Seat mount tied into Cage:

#1

Hello all,

First time posting here, I know many of you from the track and BMW events. First off, I should say that I don’t own a SE30, I just work on them. :slight_smile:

I searched the forum without finding an answer, so I would like to get some thoughts from you guys, unofficial I know, but you guys will probably be able to clear this up without a rules clariication.

It makes sense to me that one would want their seat connected to the same structure that their harness is mounted to. God forbid anyone gets into an accident where the seat tries to seperate itself from the car, I would want the seat to be connected to the cage, NOT the body (floor). If the seat does not stay in position relative to the harness, your safety could be compromised. I have seen Bimmerworld cages designed for GTS NASA, where they have mounted a small frame structure tied into the cage. Now the grey area of the rules comes into play because the small seat mounting structure must weld to the transmission tunnel on you right, this could be thought of as a cage “point” I wouldn’t agree, but someone might stretch the language to think so. I think about this in the same way I think about foot protection (6+2 cage design) you still have your six main cage tie-ins, but you are allowed to add protection for your feet in the name of safety.

Anyone care to comment? Am I completely off base? Been covered before? (appologies in advance)

Thanks,
Nate [file name=BW_seat_mount1.jpg size=356102]http://spece30.com/media/kunena/attachments/legacy/files/BW_seat_mount1.jpg[/file]

#2

I’m no cage expert, but I see nothing in the rules that preclude this. NASA CCR Para 15.6.13 says 6-8 attachment points on the floor, but you’re talking about the transmission tunnel, not the floor.

Para 15.6.2 says that the Chief Scrutineer can flunk a cage if he decides that you’re more oriented on chassis stiffening than safety. I would interpret that as meaning…the cage design is ok as long as your Regional Director, or his senior Tech representative, blesses it.

#3

I guess if you welded tabs onto the trans side of the frame and bolted them to the car you’d achieve the same rigidity and safety without looking like you’re in there to “stiffen”, just mount. In fact you could actually mount the entire structure with tabs and bolts.

This approach is often used in NASCAR cars… I’ve seen where they ties the seat mount to the main hoop rather than the door bars with the same rationale you mention. “feet” on the floor are necessary to restrict “bounce” while in the seat.

Best advice - call the NASA National or Regional Tech Advisor - who is that? Not sure.

Kieran

#4

Thanks guys, appreciate the quick replies. I will talk to our NASA Tech to confirm, but it sounds like this is a reasonable request.

Thanks again! See you at the Track!
Nate

#5

technically, I think it adds another cage mount point, but I think this is something that should be allowed. I’m going to make some inquiries at national.
bruce

#6

Hey Bruce, I sent some emails inquiring, but any help would be appreciated. I truly believe this is within the spirit of the rules, there is no torsional rigidity gained from these small diameter, un triangulated bars. Rather, this is about safety; I would much rather have my butt tied to a DOM spaceframe than some .060" sheetmetal that was spot welded 20 years ago. :slight_smile:

Since I made that post this morning I am finding MANY GTS guys that do the same thing, the more racers I find with seat mounts connected to the cage, the more it makes me think that it is common practice and I am just spending too much time with the BMWCCA guys, haha!

Regards, Nate.

#7

I would argue that if you set the main hoop on plinth blocks and ran a cross tube from the plinth block to the tunnel for the seat anchor that you haven’t increased the cage mounting points. That sort of side steps the cage rules.

#8

jlevie wrote:

I would agree with you, but that is NOT exactly what I am trying to do, I am just trying to COPY the bimmerworld GTS seat mount design, which is pictured, as I believe it to be safer from an safety perspective.

Regards, Nate

#9

my (driver) seat and harnesses mount to little rails that extend forward from the main hoop, if you want i can try to grab a pic or two.

#10

Thanks Jason!

#11

I don’t really see how that would be safer than just welding the tubes from the trans tunnel to the body under the door. In fact I think it would be stronger attached to the frame than that small longitudinal tube. You could make that tube the same size as the rest of the cage though.

