Nataha Hopkins posted that it was "bloody ridiculous -- I'll be surprised if it [the road] has any stones left at the end of the day".
Sam Ann said his car was still spitting out loose stones by the time he got to Carterton.
"These ones are bigger than normal too."
Tash Knofflock said her car was still rattling with stones by the time she got to Greytown, while Anita Wilson said her wheel arches still had stones in it as far as Featherston.
Ginny Myers said she suffered a crack in her windscreen from a loose stone.
Aroha Geange posted she had melted tar and stones under her car. "Ridiculous!" she said.
NZTA operations manager Marc Owen said they are monitoring the situation with CCTV and a road crew is using a water cart to cool things.
"It's a bit of a challenge in heat, very delicate, but it will settle down.
"Once it cools down tonight, they will sweep up.
"We have extra stone as well."
The road was sealed overnight, but it takes 24 hours for the chips to roll over and lock in.
"The traffic movement is part of the process," he said, explaining they adjust car movement to lock in the stones.
They could use a roller but "there's nothing as effective as cars".