BMW 1 Series Coupe Forum / 1 Series Convertible Forum (1M / tii / 135i / 128i / Coupe / Cabrio / Hatchback) (BMW E82 E88 128i 130i 135i)
 





 

Post Reply
 
Thread Tools Search this Thread
      05-09-2019, 10:03 AM   #1
Bodie217
Second Lieutenant
Bodie217's Avatar
27
Rep
221
Posts

Drives: '10 135i, '18 ZL1, '14 Sequoia
Join Date: Dec 2008
Location: Denver, CO

iTrader: (1)

Half cage - Questions on safety

Hey guys, I'm transitioning my weekend/autoX 135i into more of a dedicated racer. My initial desire was to get a half cage, seats, and 6pt harnesses. I read various threads on these set ups, and almost every time I see someone talking about the dangers of having a 4-point half-cage in a roll-over situation. The fear is landing upside down and the roof caving in, and the half-cage not providing enough strength or headroom to keep your neck in 1 piece.

The other concern is an instructor refusing to ride passenger because of the 4-point cage, meaning my upcoming HPDE would be ruined.

My reason for wanting race seats is that the stock seats do not offer enough lateral bolstering, requiring more effort in high-G maneuvers. Also, after every track event, the outside of my right knee is heavily bruised from bracing against the center console.

Does anyone have a professional opinion on half-cages?

Thank you!
__________________
-2010 BMW 135i - Titanium Silver - Procede v3/ETS 5" IC/AR Catless DP>N54mid>Berk Race/BMS OCC/VRSF Turbo Inlets & CP/SP rotors/Pagid RS29/APEX ARC8/Ohlins DFV/M3 Full Suspension and Bushings/Wavetrac LSD // 395rwhp/469rwtq on 91oct
-2018 Chevy Camaro ZL1 - Stock DD
-2014 Toyota Sequoia Platinum - Overlander
Appreciate 0
      05-09-2019, 10:53 AM   #2
lowside67
Second Lieutenant
121
Rep
285
Posts

Drives: 2011 BMW 128i
Join Date: Apr 2015
Location: Vancouver, Canada

iTrader: (0)

I think this fear is unfounded. The (general) issue is with fixed back race buckets and no rollover protection because the seats do not collapse in the same way stock ones would.

However, a modern car has an incredibly strong A pillar and further, a properly designed 4 point bar should not move or deform whatsoever. So as long as you can apply the formula car style test where you compare an imaginary line from the top of the roll bar ("half cage") you are having built to the top of the hood area with the top of your head and are comfortable you are under it, I wouldn't lose a moment's sleep.

I also do not know that many organizations prohibit fixed backs with a half cage - I think it usually just without any rollover protection.

-Mark
__________________
Appreciate 0
      05-09-2019, 11:31 AM   #3
bbnks2
Lieutenant Colonel
807
Rep
1,568
Posts

Drives: 135i N55
Join Date: Jan 2017
Location: NY

iTrader: (0)

Just put the seats in and drive it lol Skip the cage. It causes more liability than safety most of the time. Unless you are building for some specific racing class which has specific rules regarding seats/cages...
__________________
135i: E30 map by TwistedTuning, VRSF DP, Kerscher +15mm fenders, Kosei K8R 255/40/17, M3 control arms, UUC trans mounts, DV+, Whiteline RSFB, 5" intercooler, Charge Pipe, PC925 (23lb), UUC SSK, YCW Coilovers 6k/16k, Monroe shock mounts, Diff lockdown, Catch Can, N20 TMAP, 335is clutch, SMFW, 034 engine mounts, M3 Steering rack
Appreciate 0
      05-09-2019, 12:20 PM   #4
Bodie217
Second Lieutenant
Bodie217's Avatar
27
Rep
221
Posts

Drives: '10 135i, '18 ZL1, '14 Sequoia
Join Date: Dec 2008
Location: Denver, CO

iTrader: (1)

Quote:
Originally Posted by bbnks2 View Post
Just put the seats in and drive it lol Skip the cage. It causes more liability than safety most of the time. Unless you are building for some specific racing class which has specific rules regarding seats/cages...
Good point... Where would you mount the shoulder harness straps?
__________________
-2010 BMW 135i - Titanium Silver - Procede v3/ETS 5" IC/AR Catless DP>N54mid>Berk Race/BMS OCC/VRSF Turbo Inlets & CP/SP rotors/Pagid RS29/APEX ARC8/Ohlins DFV/M3 Full Suspension and Bushings/Wavetrac LSD // 395rwhp/469rwtq on 91oct
-2018 Chevy Camaro ZL1 - Stock DD
-2014 Toyota Sequoia Platinum - Overlander
Appreciate 0
      05-09-2019, 12:47 PM   #5
fe1rx
Lieutenant
660
Rep
599
Posts

Drives: 2008 135i, 2011 328i xDrive
Join Date: Jan 2008
Location: Canada

iTrader: (2)

Quote:
Originally Posted by Bodie217 View Post
I read various threads on these set ups, and almost every time I see someone talking about the dangers of having a 4-point half-cage in a roll-over situation. The fear is landing upside down and the roof caving in, and the half-cage not providing enough strength or headroom to keep your neck in 1 piece.
It is hard to imagine how having the half-cage could be worse than no cage in this situation. It can't make the OE roof weaker.

I suggest checking with the oganizer rather than make any assumption about acceptibility.

As to your motivation for adding the half cage, seats and harnesses - makes perfect sense. Gives you somewhere to attach your harnsses and lets you use a HANS too. This is exactly why my car has a half cage, race seats and six-point harnesses.

