Hey everyone, I'm having some weird issues sometimes when my car shifts.. First off I drive a '99 3.8L V6 which I recently bought used from a dealership. (Forgot to mention she's a 4spd automatic)

Anyway, I notice that occasionally the first shift on my car is a really rough jolt that kicks you back in your seat. It only happens sometimes and only the first shift. Doesn't matter if I'm doing 1/4 throttle, half, or full, it still occurs. Had her taken to the dealership since she was still under warranty and they checked it out and said everything was fine.

Any possible reason as to why she'd be shifting hard on me?

 

Gee, I'm really surprised the dealer said everything was fine. (that was sarcasm btw) Did they also tell you "they all do that"? You think it has something to do with them wanting to weasel out of a "warranty" they gave you?
How many miles on the car, and has the trans fluid ever been changed?

 

Yeah I figured that might also be the case, but the place I bought the car from is considered a fairly reputable dealership. The car had 118,000 miles when I bought her and I've put two thousand miles on her so far. I honestly have no idea if the trans fluid has ever been changed.

 

Then a fluid change might be a good place to start. At least you'll know the service of the trans at that point, and whether or not that's the cause. Have you looked at your fluid to see if it's red, or brown and smelling burnt? I prefer having a complete flush done which changes all the fluid, as compared to doing a pan drop and refill which only gets less than half.

 

Checked the fluid with the car in park and the engine idling, the fluid was a brownish/reddish color and did not smell burnt. Since I don't know if the fluid was ever changed this might be irrelevant, but in an auto if the fluid was never changed before isn't it best to leave it as it is once the car reaches a certain amount of miles? Or at the least drain most of the fluid out, and leave some left in there?

 

That's the "theory", that when there is old fluid in the trans that's never been changed, there is an amount of grime/grit embedded into the clutch packs. Then flushing the trans with new fluid with fresh detergents can wash out the clutches and make them slip....
That could be true if your trans is teetering on having slipping clutches right now. But I would be less concerned about it if your trans is shifting good and strong with no signs of slippage at all.
I've heard of it happening, but I would like to hear from someone where that's happened to them.
That's a chance you take I guess, if it's never been changed. But has it? You don't know the car's history.
And you didn't say how many miles yet.

 

With random hard shifts into second gear and no other problems they need to look at a sticking second gear accumulator. It may not show up on any test. They just need to be driving/riding it when it happens. Is the warranty GMPP or some other company?

 

Camaro69, I said that I bought the car at around 118k miles and have since put about 2.5k on her. She's sitting at 121k miles right now.

The warranty is a 3-month 3 thousand mile powertrain warranty backed by the dealership. When I took it there they took her out and drove her around and noticed nothing out of the ordinary. Either the issue didn't occur or they didn't want to have to spend money trying to diagnose and repair the problem.

Would the second gear sticking accumulator throw any codes or would you have to physically look to find out?

 

I do not know if it will throw codes, I do not really know the electronic controled trans very well. But I used to be pretty good the the 700R4 tranny. All a accumulator is is a piston with a spring behind it. When hydralic fluid engages a clutch it must also Pushes this spring loaded piston back. Because it is doing both things it can not build pressure very fast. The heavier the spring behind the piston the harder the shift. Now if the piston gets stuck all the way back the spring can not do its job and the cluch get the full hydralic pressure all at once. On the 700R4 there was no real way to test for this. You just made sure there no other probelm and you fixed the accumulator.

You could take to a well known trans shop and get a quote. The take that quote back to the dealership. Or you could just bluff and tell you had it checked out and they think the accumulator is sticking.

 

So I found out my car isn't under warranty anymore. Meh. If I just let this go how much of an issue could it be down the line? If it is the second gear accumulator sticking can I fix it myself, or do I need to have a lot of knowledge about cars/transmissions?