Following link is my new home made harness bar. \

http://207.6.250.15/v67-gsr/Harness%20Bar.htm

I have a question regarding the use of bolt. As you can see in my pictures, I only use 1 bolt to mount the bar with the bracket. Should I use 2 instead of 1?

 

I would seriously beef up the mounting bracket as well as use bigger/stronger bolts. In a high speed impact, even at lower speeds, the bar will rip right thru the braket you made a cause harness separation, which will in turn cause you to have no support on shoulders, and the harness bar will come into the back of the seat causing further problems. My 2Cents

 

My bar will only use in autoX races. So nowhere I will get in high speed, and chance to crash is nearly zero.

The reason I ask should I go for 2 bolts instead of 1, is if that will increase the rigidity of the bar, in the other words, stiffen the chassis. Or I should just stay with 1 bolt and be ok.



[Modified by v67-gsr, 10:50 AM 3/3/2003]

 

For an autocross setup if you are running properly designed (read: safe) courses then you should have no problems with that setup. It looks pretty good, i actually designed a bar nearly identical to it for my SC2 (never used it though).

If you are doing open track events, you'll need to get a rollbar and use stock seatbelts if you dont provide a seat and 5pt for your instructor. FYI.

 

I don't know, those brackets look weak. I'm not sure of the speeds you see on course, but some of our tracks you can reach 60+ mph. I think I'd supplement my belts with the stock seatbelt just to be sure. There's always something to hit, even in autocross, light posts, curbs, islands, trees.

Here's the harness bar I use.



http://www.schmiechen.com/harnessbar.lasso

 

I wouldn't drive the car at an event with that harness bar arrangement. The forces in a crash at even 40mph would be enough to bend or break the channel you have used as a bracket.

Accidents happen at autocrosses, even at "safe" courses.

The one in the red car looks a lot more rigid, and the downtubes prevent rotation, but I have to ask why not just get a 4pt bar?

 

His bar sure looks good. But personally, I will never pay that much for a harness bar (totally out of my budget) since all material and machinery that require making this parts are free to me.

I did consider the same design but end up using my current one for several reasons.
-Easier to make. Don’t need to make the down-tubes to prevent rotation.
-Easier to remove. Just 2 bolt.

The speed of the autoX event in my local area rarely reaches 60mph or 100 kph. We don’t have big enough area to make a big, high-speed course. About the chance to crash, since we are running on airport runway, there is simply nothing we can crash into. No trees, no rocks, not even long grasses.

 

I agree with the others, looks weak. You want crash force to go shear to the plate, it won't bend in that direction. Something like the second one posted is much better.

 

Its funny you guys keep mention about crash. Did you guy plan to crash or something in autoX?

I never plan so, and from the safty history of my local event, I don't think it will ever happen (only 1 accident in the last 10+ years).

And I keep mention I use it in low speed autoX (max 70~100), but some of you guys keep thinking that i will run it in some high speed event like Solo 1. All i ask is if I should use 2, instead of 1 bolt. It not for safty issue, but the ridigity of the b-pillar. If i need something safe in case of crash, i will either go with roll-bar & 5 points setup, or not at all with just stock seat belt.

 

most people dont "plan" on getting into an accident, unless of course they are trying to kill themselves and swerve at the lightpole. In our events, i can get up to 65 MPH before hammering the brakes at the turnaround, and at one event last year hit 85 right before the turnaround. You asked what everyone thought, your brackets are weak, that is a fact. bolts will not change that but let me know when you meet someone at an event that runs OC into the dirt then comes back to grid and says "i meant to do that"

 

how do you know the brackets are weak? You dont even know what they're made out of! Sure, the bend in the bracket provides a convenient failure point but still.

 

The bar and the brackets both use 3/16 stainless steel. The " U " shape bracket was bended by a 200 ton press.
It may not be the strongest material I should use, but I bet it is something close.

I can also use normal steel and then powder coat it since the process is also free to me. But i still prefer stainless cause the look.

BTW, the max 70 ~ 100 i mention is in kph, not mph. I am in Canada.

Now, back to the original question. In terms of chassis stiffness, should I use 1 or 2 bolts?


[Modified by v67-gsr, 4:58 AM 3/4/2003]


[Modified by v67-gsr, 4:59 AM 3/4/2003]

 

Hello V67-gsr,

You are wrong about the speeds at BB, your home made bar will never pass tech at any event in the Vancouver area. And you are also wrong about the history of accidents at BB. The number of cars damaged last year alone was greater than 4 in various off course incidents.




