Jump to content

Door bar spacing


ETR
 Share

Recommended Posts

Just a heads up, I feel this will be getting some attention this year.  From what I've seen looking around... super common issue.

 

3.2.3.1. The spacing between the fore and aft terminal ends of all door bars (including X-design) must include a separation of no less than six inches of open space when measured at the center-line of each bar. Triangulated bars that meet or join at the front hoop are allowed so long as the spacing of the upper and lower bars (attached to the main hoop) is a minimum of six inches when measured at the centerline of the tubing bar.

 

My forward ends have less than 6" of open space and I'm working to correct it, which is proving quite difficult in my car.  Ugh.

Link to comment
Share on other sites

46 minutes ago, turbogrill said:

For us that don't have a PhD in quantum physics, what does that mean?

 

Is it that the top and bottom bar can't have more than 6" between them?

 

Quite the opposite.  You gotta have a minimum 6" of air between the bars.

 

38 minutes ago, Grufton said:

A picture would help

 

Attached.  The circled portion near the "front vertical legs" is what will get a lot of us, especially miatas.

 

Edit- I find it interesting that the rule says "3.2.3.1. The spacing between the fore and aft terminal ends of all door bars...".  That ropes in even more cars, I had previously thought that you were OK with 3 as long as your lower and uppermost bars were 6" apart.  This indicates ALL bars require 6" of clearance.  Dang.

 

Capture.JPG

Edited by ETR
Link to comment
Share on other sites

As far as I know, that arrangement is likely fine even if the space between the top two bars is less than 6".  The measurement that matters is between the top and bottom bars.

 

I believe that rule is written with two bars only, the third is gravy.

Edited by Grufton
  • Like 1
Link to comment
Share on other sites

19 minutes ago, ETR said:

Edit- I find it interesting that the rule says "3.2.3.1. The spacing between the fore and aft terminal ends of all door bars...". 

 

My cage won't pass that interpretation on either side.  Must be a mistake somewhere, cause a LOT of well built cars will fail that measurement.  I'm not worried.

Link to comment
Share on other sites

My car started out as a Spec Miata so it had to have a dash board.  This forced the forward termination of the driver side bars to be closer than 6" (by about 3/4").  When I first brought the car to Champ I was offered to gusset the top and bottom, add a diagonal from the bottom one down lower on the A-pillar bar.  Life was good from 2016 until 2021 when I was told my car was "garbage" and it needed to get fixed.  The proposed fix by tech was to cut off the door bar from the A-pillar and heat it up then bend it so it could reattach higher. 

 

I cut the bar off and refabbed it.  Not sure what I gained in the process.

1 hour ago, ETR said:

 

Quite the opposite.  You gotta have a minimum 6" of air between the bars.

 

 

Attached.  The circled portion near the "front vertical legs" is what will get a lot of us, especially miatas.

 

Edit- I find it interesting that the rule says "3.2.3.1. The spacing between the fore and aft terminal ends of all door bars...".  That ropes in even more cars, I had previously thought that you were OK with 3 as long as your lower and uppermost bars were 6" apart.  This indicates ALL bars require 6" of clearance.  Dang.

 

Capture.JPG

How's the spacing on that lower "intrusion bar" count towards the 6"?

Link to comment
Share on other sites

Couple things

 

A sill bar does not count as a door bar. If it’s cL of the sill then it’s a sill bar. 
 

if you got two doors bars then they must be 6” apart at the A pillar bar and the main hoop.

 

if you got 3 door bars then two of them must be 6” apart  at the A pillar bar and the main hoop.

 

if you’ve got 4 door bars then two of them must be 6” apart  at the A pillar bar and the main hoop. 


This rule has been there for a long time. We mostly see an issue on SpecMiatas that are brought to our series that the two bars meet the A pillar bar closer than 6”. 

  • Thanks 1
Link to comment
Share on other sites

7 hours ago, jakks said:

Couple things

 

A sill bar does not count as a door bar. If it’s cL of the sill then it’s a sill bar. 
 

if you got two doors bars then they must be 6” apart at the A pillar bar and the main hoop.


This rule has been there for a long time. We mostly see an issue on SpecMiatas that are brought to our series that the two bars meet the A pillar bar closer than 6”. 

 

As the rules are written this is incorrect.

 

There is nothing stating a sill bar is not considered a door bar.  In fact the 3.2.3.4 says that the passenger "door bar" may be of the floor, sill, or mid level type.

