We had a few things to take care of before our next race. One was that the power steering system had acted up towards the end of the July race. The other was that our gearing was currently way too low.
Our electric power steering had cut out in the heat of the race, and in listening back on video I could faintly hear it beeping around the time that it gave up. I tried doing a bunch of searching around the internet for beeping electric power steering, but apparently that's not a common issue. From what little I gathered, the system seemed to be overheating, and then giving up. I had initially mounted the controller to the roll cage along with the thermal paste, but it was attached to steel instead of a large aluminum column like it was designed. I needed some way of getting some heat out.
Since the box is up under the dash fully protected from any moisture, I drilled some vent holes in the cover of the electronics.
I then took an old graphics card fan along with it's heat sink, and attached that to the bottom of the controller along with some thermal paste. I wired it to be on any time the power steering is on. That should do it. It had acted fine during the October race, so I think we should now be just fine.
The next issue was gearing. And that was really two issues. I was still struggling a bit with the weirdness of downshifting into 4th gear for the very tight chicane at Portland, it just doesn't seem natural. The other much bigger issue, is that our driveline vibrates at high speed. We actually went through great lengths to try to help this, and even sent back our driveshaft to get a different one that had been more finely balanced. Oddly they accidentally made the second one an inch shorter, but we weren't making a ton of power so it still worked with a little less splines engaged. However no matter what we did, the driveshaft started to resonate once we got deep into 6th gear. You can actually see/hear it in video, it starts to really shake the camera and you can hear the resonance. The fix? We needed taller gearing to match the 350Z transmission! The 240SX has a 4.08 final drive, and the manual 350Z has a 3.538 final drive.
We were running the helical limited slip from the 99-01 Silvia (Japan only), but in the S13 (89-94) 240SX pumpkin with factory 4.08 gearing. This differential works great, I just wanted different gearing. The 350Z pumpkin is a massive amount of rework to get it to work in a 240SX. It's been done, but I wasn't interested in changing axles, mounting, etc. After poking around various R200 options, I finally stumbled on exactly what I needed. I found an S15 entire pumpkin complete with a 3.692 final drive on Ebay! With my wallet a little lighter, we got to work.
This is the front mounting ear of the S13 240SX, it is solid mounted in the front and rear.
Here is our S15 differential getting drained and cleaned. We had already popped the cover, so the four-bolt S13 one is laying there. Here is where I got a little lucky. This differential with it's speed sensor on the front of it, is about an inch longer. Now our driveshaft would be perfect! You can see the front differential mounting ears are much larger openings, they are intended to hold a rubber bushing.
I hoisted the differential into place, and the top of the differential hits before the ears touch. This is going to need some spacers.
After using my patented "Differential Spacing Device", I determined that I needed 0.562 inches of spacer to get the pinion matching the previous differential.
After bribing our machinist friend Greg, we got some nice aluminum spacers turned to fit the hole. Then topping that all off with some industrial thick washers from the hardware store and we were fitting nicely. And since our speedometer has not moved since we put the VQ30DE in, maybe someday this speed sensor will be useful... for now we were running out of time and it was ziptied out of the way. I start torquing all the bolts to spec... and disaster strikes. One of the front mounting bolts goes soft when torquing.. it has pulled the threads. I only have a couple more days I can work on this car before our next race at the Ridge. My dad and I start brainstorming to see if there is a way we can fix this without swapping the entire subframe, as we just don't have the time to do that.
First up is some exploratory surgery. We do have a spare subframe that can serve as a donor, can we get the captive nut removed from it? I plasma in, not being shy about how big the hole is, mainly just not wanting to damage the nut. The cage that holes the nut has an opening on the front of the subframe... this may just be possible.
With some more careful plasma surgery in place on the subframe in the car, I open up a hole.
With the help of an old farmer's cow magnet, I extract the stripped nut! I am then able to slide in the replacement, torque it down properly, and cover up the hole. Success!!
Another issue we had been having was our 5th gear synchro was getting pretty crunchy. We had initially thought we were buying a CD009 350Z transmission, which is known to be the "one to get". It turned out that the years that G35s and 350Zs got CD009s were off a bit, and we ended up with a CD008. I started looking around to try find a CD009 to replace, and found someone parting out a 2006 350Z with some rod knock. After hearing the engine run (and knock quite loudly), we made a deal to pick up the engine with transmission, wiring harness, and another engine that knocked for $1k. Since these transmissions can often go for $800-1000, I was pretty happy with this deal. These engines may come in handy some day... He needs time to pull the drivetrain from the car, so we'll pick these up sometime after the race.
Hmm.. these brake pads are finally getting down there a bit. But.. they'll last another race or two.
Randy Pobst is going to be at this next race at the Ridge, so I am really hoping we can get him into our car. I've been saying for years it would be awesome to get a pro in our car that could tell us what is good or bad about it, and so we could see what the car is really capable of in the right hands!