bump!

 

I don't know about fabricating a bar. I have the 4 point rallye harness; the track here hasn't bothered me about the angle, but if they did, I would probably simply drill new holes in the floor board behind the seat to get the 40 degrees and bolt in enough metal strips or big washers under the floor board for proper floor loading distribution.
Now, my rear seat has been taken out and you still want your seats, so I'm not to sure how far back you can go before you run into interference with the fuel tank. Anyway..just my take on it.

 

Sorry Bobby, I really don't want to drill through the floor just yet.

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by P-51:
Why not make a bar that clips onto the metal loops that the upper seats hold onto when they are upright? Flip the seat down, clip the bar on and you're done?<HR></BLOCKQUOTE>

Aha! That sounds like the ticket! What kind of clips would work for this? Is there something I could buy and weld to the tubing?

Or would something like a steel carabiner work, fastening to loops on the back of the tube?

 

Why not make a bar that clips onto the metal loops that the upper seats hold onto when they are upright? Flip the seat down, clip the bar on and you're done?

 

Here's my latest idea after having a brainstorming session with some friends:

I make an insert from thick steel plate that fills the void inside the P-shaped seat brackets. That insert is then welded to a larger steel plate that will sit on top of the bracket. The tubing is welded to that top plate, and there is another plate bolted on the bottom, holding the assembly in place.

That way any shearing load is taken by the plate interted into the bracket, and the bolts just function to hold it in place.

What do you think? Would you trust your life to this type of setup?

 

SCCA I think discourages the use of harnesses in non roll bar equipped vehicles. They contend that they restrict the ability of the driver to duck and thereby avoid head injury in a roll over. Just food for thought.

On the bar idea, I wouldn't trust my life to a bar that only mounts in two points and traverses the width of the car. I think that 3" racing harnesses are rated at over 9000 lb load. Would a bar in that configuration be as strong?

Rich
teamDFL...a supporter of real cages

 

9000 pounds!

Wow, Rich, I never expected loads like that. That's 45 G's for a 200 pound driver! The harness would probably act like a strainer!

I'm aware of the potential danger of a harness in a non-roll-cage equipped car. Would you ever really have time to 'duck' out of the way?

Well, I did some stress calculations today, and I've abandoned the bar. Here's the spec's I used: 2.25", 0.120" wall, mild steel tube, with harness mounting points at 5" and 10" in from the driver's side wall. The tubing in this setup would yield at around 1100 pounds on each shoulder strap. Not good enough!

But I checked the strength of the bracket itself (the wire loop), it can handle around a 2600 pound load before yielding. That's around 13 G's for a 200 pound driver. I'm not sure how much additional energy could be absorbed in plastic deformation, but I would feel safe with this for autocross (i.e. extremely low risk of collision) use only. Plus it's easier to make just one bracket and it's lighter than a giant steel tube. I'm not really surprised by the strength of the bracket, considering it would hold a middle passenger in place in a head-on collision.

I may still wear my stock seatbelt over top of the harness just for the piece of mind.


Just out of curiosity, what kind of G-forces are used in seatbelt calculations by manufacturers? Realistically, I guess the harness should never break, even if the person is crushed by the loading. That way the investigators can't blame the injuries on the harness breaking.

[This message has been edited by corey_dyck (edited 05-06-2001).]

 

I believe that each belt needs to support 3000lbs. Let me check my old emails, I discussed this with some people a while ago...

 

Hmmm, 3000 pounds, is that yielding or ultimate load? This may not be possible after all. I'd hate to go through all this work and then have it fail technical inspection, or worse, fail in a crash.

What other options are there? How about putting both shoulder straps up into the driver's side upper rear belt mount, on top of each other? Maybe Bobby's solution of new mounting points further back is the only practical one, but that would mean buying a very long harness (more $$!).

Rob, how does your harness pass tech? If I remember correctly, your harness setup is the same as my present one, but you're not encountering any tech problems?

Right now, I'm starting to lean towards going with the single plate mounted to the seat bracket holding both shoulder straps. Then, I could also wear the stock belt just in case I manage to drive way off course into a brick wall! The harness would hold me in place for cornering, and the seatbelt for safety. Silly, or smart?

By the way, thanks for the help on this one, guys!

 

Not to jump in the middle of this, but I'll do it anyway.....

P-51 and I are going to fabricate a roll hoop for his car. Based on how it goes, I may be able to be talked into making some removeable roll hoops/harness bars for other Focus people.

Is there interest for something like this???

------------------
00 HS Focus ZX3
78 ITC VW Scirocco, totalled and out of commission
73 Porsche 914, 2.0L
84 Rabbit GTi, ITB car in process

 

I've done the dual belt thing before in my Stang. It was OK with tech, but it's not comfortable.

I have only passed tech for autocrosses in my Focus. I wouldn't even dream of passing tech for lapping like this. That's why Groot might be helping me make a roll hoop.

The 3000lbs is the Transport Canada (CDN equivalent of NHTSA) requirement I think.

Anyway, at SCCA autocrosses, the tech guys always give me a warning that it is unsafe and I should fix it, but they don't ban it.

 

groot - please do jump in! About your roll cage, how difficult would removal be? Is it something that you would want to/could install before and remove after every race?

My car hasn't become a full-on race car just yet. I have 5 people in the car once or twice a week, so anything I do has to be removeable or inobtrusive. It does sound like something I'd eventually get though!


Rob - This is only for Autocross as well. If I ever do get to do any more lapping this summer, I'll just wear the lap belt portion to keep me planted in the seat with the stock seat belt over top. I wouldn't trust the 4-point harness outside of the relatively safe autox environment.

 

I'm only talking about a roll hoop. A cage is a different animal. I'm working on a cage for my IT car now and I would never consider a removable cage as a very "safe" option.

But, for the roll hoop...... P-51 and I will work on it this weekend and we'll post on it next week. The goal would be to make something that could be removed and bolted in fairly easily. The other design considerations include appropriate mounting for the shoulder harness and additional stiffness for the chassis.

I've seen enough crappy Autopower roll hoops and bolt in cages to know that they don't spend much time designing. We won't make that mistake.

------------------
00 HS Focus ZX3
78 ITC VW Scirocco, totalled and out of commission
73 Porsche 914, 2.0L
84 Rabbit GTi, ITB car in process

 

I want provisions for two harnesses, and I would like it to tie into the rear shock towers. That's my goal. Later on, I may make a provision to hold a full size spare a-la WRC. I'm thinking more and more of putting the battery in the spare tire well, and just carrying a can of fix a flat and a tire plug kit. If I go on a rally or long trips, I'll bolt in a full size spare.

I doubt we could come up with something "easily removable" but it won't be permanent that's for sure. I want to make sure the car is always convertible to stock-looking form if I ever need to. At least until it's paid off.

This thing will be bolt in with backing plates underneath.

 

I totally forgot to post an update on how this all went! I’m now using the plate mounted on the seat bracket. Here are some pictures of the setup, click on the links to see them:

Pic 1

Pic 2

Pic 3

Pic4

Pic 5

When I did my lapping session, I wore both the four-point and the stock belt. The harness held me securely in the seat, and the stock one gave me piece of mind.


[This message has been edited by corey_dyck (edited 06-06-2001).]

 

WOW! Looking good Corey.