Th400 slipping

[Nolan M]

So I just bought a 1984 c30 knowing it was missing reverse. I drove it home (about 30 miles) with no problem just riding in second at 40 mph because it had bad tires. Replaced the tires and took it for a drive. It shifted fine between 1 and 2 but wouldn’t go to 3, checked the trans fluid and added about a quart. After that it would go to a neutral when you got to 45 mph. I’m guessing it’s slipping.

I bought a new vacuum modulator as someone said it could be the issue. After installing that, it only has first gear and will slip in first at about 15 mph. Any advice would be so helpful

 

[Blue Ox]

Direct and reverse use the same clutch pack in a 400. AFAIK it's the "common" failure on them. Although it's not a failure prone transmission. Unless it's mine.

 

[HotRodPC]

Low/Reverse Clutch pack OR the Low/Reverse band. Chances are it's the Clutch pack though since the Low/Reverse Band is needed to make Reverse and Give manual 1st gear engine braking but not needed for manual first pulling.

 

[Nolan M]

Hey guys, sorry I'm so late getting back to y'all but i put a new tranny in and now every gear works fine. Thank you for the help