I just ahd my tranny rebuilt and my 2nd gear is grinding. Some days it isn't that bad and others it is. If I drive the car for a while it stops grinding. On some days when I start driving it it grinds for the first 5 minutes or for the first 30 minutes. What do you think the problem is?

 

either you cant shift 2nd gear good or your 2nd is bad....also check fluids and how much is in there! or take it back and demand it be fixed!

 

How come it stops doing it after driving it a while?

 

Does anyone know?

 

It's your 2nd gear synchro.

 

What did they do wrong for it to do that?

 

Synchros wear out. Maybe they test drove your car and missed 2nd gear really bad, or maybe it is just a coincidence. They should have noticed the synchro was bad though, it's not hard to tell if you know what you are lookin for.

 

Well the thing that was weird is that it never did it with the old tranny but just the rebuilt one.

 

Maybe the gear oil is warming up? What oil u got in there? I don't have synthetic, but at least it's gl-4 (not 5). It takes a little time for it to warm up, so i baby it till the temp needle is at normal.
Jae