#12

turbo329is wrote:

There is not a substantial frame to tie into, the metal is thin, anytime you weld two substantially different thicknesses you are always balancing your torch, mainly focused on the thicker material; It’s just not ideal. Rather - you can have a joint with a perfectly notched tube with a much thicker wall, there just isn’t much comparison.

I will post up the results when I receive a reply from the tech steward.

Regards, Nate.

#13

The frame rail may be thinner than the tube but it is stronger due to the difference in diameter. A plate would work fine to spread the load more across the sheet metal frame. You didn’t say how thick the tube you planned on using was, but I assume it is the thickness of your cage tubing or less. If I was trying to add weight there I would do it your way, if I wasn’t I would do it mine.

#14

Not trying to argue really, it’s not even my car :slight_smile:

Just trying to provide the safest solution possible, nothing more. You are absolutely right about the weight though, we definately don’t need anymore left side at all.

#15

TOOLEAN wrote:

[quote]Not trying to argue really, it’s not even my car :slight_smile:

Just trying to provide the safest solution possible, nothing more. You are absolutely right about the weight though, we definately don’t need anymore left side at all.[/quote]
You saying I need to lose weight??? :huh:

#16

Z3SpdDmn wrote:

[quote]TOOLEAN wrote:

[quote]Not trying to argue really, it’s not even my car :slight_smile:

Just trying to provide the safest solution possible, nothing more. You are absolutely right about the weight though, we definately don’t need anymore left side at all.[/quote]
You saying I need to lose weight??? :huh:[/quote]

:dry: hahaha…I mean…it would help your cross weights, ha!

#17

this is the only decent pic i have http://cerient.net/photos/spec_e30/jan27/iphone_pics/img_0136.jpg.html

#18

Thanks for the picture, that’s exactly what I am talking about.

Clean car by the way.

Regards, Nate

#19

Sorry to burst some bubbles but this question was brought to me by Anthony who I then forwarded to our Regional Competition Director who then forwarded it to Jerry Kunzman. Jerry sent me a brief email asking what was the question so I sent him this:

Michael Osborne wrote:
“If a frame is fabricated to hold the seat and is attached to the cage (door bars or rear hoop) so as the seat moves with the cage but is also attached to the car (such as the tranny tunnel) is this allowed? Or would it be considered another cage attachment point(s). This frame to hold the seat will be structural.”

Jerry Kunzman wrote:
“It would be an additional mounting pt. In some series that doesn’t matter, however.”

So I would say it is not allowed in this series as cages are regulated. I would also say that the picture with the harness mounted to a tube from the cage to the tunnel would fall under his as well.

Sorry.

Michael
Great Lakes SE30 Series Director

#20

ilateapex wrote:

[quote]Sorry to burst some bubbles but this question was brought to me by Anthony who I then forwarded to our Regional Competition Director who then forwarded it to Jerry Kunzman. Jerry sent me a brief email asking what was the question so I sent him this:

Michael Osborne wrote:
“If a frame is fabricated to hold the seat and is attached to the cage (door bars or rear hoop) so as the seat moves with the cage but is also attached to the car (such as the tranny tunnel) is this allowed? Or would it be considered another cage attachment point(s). This frame to hold the seat will be structural.”

Jerry Kunzman wrote:
“It would be an additional mounting pt. In some series that doesn’t matter, however.”

So I would say it is not allowed in this series as cages are regulated. I would also say that the picture with the harness mounted to a tube from the cage to the tunnel would fall under his as well.

Sorry.

Michael
Great Lakes SE30 Series Director[/quote]

Thanks for the clarification, no reason to appologize, that’s why I asked FIRST. But I was under the assumption that GTS and SE30 had to follow the rules for the cage, I guess I was wrong.

This maybe something for you guys amend for next season, as it seems to be an area of improvement.

Regards, Nate