rc951

I recently ran across a Brey Krause harness bar that was originally purchased for a 968. Does anybody know if it will fit in a 944? If so, would anyone post a pic of the installation?

Skip

It will fit. I don't have a picture handy, sorry.

Tom Pultz

As installed in my S2. Belts go over the bar and down to the existing rear seat belt mounts. I use Sparco H style harnesses because you need something relatively long to reach.

Z-man

I have a Stable Energies harness bar that's just mounted to the C-pillars straight across. Allows for maximum movement of the front seats, and easy access to the rear seats. You can even fit two people back there, but I'd recommend using temp. padding on the bar for that.

At around $100, it's a great price. <a href="http://stable-engeries.com" target="_blank">http://stable-engeries.com</a>

But I don't know if the BK bar from a 968 will fit a 944. Sorry.

-Zoltan.

ian

What are you going to use the harness bar for?(yes I know you are going to mount harnesses to it) Are you going to be doing Driver Events? Or Auto-X? Or just street driving (I would say you are bit off if this last one is your intent).

If you are going to be doing DE's I must stress for you not to get a harness bar. Yes it is nice to be planted in the seat, and it will make the DE a little bit more enjoyable because you can concentrate on driving, but please do not get harnesses with out a roll bar. The high speed nature of DE's leads to occasional crashes, and while I don't with that uppon you I'm just tyring to be cautious. If you happened to roll the car with harnesses and not roll bar the roof could cave in on your head and you would not be able to get out of the way and the probabable result is a broken neck. I will not ride in a car out on the track with the harnesses on if they don't have a roll bar, I would much rather the standard belt.

If you are useing it for Auto-x you should be fine. And if you are using it for the street, well you must drive much harder than I do.....

Z-man

Ian: I thought that our cars had sufficient roll-over protection for the occupants. I believe the government requires a rather high level of protection.

If our car's do not have such rollover protection, I don't see how having a harness bar would really make it worse: with all the forces around you, you would not have the strength to move "out of the way," even with more movement that is allowed in a flexible seatbelt. Even if I'm in a fetal position during a rollover, the G-forces that are present will sent me every which way. A harness setup will at least keep me in place a little better.

Regarding harness setups on the street: ALL race type harnesses are NOT street legal, and should not be used at safety devices there. I believe they are not legal because they do not have built in tensioners, UV protection, and are not controlled by the feds.

Getting a harness setup for just autox is a bit overkill, IMO, unless your the SCCA national champ! (For autox, they have torso harnesses, which is a $20 belt type thingy that straps around you and the seatback and helps keep you in place.)

-Z.

ian

Z-man,
yes our cars have good roll over protection for the street, but that does not mean they will not calapse with a high speed roll over.

Also when a roof is colapsing it would push your head out of the way with a standard seatbelt. With the Harness you are stuck in the upright position and it would move the only thing it could and that would be your neck.

Also to show that our roofs will calapse I pass on these pictures which have been posed before.

Z-man

Ian:
Ouch! Rough pictures. Point taken.

But my I counter: while your head may move out of the way, a stock 3 point belt will not prevent other harm from happening to you, like compression of the spinal column, lower back injuries, and there's a greater chance of being thrown from a car with a stock seat belt. If my car is going to roll, and the roof will collapse, without a rollbar, I'll be pretty much toast!

Currently, I am just starting with the DE stuff: I'm only in Yellow Run group (second from the bottom). The people in my group (myself included) aren't pushing the cars nearly as much as the higher run groups. Less speed, and farther away from the limits of our cars. Granted, roll-overs can happen in any run group, but the chances of it happening in the lower ones are far less.

As I progress through the groups, at some point, I plan on either making my S2 a track car (complete with rollbars), or buying a dedicated track car (again with rollbars installed).

I believe in safety, and do not discount what you have posted. But I still feel that a 6 point harness setup (without rollbars) offers greater protection for me than a stock setup. Keep in mind that my driving ability is on the low side.

One more point regarding harnesses: if you're installing a harness setup, make sure you have a properly attached harness bar as well! If the shoulder straps are anchored to a point below and behind your shoulders and you are in a front end collision, the shoulder straps will not work properly: they will pull you down, and back into your seat. You can get spinal compression with this setup!

