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I don't honestly remember which CV joint it was, and you'll soon understand why it doesn't matter, but after much searching, Tim found some Audi axle that used a high-angle joint and a hollow axle shaft. The hollow shaft was critical, since the stress on the shaft is distributed over a much larger diameter, it's much easier to make modifications to the shaft (like welding roll bar tubing to it to make it longer) without worrying about those modifications being snapped off when the torque arrives.
Viewed from directly under the RX-7 diff, the steep driveshaft angle to the diagonally-mounted engine is obvious. In a car with anything resembling a normal wheelbase, this might have worked, but the short driveshaft requires extra-sharp bends.
Meanwhile, the engine was turning out to be a headache in itself. Tim somehow managed to land a very low-mile CBR1000 engine for only $300 on eBay, but there turned out to be a good reason for the low price. Blurry cell phone pictures had scared away most bidders, as did a cracked case that rendered the engine useless for those without Tim’s welding skills. It turns out there was a third reason, though. The engine was a 2008, which seems like good news, but it turns out Honda started implanting chips in their keys that year that communicate with the ECU, making it impossible to start the engine without the original key. The engine did not come with a key, and Honda has no interest in being helpful in cases like this.
Enter Neel Vasaveda, owner of Apex Speed Technology and a whiz at making bike engines run (and just about any other engine). Neel fell in lust with the Hamster as soon as he saw it and offered to figure out how to make the engine run in exchange for a chance to drive the beast in the next LeMons race.
So it was with this debt of gratitude that Tim pulled a tragically heroic week of all-nighters to get the Hamster ready for the 2010 Buttonwillow LeMons race, the closest race to Neel’s Southern California home, only to set what is hopefully a record for the shortest LeMons race in history.
Driveshafts spin a lot faster than axles. On average, about 4 times faster. A CV joint on the driveshaft of a car going 60 mph is spinning as fast as a joint on the axle of a car going 240 mph. That said, there are plenty of production cars that go much faster than 60 mph and come with CV joints on their driveshafts. That does not mean, however, that these CV joints rated to operate at 30 degrees could also survive life on a driveshaft. This is where the time machine would have come in handy…
On the second yellow flag pace lap, the CV joint, spinning at 240 mph, flung all its grease out into the boot, leaving the joint under-lubricated. The hard-working part rapidly overheated and failed so spectacularly that it shit a glowing-hot CV joint cage onto the track, which promptly melted through the tire of the Phony Express Lincoln behind it. And so it was that the smallest car in the race took out the biggest one before the green flag even dropped.
It was months before Tim was willing to even look at the Hamster again, but when he did, the new driveshaft solution would add a fantastic new layer of strange to an already wacky car. One of the few cars to run driveshaft angles as severe as the diagonally mid-engined Hamster is a Jeep. Jeep front axles are a long drop from their transfer cases, so their front driveshafts must have a durable high-angle solution that can spin at driveshaft speeds. Jeeps (and lots of other similarly tall vehicles) use double-cardan joints for this.
A double-cardan joint is basically two U-joints joined back-to-back with some kind of spring mechanism in the carrier keeping both joints at the same angle. Using two joints more than doubles the safe operating angle of a single joint. Single U-joints are typically angle-limited by the fact that the output speed oscillates, and the steeper the angle, the bigger the oscillation. Putting two joints back to back cancels this oscillation, allowing high angle operation without the fickle lubrication requirements of a conventional CV joint.
While he was in the Jeep section of the junkyard, Tim also realized Cherokees and Wranglers used a Dana 30 front diff with a Hydra-Lock LSD. That's basically a clutch-type LSD where a little oil pump, driven by the speed differential between the two driven wheels, is used to load the clutches. Kinda strange, yes, but it's a limited slip, so who's complaining?
It turns out these axles are dirt cheap, and the ones with the taller gear ratios that the Hamster's bike gearbox demands are even cheaper. Like FREE cheaper. All it would take is a massive amount of fabrication to mount the Jeep front diff upside-down in the back of the Hamster, offset to the engine side, outputting to 4-bolt flanges and carrying RX-7 brakes. Simple…
If you read part 1, like I suggested, (or follow Project Miatabusa for that matter) you already understand the level of Tim's fabrication skills, so you shouldn't be surprised that there's nothing more between “Tim decided to put a Jeep front axle in the rear of his Honda” and “Here's what it was like to drive” than these three pictures.
