• From: NEPA
  • Registered: 2010-01-02
  • Posts: 44

Topic: Non-standard tubing for harness bar?

Hey guys,
      Long story short, I need to make a new harness bar - don't have any round tubing or a good way to bend it. I do, however, have a piece of 1.5"x1.5"x1/8" square tubing that we had bought for something else and not used. Do you think anyone would care at tech if we used it for our harness bar? It's plenty stiff and as it's not a load-bearing member, so I assume it really doesn't have to be 1.5/1.75" round tubing. Thoughts? I'd go with round tubing if it looks like it will be an issue, but since I have this tubing on hand and can form it appropriately, I'd like to try it...

Shallow Pockets Racing, aka the newbies in the BP-themed Golf
-Summit Point 2010, 29/86, 0 mechanical problems - "Are you sure it's a VW?"
  • From: Craphole, NJ
  • Registered: 2009-05-01
  • Posts: 517

Re: Non-standard tubing for harness bar?

Would it pass tech?  I have no idea.

Don't invite extra attention at tech.  Get a piece of round tubing that matches the rest of your cage.  You don't want to have to replace that bar in the paddock while the race starts.

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  • RobL
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  • From: Philly area
  • Registered: 2009-04-30
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Re: Non-standard tubing for harness bar?

You have at least one weekend to make this right (assuming that you are doing the North Dallas Hoopty).  Order a tube from McMaster if you have to.

Side question - why would you need to bend a harness bar?

--Rob Leone Schumacher Taxi Service
We won the IOE at Southern Discomfort.
We got screwed at The Real Hoopties of New Jersey  and we took cars down with us.
We got the curse at Capitol Offense but they wouldn't let us destroy the car.

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  • VKZ24
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  • From: Wilson, NC
  • Registered: 2009-05-20
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Re: Non-standard tubing for harness bar?

RobL wrote:

Side question - why would you need to bend a harness bar?

Depends on the relation between the seat and main hoop.  The harness bar in my street/HPDE car is bent on the ends to allow for full seat travel.

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5 Reply by RobL (edited by RobL 2010-05-25 10:48 AM)

  • RobL
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Re: Non-standard tubing for harness bar?

VKZ24 wrote:
RobL wrote:

Side question - why would you need to bend a harness bar?

Depends on the relation between the seat and main hoop.  The harness bar in my street/HPDE car is bent on the ends to allow for full seat travel.

And you also have a full cage in that car? 

The gist of my question is that with a properly positioned main hoop, the cross bar/harness bar is there to keep the diagnal stable in the event of a crushing force on the main hoop.  With it bent, it looses strength.

If you need to bend a harness bar to get the seat under the main hoop, I would think that you would have wanted to move the main hoop back.

--Rob Leone Schumacher Taxi Service
We won the IOE at Southern Discomfort.
We got screwed at The Real Hoopties of New Jersey  and we took cars down with us.
We got the curse at Capitol Offense but they wouldn't let us destroy the car.

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  • From: Merrick, NY
  • Registered: 2009-05-13
  • Posts: 2,155

Re: Non-standard tubing for harness bar?

I'm no cage expert but I had one (RobL) put the cage in my car and if he says its not a good idea I would 100% agree.  Not that I have any clue but it seems the stiff 90 deg bends of a harness bar probably wouldn't be good for force distribution as well but I really have no clue if thats true or not.

In my experience with Lemons as well I wouldn't give them any sort of reason to decide no, and since the track provides the safety inspections in many cases , JMO not worth it.

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  • DaveH
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Re: Non-standard tubing for harness bar?

I wouldn't use square tubing.  It has a tendency to fail when stressed in the wrong direction, not to mention that it puts more stress on the belts.  Unless you can do your own finite element analysis, innovation is not something you want to do in cage design.

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  • From: NEPA
  • Registered: 2010-01-02
  • Posts: 44

Re: Non-standard tubing for harness bar?

Good enough, I'll just have to see if we can get something bent up. The reason it needs to be bent is that otherwise it will be touching the back of our seat, not leaving enough room for the belt hardware between the bar and seat.

Shallow Pockets Racing, aka the newbies in the BP-themed Golf
-Summit Point 2010, 29/86, 0 mechanical problems - "Are you sure it's a VW?"
  • From: Merrick, NY
  • Registered: 2009-05-13
  • Posts: 2,155

Re: Non-standard tubing for harness bar?

docrice wrote:

Good enough, I'll just have to see if we can get something bent up. The reason it needs to be bent is that otherwise it will be touching the back of our seat, not leaving enough room for the belt hardware between the bar and seat.

As mentioned before I'm no expert but I believe if you do bend a harness bar like that additional bracing is required.  Hopefully RobL can chime in for sure on this one although he may be busy drinking his 30's away today!

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  • bob-e
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  • From: Middle, TN
  • Registered: 2009-06-08
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Re: Non-standard tubing for harness bar?

my autopower is bent and it passes nasa and Lemons. 

http://www.autopowerindustries.com/Images/lg/DSC_2840.jpg
I really wouldn't go square on the harness bar.  Cages aren't something you really want to think outside of the box on.

  • RobL
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Re: Non-standard tubing for harness bar?

There are two things - the bar provides strength to the cage.  From this aspect you lose some strength but not enough to fail tech (ideal world vs. real).  My personal main concern is that you would be moving your seat back into the area where your helmet would hit the cage in the case of an accident.  SFI padding in this case is highly recommended and soft/no padding will cut through a helmet like it wasn't even there.

--Rob Leone Schumacher Taxi Service
We won the IOE at Southern Discomfort.
We got screwed at The Real Hoopties of New Jersey  and we took cars down with us.
We got the curse at Capitol Offense but they wouldn't let us destroy the car.

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12 Reply by Evil Genius (edited by Evil Genius 2010-05-28 09:13 AM)

  • From: Davis, Ca
  • Registered: 2009-04-30
  • Posts: 1,843

Re: Non-standard tubing for harness bar?

Don't use the square tubing.. get some proper round tube.

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