Quoting MortalSwordsman .
Great idea. I think an old technic set (8860) had pictures on the box of a similar technique, but the actual pieces supplied were the traditional springs. very handy that the spare springs come in sets of 4 :)
Thanks. C:
I never knew about that set, and I'm glad that you like this idea. And yeah, every spring comes in fours. Some pull, and others are compression springs. There's an example of the pull spring in my 6x6 chassis.