[Modified by DB1-R81, 9:23 PM 3/3/2003]

 

Well, he's got a point. If the cones are the only thing you can hit, I would say you would be alright. But, that's just going on his statement.

 

I have seen cars impact dumpsters and fences at high rates of speed. But i dont think it would make a bar like that fail.

All IMO

 

There is plenty to hit at BB, Boundary Bay airport from drainage ditches on booth sides of the runway too thousand pound concrete blocks in the "weeds" which reach well above head height. Here are brief illustrations of five accidents that occurred in the last two years alone. There are airport runway lights in the middle of the runway at the West end seen in the first picture infront of the corner worker which were struck by a 944 over $6000.00 damage. A Suzuki Turbo over steered got sideways hit the uneven concrete snapped it's suspension rolled and totalled. Last year alone WRX in the drainage ditch $7000.00 damage. 70’s Corvette over ran the finish struck a 4" fence post at the East end of the runway flipped, totalled. Z06 lost control at the finish struck 2 cars in grid over $5000.00 damage.

His statement is way off base. Believe me there have been plenty of cars damaged on course and off course at BB, judge for your self!











[Modified by DB1-R81, 11:46 PM 3/3/2003]

 

The speed I stated is all under my personal experience. So far, the course layout I ever driven in did not require me to shift to 3rd. And most should know GSR 2nd gear can reach up to ~100 kph. That may not apply to you, Marc, because you car is heavily modify in engine, so it is possible in your case to reach 100+.

BTW, I don’t see any reason why will my home / factory made harness will fail in event tech beside the bolt size I am using now are 9mm, which minimum required is 10mm.

Btw, I can make a roll bar/cage that fit all requirements in the rulebook with 1 inch tubing, and still pass the tech. All it said in the rulebook is “recommend” tube size, not “required” size. The material I use now is bigger than the “recommend” size.



[Modified by v67-gsr, 6:59 AM 3/4/2003]

 

Hello v67-gsr,

Size of materials is only one part of the equation when constructing safety equipment, think about design, assembly and testing.

 

Personally, I wouldn't trust that setup.... I've got a roll bar with a built in harness bar sitting in my garage right now, it's going in this weekend.... Skimp on tires or shocks, or something like that before you go cutting corners on safety.

Dan

 

Look at it this way. Your stock seat belt anchor points must hold a 3,500 lb pull to meet FMVSS. I don't think your bar can take that. Could you pick up the whole car by the bar?

 

Could the "nicely done" bar in the red integra pick up the whole car as well?
Seriously, I don't think so.

 

OK, so you're both going to die. Actually, the set up in the red car looks very good. Thicker tubing, and the lower braces tie it to the car at two additional points.

175 lb occupant in a 15g crash = 3,500lbs.

Pray you don't hit a light pole at 35mph while autocrossing (I've witnessed it in person; seen a car flip at an auto-x too).

It's your butt. If your comfortable with your bar...drive on!


[Modified by Track rat, 6:31 PM 3/4/2003]

 

Actually, I'd bet that the bar in my car (the red one) would pick up the car. It's built just like a roll bar would be. If my bar would fail, so would any harness bar connected to a cage.

I too was going to point out that at any of our club's events, that roll bar would also not pass tech. You may have complied with thickness in tubing, but construction looks way off. Use that harness bar to hold you in place for better car control and use your stock belts as the safety measure.

It looks like most agree that your bar probably isn't safe. So, it's your life your playing with. Go a head and use it.

 

Except that instead of having large flat plates bolted through the floorpan you have a bar butt-welded to a cantilever plate constrained in rotation by a 1/2"? rod-end. A rollbar has a much larger moment arm to resist any loads imparted by the belts.

The autopower 4pt rollbar is pretty inexpensive (<300?), and has the added bonus of rollover protection. Seems to me to be the way to go if you're going to be giving up the back seats anyways. If you remove this thing between events thats a different story.

The bar from the first post would be substantially stronger if the bend U-channel was boxed in by welded plate on the ends. This would help prevent the channel from collapsing and being sheared by the bolt.

A simpler solution would be to weld a cantilever plate on the end similar to the bar in the red car, but just long enough to clear the factory belt mount. Orient the bar before tightening such that the belts pull along a line between the center of the bar and the center of the mount bolt. This way no reaction moment is required.

 

I don't understand this debate.

A real rollbar is about $ 300.00 and a new wheel chair is about the same.

Choose ~ Choose

Of course, a nice casket is going for about $ 800.00 direct.

Do yourself a favor, invest in your safety. if you need some time, use a chest strap until you can go whole hog. Nobody wants to add to a thread mourning your injury/loss