I have a four point Autopower roll bar in my Miata. I'd like to add a harness bar and a diagonal. The bar is made of 1.750 x .120 DOM and I have about six feet of the same material.
1) If I add a harness bar between the front tubes, it will be too close to the back of the seat. The rear tubes angle inward. If I add the bar between them, I will not have room to wrap the two harness straps without offsetting them toward the center of the car. Would the bar be SCCA legal if I mount the harness bar to the rear tubes and add tabs to mount the harness to?
Something like this, except closer and with better welds. And the tab on the right would butt up against the down tube as well as the harness bar.
2) Can I legally run a diagonal at approximately 45 degrees from the center of the top bar to the point where the harness bar meets the rear down tube?
see how far below your shoulders the cross bar needs to be then put a couple of Minor bends where it will rise up to meet your roll bar then you may be able to keep it all Including the 45 as bolt in. I really have no Idea what is legal but that sounded Good
I have no ability to bend tubes, and even if I did, I'd have to nail the length and deal with compound angles on the fishmouthed ends. Unpossible with my skill set.
Bet you can do this for 100 bucks. some one with the tools and Skill set is a close as... well I don't know where you live but I bet Close.
Or the easy solution is to buy the Hard Dog bolt-in harness bar. $150.
https://www.bethania-garage.com/harness_bar.htm
It looks like this:
In reply to codrus:
That won't work for me. It bolts to the same spot as the front legs of my bar.
Supposedly it fits with the Hard Dog bars that also bolt to that location with the front legs, but no idea about the Autopower.
I can't help you with the legalities side, but if you get in a bind you're welcome to make the trek up to use my tubing bender. You can bend any size tube you want as long as it's 1.75.
In reply to WonkoTheSane:
Thanks, I may take you up on that. I'm going to do a PVC mock-up to see how much clearance I have with a straight bar. Right now, I'm waiting for my seat to arrive, which hopefully will be today.
Would it help if you mocked up the amount of bend you need for the front bar mounting plan, by using electrical conduit and the hand bender that goes with it?
I have no idea myself. Just something I saw in a magazine article on bending roll cages a couple years ago.
This guy has a technique to fishmouth without a tube notcher. The Fabrication Series
I also have one of these for notching complex shapes which worked pretty well:
In reply to WonkoTheSane:
that's neat!
WonkoTheSane wrote:
I also have one of these for notching complex shapes which worked pretty well:
That is seriously cool. What size is it?
Mine is for 1.75. It was really handy to do the back bracing at the top of my hoops:
There's an angle intersecting an arc, which meant that there's no way to do it with the standard hole saw jig.
Robbie wrote:
In reply to WonkoTheSane:
that's neat!
It is pretty cool!
I got it from Speedway. Linky
