Seen a few but one that sticks in my mind was at Hull in 1977; Birmingham team manager Graham Drury and the late Mike Curoso who happened to be Viking teammates at the time. One minute they were sat in their bikes at the pit gate ready to be pushed off then, literally within seconds, they were rolling around on the deck before being separated by riders and officials with Drury holding the upper hand at the time. This was in the days before fixed starting positions and it turned out one had lent across to the other saying "I'm having gate such and such, ok?" before the more thorough and physical discussion took place on the track, literally.
Also remember James Beaton Snr waving a fuel can and chasing an opposing rider through the Hull pits due to feeling agrieved over tactics meted out either to son Bobby or James Jnr (Jim) Beaton. Don't recall the identity the rider he was less than pleased with however.
Regarding Gresh, there was the time he kicked off in the Belle Vue pits v Reading in 1982, Ian Thomas' first meeting as Aces team manager. It was reported the Gresh laid Bobby Schwartz spark out, kicked Thomas where it hurts most with his steel shoe and decked another rider. "An action-packed 30 seconds" as my brother said at the time when I passed on what I'd read....