Cage Install - 986 Forum - The Community for Porsche Boxster & Cayman Owners

truegearhead · 12-31-2018, 06:38 AM

I'm almost done with my cage and thought I'd get you alls feedback before I pull it out of the shop. Oddly the pictures don't translate how this thing actually looks. In person it almost has an Arial Atom look due to the bends we put in it to allow 6'3" me to squeeze between the cage and the halo seat. I wanted to add a vertical bar at the A-pillar but I just can't find a way to do it and also get into the car. Let me know if you have any feedback. (the passenger bars are not in yet, also we're adding the cage onto an existing roll bar which I installed so I could still use the soft top, hence the two back bars. The original back bars which fit around the convertible top are at 27 degrees, they have to be 30 to be legal...very annoying).

Cheers,

thstone · 12-31-2018, 03:14 PM

I'd suggest that you really want the FIA bars (the two vertical bars that support the windshield).

Take a look at these photos from a Boxster Spec roll-over. This was the result of minor contact between two cars at around 85mph. This car was the innocent driver - he was tapped in the rear, spun off track, caught in the dirt, and rolled. It doesn't happen often but it can happen and a cage is there for exactly that worst case scenario.

Most cage builders think that the cages they build without the FIA bars are more than adequate - but the pictures tell a different story...

thstone · 12-31-2018, 03:23 PM

My cage also has reinforcement at the top rear corner. The objective of the FIA bar and the rear corner reinforcement is to keep the upper roof bar (horizontal) from coming downward towards the driver.

jmitro · 12-31-2018, 04:48 PM

ouch that pic is scary.

OP - so the black rear down tubes will be removed b/c the angle is too steep? I think the unpainted down tubes are better placed anyway.

the A pillar support bar would be nice. but you also need easy ingress/egress in case of a fire

itsnotanova · 01-01-2019, 05:37 AM

This happen to a friend of mine doing about 100 at TWS a few years back. Anther driver cut down on him and sent him sliding into the dirt sideways. He hit the dirt and rolled 3-4 times. His cage didn't budge and the car is back on the track.

I agree with the thstone and jmitro. Specially about that black tube in the rear

itsnotanova · 01-01-2019, 05:39 AM

Lemming · 01-01-2019, 05:13 PM

Have you checked your seat placement? The straight bar behind the driver may be an issue for fitment. I'm short and needed to have mine moved back as in Stones pic.

truegearhead · 01-03-2019, 03:44 AM

Thanks for the feedback guys. I asked my guy to go ahead and atonal that support bar on the B pillar that Stone has and next time I’m in the shop we’re going to take a look at the FIA bars. I have no idea how you guys are getting in and out of your cars with those bars in place. I’d need to start going to yoga with the wife.

Greg Holmberg · 01-03-2019, 11:10 AM

Also consider this language from the PCA SPB rules:

Quote:

Roll cages may not pass through walls or sills but may pass through the
front bulkhead and be tied to the shock tower.

Might be useful when hitting a wall straight on.

JayG · 01-03-2019, 12:56 PM

[QUOTE=thstone;586640]I'd suggest that you really want the FIA bars (the two vertical bars that support the windshield).

That's interesting as our cars have high strength boron steel in the A pillars to keep the windshield from collapsing.

Not saying you can't be too safe however and from the pics, it looks like the boron steel is not enough.

I know from an acrobatic experience at the track that the windshield is very strong at least in a slow single roll over. In this case, no cage, just a brey krause roll bar extension. We walked away without any injury to us.

rastta · 01-03-2019, 04:55 PM

I looked up the FIA regulations on cage design and didn't see any thing that looked like the bars that Tom has in the diagrams. I know that sometimes people reinforce the connection to the windshield pillars.

Looks like the collapse occurred in part due to lack of connection or a poor connection to the windshield pillars.

thstone · 01-03-2019, 05:38 PM

2014 GT-3 Cup car cage has the same design...

truegearhead · 01-04-2019, 04:23 AM

Quote:

Originally Posted by thstone

2014 GT-3 Cup car cage has the same]

Wow those sill bars are low. That would certainly help with ingress and egress.

truegearhead · 01-04-2019, 04:27 AM

[QUOTE=JayG;586761]

Quote:

Originally Posted by thstone

I'd suggest that you really want the FIA bars (the two vertical bars that support the windshield).

That's interesting as our cars have high strength boron steel in the A pillars to keep the windshield from collapsing.

Not saying you can't be too safe however and from the pics, it looks like the boron steel is not enough.

I know from an acrobatic experience at the track that the windshield is very strong at least in a slow single roll over. In this case, no cage, just a brey krause roll bar extension. We walked away without any injury to us.

High strength boron is strong but brittle (just like the factory stainless roll bar). So probably great for a slow roll over but when it fails it won’t bend like a mild steel cage it’ll tear. This is why cages have to be carbon steel

JayG · 01-04-2019, 05:51 AM

[QUOTE=truegearhead;586787]

Quote:

Originally Posted by JayG

High strength boron is strong but brittle (just like the factory stainless roll bar). So probably great for a slow roll over but when it fails it won’t bend like a mild steel cage it’ll tear. This is why cages have to be carbon steel

That makes perfect sense

steved0x · 01-04-2019, 08:00 AM

Here's one with multiple rolls, still held up pretty decent, I guess these were slower speed rolls, it says they left the track at 65?

https://www.youtube.com/watch?v=Syw3q-H9-XY

I think there is another video out there showing this from the following car but naturally I can't find it now.