Project Singer-ish BMW - ///Motorsport Inspired Roll Bar

[DrftKingIII]

I posted this in my build thread, but I'm pretty excited with how it turned out so I thought it deserved it's own thread.

When I first bought this car it was gutted from the front seats back and had two fixed back bucket seats. My goal was to turn it back into a more street friendly car, something I could take on road trips and around town with the fiancé. Over the following year or so I sourced a full black interior to swap out the tired Dove Grey bits and returned the car to full interior and with manual Vaders. Here I am, some three plus years later, finding myself leaning back towards a bit more aggressive track prep while still maintaining the street car essence. The car, in it's current format, is very capable on our local small track and twisty back roads, but with my apparent inability to hold still and leave things alone, I've found myself asking for more ways to shave time and be more athletic with the much faster cars at the track. I've had a full "track spec car" before; fully gutted, seam welded chassis, buckets, full cage, harnesses, sound deadening removed, and stupidly enough, A/C delete. It was a cool car, but approaching thirty years old, driving around for an hour and losing 2 pounds of water weight from sweating, a headache from straight pipe exhaust, and smelling of fuel and exhaust for the rest of the day isn't so appealing to me anymore.

So how do you make an old BMW able to hang with a brand new Porsche GT4 at the track but still maintain it's composure of a classy, near vintage German street car? I looked to some of the Porsches of Singer Vehicle Design as they seamlessly blend form and function. Unfortunately I don't have thousands and thousands of disposable income to put into the M3 but I did pick up on one thing that they do that I love. Roll cages. But not just any regular ones, they'd wrap it in the same leather used to reupholster the seats, dashboard, door cards, etc. They effortlessly took something that is so obviously utilitarian and made it look civilized.

This made the gears in my head start turning. I appreciate the M3 for being somewhat subdued, almost unexpected for a mostly stock looking car being able to produce serious lap times. So when I came up with the idea to attempt my own Singer style cage I realized I wanted it to be subtle while paying homage to the ///M heritage of the car.

Not wanting to do a full roll cage again, as driving to dinner with a helmet on doesn't sound ideal, I started looking for an easy bolt in roll bar that retains the ability to keep the rear interior mostly intact. Luckily not long after I came up with the idea a Kirk 4-Point came up for sale locally for a good deal. I can't say for certain that the fiancé was too stoked on having this in our living room for a while.



Luckily I had already sourced a leather like vinyl for the door panel reupholstery project I had been working on. I went back to the store and picked up a couple more yards as I love the grain and texture it has.



I took measurements of the overall diameter of the bar and started drafting up whether I was going to do a butt-seam or if I was going to roll them over for an embossed stitch. I landed on this style, I'm not sure if there's a formal name for this type. There's about 1/8" of fabric rolled underneath to raise the stitching and make for a smooth seam. The strips then have to be cut about 1/4" shorter than the overall diameter as you want it to stretch a bit when you pull the stitching together. If it were loose the material would be free to twist and make the stitching line wavy.



Next up was to decide the colors and thread size. After digging around for a while I found a vendor for Serafil thread, supposedly the brand that BMW uses for their steering wheels and the like. The modern day colors are light blue, dark blue, and red. However if you look at the badging on the trunk, door jams, or really anything pre-E46 it was mostly light blue, violet, red. Continuing to try and stay "period correct" I opted for the violet center thread.




With all the materials gathered came the hard part. The main hoop had to be done in three separate pieces, one piece for the harness bar, and separate pieces for the rear supports that tie in to the rear wheel wells. Many hours of measuring, tracing, cutting, and planning how the pieces would tie together, I had all of the pieces cut and mocked up accordingly.



I briefly looked at purchasing a sewing machine but having literally zero experience with one and surprising expense for a newer one, I decided to sublet it out to someone who knew what they were doing. With all of the pieces cut and labeled I made directions for a local seamstress to run them through a sewing machine with the respective colors in place.



Once they were back from the seamstress it was time for the most time consuming part of the entire project: hand stitching the pieces onto the bars. I broke it up into sections, working about 3-4 hours a night on the weeknights. I started with the rear bars since they were smaller and removable so I could work at the table instead of hunched over on my living room floor. Turns out the two short bars that tie the rear supports to the main assembly came up about a half inch short overall, so these will need to be redone to be perfect.




It's an extremely time consuming process to get right. Again, I have no experience with anything like this, so I wouldn't be surprised if there are shortcuts that I don't know about. Once I got in the rhythm it was easy and straight forward, just time consuming. I was keeping track of the time invested but I lost count when it got over 20 hours.




Seaming the pieces together is a tricky part. I knew when developing the templates that I couldn't accurately guess exactly how the material was going to lay down once it was pulled tight and stretched, so I tried my best to guess. Most of it turned out pretty good, some other areas could use some improvement.



I think all said and done from start to finish I probably have 50+ hours in the project, but I'm very happy with how it turned out for being my first time ever doing anything like this.



