Let me say I am far from intelligent when it comes to transmissions. However the basic understaning I have is the purpose of the torque converter is basically a clutch for an automatic transmission. It allows the motor to run and the vehicle to be stopped.

Fluid passes by fins in the converter and when the fluid moves fast enough the power is transferredt hrough them to the trans.

It sounds like when you let off the gas you are becoming completely disconnected meaning it'* acting like neutral.

Maybe one of the people that understands transmissions will chime in soon with better info for you.

I've heard of replacing torque converters..not sure if they are rebuildable.

Iam no tranny expert either...but i have done some reading on the subject. The convertor is a welded assembly and isnt rebuildable. From my knowledge your problem may be sludge/dirt particles/ or a sticky seal in the valve body. My also be caused by a weak tranny pump...you reallly need an expert to diagnose your problem....a tranny shop may say it is better to just rebuild your tranny...since there could be more than one problem causing your rough shift. Although I had an Imperial that had a sticky seal in the valve body that caused the sysmptons you describe. They are actuators and pistons in the valve body which direct the fluid flow through your tranny,the direction and the path of the fluid determine which gear your tranny is in....if the seals on these pistons stick due to old age/wear, the tranny will be slow to shift into the gear it should be in. Hence, when you come to a stop off the expresway...the car may have shifted into second gear just fine....but is unable to shift into first because of sticky seals....the tranny will increase fluid pressure until the proper gear is actuated,,,,this build up of pressure causes the bang you hear and feel....excessive pressure is built up because of the faulty seal....its a theory....they can measure your fluid line pressure at different speeds to determine whats actually wrong.

Your trans was obviously having issues before the filter change, but you induced another variable when you used the synthetic blend. Granted it'* a BLEND, and you only replaced 1/3 of your fluid, but it'* not a good thing.

As the clutches in our transmissions wear, increased lubricity of synthetic fluid can add to the problem. My suggestion is this:

Get a professional flush with non-synthetic fluid, then let'* see how she does and get back to the root problem. 67k is way low for a 4T60 to fail. 100k or more for a SC version, around twice that for a NA. However, your car obviously sat around alot, which isn't a good thing for it.

Yeah it probably did sit around way too long since my uncle was well into his mid 80s when he bought the car and he rarely drove it car much during those final years from what I recall.

When I first got the car back in 2000 there was not even the slightest hint that anything was noticeably wrong with the transmission based on my driving the car daily - though I know that means very little because many things could have already been happening to the tranny without my knowing until it became obvious!

I also know that when the fluid and filter were eventually drained and replaced in 2002 it was pretty bad! The only thing good about the fluid was that it was well within the the proper level and that was about it.

I know that the fluid that'* been in there recently is going to be flushed just to get that damn synthetic blend MerconV crap out of there. Hopefully going back to the regular non-synthetic fluid that was INTENDED for these transmisison will help out somewhat, even though whatever repairs I expect will be needed WILL finally get done. sometime very soon!

Just me..I'd rather buy a higher mileage great running car than one that sat. For all the reasons we are seeing here.

I'ver long been thinking that same, very exact way - espcially over the last week! But you know when someone is GIVING you what seems like a solid car (which it is except for the tranny situation) it'* hard to turn down.

By the way, I see that GM has announced the closing of yet another 9 plants which will eliminate a few thousand jobs. Feels like yesterday when I'd ride my bike over to watch them make Toronados, ElDorados, Rivs, and Sevilles back in the 1970s and 80s at the Linden, NJ facility which is also closed...

Wasn't there a time when the often cited but misquote thjat became somewhat of a slogan was "What was good for GM is was what was good for America?" Man how times have changed and not for the better!

After a few weeks of having both my mechanic and ultimately an outside independant transmission shop look at my car and check everything out as far as the tranny went, it turns out that the problem I was experiencing was due to two very badly damaged transmission mounts which cost me a total of $215 plus tax to have replaced, and which I learned can often simulate the feeling of a badly slipping transmission as the damage progresses over time.

I've had the car back since last weekend and the problem is completely gone as far as I can tell. I brought the car back yesterday so the guy who owns the trans shop can take it out for a drive himself and make sure everything is okay (which it is) and he now seriously wants to buy the car from me! The guy could have suckered me in for an expensive rebuild (whether I needed it or not) but he didn't.

I realize that I was fortunate enough to find a reliable and honest transmission mechanic because the Pontaic service center who looked at the car in late October first recommended a complete fluid flush and recently decided (after driving the car) that a complete rebuild would be needed sometime very, very soon. I took the car over to the dealer tonight and asked them to drive the car again and they said that there seemed to be nothing wrong with the transmission from what they can tell and that no service was needed - though the issue of a complete flush was again brought up and strongly suggested.

When I told the service deaprtment manager that two mounts were badly damaged and needed to be replaced he looked shocked and then embarassed that his workers failed to check the mounts before telling me what they thought needed to be done to the car. They must have known they made a mistake because they gave me a voucher for three free oil changes during the upcoming year.

I am not saying that this is the remedy everyone else migth benefit from with their tranny problems but I do know that the problem has been corrected by replacing these damaged mounts on my car.