Addressing your comfort and safety should be priority one and satisfying armchair critics should be priority zero.
Appreciate 1
dtla1296.00

      05-09-2019, 12:52 PM   #6
bbnks2
Lieutenant Colonel
807
Rep
1,568
Posts

Drives: 135i N55
Join Date: Jan 2017
Location: NY

iTrader: (0)

Quote:
Originally Posted by Bodie217 View Post
Good point... Where would you mount the shoulder harness straps?
A half cage (usually just a beefed up strap bar) is convenient but not necessary at all to run a harness... You can bolt the harness traps somewhere underneath the rear bench. Just gotta find a place that gives a decent angle.
__________________
135i: E30 map by TwistedTuning, VRSF DP, Kerscher +15mm fenders, Kosei K8R 255/40/17, M3 control arms, UUC trans mounts, DV+, Whiteline RSFB, 5" intercooler, Charge Pipe, PC925 (23lb), UUC SSK, YCW Coilovers 6k/16k, Monroe shock mounts, Diff lockdown, Catch Can, N20 TMAP, 335is clutch, SMFW, 034 engine mounts, M3 Steering rack
Appreciate 0
      05-09-2019, 01:58 PM   #7
Mark Aubele
Private
26
Rep
68
Posts

Drives: '12 135i
Join Date: Sep 2017
Location: Pittsburgh, Pa

iTrader: (0)

Fixed back seats without a 4 point bar sketches me out. Anything as new as the 1 series has an incredibly strong roof structure, and honestly I'd rather roll a 1 series without a bar than a Fox body Mustang with one, but I think the four point makes mounting the harnesses easier and safer. Never liked having that much length in the shoulder belts going to the rear seat area (how most would mount them without a bar). We have an autopower in my wife's 135i, it is SCCA Level 4 TT legal (she hillclimbs the car), and pretty cheap. The other bars I have seen available for this chassis would not pass our tech, and are stupid expensive.
Appreciate 0
      05-09-2019, 02:07 PM   #8
crowtrobot
Second Lieutenant
187
Rep
212
Posts

Drives: 2011 128i
Join Date: Sep 2015
Location: Philly

iTrader: (1)

I'm in a similar situation with my car; the sport seats do not offer enough lateral support as I've gained experience and gotten faster.

Supposedly, the Cobra Nogaro fixed back seats will be compatible with Schroth Quickfit harnesses, so you'll be able to have a 4-5pt harness without the need for a rollbar. The tradeoff is that the seats are not particularly cheap. The Quickfit Pro's allow for a HANS device and potential upgrade to an anti-sub strap.

The other issue is different rule sets for different clubs. I guess if you can find someone that lets you run your desired setup, just keep with them...
Appreciate 0
      05-09-2019, 05:06 PM   #9
The Wind Breezes
Lieutenant Colonel
The Wind Breezes's Avatar
753
Rep
1,775
Posts

Drives: 135i N55 DCT
Join Date: Apr 2015
Location: USA

iTrader: (0)

Half cages are bad. Enjoy your harness while the A pillar crashes down and doesn't kill you but leaves you paralyzed. In other words, what's the point?

If you think you're moving around too much do the "seat belt trick". If you really need more gear, do it right. Full cage or no cage.
Appreciate 0
      05-09-2019, 05:15 PM   #10
Mark Aubele
Private
26
Rep
68
Posts

Drives: '12 135i
Join Date: Sep 2017
Location: Pittsburgh, Pa

iTrader: (0)

Quote:
Originally Posted by The Wind Breezes View Post
Half cages are bad. Enjoy your harness while the A pillar crashes down and doesn't kill you but leaves you paralyzed. In other words, what's the point?
Do you honestly think a four point with harnesses and fixed back seat is less safe than a bone stock car? Guys have been tracking/hillclimbing/etc with this setup for years and years.

Some organizations (such as the SCCA level 4 TT) require a bar, 5 or 6 point harness, fire extinguisher, suit, and gloves.
Appreciate 0
      05-09-2019, 07:54 PM   #11
fe1rx
Lieutenant
660
Rep
599
Posts

Drives: 2008 135i, 2011 328i xDrive
Join Date: Jan 2008
Location: Canada

iTrader: (2)

Quote:
Originally Posted by The Wind Breezes View Post
Half cages are bad. Enjoy your harness while the A pillar crashes down and doesn't kill you but leaves you paralyzed. In other words, what's the point?
Point to any evidence of this actually happening. Ever.
Appreciate 0
      05-09-2019, 08:00 PM   #12
fe1rx
Lieutenant
660
Rep
599
Posts

Drives: 2008 135i, 2011 328i xDrive
Join Date: Jan 2008
Location: Canada

iTrader: (2)

Quote:
Originally Posted by The Wind Breezes View Post
If you think you're moving around too much do the "seat belt trick". If you really need more gear, do it right. Full cage or no cage.
The seat belt trick is virtually useless, even with sport seats. A Schroth Harnessbelt is a better half measure, but it is still nowhere near the equal of a race seat and 5 or 6-point harness in terms of holding the driver in position.

As for full cages - these are useless on the street unless you drive around with a helmet on all the time.

Do it right is a great idea, but right for what?
Appreciate 0
Post Reply

Bookmarks

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -5. The time now is 08:48 PM.




1addicts
Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2019, vBulletin Solutions Inc.
1Addicts.com, BIMMERPOST.com, E90Post.com, F30Post.com, M3Post.com, ZPost.com, 5Post.com, 6Post.com, 7Post.com, XBimmers.com logo and trademark are properties of BIMMERPOST