Welcome to Thursday Trivia where we offer up a historical automotive trivia question and you try and solve it before seeing the answer after the jump. It’s like a history test, with cars!
This week’s question: How did a vibration discovered during its development ultimately lead Nissan to try and make the 240Z lighter?
If you think you know the answer, make the jump and see if you are right.
Datsun’s 240Z proved to be – like the first Mustang just six years prior – a rabid success. It was so much so that the initial supply couldn’t hardly keep up with demand, and using basic High School econ logic, dealers tacked on onerous markups.
The S30 may not have been so popular if Nissan hadn’t worked so hard to get it right from the start. That included a number of trade-offs that were made while the car was undergoing real world road testing here in the U.S., even while the assembly lines back in Japan were starting to crank the cars out. One of those trade offs started with a shimmy.
From Zhome.com:

Problems identified along the way were reported back to the factory by the Test Drivers. Problems identified included road noise, vibration from rear axle and steering wheel kick-back. The fiberglass headlight nacelle also developed cracks. As a result of unacceptable vibration, regular production of the Datsun 240-Z that had been ramping up from 52 units in Oct., to 388 in Nov. at the production facility, was slowed to all but a complete halt in Dec. 69 with only 97 240-Z’s being produced that month.
The angle between the differential and half-shafts was determined to be too great, resulting in the unacceptable vibration. The solution was to move the differential rearward, but that presented a problem of interference with the gas tank. As a result the gas tank had to be made smaller, but to maintain the driving range necessary for America, the Z had to be made lighter.
Every aspect of the construction of the Z was thus reviewed with the goal of making it lighter without sacrificing strength. A crack developed during US Road Testing so the fiberglass headlight nacelles were doubled in thickness and thus strength. Which solved the problem but added some weight back to the car.With the early results from the US Road Test Cars, Nissan had the problems mostly corrected by the end of Dec. 69 and regular production began to ramp back up in January 1970.

I have a ’71 240Z and I can attest to the fiberglass sugar scoops’ penchant for cracking with age. Of course my car is well out of what the Nissan engineers originally spec’d for the cars’ lifespan, so I’m not complaining.
Image: Zhome