Preparing a E36 M3 per IS rules. Noted that BMWCCA club racing will mandate a weld in cage after 1/07.
Have a bolted in Kirk roll bar with aluminum seats back braced in place.
Was planning to extend the roll bar into a roll cage this fall. Big difference in cost vs new welded cage from scratch.
How much more of a safety factor with a welded in cage vs a well fabricated maximum reinforced bolt in cage?
How much difference in body stiffness/performance between the two?
Can a bolted in cage be welded in place after installation,
Can a bar be built in behind the dash parallel to the windshield without removing the A/C heater core etc per IS rules?

Lynn

you should talk to a good fabricator.

Preparing a E36 M3 per IS rules. Noted that BMWCCA club racing will mandate a weld in cage after 1/07.
Have a bolted in Kirk roll bar with aluminum seats back braced in place.
Was planning to extend the roll bar into a roll cage this fall. Big difference in cost vs new welded cage from scratch.
How much more of a safety factor with a welded in cage vs a well fabricated maximum reinforced bolt in cage?
How much difference in body stiffness/performance between the two?
Can a bolted in cage be welded in place after installation,
Can a bar be built in behind the dash parallel to the windshield without removing the A/C heater core etc per IS rules?

Lynn

if your rollbar is like mine, it's a POS bolted to the soft floorpan. welded would be much safer, stiffer, and of course, more expensive.

go welded all the way

do a search on that incredible spill that Joey Hand took in the Grand-Am race recently and then see if you want to invest in a bolt in cage.

do a search on that incredible spill that Joey Hand took in the Grand-Am race recently and then see if you want to invest in a bolt in cage.

Yes, I saw the spin, quadrudple flip with a double twist. I guess what I am asking is that I know why a Hans device is required because I have read the SAE papers on its testing therefore I know why I am investing in it. I do not know the relative safety of a bolted in cage vs welded. I know it is better, but by how much? Has anyone had firsthand knowledge of how a bolted in cage worked in a serious incident.

Lynn

http://www.youtube.com/watch?v=dxnzhtjfm50

I can understand him having a headache after that...

Make sure your bolt-in roll bar at least has big enough support plates underneath it, otherwise it could push right through the relatively soft cabin floor. Mine doesn't (bought the car this way), and it'll have to be addressed eventually. If SCCA will require a weld-in, you might as well swallow that bullet and go for that. Buy once, buy right.

Crazy compromise idea: have someone build the front end of your cage as weld-in, welding to the bolt-in rear part until you eventually upgrade that part to weld-in separately when your budget allows? Price difference of that versus a full weld-in cage might not be that big, though.

-FDj

Yes, I saw the spin, quadrudple flip with a double twist. I guess what I am asking is that I know why a Hans device is required because I have read the SAE papers on its testing therefore I know why I am investing in it. I do not know the relative safety of a bolted in cage vs welded. I know it is better, but by how much? Has anyone had firsthand knowledge of how a bolted in cage worked in a serious incident.
Lynn

I have heard of an Autopower cage punching through at Mid-Ohio (the same track Joey Hand had his incident). From what I recall that racer was paralyzed.

I would never recommend a bolt in cage to anyone I knew or cared for. Do it right the first time, don't become the test dummy for what could happen with a crappy bolt in cage. That being said I have seen some crappy custom cages with really poor welding, find a good cage builder. And yes the crossbar behind the dash can be done in an E36 keeping all the a/c and heater functional. Mark McMahan just did one not even two months ago. If I can swing it I will have Mark build a very similar cage in my E36.

-Carlos.

So what makes the attachment of bolt-in and weld-in different (other than the obvious)? How is a weld-in cage tied to something other than the floorpan that makes it safer? Anyone have photos?

So what makes the attachment of bolt-in and weld-in different (other than the obvious)? How is a weld-in cage tied to something other than the floorpan that makes it safer? Anyone have photos?
Lots of photos of well-built cages at www.tcdesignfab.com (http://www.tcdesignfab.com) -> Custom Projects (at top right). Example:

http://www.tcdesignfab.com/pages/billym3-07_jpg.htm

See how the vertical is attached to not just the cabin floor like a bolt-in would be, but also to the side and thus the frame of the car. Note that a good builder would probably refuse to even think about the compromise idea I mentioned above.

-FDj

Lots of photos of well-built cages at www.tcdesignfab.com (http://www.tcdesignfab.com) -> Custom Projects (at top right). Example:

http://www.tcdesignfab.com/pages/billym3-07_jpg.htm

See how the vertical is attached to not just the cabin floor like a bolt-in would be, but also to the side and thus the frame of the car. Note that a good builder would probably refuse to even think about the compromise idea I mentioned above.

-FDj

Okay, so the "L" shaped plate below there is attached to the frame rail, bascially, and the bottom part sits on the [weak] floor pan? Makes sense - I understand how that is more secure.

Since you are in AL, go see the folks at Kirk Racing (http://www.kirkracing.com/index.cfm?FuseAction=catalog)

I have heard of an Autopower cage punching through at Mid-Ohio (the same track Joey Hand had his incident). From what I recall that racer was paralyzed.

I would never recommend a bolt in cage to anyone I knew or cared for. Do it right the first time, don't become the test dummy for what could happen with a crappy bolt in cage. That being said I have seen some crappy custom cages with really poor welding, find a good cage builder. And yes the crossbar behind the dash can be done in an E36 keeping all the a/c and heater functional. Mark McMahan just did one not even two months ago. If I can swing it I will have Mark build a very similar cage in my E36.

-Carlos.

Thanks for the input, will make the call to Kirks or Treehouse Racing next week.