Again, just my $0.42
-Zoltan.

smokey

The BMW Club does not allow full harnesses on the track without a roll bar, probably because of that picture posted of the rolled BMW. I think that 944's have a stronger roof, but I installed a Redline Rennsport bolt-in roll bar to meet the BMW Club requirements in order to run with them on the track with a harness. This roll bar bolts onto the rear seat harness mounts, with Grade 8 bolts that have a shear strength of about 13,000 lbs each. This is by no means sufficient for all-out racing (I'd want a full cage), but provides some protection. I haven't tested it in action, and I hope I never have to.
One thing that doesn't make sense to me is to run belts over a harness bar and to then attach the harness to the seat belt mounts. If you add the force vectors, this puts much more force on the harness bar than simply attaching the belts directly to the bar. In a crash, the seat belt attachment bolts will hold, but the harness bar will bend or break. If the belts comes off the guide bar at a 90 degree angle, the forces increase by 41% compared to having the belt around the bar. Who dreamed up this rule?
I used the Stable Energies harness bar before I got the roll bar. That harness bar was roll bar stock, attached between the C-pillars, and I just wrapped the harness around the bar. What is the rationale for not using the harness bar as the attachment point? If the harness bar is too weak to take the forces, increasing the forces by 40% doesn't solve the problem.

Bri Bro

Smokey, after looking at all the options, I purchased the same setup as you did for the same reasons. It just isn't worth the risk to do less.

Z-man

[quote]Originally posted by smokey:
<strong>...One thing that doesn't make sense to me is to run belts over a harness bar and to then attach the harness to the seat belt mounts. If you add the force vectors, this puts much more force on the harness bar than simply attaching the belts directly to the bar. In a crash, the seat belt attachment bolts will hold, but the harness bar will bend or break. If the belts comes off the guide bar at a 90 degree angle, the forces increase by 41% compared to having the belt around the bar. Who dreamed up this rule?
...</strong><hr></blockquote>

I am not an engineer, but can you explain how attaching the shoulder straps to the seat belt mounts and looping them over the bar exert so much more force on the bar than just attaching the straps directly to the bar? In an impact, wouldn't the forces on the bar be similar? I can't image a 41% increase in force. Also: why would PCA enforce such a rule if it is more dangerous than an alternative setup?

Very informative thread, BTW. (But let's not get into the open face vs. full face helmets controversy, PLEASE! )
-Zoltan.

Skip

[quote]Originally posted by Z-man:
<strong>(But let's not get into the open face vs. full face helmets controversy, PLEASE! </strong><hr></blockquote>

Doesn't that just depend on how ugly you are to begin with?



Skip [with a $500 head... give or take $499]

smokey

I don't know why PCA has that rule, and I stess there could be a reason I'm not aware of. But the force principles are very simple, and are explained in any introductory text on engineering mechanics. I don't know how to do graphics here (I'm an old f*rt who grew up with punch cards and Fortran) so I'll take a stab at explaining it verbally.

Consider a tug-of-war with five people on each team on the ends of a (strong) rope, each member exerting 200 lbs for a total of 1000 lbs on each team. The tension force on the rope is thus 1000 lbs in the middle, with a pull of 1000 lbs at each end (Newton's First Law, I believe). Now, let's tie the rope to a post, and have one team pull on it. The tension on the rope is still 1000 lbs, as the five-person team pulls at one end and the post resists their pull, with a 1000 lb tension force on the post. Now, let's pass the rope around the post without tying it, and double it back, and have the two teams pull on each end of the rope passing around the post, parallel to each other, with 1000 lbs. (I wish I could draw it, but I hope it's clear.) What's the force on the post? It's now 2000 lbs.

If you move the teams apart so that the rope makes a 90 degree angle, the force on the pole will be the square root of two times 1000 lbs (It's Pythagorian, trust me), or 1,4142 lbs. Exactly the same principles apply to the harness bar, except we're dealing with crash forces rather than tug-of-war teams.

Are there any engineers on the PCA rules committee? Again, I may be all wet in my reasoning here, and would be glad to have any errors pointed out. But I believe that Newton's Laws apply even in a Porsche. Incidentally, how do you insert the little grinning faces and beer-drinking thingies in a post? I could have spiced this up a little if I were net-literate.

Z-man

Smokey: excellent explanation! Thank you! Believe it or not, I understand!

Now my question is this: were our harness bars tested to withstand the greater force if the shoulder straps are looped over? Hopefully for me, that answer is yes!

Fortan and punchcards? I grew up with Assembler and Pascal,so I'm not too far behind you!

Smiley thingies: down and to the left of your 'writing box' is a number of "instant graemlins." Place your cursor by the text where you want the smilie guy to appear, click on one of the smilies, and viola: he'll be in your post when you submit it. You may see something like this: :smilie-guy: in your post before you hit "add reply." Hope that makes sense.

Later,
-Zoltan.

Crackhead944S

I am considering this <a href="http://www.homestead.com/redlinerennsport/SafeguardPage.html" target="_blank">Redline Rollbar</a>. Anyone using this. I stole the idea for this from Tabor(saw it on his web page), so Thanx

Mark
'88 944S