When I started with racing radios in 1986 we didn't give out freqs, the teams did not want anyone spying on them. This was long before pit intercom systems so lots of driver to engineer chat was done over the radio. Derrick Walker told me they noticed another team was making similar changes to their car as Derrick's team at Mid Ohio so they called for a fake set of front springs to see if the other team would make the same change.
One of the mechanics didn't get in on the deception, looked in the spring cabinet and realized they didn't have that size. He took off running back to the transporter to get them.