It came out exactly how I wanted it to, subtle and unassuming, but classy and tasteful. From ten feet away from the car it looks like just another bolt in roll bar, but when you start looking at it closely you notice the details. It's not 100% done yet as I need to re-do the two rear supports where the nuts and bolts go through as they ended up short, develop the pieces that tie the main hoop into those supports, and then weld some harness slide supports onto the bar rather than using collars. Once that's done it'll be quick to wrap that final piece and ready to go into the car. Before I can put it into the car I have to finish my OEM styled rear seat delete that I decided to make to help offset some of the added weight from this roll bar. Overall I'm real stoked on how it turned out and cannot wait to get it into the car and move on to the next stage of my interior overhaul.

[ScotcH]

impressive work!

[pbonsalb]

Very cool and superbly done! Will it pass tech?

I have a Kirk bar in my turbo e36m3. I have some of the non certified Jegs or Summit padding that is a cousin of a pool noodle. I worry a little about whacking my head on the bar in an event where the bar serves a purpose. I drive on the street without a helmet. Maybe a version of what you did but with 3/16 foam under the leather would be a good compromise.

[DrftKingIII]

impressive work!

Very cool and superbly done! Will it pass tech?

I have a Kirk bar in my turbo e36m3. I have some of the non certified Jegs or Summit padding that is a cousin of a pool noodle. I worry a little about whacking my head on the bar in an event where the bar serves a purpose. I drive on the street without a helmet. Maybe a version of what you did but with 3/16 foam under the leather would be a good compromise.

Thank you both.

I assume it'll pass tech, guess there will be only one way to find out. The car is mostly used for HPDE stuff, no W2W, so hopefully it's all good. I used to use the ol' pool noodles back in the day. Schroth has a great article somewhere that details how much your head/body moves around during impacts at different speeds and fortunately, by their conclusions, the Kirk is far enough behind the seats that I'm in the clear of any impact to the noggin, given my seating position and firmly strapped in with their harnesses. Wrapping the bar in a thin foam and then leather is a clever idea for someone who needs the extra insurance.

[Braymond141]

Wow, well done.

[pbonsalb]

Schroth has a great article somewhere that details how much your head/body moves around during impacts at different speeds and fortunately, by their conclusions, the Kirk is far enough behind the seats that I'm in the clear of any impact to the noggin, given my seating position and firmly strapped in with their harnesses. Wrapping the bar in a thin foam and then leather is a clever idea for someone who needs the extra insurance.

I’ll try to search for the article, but I am 6’3” and pretty sure that in a roll over my head could hit the bar that is not far behind and above my head and not far behind my head to the left. I don’t really like the thick foam, but suspect it will be a while before you are selling the foam lined version of the leather cover for a price I can afford.

[DrftKingIII]

I’ll try to search for the article, but I am 6’3” and pretty sure that in a roll over my head could hit the bar that is not far behind and above my head and not far behind my head to the left. I don’t really like the thick foam, but suspect it will be a while before you are selling the foam lined version of the leather cover for a price I can afford.

I'm trying to find the article again. I printed it out and brought it home, hope I didn't throw it away. If/when I find it I'll be sure to forward it over to you.

[sirhodjibob]

This looks awesome. Nice stitching work!

[pbonsalb]

I'm trying to find the article again. I printed it out and brought it home, hope I didn't throw it away. If/when I find it I'll be sure to forward it over to you.

Maybe Shroth is explaining that if you use its 3 or 4 or 5 point harnesses, contact is less likely. Or if you use its roll bar web protection thing that is designed to reduce contact with it.

[NeilM]

Man that's some beautiful work! Love the overall aesthetic and the level of finish.

But given how an occupant gets thrown around in an accident, plus allowance for seat flex, your head could well contact the B pillar area of the main hoop, or the diagonal brace — at the very least. Unless, maybe, you're fairly short and have a very forward seating position that gets you out of the way? I'd figure that any cage element that's within about 10-12" of your head could be considered a potential point of contact that should have padding. However only inspection of the bar as installed in the car can really answer such concerns.

Adding foam backing to your cover would do nothing for safety (nor does pool noodle). Those are just comfort padding. What you'd need is this stuff: https://www.hmsmotorsport.com/produc...l-cage-padding

Neil

[pbonsalb]

I should buy 6 or 9 feet. Is the price per half? Zip tie?

[DrftKingIII]

Thanks Neil!

The back of the headrest on my Sparco is about 10" from the main B-Pillar (where the main hoop sits), I sit pretty far forward I suppose. With how far it is in distance, plus the overall width of the headrest itself, coupled with the 4-point harnesses holding me in place, I'd think it would be pretty tricky to get my head back there in any scenario. Still good conversation and food for thought for anyone else thinking of a roll bar in their street car. Once it's in the car I'll update this thread with installed photos.

[JitteryJoe]

I'll probably never go the roll bar route, but if I did, man that is some impressive work. Love seeing that attention to detail!

[pbonsalb]

Could not get a clear picture but my Kirk is practically right above and next to my head.D0CC729B-E0E6-4F0B-B229-7D017E8BD608.jpeg

[NeilM]

I should buy 6 or 9 feet. Is the price per half? Zip tie?

Comes in 36" lengths, and yes it's a half, which is all you use, oriented appropriately. This allows mounting to zero clearance elements, such as the main hoop at the B pillars. There's a peel & stick backing, but zip ties are normally used.

Neil

[xxxxxxx]

This is awesome.