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Show off your roll bars / cages
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Sunset924  



Joined: 30 May 2017
Posts: 27
Location: PA, USA

PostPosted: Sat Dec 30, 2017 2:23 pm    Post subject: Show off your roll bars / cages Reply with quote

In the beginning stages of designing a roll bar for the sunset924. My hope is to retain the functionality of the less than functional rear seats, tie into key structural portions of the uni body, and come up with something that's aesthetically pleasing as well as meeting the scca requirements.

Roll bar will be constructed from 1 3/4" DOM, I am fortunate enough to have access to a cnc tubing bender, a notcher setup on a Bridgeport and some great TIG equipment. So its all up to me on the design at this point. I would like to see what you have done to your cars, and any helpful suggestions you may have with this regard.

thus far, this has been my inspiration:



a design similar to the but extending slightly further back into the hatch area in order to follow the angle of the rear glass. this rear portion would come off a main hoop similar to this:
https://rennlist.com/forums/attachments/parts-marketplace/597202d1326045184-tequipment-roll-bar-for-sale-tequipment-roll-bar.jpg
sans harness bar and vertical cross support (leaving seat area open)

What are your thoughts on attaching the main hoop to the sides of the rear uibody in this fashion:



thanks in advance!
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Cédric  



Joined: 27 Aug 2004
Posts: 1681
Location: Sweden

PostPosted: Sat Dec 30, 2017 7:25 pm    Post subject: Reply with quote

I will supply pics from the wiecher sport roll bar i installed recently. Stretching the bars all the way back is nowdays not legal in our racing rules anymore since its not a safe way of designing the cage.
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Carrera RSR  



Joined: 08 Jan 2010
Posts: 1533
Location: Somerset, UK

PostPosted: Sun Dec 31, 2017 3:34 am    Post subject: Re: Show off your roll bars / cages Reply with quote

Sunset924 wrote:

What are your thoughts on attaching the main hoop to the sides of the rear uibody in this fashion:



thanks in advance!


I assume there is a spreader plate welded under the body because there isn’t one between the cage foot and the body. Surprised to see this image is on the Safety Devices website.
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Carrera RSR  



Joined: 08 Jan 2010
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Location: Somerset, UK

PostPosted: Sun Dec 31, 2017 3:41 am    Post subject: Reply with quote

You won't make a cage race legal and retain rear seat functionality. Too much protection needed in too little a space. Even if you did, the passengers will be too close to life threatening metal bars to be safe in even a small impact.

Here's my Safety Devices full cage. Door bars not installed in this pic


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Cédric  



Joined: 27 Aug 2004
Posts: 1681
Location: Sweden

PostPosted: Sun Dec 31, 2017 5:58 pm    Post subject: Reply with quote

Oops, posted in wrong thread, this should be here instead..


https://drive.google.com/folderview?id=0B3GfYntUoi5aZFBiLUptSV81dVk

Check my Google drive link for some pics of the roll bar installation. Steel plates are 12x10cm. Except for the one inside the wheel well which is smaller. The thick threaded plates are inserted inside the body, but could be welded aswell.
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KDJones2000  



Joined: 14 Sep 2010
Posts: 290
Location: Phoenix, AZ

PostPosted: Mon Jan 01, 2018 4:48 am    Post subject: Reply with quote

Carrera RSR wrote:
You won't make a cage race legal and retain rear seat functionality. Too much protection needed in too little a space. Even if you did, the passengers will be too close to life threatening metal bars to be safe in even a small impact.

Here's my Safety Devices full cage. Door bars not installed in this pic



Sorry, but that is not a full cage. You don't have a diagonal bar on your main hoop. The rest looks good, other than the door bars that you mentioned. The only other serious issue I see is that you have "Y" mounts for your harnesses, which also are not allowed.