 

The second half of 3.2.3.1 reads:

 

Triangulated bars that meet or join at the front hoop are allowed so long as the spacing of the upper and lower bars (attached to the main hoop) is a minimum of six inches when measured at the centerline of the tubing bar.

 

This means if the 2 door bars meet at the front hoop and are 6 inches apart at the rear hoop they're legal.  Yet tech is telling people to cut apart cages because the rear bars are 6", and the front is 5".

 

No wonder the series is struggling in the west, and losing entries in other regions.

Link to comment
Share on other sites


 

If the rear bar is at 6” and the front is at 5”, doesn’t that mean centerline is at 5.5, which is less than 6”? If the bars are straight of course. 
 

Also, sill bars are not required if the 3.2.3.3 is met. I was only stating that if you only have two bars on the drivers side, both of them need to be above the lower(rocker) sill, but make sure you’re following 3.2.3.3. 

 

Edited by jakks
Link to comment
Share on other sites

2 hours ago, Ian said:

 

This means if the 2 door bars meet at the front hoop and are 6 inches apart at the rear hoop they're legal.  Yet tech is telling people to cut apart cages because the rear bars are 6", and the front is 5".

 

I'll buy you a nice lunch if that's the case.  Rear is 7", front is 3", common in a spec miata style cage. 

 

@Ray Franck pointed it out to me late last year and will probably do the 2023 tech.  Any input?

 

Still in discussions with the fabricator, but I'm running out of time and it will be quite difficult with the front hoop so tight to the shell.

Link to comment
Share on other sites

1 hour ago, jakks said:


 

If the rear bar is at 6” and the front is at 5”, doesn’t that mean centerline is at 5.5, which is less than 6”? If the bars are straight of course. 
 

Also, sill bars are not required if the 3.2.3.3 is met. I was only stating that if you only have two bars on the drivers side, both of them need to be above the lower(rocker) sill, but make sure you’re following 3.2.3.3. 

 

 

The rule is ambiguis.  Being that is says in parenthesis (attached to the main hoop), the rule reads that a gap of minimum 6" at rear and 0" at front is legal, while 6" at the rear and 2" at front is not.  I feel like it used to be worded differently to make the minimum at the midpoint between front and main hoop 6" or more.  As it stands the rule makes door bars that have 10" separation at rear and 2" at the front illegal, when in reality they meet the intent of the rule.

 

Also, not saying sill bars are required.  You said "a sill bar doesn't count as a door bar", which is nowhere in the rules that I can find.  A sill bar, and a single bar 6" above on both ends is legal to the rules.  (Notice I said legal, not adviseable).

 

I'm not worried about our cage.  It exceeds the minimum door bar rules in a few ways.  What I am worried about is another instance of tech reinterpreting rules and telling people that cars that were legal, now are not.

 

It's even more annoying than getting told that your window net isn't legal, and you need to add a piece of lexan to cover off the front of which our tallest driver (me) could barely get a finger out when belted.  Only to be told 2 races later that said lexan needs to be removed because it might hinder egress in the event of an accident where the door is pinned shut.  Thanks.

 

 

Link to comment
Share on other sites

  • Technical Advisory Committee
On 1/15/2023 at 9:34 AM, jakks said:


 

If the rear bar is at 6” and the front is at 5”, doesn’t that mean centerline is at 5.5, which is less than 6”? If the bars are straight of course. 
 

Also, sill bars are not required if the 3.2.3.3 is met. I was only stating that if you only have two bars on the drivers side, both of them need to be above the lower(rocker) sill, but make sure you’re following 3.2.3.3. 

 

No it means they are at 7.5

 

6" of air with 1.5" OD tubing means 6" + 1.5"/2 + 1.5"/2 = 7.5"

 

The "centerline of tube" means of the tube, not at the centerline of the door opening or centerline of the car.

 

The rule is confusing as frack and contradicts itself multiple times. First it says "fore and aft ends" must be 6" of open space. then it says fore ends can touch as long as aft ends have 4.5" of open space (6" centerline of tubing).

 

Its time for a re-write.

  • Like 4
Link to comment
Share on other sites

  • Technical Advisory Committee

Some members of the TAC pointed out how badly this rule is written when TAC was formed 3-4 years ago.

Despite it being brought up several times over the past years, the wording has remained the same.

@Chris Huggins agrees (above) - Hopefully we can revisit it (again) and get it straightened out.

  • Like 4
Link to comment
Share on other sites

  • Technical Advisory Committee

 When the rule book says a minimum of 6" c to c of ALL door bars where they join the A and main hoop that's the minimum, peroid . Also says 2 continuous bars, period. 

