The 24 Hours of Lemons Forums → Lemons Tech → Rear diagonal needed?
I thnk I messed up and misread the rules a few months ago when I was doing our roll cage, after reading posts about the rear diagonal that was added on to the specs. I have a Jegs kit and the side supports come up pretty high, any chance one of the tech judges could tell me if I need to redo this to include the full length cross diagonal?
and
TIA,
Do you have a wider angle picture? I think I see what is going on but would like to see the whole scene before anyone tells you something.
The requirement is for "one main hoop diagonal", which you don't really have.
What you need is a diagonal from top left all the way to bottom right in the main hoop. I'd bet you won't get past tech with what you have. Even if you did... it's not doing such a hot job of protecting your head. You want that extra point above your head.
The "V" you have in the middle does next to nothing, I'd consider removing it for simplicity. The diagonal that you add should be one continuous piece, so plan on notching the harness bar to accomodate it rather than the other way around. Pain in the ass, but that would be the proper way to do it.
Try standing sideways and looking at the first pic, I did not edit to rotate it sorry. You can see the whole back hoop and supports. The 'stang is crowded and hard to get pics, the one I took through the rear window to get a view!
Laren -
That's what I was figurin' I had to do - rent a slow rpm 1/2" drill and put my notcher inside the car to cut a diagonal slot in the harness tube, remove one of the upside down V supports and make it up to to the driver's head corner.
does it need to hit the baseplate or can it hit the main hoop upright if less than 4" from base, and does the upper end need to attach at the highest point or can it attach at the center of the bend and pass? I just want to know the proper way so I don't have to redo the *#*$^^# again. I swear, the rules must have changed after I did this SOB, or at least that's my excuse.
I do have X door bar added.
The "useless" V you mention is part of Jegs 8 point kit and they show them as even less beefy, only attaching about 8" from the main hoop and being short little braces. What I did was a huge improvement on that, joining with other side at least.
from the pictures it looks like your harness bar is mounted too high.
3.5.1: Harness Mounting: Grade 8 or better hardware and 3-inch or larger load washers are required when mounting to sheetmetal. Shoulder harnesses should be within 15 degrees of horizontal from load point to seat entry.
probably should get that checked with jay, nick, or dan before you go hacking on things to make a diagonal.
The 'v' doesn't appear to be on the same plane as the main hoop so you may get away without cutting it out. The diagonal must go from the bottom of the passenger side main hoop to the top driver side main hoop. The strongest way is to make the diagonal one piece, but since you have the horizontal bar already in place, a two piece diagonal is acceptable. Check with Nick...
I think the V is a good idea...it ties your main hoop to the crossmember for little additional weight. I'd leave it in. What model of Mustang is it?
I think contacting Nick would be your best bet. Time is short and you want to get this right the 2nd time. Find out what the powers that be want you to do to make that cage good.
We all have opinions... but ours don't count.
Your harness bar is too high for proper belt placement. Optimum harness angle when not using a HANS is 0-20 degrees downward off of the shoulder. The seat holes should not contact the harness webbing. Simplest thing would be to cut out the harness bar and put in a new main hoop diagonal then add a 2 piece harness bar back in the proper location.
The "D" bars arent really doing much (they're a drag racing thing) but they don't look like they're in the way.
Your harness bar is too high for proper belt placement. Optimum harness angle when not using a HANS is 0-20 degrees downward off of the shoulder.
Downward...NO! A downward angle can cause compression of the spine. 0-30 UPWARD would be where it should be. See figure 2 of this document from G-Force.
from the pictures it looks like your harness bar is mounted too high.
3.5.1: Harness Mounting: Grade 8 or better hardware and 3-inch or larger load washers are required when mounting to sheetmetal. Shoulder harnesses should be within 15 degrees of horizontal from load point to seat entry.
probably should get that checked with jay, nick, or dan before you go hacking on things to make a diagonal.
Is seat entry the bottom of the hole that the belt goes into or where the harness is when someone is strapped into the seat? We just added a second harness bar to our car to get it up higher. I think it will be about an inch above the shoulder for most of our drivers but 3 inches above the bottom of the slot. The slots on our seat are pretty big.
Downward...NO! A downward angle can cause compression of the spine. 0-30 UPWARD would be where it should be. See figure 2 of this document from G-Force.
The FIA, SCCA and NASA etc require a 0-20 degree downward angle IN THE RULES. In GF's own text from the link above: "Shoulder harness should not be anchored more than 1”- 4” below shoulder height." Depending on seat placement, 1" is around 15-20 degrees.
