[jklightner]

Hoping for a little help from anyone. I have a NAG1 transmission that shifts fine in every aspect, except when it goes from 1st to 2nd. When it shifts it slams really hard. It almost feels like being rear-ended. Any ideas out there?

When was the last time the fluid and filters were changed?

 

[jklightner]

Flush when I got it last month. Flushed all the fluids, bad habit I have.

So what do you have as far as year, model, engine?
You should fill out your signature form so people can have an idea.
Did you do it or did a shop flush it?

 

[jklightner]

Took to a shop, 2006, 3.7L, NAG1

Pan was clean?
Does it shift 1-2 at a higher rpm than the other shift points?

 

[jklightner]

I thought my transmission was shifting hard until I realized the upper differential mount was shot. Replaced that and the transmission was smooth as butter. ...just something to check if you haven't already.

Wouldn't that happen in all shifts, not just 1 - 2?
And on downshifts too?