Hi I have a 84 z/28 with a 700 tranny. Drove one night shifted fine. a few hours later went to drive home would not shift out of first.Can anyone tell if this can be fix or do i need to have it rebuilt.

 

What's the fluid look like?? Could be a clogged filter

 

Other Possible cause:
Govenor failure (Govenor can be fixed externally but most of the time it sends metal into the trans)
Second gear seal failure (required rebuild)
Second clutchs are worn so thin the piston popped out (required rebuild)
Second gear accumulator failure (possible external repair)
Gummed up valve body (possible external repair but the Gummy crap is all thru the tranny)

Second gear seal failure would be the most common all for all at once failures closley followed by Second gear Accumulator failure.

How does reverse feel? When a filter plugs it starves the tranny of fluid. It can cause the govenor pressure to drop low enough it will not up shift. Reverse requires the most pressure to work. If your filter is blocked reverse will feel very soft and it will tend to slip. If the valve body is gummed up sometimes changing the fluid will help free things up.

Step one would be to pull the pan. Look to see how much black gunk is in the bottom and try to blow thru the filter.

 

tranny not shifting changed fluid and filter drove around the block still not shifting

 

Was there a lot of black clutch material in the pan? If so its rebuild time. A tranny shop can check your pressures to see whats going on but you can spend another hour or two ($80-$200) just to be told it needs rebuilt. If it is a high miles and you want to save money you could pull it yourself and take it in for rebuild or roll the dice and by a used one.