The 24 Hours of Lemons Forums → Lemons Tech → Rule 3.1.4 - spreader plates
"Spreader plates of at least 24 square inches"
Does this mean all spreader plates have to be 5"x5", 4"x6", ect What if you have a 4"x4" plate but it boxed between the floor and rocker. Would a smaller plate be ok if you have a minimum of 24 inches of weld between plates and sheet metal?
Like this
To be honest I think they may have an issue with the box mount you built for the cage...
I think a lot ( most ) of us will have to modify our roll cage mount plates...
Is that what I am reading here?
KT
It'll be interesting to see how our cage passes. We have 2x3 tubing as our roll cage mount with spreader plates on top of that. I got an answer of using 10 square inches for the spreader plates a month ago. I wonder if the tubing will "count" towered the 24 square inches.
To be honest I think they may have an issue with the box mount you built for the cage...
Why would you say that? Those boxes, which are called 'plinths', are very common when putting a cage in a production car. The reason for using them is to be able to tilt the nose of the cage down to gain access to the top of the halo for 360 degree welding.
If there is a problem with this design we are hosed and so are many other teams.
We went overkill with our two builds and used 6"x6" plates. Thank goodness....
I foresee Dan and the rest of the tech guys having a fun year of telling teams they need a few mods to their cage.
yeah I'm fairly porked here. My main hoop plates are 3.5 square. I also used plinths up front but the box lands on a 6x8 spreader, so I bet im OK there. my Backstays may be an issue too. they mount on angle welded to the shock tower. each face of the angle is about 10in^2. I'll have to get a ruling from Jay on those.
I don't know how the hell to swap the main hoop plates. cutting those out without trashing the floor there will be a real trick. any suggestions?
I don't know how the hell to swap the main hoop plates. cutting those out without trashing the floor there will be a real trick. any suggestions?
No idea. Would a plate welded on from underneath the car work? Perhaps a real tech person will have a suggestion.
I suppose we could cut flush with a sawzall along the top of a mount plate that is to small.
Then slide a new plate on top of the old, weld it in then a new 360° weld around the base of each tube.
Not hard, but a time consuming bummer.
Why can't previously teched cars get grandfathered, while new builds comply?
KT
I suppose we could cut flush with a sawzall along the top of a mount plate that is to small.
Then slide a new plate on top of the old, weld it in then a new 360° weld around the base of each tube.
this is what I was thinking too. probably easier than trying to get the old plate out.
John
JMo wrote:I don't know how the hell to swap the main hoop plates. cutting those out without trashing the floor there will be a real trick. any suggestions?
No idea. Would a plate welded on from underneath the car work? Perhaps a real tech person will have a suggestion.
Nope. spreader needs to be on top to prevent the tube from punching through the sheetmetal in a rollover. A plate on the bottom would not be compliant with the rule.
I suppose we could cut flush with a sawzall along the top of a mount plate that is to small.
KT
Sawzall may not get flush. Try a cutoff wheel.
from Jay to me, I have 4x4 plates:
"If you're in a situation where the plate does need to be extended, you can just butt a new section onto the edge of the existing plate and weld it all together--that's fine.
Note that the rule in question (3.1.4) says the 24-inch spec is "generally required" to meet the goal of the rule. You're not a dumb guy, and if you think the 4x4-inch plates you have now are sufficient to meet the purpose of the rule, you can always just leave them alone. Of course, ultimately the question isn't what YOU think, but rather what the inspector thinks, but I believe that if you look at it with an impartial eye, you should be able to see it like they will. A 4x4-inch plate in a really sensible location on really strong metal is probably not going to give them any heartburn."
from Jay to me, I have 4x4 plates:
If you're in a situation where the plate does need to be extended, you can just butt a new section onto the edge of the existing plate and weld it all together--that's fine.
Really? That's cool. And easy. And fast. And cheap.
Can we get an official stamp of approval on this mod?
I think leaving them alone if they are too small, even if they have passed tech multiple times before the rules change is looking for a fail at tech. I don't want to weld on the car on Friday night to get a late tech/start on Saturday.
Not worth the risk, in my opinion.
KT
In the end, take pictures, send questions to Nick, Dan, and John, and get an official word before you go cutting and welding.
The spreader plates on my car are the same width as the uni-body frame rails- 3 inches.
And 4 inches long.
That was always a pass ( four races ).
Now, no good?
KT
Riktor wrote:To be honest I think they may have an issue with the box mount you built for the cage...
Why would you say that? Those boxes, which are called 'plinths', are very common when putting a cage in a production car. The reason for using them is to be able to tilt the nose of the cage down to gain access to the top of the halo for 360 degree welding.
If there is a problem with this design we are hosed and so are many other teams.
It may be adequate for the purpose but personally i would have triangulated it with a pyramid designed plinthe. I see a problem with the cube as cubes are inherently weak with no internal structure. But this is my personal opinion and it may not be a factor with the ruling party.
As far as welding the top of the cage. Use a 3" hole saw to cut through the floor where the tube will mount prior to inserting the tubes into the car and you place the shaped bracing plate under to keep it from falling through. We usually tack weld it to the plate and then grind the tacks away when we need to drop the cage through the floor to weld the top.
Once everything is welded up we roll under the car and weld the holes to the bottom of the plate. It adds additional mounting to the plates.
But like I said... just my opinion and practice.
While I do realize this is Lemons:
SCCA rulebooks give maximum spreader plate sizes- not to exceed, if I read the book correctly. Some as small as 3x3.
Does anyone else recall this?
I'm just trying to figure out where this is coming from. Door sills are only a few inches wide, do you now need the plate to be 8x3, instead of 4x3? You're already on top of a very stiff boxed section.
Yep, 3x3 for the SCCA.
I imagine that Jay is coming at it this way because people are welding to rotten and rusted material. I do know that every cage that I've done so far would need additional spreader plate material added. Not something that I am looking forward to doing but it shouldn't take too long to fix.
Where ya been Rob? I haven't seen you on the forum in quite a while.
I'm around, just not posting. I've been really busy at work and "Call of Duty:Black Ops."
Jay and I have been having an email conversation about this topic. I'm not going to quote him directly because I think that's unfair and maybe easy to take out of context. But the basis of his intent is to make sure that the builders of bigger/heavier crapwagons use big enough spreader plates to keep their cages from punching through rusty tinwormed sheetmetal. The use of 24 square inch spreader plates isn't mandatory so much as it is a suggestion, as indicated by the use of the words "are generally required" in the rule. So long as the cage is properly functional, the use of smaller spreader plates will not cause a team to flunk tech. But if I were building a new cage on a new project (which I'm about to start), I'd use larger plates.
As regards other orgs, BMWCCA and NASA both require 9 square inch minimums, PCA and SCCA don't state minimums. FIA regs for WRC cars require 18.6 square inch minimums (120 cm squared). So Jay's picked a bigger spec (6x4/5x5/8x3, basically) just to be on the safe side. Also, according to an above post, the 24 square inches need not be all in one plane, so I think if you're building a boxed or plinth mount for your cage (as is necessary on some cars where you can't land right on the will panel), the box/plinth counts toward that 24 square inch number anyway. YMMV. Good luck.
Mulry, your explanation just eased most of my concerns. I still may add larger plates just to be sure though.
Can we get a 'wink and a nod' on previously teched cars?
KT
Butt-welding on additional area is not the way to go. The weld joint will be in shear and it's not very stiff in that direction; very little force will go down that load path. If you have to, weld it so that it is angled down to meet the floor.
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