Reply To: 2017 SS manual grinds going into third and I think the previous owner was a bit

[Finn Dawson]

Third gear synchro on the TR6060 is genuinely one of the known weak points on these boxes especially when the previous owner was enthusiastic with no lift shifts so you are probably diagnosing this correctly. Try the fluid change first because it genuinely does help on these transmissions and costs almost nothing compared to a rebuild, Redline MT90 specifically has a good reputation for smoothing out TR6060 synchro grind in the early stages. If the fluid change makes a noticeable difference you have bought yourself time, if it does nothing then the synchros are too far gone and the rebuild conversation becomes necessary.