The 24 Hours of Lemons Forums → Lemons Tech → Cage / Weight requirements (Newbie question)
Hey fellow racers,
This may be a dumb question but having never done a cage before I just want to be clear on the spec requirements before I purchase the material (Shop will be doing the install)
My donor car currently weights about 2700lbs without driver. Is there a reason why I can't use the 1 3/4 tube sizing instead of 1 5/8? (Over engineer)
Thanks and looking forward to racing in Nov @ MSR.
- Newbie
It is always ok to use the more robust option, and it will save any questions of "are you sure you're under the weight".
However, check the rules and your notes, 1 5/8 isn't one of the options.
3.E.1.a Rollbar Tubing and Spreader-Plate Specs. Minimum tubing size for cars weighing under 3000 pounds as raced is 1.50″ x .120″ or 1.75″ x .095″. Cars weighing over 3000 pounds as raced must use a minimum tubing size of 1.75″ x.120″.
And the .095 x 1.75 weight less per foot than .120 x 1.5 (shocked me when someone mentioned it) so there is no real weight penalty that cannot be offset with a healthy bowel movement.
However, check the rules and your notes, 1 5/8 isn't one of the options.
3.E.1.a Rollbar Tubing and Spreader-Plate Specs. Minimum tubing size for cars weighing under 3000 pounds as raced is 1.50″ x .120″ or 1.75″ x .095″. Cars weighing over 3000 pounds as raced must use a minimum tubing size of 1.75″ x.120″.
It isn't one of the explicitly listed options, but since the rules only specify a minimum, presumably something like 1.625" x 0.120" would be okay. It's worth checking with HQ before buying it, of course.
Sure, it probably would be ok, I just think it invites headaches at tech. If you stick to the common sizes you'll have less questions. 1.5" and 1.75" are the common roll cage tubing sizes.
Not to mention any roll bar clamp accessories are mostly going to be in the 1.5 and 1.75 size.
We are under the 3000lb pound mark but chose to go with the 1.75 x .120 tubing. Something about not wanting to give the significant others the life insurance money just yet.
Experienced people [for my _future_ future reference]:
How is the 'as raced' weight evaluated? Does it include _all_ things in the car, like a filled cool shirt cooler, a full tank of fuel, and the heaviest driver? Or the stripped vehicle before all the safety equipment goes in?
I checked the Roll Cage Components web site. Their stated weight for a Lemons roll cage is 250#, without any selections other than the basic 'this is a generic cage'. I don't know if that's shipping weight including dunnage, every possible add-on, or just the material for the minimum number of cage components.
OP:
Your stated weight of 2700# - does this include everything else you'd be required to have in the vehicle?
50# is an aufully narrow margin ...
Setting aside the presumed additional safety margin, I don't think I'd chance the <3000# required tubing if it were that close.
I believe the "as raced" verbiage means as it rolls out onto the race track at the green, basically the heaviest your car could be at any point during race weekend.
1.75x.120 wall DOM or nothing is my two cents. If a full size Lincoln happens to t-bone you, you will be happy you had it. If you're worried about added weight from thicker tube just remember, Lemons
And from a practical standpoint, as a welder, which would you rather weld to 1/8" spreader plates? .120 or .095? Can you do both...sure but having same thickness metal after struggling on 1/8" to sheetmetal just makes a guy smile.
My donor car currently weights about 2700lbs without driver.
If you're looking at approx. 200 lbs for a roll cage, how much do your drivers weigh?
Unless you can find 200 lbs you can remove from the car to offset the cage weight,
I think the rules will require you to use the 1.75 x .120.
Agree with OnkelUdo. From a fabrication standpoint, 1.75 x 0.125 is significantly easier to work with. The weight difference is negligible (definitely won’t make or break a class win).
Thanks for all the help guys!
Wanted to clarify that I plan on ordering my cage from Rhodes Racing. They offer the following DOM SKUs
For cars weighing less than 3000 Pounds cages are made from the following materials:
1 5/8"x.120" wall DOM Tubing
For cars weighing more than 3000 Pounds cages are made from the following materials:
1 3/4"x.120" wall DOM Tubing
Not concerned about the weight difference, just want to pass tech and have maximum safety.
Looks like general consensus is that I use 1 3/4 x .120 and call it a day.
We weigh nothing, went with 1.75. If I need it, bigger is better
Like Guild said, none of the roll bar clamp accessories are going to fit if you use an odd tube size.
Also as others have said in the past, the cage has to not JUST be legal, but able to stop a charging Crown Vic from ending up in your lap if you get T boned on track.
Go for the larger size, and add a few extra tubes in the drivers door, its 100% worth it.
You can always go more safe than the rules. We use 1.75" DOM on everything we build. Pagel will never complain about the car being too safe.
It is always ok to use the more robust option, and it will save any questions of "are you sure you're under the weight".
However, check the rules and your notes, 1 5/8 isn't one of the options.
3.E.1.a Rollbar Tubing and Spreader-Plate Specs. Minimum tubing size for cars weighing under 3000 pounds as raced is 1.50″ x .120″ or 1.75″ x .095″. Cars weighing over 3000 pounds as raced must use a minimum tubing size of 1.75″ x.120″.
1.5x.120 is the minimum. I can tell you from personal experience that 1 5/8 will pass tech. My car has an 1 5/8 x .134 wall cage and has passed tech twice. The first time it was teched by Mr. Pagel himself. Car weighs #2900 full fluids/fuel/driver.
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