  These spec Maita and such were never built or designed to race against Buicks, LTDs, Camaros and such at much higher speeds than a spec Miata ever dreamed of achieving. 

  I am the guy that sticks his head in these things and sees A post buckled and moved in a foot , floors, tunnels, petals bent, seats twisted after crashes.  Of course I am not the only one that checks them out Thomas, Bill & Andrew along with race directors, and we know why the rules are written the way they are.. 

   PS. If a bar is not within the door frame it cannot be a door bar , duhh

Edited by Ray Franck
Link to comment
Share on other sites

3 minutes ago, Ray Franck said:

 When the rule book says a minimum of 6" c to c of ALL door bars where they join the A and main hoop that's the minimum, peroid . Also says 2 continuous bars, period. 

  These spec Maita and such were never built or designed to race against Buicks, LTDs, Camaros and such at much higher speeds than a spec Miata ever dreamed of achieving. 

  I am the guy that sticks his head in these things and sees A post buckled and moved in a foot , floors, tunnels, petals bent, seats twisted after crashes.  Of course I am not the only one that checks them out Thomas, Bill & Andrew along with race directors, and we know why the rules are written the way they are.. 

I think everyone is just confused by the wording and what is actually meant, rather than campaigning for lenient/unsafe door bar design.

 

A 2-bar setup where the two bars are parallel and are 8" apart is fine. What about a 4-bar setup where the spacing between adjacent bars is only 4"?

 

- top bar -

4" gap

- bar -

4" gap

- bar -

4" gap

- bottom bar -

 

The way I read it, this wouldn't be legal, but I have to assume it is far more protective than the 2-bar setup.

  • Like 2
Link to comment
Share on other sites

1 hour ago, Ray Franck said:

 

  These spec Maita and such were never built or designed to race against Buicks, LTDs, Camaros and such at much higher speeds than a spec Miata ever dreamed of achieving. 

 

 

Au contraire mon frere.  The SM rules are the same as many other cars of considerably higher speeds and weights.  There are both additions and restrictions for SM vrs some of the bigger cars, but not with respect to door bar spacing.  IIRC the last major re-write of that set of standards was in about 2008. 

 

Was the 6" spacing the result of quantifiable testing or stress analysis or is '6" center to center' and easy thing to check so that's how it got written? 

 

Link to comment
Share on other sites

I had my new car's door bar issue earlier this year right after it was built. Do I think there needs to be some clarification? Yes. New car is an NB miata. We have NASCAR bars in our current NA....keep reading to experience our emotional roller coaster

 

This time around we decided to switch to an "X" bar with an additional FIA bar. My cage builder built an "X" bar as he has for over 10 years. Had one broken bar and two unbroken with one of those two being a sill bar. In my excitement and ecstasy I loaded up the car and took it home, eager to marvel at the artwork now in my garage making our current car's cage look like something a drunk toddler created. My brother sent some pictures to Tech for a pre approval pat on the back in hopes of avoiding a tech failure. And thankfully he did that....because we were told our cage would not pass due to the door bars. Real kick in the plums. What was explained to us afterwards by Ray was that a "Double V" satisfied the two unbroken bar "X" style and that a sill bar did not meet the requirements for a door bar because of it's positioning, despite being above the driver's hip (which is the standard my builder used). Builder argued that because it spanned across the bottom of the door, it was a door bar. Ray explained that if it is not in the door opening, it cannot be considered a door bar. Makes sense now, but admittedly hard for me to understand at this point in our journey because I had two interpretations in my ear at the same time and I was still nursing my recent plum kicking. And both interpretations made sense to me. Ultimately it was corrected and I forsee no further issues. Thankfully I wasn't charged for the fix but it was a real ball ache. So who's to blame? Me? The builder? Tech? After calming down I don't blame Tech at all. Why? Because it IS clearly stated what is required. But as I've learned, some builders interpret an "X" bar and sill bars differently and this attached picture from the appendix in the 2023 BCCR didn't help much. After all this I believe it needs to be explained as a "Double V" like it was to me after the fact and the pictures in the BCCR need to reflect that. We're not all cage builders and are too often at the mercy of a builder who knows exactly what they're doing but whose experience causes a different interpretation.