Not to be a curmudgeon, but if you want to pass SCCA requirements for a full race cage even your "inspiration" design won't pass tech. inspection, as it also doesn't have the full diagonal bar in the main hoop.
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Cédric  



Joined: 27 Aug 2004
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PostPosted: Mon Jan 01, 2018 6:10 am    Post subject: Reply with quote

You didn't notice hes not in the us though. Every country have different rules for different levels of racing. I thought we talked roll bars and not full cages since that's what the first post says. Anyway, in general terms this is how they can look over here, but that doesn't heltp at all, just ask scca if they set the rules.


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Sunset924  



Joined: 30 May 2017
Posts: 27
Location: PA, USA

PostPosted: Mon Jan 01, 2018 6:11 am    Post subject: Reply with quote

To clarify the purpose / intent of a roll bar for my 924: I am intending on attending a few PDE (Performance Driving Education) events to get out on the track. I figure this is the perfect way to get acclimated to road racing and my local track. If time/ interest permitting, the car may go further down the rabbit hole and become a dedicated use vehicle, then all of this goes out the window and its full cage time.

Even though the PDE events are very controlled, an extra measure of security is never a bad thing, hence my interest in a roll bar. As the car is street driven, a full cage is not what I am going for at this point because without a helmet, this is more of a hazard than a benefit. My local PDE events do not require any type of cage / bar (other than in a convertible) and factory seat belts are fine. I do not intend on switching over to a 3 to 5pt harness, as this is primarily a street car.

Although few and far between, sometimes my wife, daughter, and son want to go for a ride in the car and the back seat becomes necessary. Most of the time, its just me + 1 This is my interest in having use of the rear seat.

As far as SCCA requirements go, I just want to make sure my main hoop follows proper specification in the event i want to build off of it later, hence my use of 1.75 DOM (over sized for the weight class of the vehicle) and due to this, allows me a little more variance on the degrees of my bends, and the number of them, thus allowing me to tuck this thing close as possible to the interior of the vehicle




Carrera RSR,

Thanks for the input. Referring back to my comment about me not wanting a full cage in a street car, I fully understand your train of thought, and it is quite correct. I am thinking I may be able to design the main hoop as to stick tightly to the interior contour of the car, and locate the main supports in such a way to still have the top of the rear seat in place. Keeping in mind, both children are in full containment style car seats (no possibility of contact with the main hoop) and I will not be needing a harness bar.


Cédric,

Thanks for the pictures! This is very helpful! Looking at the design of your bar, it appears as though if i eliminated the harness bar, and adjusted the main supports a few degrees so they end up just after the wheel arches in the trunk area, the use of the back seat could be possible. I am by no means a professional chassis designer, so I will have to continue my research to see if this thought process would hold up in the event of a rollover. With regards to the mounting, I will most likely be going the same route you have, with plates sandwiching the uni body of the vehicle, 12.9 grade metric bolts.
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Dutch924-racer  



Joined: 23 Jul 2007
Posts: 1000
Location: The Netherlands

PostPosted: Mon Jan 01, 2018 6:47 am    Post subject: Reply with quote

not a very good picture, but here is mine:



Is is bolted, but the point where it is bolterd I welded a 3mm plate on the body for reinfocement.
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Carrera RSR  



Joined: 08 Jan 2010
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Location: Somerset, UK

PostPosted: Mon Jan 01, 2018 9:37 am    Post subject: Reply with quote

KDJones2000 wrote:
Carrera RSR wrote:
You won't make a cage race legal and retain rear seat functionality. Too much protection needed in too little a space. Even if you did, the passengers will be too close to life threatening metal bars to be safe in even a small impact.

Here's my Safety Devices full cage. Door bars not installed in this pic



Sorry, but that is not a full cage. You don't have a diagonal bar on your main hoop. The rest looks good, other than the door bars that you mentioned. The only other serious issue I see is that you have "Y" mounts for your harnesses, which also are not allowed.

Not to be a curmudgeon, but if you want to pass SCCA requirements for a full race cage even your "inspiration" design won't pass tech. inspection, as it also doesn't have the full diagonal bar in the main hoop.


Well it may not be SCCA complient but this full cage does has FIA and MSA certification for use in Europe. The harnesses are also compliant for Clubman motorsport such as sprints and hill climbs but are certainly out of date for full on racing. But I’d be stupid to race my car!!

