vs gearbox sliping in 3rd when hot

[STL17]

hey lads i have a slight problem i have a vs ecotec in my vn with a vs box behind it and last night i was at the drags and after the 4th run my box lost 3rd gear i thought for sure i had blown it but this morning i took it for a lash and i had all gears again so i am putting it down to heat maybe. i have a trans cooler and its going through the radiator to the cooler and i also have a shiftkits australia shift kit [electronic] is there anything else i can put in it to stop it from slipiing in 3rd i see you can get 2nd gear servo's for the auto and it helps 3rd gear shifts aswell as 2nd should i get one of them aswell as a transgo stage 2 shift kit

its only done it since i put my 3.73 diff gears in

[D3V14NT]

Check your tranny fluid levels, should be spot on with it. Also give the trans a service if you haven't recently.

Check the state of your trans fluid when you do the service. Dark brown with a burnt smell is bad news. Could be a failing 3-4 clutch pack, a faulty valve, worn governor gear, or a multitude of other things but do those couple of things first and see how you go.

[STL17]

Yeh i done a service last week and the oil was brown but there was a small amount of metal colour in it

[D3V14NT]

More than likely a failing 3-4 clutch pack. You can probably drive it around carefully for a little while before it completely gives out but I'd take it in to a trans shop as soon as you can. Get them to diagnose it properly and go from there. You'll probably be looking at a rebuild or you can try and pick up another second hand unit to swap in.