom seat cushion, and you have some side bolstering. And if you are tall enough, your shoulder belts will be above/to the sides of the seat back so you don't have to worry about them twisting or going around the seat back.

4) The initial question was about autocross. For autoXing, you don't need four-, five-, or six-point belts. They can come in handy, as they will hold you in place better and you won't have to "hang onto the wheel for dear life", as Summersled put it. A four-point belt is more than good enough for that.

Frankly, for autoXing just about anything you can get from a reputable retailer is going to be just fine. You start worrying about exact details (camlock vs. latch-lock; belt widths, belt placements, seat holes, etc.) when you go to the Big Track. AutoX is a much lower-speed event with much less risk. Lower-impact, so to speak...

BTW, my car is one of the ones with the shoulder belts attached to the harness bar. This is not the best setup--by far!!--but it is legal for time trials with the local PCA (Zone 7). I did not want to drill extra holes in my car when I was installing them. I will seriously re-consider that position if/when I make track events a regular thing for that car.

--DD
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Old 08-14-2002, 08:31 PM
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What is the problem with attaching the shoulder straps to the harness bar?

And should the straps mount above or below the occupant shoulders? stock belts are above the shoulder.
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Old 08-15-2002, 03:10 AM
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Great info guys. Thanks for all the responses. I am going to go ahead and get the SCCA rulebook. No sense in having to do something twice.
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Old 08-15-2002, 05:32 AM
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Whatís the problem with attaching the harness to the bar? I think it may be safer to attach directly to the bar. Let me explain.

If we assume that in a front end accident, we load each shoulder strap with 100 pounds of force.

If we attach the strap to the bar directly, That force will go to the bar and pull on the bar with 100 pounds.

If we go over the bar and down to an infinitely strong point, then we have a pulley system. In a pulley system where the two straps are parallel, the force on the pulley is twice that of the straps. Our straps will not be parallel, so it wonít be quite that bad but you can see where I am going with this.

If the strap from your shoulder to the bar is horizontal, and the strap from the bar to the ground is vertical, And we load the belt with 100lbs, then the reaction force on the bar will be 141 pounds.

If the strap from your shoulder to the bar is down by 30 deg, and the strap from the bar to the ground is vertical, And we load the belt with 100lbs, then the reaction force on the bar will be 173 pounds.

For the reaction force to be 100 pounds, the front strap would need to go UP by 30 degrees. Or the back strap would need to go back by 30 deg. Basically, the angle of the straps need to be greater than 120 degrees. Doable in a car with a back seat, not in our case.

I copied DDís setup with Crow harnesses. Itís an excellent system for $89 per side. I did have an instructor tell me that the sub straps under the legs would push me through the roof. I countered that the lap belt would do its job and we had a great day at the track.
Dave, do you still have pics of your setup?
Old 08-15-2002, 05:33 AM
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Also, think about how your harness is supposed to work before you strap in:

The shoulder straps are there to prevent a forward motion of your upper body on impact NOT to prevent an upward motion (like in a roll), in which case (if worn or installed wrong) they'll compress your spline

The lap belts are there to prevent upward motion (and thus preventing the shoulder-straps to compress your spline in al roll)

The sub-strap is to prevent "submarining" or you slipping through underneath the lap-straps

Correct order to tighten the straps:
1st lap-straps so your but is planted firmly into your seat. These straps are supposed to run over your PELVIC area

2nd sub-strap. Thighten to make sure the buckle stays as low over the pelvic area as possible (no, the buckle is not supposed to be in your crutch 8^)

Now you can thighten the shoulder-straps. Check that you didn't pull the buckle up.

I can't believe how some people wear these types of belts...
Usually people have the buckle on their belly or just under their ribs... Imagine the internal damage the buckle will do on impact!
And it won't keep you from moving upward in a roll either...

I've also seen numerous times that people bolt the shoulder-straps to the floor right behind the seat.
This way, the shoulder-straps are useless, won't work in a frontal impact (possebly breaking the seatback) and will most likely compress your spline in a roll.
The angle between your seatback and the shoulderstraps should be between 90 and 45 degrees (where 90 deg. is preferred).

Also, depending on how far forward / backward your seat is possitioned, the original lap-strap mounting points may be less than optimal.
The lapbelts should run down for the guide holes in your seat.
If they don't, the lap-straps won't sit correctly on your pelvic area.
So, moving the mountingpoints further back or forward may be required...

be safe,

Jeroen
Old 08-15-2002, 06:26 AM
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My belt setup can be seen on the following page:
http://members.rennlist.com/damp_dave/belts.html
Yup, Crow harnesses for me. But I don't feel that comfortable using the harness bar as the attachment. Partly because it looks like it could swing forward (supposedly it can't really do this, but it looks like it could). I have also been told by a number of people that it will not meet SCCA tech. (Nor will my sub-strap attachment, because it mounts to the same eyebolts as the lap belt and all the belts are supposed to have separate attachments.) But I don't run with SCCA--and I know the risks I am taking with a suboptimal belt setup. "Do as I say, not as I do!"


Jeroen, I will disagree with you on one point--
I don't think the actual function of the "sub strap" is to prevent you from going underneath the lap belt. Frankly, if the lap belt is in place and you are not lying down when driving (a la Indy car or F1) you just about cannot slip under the lap belt. I think that the primary function of the sub strap is to keep the lap belt down on your hips where it belongs.

Everything else you say is spot-on, IMHO.

--DD
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Old 08-15-2002, 07:50 AM
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