|Home > RX-7 > My RX-7 > Project Tina > Project Tina, Fall 2008: Dash Serial Port, Rear Strut Bar, Drag Strip Fun|
The snow will be arriving soon in Southwestern Ontario. In fact it's already snowed once just a few days before Hallowe'en. What's up with that? As I just put the car away for the winter last weekend I figured it was a good time to make another short update thread about what's going on with the project. This is a quick and dirty thread with only a few pictures of some of the miscellaneous work done over the summer. Most of it covers fabrication of a rear strut bar.
We left off in the previous thread with the installation of the center console trim, vents and switches. This followed the installation of the interior including full Dynamat coverage, new carpets, new sport seats and all new trim. There are still a few loose ends to tie up though. The serial port needs to be installed in the dash to allow programming of the Microtech, that shift knob is horrid, and there's a hole where an ashtray should be.
First I made a small male to male 9 pin serial cable. I just used two serial ports from old computer cases. The motherboard side connector was cut off and the wires were soldered together. I could have been a bit more elegant by using crimp on DB9 connectors from the electronics store and a bit of ribbon cable, but really, there are two massive boxes of these connectors at our computer shop so I just grabbed a hand full before leaving one night. If anyone wants 10,000 DB9 serial motherboard cables, let me know.
After a minor adjustment to the mounting holes, the DB9 connector was mounted in the dash. Behind the console it plugged into a 9 pin serial cable I had previously ran.
I guess I don't have a picture of the new ash tray but I'm sure we all know what an S4 FC ash tray looks like. The original that came with the car had been used to...gasp!...hold ashes so it was no longer in decent shape. The sun faded the top of the door and the orange lettering was worn off the latch. It could not be easily saved so I purchased a new one at the dealer. It was $65 well spent. The old shift knob has been replaced as well with my classic 8-ball.
OK, time for some fun stuff. After long last I purchased a TIG welder and thus had a whole new world of material choices available instead of just plain old steel. As a first project I decided to fabricate an aluminum rear strut bar. The first step was to figure out the shape for the mounting flanges.
Apparently the inner surface of the rear strut towers is a very irregular shape. The logical place to start is with a cardboard template so it can be easily trimmed to fit.
I then transferred the template shape to some 1/4" 6061 aluminum.
The center hole was drilled with a large 4" hole saw. There's nothing like a huge hole saw to test out a drill. I had recently purchased a new 18V Li-Ion Mastercraft Maximum cordless drill and this was the first major task I put it through. Drilling that hole took just a bit less then one battery pack so needless to say I was impressed. The rest of the flange was cut out using the jigsaw and then any minor adjustments were made using a file. A second flange was cut for the other strut tower as well.
A little bit of work with the jigsaw was necessary to make space in the speaker tower for the bar to pass through. The idea is to keep the bar as centered on the shock as possible so the only force it needs to withstand is compression or tension. This is only a two point bar so I didn't need to drill holes in the floor. A three point bar would have been better but I didn't want to give up the cargo area. Going to three points would cut the hatch area in half and cause me annoyance when I needed to carry something.
It took a little filing and adjustment of the bolt holes to get the flange sitting perfectly in the shock tower. Such is the case with hand fabricated parts. I took the opportunity to also draw the shape up in CAD so the machine shop can easily reproduce with a laser cutter, just in case.
The bar was then measured and cut. Here it's just lying in place. I used 1.5" SCH 10 aluminum pipe, because it was convenient to pick up at the metal store. They didn't have tubing with enough wall thickness in stock.
Once the bar was lined up, a few tacks held it in place. For the first time I have welded aluminum in three years, I picked a hell of a project. Getting the TIG torch into the confined space while trying to bend over the car, operate the foot pedal, handle the filler rod and fill the big gap between the round bar and flange was a little more difficult then I had imagined. I think I may have used more tungsten then filler. Note that I cut notches in the bottom of the bar so it sat flat on the flange.
Here's the alignment of the bar. You can also see the notch out of the end allowing to sit flat. There's still a good amount of area that needs to be filled by weld though.
I then brought the bar out of the wind and rain into the garage for final welding. As I may have mentioned before, the environment in my garage is not great for TIG welding. Minimal space makes finding a comfortable position an exercise in frustration. Next on my list of purchases is a simple stool, because standing and trying to weld something sitting at waist level isn't fun.
With the bar welded, I cleaned it up a bit on the wire wheel and then upholstered it with leftover material from the carpet. ACC had thoughtfully included the two squares cut from the storage bin area as extra, so I cut them into strips and wound them around the bar. Permatex spray adhesive secured the material. I think it came out rather well. Could have been better, but it's good enough. Now I just need to find two maroon speaker covers in good shape (Mazda no longer stocks them).
And that's it for this update. It was nice for a change to spend the whole summer driving the car instead of building it. As much as I enjoy working on it, the whole point is so that it can be driven. Every time I sit down, turn the key and listen to the engine fire up it's nice to know that it's due to my own hard work and is something I alone have been responsible for creating.
What's next? Well, I have a few more plans before I can consider this phase of the project complete. I need to fix the blasted oil leak at the front hub. Since I need to pull the front cover and pan for some oiling mods that won't be a huge problem. I will be fabricating a new fuel tank from stainless steel as my existing tank is worn and somewhere has a tiny pinhole which causes fuel stink to escape, but not fuel. A sump will be included on the new tank as well so I don't have to worry about the pump sucking air at low fuel levels. I may also add another resonator to the exhaust for just a bit more quiet.
Oh yeah, one other thing, and possibly the moment everyone has been waiting for a long time. I broke my transmission! Yes, my NA transmission is broken. All it took was two years and over 400 wheel HP, but it's finally showing signs of wear. The 3rd weekend of October, a few of us local owners (Sam, Martin and Jeff) went down to St. Thomas Dragway for a bit of Friday night fun. Being late in the season, the track was nearly deserted compared to the summer. But as well, the track temps were cold. Traction was not going to happen. My first run was an agonizing 14.37 with tire spin in every gear. At any amount of throttle it was just a flurry of spin and wheel hop. Next run I warmed the tires up a bit and pulled a 13.74. Not great, but better. The final run (yes, final) I made full use of the burn box before pulling to the line. The car hooked well, but still not well enough to pull off a better 60 foot time then 2.2. Light throttle through first gear got me going until I hammered it in 2nd and didn't let up until we crossed the line. As the temperature had dropped several more degrees by that time, the car was pulling hard when the upper gears allowed it to actually put the power to the ground...A bit too hard in fact. As I pulled away from the timing booth (ET was 13.31) I heard the transmission whining. I looked over at Jeff in the passenger seat and said "I think I broke my transmission". I called it a night at that point but Sam and Martin kept going until the track closed.
Some damage has been done, I guess to the cluster shaft. I have a decent whine in 1st and 2nd, which goes away in the higher gears. The car is still drivable and I continued to drive it until this past weekend, so the transmission is not dead. Aside from the whine it seems fully functional so I wouldn't hesitate to continue to drive the car if the weather would allow it. We're facing snow anytime so I decided last weekend was the last decent weekend in which to put the car away.
Do I care that the transmission is broken? Not really. Had to happen at some point. This winter I'll have a bit more space in which to work so I'll fix it up at that point. A transmission swap is in order, but not to a TII unit and not with another NA unit. You'll have to wait until the spring to get the details. At the same time I deal with the transmission I'll also install a much needed LSD rear end. Time to stop messing around with tire fires whenever I hit the throttle.
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