I am new to the forum and need some help. I have an automatic 98 3000gt a dual overhead cam and I am having trouble with the transmission. When I accellerate slowly through the shift points the transmission seems to shudder at about 40 to 45 miles per hour (when high gear kicks in). If I stay at a constant 40 (around that) the tranny acts as if it is not sure which gear it wants to be in. If I drive up through the gears a little fast then this does not happen and the tranny works fine. If I keep the car in second gear it also does not happen. It feels like it is a bad torque converter or something is going wrong with high gear. If so is this hard to change. Any help is greatly appriciated.
Thank you,
Rick

 

How long has it been since the fluid was changed?
Try driving the the OD off. If it shifts fine (1-3) you'll know the end clutches are bad (the OD gear). You can get upgraded end clutches from IPT performance transmissions.

 

This scenerio sounds like this...
If you accelerate fast all the time, the tranny learns that technique of driving and shift faster...mainly because it has to, to keep from heating up the tranny by not "slipping". If you were grandma/grandpa and always drove carefully, it would learn that technique and shift smoothly at that slower acceleration.
The harder the shift , the less the friction, the "cooler" the tranny.
You have an automatic and it's a learning tranny. If you're curious, disconnect your battery for an hour or so. Reconnect it and accelerate slower than normal for a week. It will relearn (since the old method has been erased) your new technique. The next time you accelerate fast, it will slip while shifting.

It also isn't a bad idea to change your fluid as TheStealth has suggested. Check your fluid for color and particles while your at it. One more thing...use Mitsu ATF +3 or +4 DO NOT USE auto parts store brands for your auto. Your tranny will thank you for it.

 

Hmmm...I didn't think the TCU's were smart enough to learn driving habits. Learn something new everyday I suppose.

 

Thanks so much. I drove the car today with the OD off and it shifted just fine. How hard is it to change the end gears and how expensive to pay to have the job done. I am no great machanic but I do work on my cars and am not affraid to try something new. Except if I can further mess up the problem. HA HA !!!!! I did change the fluid with synthetic a couple weeks ago. Did not change the filter though. I put in the exact amount I took out around 41/2 quarts but when I checked it in park it was way above full. Thanks for the help guys it is greatly appreciated because I love this car. Should I try the retrain thing first. Sorry one other thing my check engine light is on but I had this happen once before and I think the code was bad 02 sensor or a couple other things that code represents. I just haven't had a chance to take it to autozone.
Thanks again,
Rick

 

If it is shifting fine through the gears with the OD off, that is usually a good indicator that the end clutches for the OD are shot. You'll have to check their prices, but I want to say the upgraded end clutch kit from IPT is around a $100. I've never put one in, nor have I had it done, so I don't really have a solid answer for how much it would cost to do the job or the difficulty of it...sorry.

 

Thanks so much!!!!
I'll check the internet for IPT and ask them.
Appreciate the advice.
Rick

 

I'm sure the TCUs are preset with several maps to help it adjust to different shift patterns.

 

I would have given you the link earlier...but my work machine won't copy/paste in Mozilla for whatever reason.

http://www.importperformancetrans.co...ishiauto.shtml

Considering the trannys have a PWR/ECO button, I assumed they only had two maps. You very well could be right, I've never really researched it much.

 

the 98 has no adaptable shift qualities. there is nothing for the trans to "learn".
if its shifting poorly, there is a reason for it.