Screenshot_20230117-161010_Drive.jpg

Link to comment
Share on other sites

1 hour ago, T-PAP said:

I had my new car's door bar issue earlier this year right after it was built. Do I think there needs to be some clarification? Yes. New car is an NB miata. We have NASCAR bars in our current NA....keep reading to experience our emotional roller coaster

 

This time around we decided to switch to an "X" bar with an additional FIA bar. My cage builder built an "X" bar as he has for over 10 years. Had one broken bar and two unbroken with one of those two being a sill bar. In my excitement and ecstasy I loaded up the car and took it home, eager to marvel at the artwork now in my garage making our current car's cage look like something a drunk toddler created. My brother sent some pictures to Tech for a pre approval pat on the back in hopes of avoiding a tech failure. And thankfully he did that....because we were told our cage would not pass due to the door bars. Real kick in the plums. What was explained to us afterwards by Ray was that a "Double V" satisfied the two unbroken bar "X" style and that a sill bar did not meet the requirements for a door bar because of it's positioning, despite being above the driver's hip (which is the standard my builder used). Builder argued that because it spanned across the bottom of the door, it was a door bar. Ray explained that if it is not in the door opening, it cannot be considered a door bar. Makes sense now, but admittedly hard for me to understand at this point in our journey because I had two interpretations in my ear at the same time and I was still nursing my recent plum kicking. And both interpretations made sense to me. Ultimately it was corrected and I forsee no further issues. Thankfully I wasn't charged for the fix but it was a real ball ache. So who's to blame? Me? The builder? Tech? After calming down I don't blame Tech at all. Why? Because it IS clearly stated what is required. But as I've learned, some builders interpret an "X" bar and sill bars differently and this attached picture from the appendix in the 2023 BCCR didn't help much. After all this I believe it needs to be explained as a "Double V" like it was to me after the fact and the pictures in the BCCR need to reflect that. We're not all cage builders and are too often at the mercy of a builder who knows exactly what they're doing but whose experience causes a different interpretation.

Screenshot_20230117-161010_Drive.jpg

 

I'm glad SOMEONE finally pointed this out besides me. The explanation in the rules contradicts what appendix 4 illustrates as a "basic x-bar style door bar roll cage." I feel like MOST of the rules are pretty clear, and to me, the VERBIAGE of the roll cage rule IS clear. But having a picture that contradicts that clear verbiage doesn't do any favors. Granted, I don't write the rules. I just decipher them to the best of my own meager understanding

Link to comment
Share on other sites

 

9 hours ago, Ray Franck said:

 PS. If a bar is not within the door frame it cannot be a door bar , duhh

So the inner door skin has to be removed and the bar moved out into that area to qualify as a door bar? 

Link to comment
Share on other sites

On 1/15/2023 at 5:28 AM, Ian said:

This means if the 2 door bars meet at the front hoop and are 6 inches apart at the rear hoop they're legal.  Yet tech is telling people to cut apart cages because the rear bars are 6", and the front is 5".

"3.2.3.1. The spacing between the fore and aft terminal ends of all door bars (including X-design) must include a separation of no less than six inches of open space when measured at the center-line of each bar.

 

Triangulated bars that meet or join at the front hoop are allowed so long as the spacing of the upper and lower bars (attached to the main hoop) is a minimum of six inches when measured at the centerline of the tubing bar."

 

I read "centerline" as the halfway point between the A pillar/front hoop and the main hoop. And open space is exactly that: a 6" ball has to fit through the space between the bars halfway between the front and rear hoops. The rule specifies that the two door bars can meet or join at the front hoop and can form a triangle (which is what "triangulated" means) as long as there is 6" of open space at the midpoint of the bars. That means that there is no minimum space required at the front hoop. 

 

Let's say your door bars span a 40" opening and meet at the front hoop. To be legal according to the rule, there has to be a 6" open space between the two bars measured in the centerline (middle) of the span,or 20" from the front and rear hoop. That means that the bars have to be 12" apart at the rear hoop. 

 

Add the distance between the bars at the front to the distance at the rear and divide by 2 to get your open space at the middle of the bar. If your door bars are 2 inches apart (open space) at the front hoop, there needs to be 10" open space between the rear bars at the rear hoop. 4 inches apart at the front means 8 inches required at the rear.

Edited by mender
  • Like 1
Link to comment
Share on other sites

I think you're over thinking it. Where the bars meet on the main hoop has to be at least 6" apart, and where they meet on the A-Pillar bar has to be at least 6" apart. Centerline meaning the center of the door bar tube itself being where the measurement is taken from.

  • Like 3
Link to comment
Share on other sites

37 minutes ago, mender said:

 

So the inner door skin has to be removed and the bar moved out into that area to qualify as a door bar? 

So nerf bars allowed?  cool.

 

A sill bar is well within the door opening when viewed from the side.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...