For UK it’s sometimes best to run in Clubman track and sprint events without any race seats, cage and harnesses as they bump you out of road car class and into modified class. In this class you end up running against cars with modified motors, suspension, brakes etc.

Even with minimal rear hoop, I would not let my kids sit within inches of solid metal whether sat in a child seat or not. You may be best not running any rear hoop if you want kids in the back. I removed my bucket seats, harness and cage two years ago to allow my kids to enjoy the car with me. Seats and harnesses are long gone. Cage is in storage as it may go back in sometime in the future
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KDJones2000  



Joined: 14 Sep 2010
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PostPosted: Mon Jan 01, 2018 1:06 pm    Post subject: Reply with quote

Here are the CCR's for SCCA currently. Way more information than was requested, but if you are going to do a cage, you better have damned well read the rules first.

https://www.scca.com/downloads/39621-gcr-january-2018

Cage requirements start on Page 85.

To wit:

DEFINITION
The roll cage consists of the main hoop, front hoop, side protection, and braces as specified in these rules.
B. MAIN HOOP
1. The main hoop (behind the driver) must be the full width of the cockpit for all cars. It must be one continuous length of tubing with smooth bends and no evidence of crimping or wall failure. The main hoop must maintain a single plane.
a. On all closed cars, the main hoop must be as close as possible to the roof and “B” pillars.
b. Open cars without the windshield frame may use an asymmetric main hoop. The main hoop must be full width to the passenger side of the car. On the passenger side of the car the hoop must be at least as high as the top of the rear corner of the door as illustrated in figure 9.
9. Cars and Equipment
GCR - 84
The main hoop must be high enough that a straight line drawn from the top of the main hoop to the top of the front hoop would pass over the driver’s helmet and steering wheel when the driver is seated in the normal driving position. Additionally, the top of the main hoop must be at least 2 inches above the driver’s helmet as illustrated in figure 10.
c. On open cars retaining the windshield frame the main hoop must be full height for the entire width of the hoop. The top of the main hoop must be at least 2 inches above the driver’s helmet as illustrated in figure 11.
9. Cars and Equipment
GCR - 85
2. Main Hoop Bracing
a. Main hoops shall incorporate a diagonal brace. The brace shall either be in the plane of the main hoop, or extend from the top of one rear brace (described in 9.4.B.2.c) to the bottom of the opposite rear brace. Automobiles with mid mounted engines can have the lower mounting
point attach to the frame of the automobile within six inches of the main hoop. In the case of braces in the plane of the main hoop, the brace must span at least 50% of the width of the main hoop, and at least 75% of the height of the main hoop as shown in figure 12.
b. Cars must incorporate a main hoop horizontal brace at the approximate level of the driver’s shoulders but not lower than the shoulder belt mounting point as described in section 9.3.
Driver’s Restraint Systems. If a double-diagonal “X” brace is used in the plane of the main hoop, a half-width horizontal brace may be used behind the driver’s seat to mount the seat back and shoulder harness as shown in figure 13.
9. Cars and Equipment
GCR - 86
c. Cars must have 2 braces extending to the rear from the main hoop and attaching to the frame or chassis. Braces must be attached as near as possible to the top of the main hoop (not more than 6 inches below the top), and at an included angle of at least 30 degrees.
d. Open cars must have 2 braces extending forward from the main hoop and attaching to the front hoop, not more than 6 inches below the top of the front and main hoop. It is recommended that the front and rear braces attach to the main hoop as close as possible to each other.
e. On cars where the rear window/bulkhead prohibits the installation of rear braces (e.g. Honda del Sol), the main hoop shall be attached to the body by plates welded to the cage and bolted to the stock shoulder harness mounting points. This installation design must incorporate a
diagonal bar connecting the top of the main hoop to the lower front passenger side mounting point (Petty Bar). Alternatively, the rear window may be removed and a clear, lexan replacement installed. The rear cage braces may pass through this replacement window and through the engine cover or bodywork to allow connection to the frame or unibody. Such allowances shall be noted on the car’s specification line.
C. FRONT HOOP
1. Roll cages may be of two designs, low front hoop or high front hoop. All closed top cars and cars that retain the windshield frame must have a high front hoop design. Open cars may incorporate a high or low front hoop design. High front hoop are also referred to as side hoops.
a. Closed cars
