• JThw8
  • JThw8
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Topic: Bolt in cage

What are the legalities around bolting the cage to the floor (with proper reinforcement plates of course) rather than welding?   Seems the rules used to mention bolt in cages but I dont see it mentioned now.

The rest of the cage would be fully welded just the sections attaching to the floor/frame would be bolted.

The reason I ask is GRM is going to start allowing cages under safety equipment (non-budget) as long as they are bolted in and not welded.   As we are trying to take the Wartburg there after Lemons if it survives it would help to not have that huge chunk of the budget gone so we could make some improvements to get it through GRM.

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  • From: Columbus, OH
  • Registered: 2009-05-26
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Re: Bolt in cage

My cage was bolted in (with the standard Autopower reinforcement plates) and passed tech just fine.  You'll be allllllright.

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  • JThw8
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Re: Bolt in cage

Cool, thanks smile

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  • Riktor
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Re: Bolt in cage

dculberson wrote:

My cage was bolted in (with the standard Autopower reinforcement plates) and passed tech just fine.  You'll be allllllright.

Just use the plates like culb...

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  • From: Emeryville CA
  • Registered: 2009-04-30
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Re: Bolt in cage

Yeah, Jim, bolt-in is fine, just use the plates....

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  • JThw8
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Re: Bolt in cage

Nick_LeMonsHQ wrote:

Yeah, Jim, bolt-in is fine, just use the plates....

Most definitely using plates, no point in putting an extra couple hundred pounds in the car just for show smile

Cool, that makes the GRM effort a weee bit more interesting now...

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  • Registered: 2009-08-16
  • Posts: 11

Re: Bolt in cage

Can someone give a quick explanation of what is required from the plates.  We have a semi-custom built welded cage, but have not yet welded the plates to the car.  We are considering bolting them in, but not sure how.

How would we do this?  We have 6x6 plates that are welded to the cage--can we just drill through the plates and bolt it to the floorpan of the car?  How large of bolts/washers are required?  Is an additional plate required below the floorpan as well?

Thanks.  If we are lucky, we might just have the car ready for the race in Houston

  • JThw8
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Re: Bolt in cage

I'd wait for someone with better knowledge than I have but my intent is to weld reinforcing plates to the floor (possibly above and below, I dont trust 51 year old east german steel) and then bolt the foot plates of the cage through those.

The foot plates of the cage bolted to just the floor alone is definitely not strong enough and will tear right out in an accident.

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  • ronman
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Re: Bolt in cage

Bolting the cage in is much more easily-accomplished when the vehicle has a frame to work with... even if it's a hokey X-frame.

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10 Reply by psychoboy (edited by psychoboy 2009-10-15 06:13 AM)

  • From: oklahoma city
  • Registered: 2009-10-08
  • Posts: 1,586

Re: Bolt in cage

Revolutionary Racing wrote:

Can someone give a quick explanation of what is required from the plates.  We have a semi-custom built welded cage, but have not yet welded the plates to the car.  We are considering bolting them in, but not sure how.

How would we do this?  We have 6x6 plates that are welded to the cage--can we just drill through the plates and bolt it to the floorpan of the car?  How large of bolts/washers are required?  Is an additional plate required below the floorpan as well?

Thanks.  If we are lucky, we might just have the car ready for the race in Houston

basically you'll be building a sandwich.

the 6x6x1/8 plate fully welded to each foot of the cage on top, the sheetmetal floor (flattened out as much as possible) of your car in the middle, a second 6x6x1/8 plate on bottom.

secured with at least four high strength (grade 5 or 8 preferred) bolts (tho i would suggest 8 bolts for 1/8" plate).

i would suggest 1/4" plate, and four bolts would do the job....but 1/4" is much harder to work with unless you are already set up for it.


you have to have the backing plate, other wise the bolt heads will pull thru the sheet steel of the car.

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  • FJ40Jim
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Re: Bolt in cage

To lessen the chance of failure at the plate/floor interface, round off the corners of the square plates and stagger the plates.

The sharp corners of the squares will act like a can opener on sheet metal in an accident.

Stagger the plates (Make the upper 6"x6" and lower 6.5"x5.5") so the sheet metal is not stressed in a sharp line from above & below.

I would not recommend plates much thicker than 1/8", it is just extra weight, but no extra strength, since the doubled plates are far stronger than the unibody sheetmetal anyway.

HTH

Jim C.
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  • Registered: 2009-08-16
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Re: Bolt in cage

Thank you psychoboy!

That is exactly what we needed to know.

  • From: Toronto, Ontario
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Re: Bolt in cage

And remember, do not use lock washers! If they break, you have no clamping at all. The idea is to spread clamping force as evenly as possible around the bolt hole, then use the bolt's "stretch" for even clamping. Loctite is fine. Ideally, the holes in the plate should have a small clearance to the bolt diameter too. Use thick washers, and one only top and bottom. It's important to pull up the bottom plate so it's flush with the sheet metal...it's worth using heat here to get it to conform to the floor pan contour. I like to use areas where there's a double thickness (look for spot welds)...

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14 Reply by psychoboy (edited by psychoboy 2009-10-15 08:49 AM)

  • From: oklahoma city
  • Registered: 2009-10-08
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Re: Bolt in cage

excellent additions jim and jim.

i'll just chalk my shortages up to

"things one does without thinking about, and therefore, things one forgets to write down."

or

"things one does now because they learned a lesson the hard way, therefore things they falsely assume everyone else learned when they did."




i like 1/4" plate because i'm an overkill kind of guy, and i'm concerned about 1/8" plate bending as i bolt it down. it probably won't in this application, but i come from a minitrucking background....we build everything in 1/4" because we fully expect to grind 1/8" off on the road.

plus, you gotta have one serious welder to warp or blow a hole in 1/4" plate when welding the down tubes to it.

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