Roll bar questions
Thread Starter
Melting Slicks
Joined: Apr 1999
Posts: 2,914
Likes: 4
From: Westford MA
Roll bar questions
Hi All,
I'm trying find a roll bar to suit my needs, but I'm having a tough time. I've read a lot of posts, articles and papers, but I've still got questions. I'm hoping someone can give me guidance.
My 02 Z06 is predominantly street driven, with occasional track and autocross days. I'm thinking about adding five points (both for safety and to keep me better planted in the seat), and it seems that installing a roll bar at the same time would be wise. My goal here is a practical modification that provides a meaningful increase in safety and comfort when driving on a track, without significantly impacting street use. I'm not concerned with regulations, as that's not a motivating factor for me.
Here are my thoughts so far:
Why not a harness bar?: I've thought about a BK harness bar for years. But I'm tall enough that my head grazes the ceiling. With a helmet, my head is firmly pressed into the headliner. That's enough to make me heed the warnings about running 5 points without rollover protection. [I'm also working to lower the seat and increase headroom]
What about street driving?: I don't love the idea of my un-helmeted head hitting a roll bar. Given my height, this would be a very real risk on many of the bars I've seen, even in a simple rear-end collision. This leads me to requirement 1: The roll bar should be aft of the existing roll structure, and as high as possible. This should reduce the risk of head contact
Four point or six point? I'm not doing anything that requires a six point (by regulation) and I'm not prepared to compromise that much on convenience. So I'll go with a four point, with cross bracing
Bolt in or weld in? I've seen the notorious images of bolt-in cages punching through the floors of unibody vehicles. While I'm pretty sure most bolt in roll bars on a C5 would be fine, I've looked at the structures to which they attach, and I'm not sure I trust them any more than the floor of a unibody car. I'd much prefer something that reaches down to the frame rails. This leads to requirement 2: The mounting points should be on the frame rails, or a structural element that's known to be strong enough for this purpose
So, what mounting points to use? A lot of roll bars and cages seem to run down to the frame, right behind the seat, in front of the "wall" (not sure what you call that thing... a bulkhead?). This requires moving the seat forward a bit (that's a problem for me) and it also puts a solid tube close to one's head. I'd prefer a bar that hits the frame rails behind the wall, with supports reaching back further into the storage area. However, the fuel tanks seem to pose a problem with that idea. Some roll bars seem to mount on the beam that passes behind the seat backs (the top of the above-mentioned wall), but I'm not confident that this structure is up to the task. So I'm really not certain whether there's a mounting point that meets my above requirements
Where/how to get this? From what I've read, it seems like a custom fabricator is the best (though costliest) option. If it's possible to get a pre-bent kit that meets my needs, I'd happily install that myself. But if a custom job is what it takes to get what I'm looking for, then I think I'll go for it. I just want to have a really good sense of what I'm trying to achieve before I pay someone to do it. I also don't really know where to begin looking for a fabricator.
So here are my questions to you all:
1. What do you think of the plan overall? (four point roll bar with diagonals, mounted high and far back, welded to the frame rails, set up for harnesses)
2. Any thoughts on mounting locations that meet these requirements?
3. Any ideas on the best way to get what I'm looking for, and how to do it at reasonable cost? Any recommendations on shops in Massachusetts or NH?
4. Any concerns or issues that I'm overlooking?
5. If anyone has experience or pictures of rollbars (or cages) in C5s that have actually crashed, I'd love to hear about it. The more I can learn, the better.
To those who read this far, thanks! And thank you for any thoughts or ideas you can offer.
Scott
I'm trying find a roll bar to suit my needs, but I'm having a tough time. I've read a lot of posts, articles and papers, but I've still got questions. I'm hoping someone can give me guidance.
My 02 Z06 is predominantly street driven, with occasional track and autocross days. I'm thinking about adding five points (both for safety and to keep me better planted in the seat), and it seems that installing a roll bar at the same time would be wise. My goal here is a practical modification that provides a meaningful increase in safety and comfort when driving on a track, without significantly impacting street use. I'm not concerned with regulations, as that's not a motivating factor for me.
Here are my thoughts so far:
Why not a harness bar?: I've thought about a BK harness bar for years. But I'm tall enough that my head grazes the ceiling. With a helmet, my head is firmly pressed into the headliner. That's enough to make me heed the warnings about running 5 points without rollover protection. [I'm also working to lower the seat and increase headroom]
What about street driving?: I don't love the idea of my un-helmeted head hitting a roll bar. Given my height, this would be a very real risk on many of the bars I've seen, even in a simple rear-end collision. This leads me to requirement 1: The roll bar should be aft of the existing roll structure, and as high as possible. This should reduce the risk of head contact
Four point or six point? I'm not doing anything that requires a six point (by regulation) and I'm not prepared to compromise that much on convenience. So I'll go with a four point, with cross bracing
Bolt in or weld in? I've seen the notorious images of bolt-in cages punching through the floors of unibody vehicles. While I'm pretty sure most bolt in roll bars on a C5 would be fine, I've looked at the structures to which they attach, and I'm not sure I trust them any more than the floor of a unibody car. I'd much prefer something that reaches down to the frame rails. This leads to requirement 2: The mounting points should be on the frame rails, or a structural element that's known to be strong enough for this purpose
So, what mounting points to use? A lot of roll bars and cages seem to run down to the frame, right behind the seat, in front of the "wall" (not sure what you call that thing... a bulkhead?). This requires moving the seat forward a bit (that's a problem for me) and it also puts a solid tube close to one's head. I'd prefer a bar that hits the frame rails behind the wall, with supports reaching back further into the storage area. However, the fuel tanks seem to pose a problem with that idea. Some roll bars seem to mount on the beam that passes behind the seat backs (the top of the above-mentioned wall), but I'm not confident that this structure is up to the task. So I'm really not certain whether there's a mounting point that meets my above requirements
Where/how to get this? From what I've read, it seems like a custom fabricator is the best (though costliest) option. If it's possible to get a pre-bent kit that meets my needs, I'd happily install that myself. But if a custom job is what it takes to get what I'm looking for, then I think I'll go for it. I just want to have a really good sense of what I'm trying to achieve before I pay someone to do it. I also don't really know where to begin looking for a fabricator.
So here are my questions to you all:
1. What do you think of the plan overall? (four point roll bar with diagonals, mounted high and far back, welded to the frame rails, set up for harnesses)
2. Any thoughts on mounting locations that meet these requirements?
3. Any ideas on the best way to get what I'm looking for, and how to do it at reasonable cost? Any recommendations on shops in Massachusetts or NH?
4. Any concerns or issues that I'm overlooking?
5. If anyone has experience or pictures of rollbars (or cages) in C5s that have actually crashed, I'd love to hear about it. The more I can learn, the better.
To those who read this far, thanks! And thank you for any thoughts or ideas you can offer.
Scott
Burning Brakes
Joined: Jul 2008
Posts: 1,047
Likes: 143
From: Bellevue Ky.
2020 C5 of the Year Finalist - Modified
C5 of Year Finalist (track prepared) 2019
If you are just going to a couple of autocross days, or an occasional road course then you just need a harness bar. If you feel the need for a cage, do it right the first time and attach it to the frame.