The front hoop (side hoop) must follow the line of the A-pillars to the top of the windshield and be connected by horizontal bars to the top of the main hoop on each side (as close to the roof as possible). Instead of a single front hoop, two side hoops (down tubes) may be used. Alternatively, a top “halo” hoop following the roof line from the main hoop to the windshield with forward down tubes following the A-pillars to the floor may be used. Regardless of which one of the two approved tubing configurations there shall be a tube connecting the two A-pillar tubes at the top of the windshield.
b. Open cars
The height of the front hoop (per section 9.4.B.1.b) must be consistent across the full width of the cockpit.
c. Front Hoop Bracing
9. Cars and Equipment
GCR - 87
All open cars with a high front hoop and all closed cars except those competing in the T4, Improved Touring, Spec Miata, and B-Spec classes must incorporate a horizontal front hoop brace at the approximate level of the dashboard. It is recommended that cars competing in T4, Improved Touring, and Spec Miata classes also have the front hoop brace.
2. One tube must extend, from each front down tube, forward to the firewall or through the firewall except in vehicles in Improved Touring, Spec Miata, Touring, and B-Spec. This tube, one on each side, must connect to the chassis at a point not more than 12 inches forward of the front axle centerline.
3. Cars competing in Improved Touring, Spec Miata, Touring, and B-Spec may extend one tube, from each front down tube, forward to the firewall, bulkhead or wheel well, but not penetrating any panel.
D. SIDE PROTECTION
Two side tubes connecting the front and main hoops across both door openings are mandatory. Tubes that are welded to any part of the same mounting plate are considered to be connected to one another (see
9.4.E.3 below). NASCAR-style side protection or one bar bisecting another to form an “X” is permitted. Door side tubes may extend into the front door. In Improved Touring, Spec Miata, Touring, and B-Spec the door
window glass, window operating mechanism, inner door trim panel, armrest, map pockets, wiring harnesses for door locks, windows, power mirrors, seat wiring, etc., and inside door latch/lock operating mechanism
may be removed and the inner door structural panel may be modified, but not removed only if the door bars extend into the door cavity. The stock outside door latch/lock operating mechanism shall not be removed or
modified unless specifically authorized in the category rules. All categories except Production and GT shall not remove or modify stock side impact beams unless specifically authorized.
E. ROLL CAGE ATTACHING POINTS
1. Improved Touring, Spec Miata, B-Spec AND Touring (excluding T1 and T2) classes–The roll cage must attach to the vehicle structure within the passenger compartment in a minimum of 6 points and a maximum of 8 points as specified in these rules. Roll cage may not pass through any structural member, except Miata rear main hoop braces may pass through the package tray.
2. All other classes–There is no limit on cage attachment points. The roll cage shall be integrated into the frame or chassis.
3. Mounting Plates
a. Mounting plates welded to the structure of the car shall not be less than .080 inches thick nor more than 0.25 inches thick. The maximum area of each mounting plate in the Improved Touring, Spec Miata, and Touring classes shall be 144 square inches. Plates may be on multiple planes but shall not be greater than 15 inches on any side.
b. The thickness of mounting plates bolted or riveted to the structure of the car must not be less than the thickness of the roll hoop or brace that they attach to the chassis, and must be backed up with a plate of equal size and thickness on the opposite side of the chassis panel.
The maximum area of each mounting plate must be 144 square inches. Plates may be on multiple planes but shall not be greater than 15 inches on any side.
c. Fasteners for bolted or riveted mounting plates must be Grade 5/Metric 8.8 or better with a minimum diameter of 5/16”.
F. TUBING
1. Seamless or DOM mild steel tubing (SAE 1020 or 1025 recommended) or alloy steel tubing (SAE 4130 or T45) , or Docol R8 tubing must be used for all roll cage structures. Alloy and mild steel tubing may not be mixed. ERW tubing is not allowed.
3. For purposes of determining tubing sizes, the vehicle weight is as raced without driver, fuel and ballast. The minus tolerance for wall thickness should not be less than .010” below the nominal thickness.
4. The required tubing elements must meet the material minimums set forth above. Optional tubing elements may be any size.
5. The minus variance of tubing wall thickness due to manufacturing tolerances is limited to .010 inch.
6. Either an inspection hole between 3/16 and 1/4 inch diameter must be drilled in a non-critical area of the front and rear hoops, as well as one of the supplemental braces to facilitate verification of wall thickness; or alternatively, wall thickness may be determined by non-invasive means and noted in the logbook as inspected by such means.
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Sunset924  



