Cutting out rear seat panel/parcel shelf

[BigD]

I'm installing my rollbar tomorrow and I want the rear bars to go to the rear strut towers. I was thinking about where to cut the holes but then I realized that I could just chop the whole sheet off. It's not like it's any kind of firewall, so I guess I'm mainly concerned about how much of that area I can cut out, if any of it is structural (ie should I just cut out the vertical panel or can I cut into the parcel shelf too).

[j0oftheworld]

I've seen some pretty heavy gutting in racecars..
IE: http://picasaweb.google.com/claykos/BMWE30#

[E30Idea]

Its fine if you are going to run lexan in the rear window. I have heard rumor that the glass window likes to pop out do to chassis flex otherwise.

[FJ40]

Don't have personal experience, but if what was said above is true, don't do it! If windows pop out that is obviously a compromise in rigidity. I've always been of the understanding that the pass thru (besides the ski cut-out) was structural. If you sufficiently reinforce it with cage (most likely a full cage) it doesn't matter, otherwise just do cutouts.

[j0oftheworld]

These cars are pretty floppy w/out a cage in them..
I guess it depends on OP's car!

Mines a gutted beast so I may go this route, although I will need a battery box since you're opening the trunk (battery compartment) up to the passenger compartment.

[BigD]

Thanks guys! I'll just cut holes then and maybe if it gets to be a real pain to weld between the pipe and the fender, I'll just enlarge the ski hole.

[jlevie]

The best place to terminate the rear cage bars is to floor of the trunk above the upper spring perches. That is a more beneficial increase in stiffness than terminating them above the shock towers.

The rear panel and parcel shelf is important. Don't cut it out.

[BigD]

Yeah, that's another area I'm considering, it'll depend on which is easier to reach. I asked Mark Stewart (Kirk Racing), he said either's good.

[Skafrog]

A visual of what Jim is talking about:

[BigD]

The inner edges of the plate looks like it'd be a ton of fun to weld...

[etxxz]

fun. yes. bring it!

[BigD]

fun. yes. bring it!

Kinda early to be hittin' the bottle, no? :mrgreen:

[SA E30]

I don't see how it is more beneficial to terminate the cage bars into the floor there. To my eye it doesn't pick up any loads. Where terminating on the shock tower would pick up the forces transmitted by your damper and spring (if you are running a coilover). Which it is much easier to triangulate from there to the differential.

OP I wouldn't cut the parcel shelf or back rest out. They are quite structural in the e30. Even with a cage it still doesn't really reinforce that section so I wouldn't and didn't do it on our car.

[BigD]

Yeah, that's why I kinda settled on the strut tower. But I'll be ok with either, it'll end up being a question of which one is a lesser pain in the ass.

[jlevie]

I don't see how it is more beneficial to terminate the cage bars into the floor there. To my eye it doesn't pick up any loads. Where terminating on the shock tower would pick up the forces transmitted by your damper and spring (if you are running a coilover). Which it is much easier to triangulate from there to the differential.

That would be true if real coil overs were used on. The E30/E36/E46 coil over kits I've seen aren't true coil overs in that they use adjustable springs and separate shocks. In which case the shock towers are only picking up loads from the shocks.