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03-24-2018, 01:57 PM | #1 |
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fe1rx builds a roll bar
I have built a roll bar in to go along with installation of some race seats so I thought I would share some details, since the options for a purchased bar are pretty slim at the moment. This is a bolt-in bar, built to meet the Ontario Time Attack regulations in particular. All tubes are 1.5" x 0.120" DOM with 3/16" floor plates and backing plates. My car has no sunroof. The main hoop has a 5° rake aft, and the rear braces make an angle of 45° to vertical. All up weight is 51 lbs.
Front View Oblique View Bending the Main Hoop - bends are 5" CLR The rear braces on a bolt-in bar must be removable to enable getting the bar into the car. One of the challenges in designing a bar is to choose an appropriate method of making the connection of the brace to the main hoop. I looked to the FIA 2018 Appendix J - Article 253 for inspiration and used a joint similar to their figure 253-39 for that connection. The pin element welded into the main hoop. Fitting the pin required drilling the main hoop at compound angles. The mating saddle fitting on the brace tube. The connection to the main hoop. Connection uses a 5/16" socket head cap screw. The other end of the brace strut uses a bent lug to an existing 12 mm bolt. Not everyone uses this bolt as an attachment point, but my mounting solution allowed me to eliminate a cross bar, with its added weight. The geometry of the welded connection is such that the axis of the strut intersects the shear plane of the mounting bolt. This minimizes bending in the joint under axial loading, and makes for a good welded connection. Cross bars and diagonal bracing of the rear braces is not required by the regulations so I didn't include them to save weight. Harness guards prevent migration of the harnesses. The harness bar height provides HANS compatibility with my chosen race seats. The guards are anodized aluminum. Next post, trial fitting ... |
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xBlueStreakx97.50 BimmerAg425.00 breakfastreatre15.00 519.E82245.00 3002 tii2281.50 spidertri397.50 AndyW669.00 lab_rat394.50 |
03-24-2018, 02:39 PM | #2 |
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Wow very very nice!! Much better looking than the Autopower piece that I'm currently running lol
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03-24-2018, 05:02 PM | #3 | |
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Really nice work as always. |
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03-25-2018, 01:18 PM | #4 | |
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The driver's head in my bar is protected by the convergence of three bars - effectively the apex of a tetrahedron. That seems like enough security to me when combined with a race seat, 6-point harness and a HANS. |
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03-25-2018, 01:48 PM | #5 |
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The roll bar regs require a bolt-in cage to have backing plates at the floor mounts, so I looked for a suitable mounting area that would require minimal reforming. The soundproofing came off easily with a heat gun and scraper, then a bit of thinners to clean up the residue.
Mounting point - note depressed area Rather than work around the depressed area, I reformed it with a hammer and dolly. Mounting point - reformed flat To allow the mounting plate to sit flat, I also removed the seam sealant. Mounting point - drilled The RH backing plate includes a hole for the stud used to secure the underbody cladding. Mounting screws are aviation grade countersunk 5/16" machine screws. The 100° countersunk head conveniently avoids countersinking to a knife-edge condition in the 3/16" backing plate. RH Backing Plate Installed Th LH backing plate has an additional conflict with the brake and fuel plumbing. An additional clearance hole is needed for the stud securing the tubing braket. Plain nuts were used for fitting purposes, but self-locking nuts will be used on final installation. Measuring for the carpet cutouts is a challenge. The cutouts were made with some sharpened steel tube. The vertical slit in the carpet allows the carpet to be installed around the hoop tube. The result is quite neat. The carpet foam backing is quite thick, so it is necessary to mount the main hoop about an inch forward of the bulkhead if you want to do this. The rear stays pick up an existing 12 mm bolt. In place, minus one of the stays. The hole in the front of the main hoop is a required inspection hole to permit confirming the tube wall thickness. Next stop, powdercoating. |
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03-25-2018, 07:15 PM | #6 |
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I like it, except for the death trap base plates. I implore you to rethink them and tie them into the siderail.
As it is now, in a rollover situation it's just going to push right through the floorpan and allow the roof to crush. Effectively doing nothing. AND, break a fuel line creating a fire hazard. |
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03-26-2018, 10:00 AM | #7 | |
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Bimmerworld uses an interesting approach on their 3-series bar to getting some of the vertical load off the floor and into the bulkhead. I considered this approach too, but have something else in mind that is still in the works. In any case, the bulkhead is much more accessible than the side rail in terms of getting load into existing vertical structure. |
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03-26-2018, 12:46 PM | #8 |
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That BW one is pretty neat.