Joined: 30 May 2017
Posts: 27
Location: PA, USA

PostPosted: Mon Jan 01, 2018 3:30 pm    Post subject: Reply with quote

KDJones2000,

Thanks for pasting up the info for those not familiar with scca.

So according to what you have posted, my original thought process is right on track: proper main hoop with base plates and backers per regs, bolted in with 12.9 fastners, and rear braces that are at least at a 30 degree angle. So I should have no trouble extending these to just behind the wheel arches and maintain a proper angle, all in accordance with current scca rules. Now if I intend on entering a class where the cage is required (later down the road), it would only be a matter of adding my cross brace and going forward with the cage, without having to redesign my original roll bar.

carrera rsr, I respect your apprehension with having the kids so close to a cage, and that is with well deserved thought. This is my biggest struggle with this project thus far. Is the bar going to be beneficial or a detriment in the event of a roll over for a rear seat passenger, particularly a child in properly mounted car seat. This is a topic I would like to have a few opinions on for sure. In this direction: I have had a few off road vehicles (mainly jeeps) over the years with factory roll bars that were close to passengers of the vehicle. these surfaces had roll bar padding. Having me beleave at some point enough safety studies were performed that indicated a covered bar would cause no more danger than a trimmed interior b pillar. I also know vehicles of this nature are designed far differently now and presumably safer than the vintage stuff I have had. I need to continue research and see what I can come up with... I obviously do not want to perform a modification to the vehicle that makes it less safe than originally designed.

Thanks for the posts! Giving me lots of good info and things to think about.
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macBdog  



Joined: 16 Aug 2004
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PostPosted: Wed Jan 03, 2018 11:01 am    Post subject: Reply with quote

This is my CAMS (Australian motorsport governing body) nationals level cage:






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Brockoli  



Joined: 06 Feb 2007
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PostPosted: Thu Jan 04, 2018 2:26 am    Post subject: Reply with quote

Do you need 1.75" DOM? The cage I helped build in my Chumpcar teams 944 used 1.5" DOM with a 0.125" wall. We made the cage legal for chumpcar, spec944, and NASA (I think?) in case we ever wanted to sell the car. The build thread is in my signature over at straightpipe.ca

The tubing size was specified in the rules and seemed to go by the weight of the vehicle. You might be able to use 1.5" tubing which would give you a little extra room. We found that every 1/4" helped in trying to get the cage as tight to the body as possible and still being able to weld all joints 360 degrees.

We could of used 4140 for material but I think that would of been harder to form and it is harder to weld than mild steel. We could of saved a small amount of weight since with 4140 we could of used a thinner wall tube. Which I think is crazy since 1/8" is already pretty thin. We ended up using 1020, IIRC.

I also made a roll bar for my 924. It is very similar to the Heigo bar. It bolts into the rear seat belt mounts. It doesnt have the adjustable end link thingys. I just tacked in all in place in my car and then welded it fully on the workbench. Not sure I have uploaded pics of my roll bar. With photobucket being stupid I need to find a better place to upload pics in the future.
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Carrera RSR  



Joined: 08 Jan 2010
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PostPosted: Thu Jan 04, 2018 5:23 am    Post subject: Reply with quote

macBdog wrote:
This is my CAMS (Australian motorsport governing body) nationals level cage:


Wow, that is a LOT of metal!!
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