• From: New Alexandria PA
  • Registered: 2010-06-14
  • Posts: 964

Topic: Roll cage welded to frame

Good Day!

I am thinking of building up a new Lemons car and had a question about the cage.

If the car has a full frame underneath it, and the cage is welded directly to the frame, do you need to run spreader plates? 

Every cage I came across for this car has holes drilled through the body of teh car and teh cage welded directly to the frame (even the rearmost tubes).



Thanks!

Ghetto motorsports - Car #555 1980 Mazda RX7 (3x winner of BFE GP / 1x 2nd place of BFE GP...BOO!)
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  • VKZ24
  • VKZ24
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  • From: Wilson, NC
  • Registered: 2009-05-20
  • Posts: 1,840

Re: Roll cage welded to frame

I believe the whole spreader plate thing was devised for a uni-body car, but you better ask someone at Lemons HQ for a final ruling.

Captain
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  • From: Safety Harbor, FL (Tampa)
  • Registered: 2009-04-30
  • Posts: 668

Re: Roll cage welded to frame

I believe it is typical (for Lemons) to wrap the spreader plate around the frame and weld to that.  A little extra reinforcement never hurt anything!

Lemons South 2008 - Fail, Lemons South Spring 2009 - Fail, Lemons Detroit(ish) 2008 - Fail, Lemons South Fall 2009 - Fail, Lamest Day 2009 - Fail, Miami 2010 (Chump) - 2nd!, Sebring 2010 (Chump) - Fail, Cuba 2010 - Crew Chief, Roebling 2011 (Chump) - 8th!, Sebring 2011(Chump) - 19th!

4 Reply by Serj (edited by Serj 2011-01-05 09:35 AM)

  • Serj
  • Serj
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  • From: Cincinnati, OH
  • Registered: 2009-05-02
  • Posts: 1,601

Re: Roll cage welded to frame

The problem with cutting hole in the body and welding to the frame is that in a collision the body mounts will likely shear off and the body shift on the frame, effectively turning it into a press. The body can move but you can't. If you're planning a cage this way I'd highly recommend tying your seat and several areas of the body to the cage itself to limit the shift it would experience in a collision.

  • From: Houston (Spring) Texas
  • Registered: 2010-02-22
  • Posts: 1,624

Re: Roll cage welded to frame

you need spreader plates weather it is body ob frame or unibody. if it is body on frame, cut through the body and weld to the frame with spreader plates.
also if you have a body on frame, it would be smart to mount the seat on the cage structure, virsus the body.

Yee-Haw 2010 "Most Heroic Fix" & "I Got Screwed" -2 trophies for 1 lap, but I took checkered on my lap.
Gator-O-Rama 2012 "Organizers Choice" -2 laps 1 trophy, but i still finished ahead of an E30
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  • From: Davis, Ca
  • Registered: 2009-04-30
  • Posts: 1,843

Re: Roll cage welded to frame

My work is done here, these guys have it right.    Listen to them

-John

Gosh, my business card says 'Tech Tyrant'

7 Reply by mspitzer (edited by mspitzer 2011-01-05 01:35 PM)

  • Registered: 2010-02-11
  • Posts: 23

Re: Roll cage welded to frame

Not to beat a dead horse but my rear support bars do not meet the 24 in^2 criteria.  I currently have  15 in^2 plates welded into a recess in the rear firewall so any additional plate I could weld on the sides would look like a cobbled piece of $%&^.   

The rules state:

Spreader plates of at least 24 square inches; backing panels; gussets; and/or other reinforcing
elements are generally required to meet this goal.

Does the term "generally required" mean that my current cage might pass?  The car structure and the mounting points fore and aft of the driver all meet the letter of the rules and the cage has never been questioned in my previous 2 events.  If I were building the cage from scratch I could have welded in a backing plate to facilitate the larger plates but now I'm stuck.  Still waiting on official word from HQ....

Mike