nick49

Drive it for an hour, let the trans fully warm up, where the oil is hot and thin. It should make a difference. Also try revving matching trans to crank speed, find the sweet spot and pull the lever gently from 3rd with a slight pause to neutral, then right into 2nd. You should be able to feel and sense it wanting to slip in. Or maybe it's just me as I've built many types of transmissions and can mechanically visualize what's happening. Hope it works for you.

Rickhinson

Thanks for the info, but most of my trips aren’t for an hour, just a few minutes around town. What’s wrong with a transmission that you have to drive for an hour to keep it from grinding when you go from 3rd to 2nd gear. Any help will be appreciated.

Rickhinson

Thanks for the info guys.. Let it warm up a bit today and no problem with the grinding downshifting from third to second. This forum is amazing!!!

theprf

Wrong grade of lubricant would be my guess.

garrett376

Synchros are bad. Some oils may "cover it up" better than others, but if the synchros are bad, it will continue and you are looking at a rebuild and possibly new gears if the engagement teeth welded to the gears get nicked up. The more you drive it and it crunches, the higher the rebuild cost gets!

Rickhinson

Guys, I looked at my invoice. They put REDLINE 75W-90 Gear Oil in my transmission. Anyone's thoughts on this? Thanks

powdrhound

Use Delvac 75w90 if your gearbox has a plate type LSD. If it's a stock 996tt box used on the street, use the OEM fill Mobilube PTX 75w90. This is a dealer only item.

993GT

if its Redline NS you're good.. Mobil stuff is old school but works, Motul Gear 300 in either 75w90 or 75w140 works real nice (172k km now on mine, tried about all them on mine+ customer cars..Castrol 75w90 works nice too)