slomove Posted March 11, 2013 Share Posted March 11, 2013 (edited) As some here may know I had my second rear-ender accident last year. Mostly minor sheet metal damage but since I have to repair this anyway it got me thinking about a bit more substantial cage around the tank. The car as it comes has only a 3/4" mild steel tube hoop on top, one on the bottom and 2 vertical tubes where the roll bar is attached. I believe that is kind of standard for Sevens but it leaves the tank pretty much hanging free out in the open and does not really support the roll bar in any way. So I got my welder out and with a few feet of alloy tubing and a bit of flat steel I reinforced the frame around the tank quite a bit, trying to triangulate the tubes (where possible) so that they are not experiencing bending load if that should ever happen again. Yes, it added a few pounds of steel but I can live with that. Next I got to put some new skin back on. I understand this will still not survive an impact of 20+ mph but hey, better than before. Since everything is nicely open right now I also replaced all the ball joints for the suspension radius arms and panhard rod. Was kind of time to do so, as some of the rod ends had 20/1000" play already. I hope that will fix some of the clunking noise, too. Edited March 11, 2013 by slomove Link to comment Share on other sites More sharing options...
lancylad Posted March 11, 2013 Share Posted March 11, 2013 What's a few extra pounds,,,, that only the equivalent of a couple of burgers and fries...good looking job you're doing there.. Link to comment Share on other sites More sharing options...
xcarguy Posted March 11, 2013 Share Posted March 11, 2013 Nicely done. Link to comment Share on other sites More sharing options...
Kitcat Posted March 11, 2013 Share Posted March 11, 2013 Maybe post up another pic of the original Birkin design (wherein, the spare tire bolt was perfectly positioned to pierce the gas tank upon contact:)). Another thread has just gone active again on adding a flashing brake light bar on the roll over hoop. Do you have something like that? Any theories on why those bozos have been rear ending you? You ought to send your design to Birkin/Caterham-it makes a ton of sense. I hate heim joints: clack, clack, clack,.... Link to comment Share on other sites More sharing options...
slomove Posted March 11, 2013 Author Share Posted March 11, 2013 (edited) Maybe post up another pic of the original Birkin design (wherein, the spare tire bolt was perfectly positioned to pierce the gas tank upon contact:)). Yes, my tank was punctured when I had the other accident in back in 2003. I removed the spare tire altogether after that. This was the original tube layout. What really bothered me when looking at it, is that the rear bracing tubes of the roll bar don't have any support. If they are ever asked to do what they should, they would just push they entire rear end down, and the roll bar would fold back. I don't like that idea. Another thread has just gone active again on adding a flashing brake light bar on the roll over hoop. Do you have something like that? Yes I do. Actually I fabricated my own superslim brake light back in 2003 and published the recipe on the Birkinowners Yahoo forum. But nowadays you can buy quite decent ones and no need to build it anymore. I also have a fuel cell for an added measure of safety. Any theories on why those bozos have been rear ending you? In 2003 it was the classic LA freeway rear-ender. I was standing still in traffic and the girl behind me was chatting with the passenger. Hit me with maybe 8mph or less and crushed the entire rear end: tubing, sheet metal, fenders, boot liner, tank punctured and dislodged. The center brake light was not there but would not have helped because I did not have the foot on the brake. Last year it was a botched group passing maneuver with another Seven behind me. I had to abort passing because of oncoming traffic, but the car that was being passed also braked (probably well meaning). I ended up braking hard and the other Seven ran into the rear end. The impact was fortunately cushioned by a luggage carrier rack and a duffel bag of clothes. It ended up with minor damage (even the iPad in the duffel survived functioning if somewhat bent) but could just as well have me kicked off the road at maybe 50 mph. I hate heim joints: clack, clack, clack,.... Well, they don't do that when they are new. The old ones I had were open and I guess my habit of occasional dirt road driving helped wearing them out. I now got the ones with Kevlar/Teflon liner from QA1 and will install them with grease-filled rubber sealing shells. Edited March 11, 2013 by slomove Link to comment Share on other sites More sharing options...
JohnCh Posted March 11, 2013 Share Posted March 11, 2013 Gert, do you have a brake flashing module hooked up to your rollbar light, or is does it simply glow steady upon brake application like your other lights? Although the flashing may annoy following drivers, in my experience it really does get their attention. Prior to adding the module to my car, it usually took about three separate taps of the brakes before someone following a little too closely got the message to back off. With the flashing module, I rarely have to tap the brakes more than once. Not exactly scientific, but… -John Link to comment Share on other sites More sharing options...
MHKflyer52 Posted March 11, 2013 Share Posted March 11, 2013 Hi slomove, Nice job of rebuilding the back end of your car and for showing folks how you beefed up the structure for more safety. I have a couple of photos that show how I addressed the roll-bar support and fuel tank protection on my build by extending the rear roll-bar tubes down to the lower frame and adding another downward support tube to base for added strength which can be seen in the photos below. Just an idea and another solution for anyone interested. Link to comment Share on other sites More sharing options...
solder_guy Posted March 15, 2013 Share Posted March 15, 2013 I have the BackOff XP module in my car. When I have my foot on the brake petal the light flashes fast, when I am sitting in traffic it flashes slowly. Link to comment Share on other sites More sharing options...
slomove Posted March 17, 2013 Author Share Posted March 17, 2013 That Backoff XP module looks good, I ordered one. .....I have a couple of photos that show how I addressed the roll-bar support and fuel tank protection on my build by extending the rear roll-bar tubes down to the lower frame..... Thanks Martin, I like the concept. This is the way to go if you have the freedom of your own design. For my car it would be a major change and I will stay with the modest improvement that I put on. Link to comment Share on other sites More sharing options...
Ian7 Posted March 17, 2013 Share Posted March 17, 2013 how about a Fuel-Safe fuel cell with bladder as well as the bracing.....? Link to comment Share on other sites More sharing options...
slomove Posted March 18, 2013 Author Share Posted March 18, 2013 how about a Fuel-Safe fuel cell with bladder as well as the bracing.....? Good idea. But I have a Fuel Safe cell already for many years. I bought that after the first accident in 2003. In the meantime I got the rear skin back on and polished. It was not a real difficult job, just needed a bit of patience. I used ratchet straps to draw the roughly pre-cut sheet (40 mil 5052 alloy) roughly in shape, then cut all edges using an air nibbler with a spacer on the chassis tubes as guides, banged the edges around the tubes and riveted in place. The only place I had to cheat was the main inner curves. I had to miter the sheet on the inside or it would wrinkle. Link to comment Share on other sites More sharing options...
MHKflyer52 Posted March 18, 2013 Share Posted March 18, 2013 Nice job Gert. Sure did come out smooth and very shiny. Link to comment Share on other sites More sharing options...
rx7locost Posted March 18, 2013 Share Posted March 18, 2013 Looks great! Link to comment Share on other sites More sharing options...
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