Even if there isn't something to bolt to, just a block welded to the hoop that rests on the seat pan. It's something extra. Anything to help slow that push through the floor. |
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03-27-2018, 07:28 AM | #9 | |
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fe1rx - That is some fantastic work. There should be some way to tie to the rear bulkhead easily enough, even if it is adding a bracket to it to match your bar width. But seriously, that is some nice work. |
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05-08-2018, 09:46 PM | #10 |
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Reporting back ...
I chose to fabricate some nesting angles from 4130 0.100" chrome-moly sheet, tig welded. The geometry is a bit of a challenge given that the angle isn't 90° and the vertical surface isn't flat. The angles ensure that any vertical load is transfered into a wide length of the bulkhead vertical skin. A shim is necessary though to maintain a level mounting plane for the roll bar foot. Here is the top view of the LH foot installation. And here is the bottom view. RH side is similar up top. But the bottom is simpler in the absence of fuel lines. I put the rear seat bottom back in just to provide a finished appearance, but the rear seat backs will remain removed. Here is a look with the driver's seat installed. |
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05-08-2018, 10:29 PM | #11 | |
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2008 SGM 128i - 3 Stage IM - 130i Tune - Dinan Camber Plates - BMW PE - Injen Intake - 1M Mirrors - LCI Blacklines - M4 Spoiler - Blacked 263's - Aero Bumper - Aero Side Skirts - OMGSplitter - AFE Intake Scoops
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05-11-2018, 09:38 AM | #12 |
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My passenger seat is an Evo and the driver's seat is a Circuit (chosen for its better hip and leg support vs. the Evo).
The hip belt cutout hole geometry is quite different between the two seats (surprising to me), so my lap belt attachments are different from side to side. At the moment I have only the Schroth 6-points installed but I have some brackets in the works (currently being cadmium plated) that will allow me to mount the OE inboard safetly belt buckles (with their pyro pre-tensioners). This will allow me to maintain nominal street legality. I will post some pictures once I get those installed. I used Carly to turn off the seat belt warning chimes, but still have the air bag warning light. Eventually I will get that coded off. I have had one track day with the new seats and like them. |
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06-17-2018, 01:44 PM | #13 |
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Three track days later I am getting around to installing the OE seat belt buckles for the purpose of maintaining functioning OE seat belts and thus street legality.
Brackets are formed 0.063" 4130 sheet with some turned bushings, a bit of TIG welding, some cadmium plating and some AN5 bolts. They wrap under the mounting brackets. Geometry of driver's and passenger's brackets are not mirror images because the Evo and Circuit seats themselves have different geometry with respect to harness cutouts. Driver's: Passenger's: Some coding is still needed to properly finish the job. |
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06-21-2018, 01:08 AM | #14 |
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Would you happen to have weighed your bracket before installing? I am required to maintain my OEM seat belt buckle for classing purposes so am looking for a clean and simple bracket system at minimum weight that can still accommodate.
Cheers, Mark
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12-06-2018, 11:30 PM | #16 |
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Coding out the OE seats
My short term solution to removing the OE seats was to code out the seatbelt warning chimes for both seats using Carly. That left me with an airbag warning light, which is definitely an annoyance and probably renders all airbags non-functional.
I have finally gotten around to coding out the seats, which steered me to Bimmergeeks ProTools application which does this very easily. Coding out the side airbags, seat belt catches, seat bosition sensors seat belt tensioners and occupancy sensors for both seats did the trick. https://www.bimmergeeksprotool.com ProTools runs on an Android device only. The interface is very clear and easy to follow. Unfortunately I now have 3 code readers for the BMW: 1) a Foxwell NT510 (loaded up with BMW, Porsche and Chrysler software). Incidentally, Schwaben's code reader is a rebranded NT510. 2) Carly (for both BMW and Porsche) on my iPhone 3) ProTools on an Android tablet Bought, of course, in that order of increasing capability. I got Carly because while the NT510 can register a battery change, it can't register a change in battery capacity. Carly is a very good solution for many uses but it has quite limited coding capability. ProTools is an order of magnitude more capable than Carly. The Foxwell I would rate as barely adequate, given the better options available, but it does run the ABS brake bleeding routine, which I don't believe Carly does. Incidentally Carly for Porsche was basically useless until just recently when it acquired some actual code reading capabilities. That said, it is far inferior to Durametric, which I also have ... So if you want to learn from my experience and are looking for a code reader for your BMW, go directly to ProTools. It will let you do everything you need a code reader for and everything you thought you wanted to do based on this thread: https://www.1addicts.com/forums/show....php?t=1216642 without resorting to NCS Expert and/or third party consultants. |
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12-07-2018, 01:51 PM | #17 | |
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12-16-2018, 11:58 AM | #18 |
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Very nice work! Not sure about your series, but for us (SCCA level 4 TT) every attachment point on a 4 point rollbar is required to have a minimum of three bolts per plate. So the floor plates are legal, but the rear stays likely wouldn't pass our tech.
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