From the 09 GCR: The shoulder harness shall be mounted behind the driver and
supported above a line drawn downward from the shoulder point at an angle of twenty (20) degrees with the horizontal.
Wording is similar in the NASA CCR and FIA
Regardless, check your belt manufacturers instructions for proper harness mounting and then consult the rulebook. You can't go wrong with straight off of the shoulders EXCEPT if you're running a HANS.
I know the harness bar looks high, but I did read THAT part of the rules and the seat holes for the belts is actually just slightly below that, for proper installation. I can send some other pics up later.
On the other part, I must have brain-farted the diagonal part though when I was building the cage (too much confidence after making a cage in another Lemons car a couple years ago).
I'll have to get Nick to opine as folks have suggested.
Thanks, Scott
Oh, and you CAN see the seat entry holes on picture #2. When the driver's seat is all the way back like the driver's is in the picture, it gets lower (like a stocker) and no one drives with it like. The passenger seat is in a more typical position for driving. I'm 6' but tallest and most of that is in torso.
Oh yea, in reponse to inquiry its a '98 v6 5 speed mustang, was flood damaged and odo quit working, etc, but running good.
Yeah, you need a full-length diagonal in the plane of the main hoop. It can be comprised of two separate sections on either side of the harness bar, but the two pieces must form a straight line.
However, there is another alternative that might be easier in your case--if you form an "X" across the rear stays that travels from the top corners of the main hoop down to the bottom corners of the rear stays, that is an acceptable substitute for the rear hoop diagonal. That way you can leave the existing lower supports where they are.
Do you have a wider angle picture? I think I see what is going on but would like to see the whole scene before anyone tells you something.
Damn, amazing what you see when you get home...the second photo didn't even show up when I was at the office. Loren is right, nothing we have to say really matters in the long run. You need Jay or Nick to give you the ruling which it looks like Nick did. Good luck with the rest of your build!
When did the continous diagonal get added to the rules? We took the Q to the cagebuilder months ago to add the X bar for the door but I do not remember seeing this change. This is also news to us as our design is similar to Stevebolt's and raced before. The car is loaded in the trailer ready to head out to Ohio and I am more than alot concerned right now.
Half-Assed Safety (your screen name was maybe forshadowing?)
Nick did say you could make X on back supports if they go full length.
Looks like you'll have work to do before heading back on the trailer. Good luck.
I needed additional tubing for the X on the door, Jegs has a 2 tube package thats only about $35 delivered and they ship fast, but its near impossible to find on the website you have to call or email ask for it, I tried searching my archives but I think I lost the part number.
Sorry to hear you had the same poor reading skills I have. I found my printed version of the "new revised" rules and it did have it.
I will see if I can track that down. But since we are leaving in less than 24 hours I don't see that working. Do they have the 1.75 x .120 DOM? Our cage is all built with that as our car was over 3000 lbs at date of manufacture.
When we read the new rules we saw the need for a diagonal, but knew that we already had 2 diagonals, and once we saw the picture Nick posted (the 3rd one)
http://forums.24hoursoflemons.com/viewtopic.php?id=328
We saw that as being good with the exception of the new door bar. I guess it was later said in that same forum that it was an unacceptable design.
Anyone have any other suggestions?
All I can say is perhaps go by some speed shops in-route and bring tubing to the track, there is usually some gear-heads who for the price of a few beers and pizza will want to show off their fabrication skills with a grinder/welder.
FYI for anybody who needs last minute safety gear or parts - Summit Racing is right on the way just outside of Akron on I-76. You will see it from the highway.
FYI for anybody who needs last minute safety gear or parts - Summit Racing is right on the way just outside of Akron on I-76. You will see it from the highway.
Exit 29, to be exact.
For those coming up I71, Jegs is in Columbus too.
John
Thanks to everyone for the suggestions and help. Thanks Stevebolt for posting this up here otherwise we would have gotten bit at tech and be in a really bad place. But special thanks to Lund Motorsports who has graciously suspended work on for their paying customers and their real race cars this afternoon and is feverishly welding in our diagonal support. I guess our "theme team" will be pulling a late night in decorating the car but hopefully we will still make it and be able to race. See you all in Ohio. Everyone is welcome over at our "bum camp" (you will see) because inside our cardboard shanty town the Free Candy Racing team will have their race simulator set up for some paddock fun. Thanks again everyone.
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