Improving shift quality ? 2005 Impala

[wgtoys]

My friend's Impala has developed intermittent hard shifts from first to second gear and sometimes from second to third. The car has about 65k miles on it. We changed the ATF at 30k miles and again at 60k. Several months ago he took it to a Chevy dealer with the hard shifting complaint and was charged about $1,500 to "polish the valve bodies" and again change the ATF. Two months later, the harsh shifts returned ... and the many decades old Chevy dealer had abruptly closed its doors.

Another dealer has suggested he try changing the transmission fluid again. Has anyone had any luck improving harsh shifting modern GM transmissions with MaxLife ATF or any other product?

 

[c3po]

What transmission fluid is in there now.

I would probably give Amsoil ATF a try and put a Filtermag TM360 magnet on the bottom of the transmission pan.

 

[Ken2]

Clean the transmission with Auto-Rx and flush the fluid following that cleaning, according to the instructions. If that doesn't work, there is a mechanical problem in the transmission.

 

[wgtoys]

"What transmission fluid is in there now."

Whatever the now defunct dealer put in. Probably some Dexron IIIh.

 

[oilboy123]

Clean with Auto-RX then run a good synthetic. Or re-clean with RX every once in awhile.

1500$ Valve body polish??? Never heard of that one.

 

[EricZoom]

I'm not one for miracle additives, but you can try Lubeguard products. I used Lubeguard Red in my Mazda 6 Jatco, and it seemed to smooth out the rough shifts. That's on top of 3 drain-refills using Redline D4. Worked pretty good in my ATX.

 

[WishIhadatruck]

My dad's 2000 Grand Prix with the same transmission had harsh shifts, mostly after it warmed up. It never did it cold. He was told it was the solenoid valves sticking and that it would keep bumping up the pressure to make it shift. That is what caused the hard shifts. We tried adding a cooler, Auto Rx followed up with a flush, etc. No luck. It was rusting bad under the doors anyway so he just traded it in on a '05 Impala. Hopefully he has better luck than your friend.

 

[wgtoys]

"My dad's 2000 Grand Prix with the same transmission had harsh shifts, mostly after it warmed up. It never did it cold. He was told it was the solenoid valves sticking and that it would keep bumping up the pressure to make it shift."

Hmmm, reminds me of the 60k mile Olds with a failing engine I traded in on another Olds, which then had troubles not long after the warranty expired. Finally wised up and bought a Honda, which is now near 90k miles and going strong.

 

[ponderosaTX]

I also had good experience adding Lubegard Red to the recently changed Mercon/Dexron III ATF in JATCO 5-speed transmission in my 2003 Mazda MPV. The Lubegard Red essentially eliminated a chronic shift flare problem.

 

[meep]

nobody has mentioned Dex VI???? Good fluid. meets spec. does it not? superior to dex III variants. I would not put arx in there unless I thought it's dirty or has seal problems. Drop the pan and look. dirty? burnt? filter look ok?

M

 

[WishIhadatruck]

If the dealer changed the fluid just 5k miles ago I would assume they put DexVI in it. It is the correct fluid and is what I use in my own 4T65E but he probably has a problem that is not fluid related.

 

[brian12]

Could it be the motor mounts are starting to go and its causing what you think to be a harder shift. Seventy thousand miles sounds about right for an american car needing new motor mounts.

 

[wgtoys]

Update: About ten days ago we dropped the pan, changed the filter, refilled with Mobil-1 ATF (old style as that is what the auto parts store had) and flushed an additional four quarts through the system by removing a trans cooler line at the radiator.

The pan had a light amount of dark grey stuff on it, just like the prior time we did an AT filter change on this car. The pan magnet clearly had iron/steel residue build up which took several minutes of scrubbing in a parts washer to remove. The ATF coming out was still a nice red color and didn't have a hint of that horrible burnt smell I've encountered on other vehicles before.

Anyway, we buttoned it all back up; and much to my surprise the car shifts like a dream. I just talked to my buddy today and he says the car is still shifting just like it did when new. Trying a synthetic ATF was his idea ... I was skeptical, but now am pleasantly surprised. We shall see how things go as it ages, but with a few hundred miles on the Mobil-1 ATF the car is still shifting perfectly.

The dealer installed fluid had been in there about 7k miles, and I don't know what they used.

 

[Ken2]

Originally Posted By: meep
I would not put arx in there unless I thought it's dirty or has seal problems.
If the solenoids are sticky due to varnish on the rods, then Auto-Rx will clean that. Ditto if the problem is hardened & dirty seals. I'd do a by-the-book Auto-Rx cleaning first, flush with a top quality fluid (Dex-VI if not full syn), and see how things work.

The engine or transmission mount suggestion is a very good one. The mounts must be in good condition or things will jerk around even with a normal shift.

 

[JTK]

You don't hear of many problem with the 4T65E. I've never heard of a solenoid causing a jarring shift. They are on/off valves (aside from those that are pulse-width modulated), so you'd think it has to be related to fluid pressure. Almost sounds like an accumulator piston issue. If they stick in their bore and don't do their normal fluid damping, you'll get chassis busting shifts.

Joel

 

[Ryan]

Google 4t65e hard shifting and you will find tons of links showing that the problem with this transmission is the pressure control module failing... My 02 Olds Intrigue is doing this now. What will happen is the pressure control module will bind up and cause the shifts to get a little sloppy... after the transmission detects about 6 sloppy shifts, it will go to "max adapt" shifting to prevent slippage. After turning off the car for a while, this will reset until it does it again. It will set off a diagnostic trouble code, but it will not cause the "service engine soon" light to come on. In 2003, a revised pressure control module was made to help fix this problem, but apparently it still exists. I dropped the pan and changed out the filter and then ran Auto Rx in the for 1,000 miles then had a shop do the flush and the problem still came back. To replace the pressure control module, you would need to remove the side pan on the transmission, which isn't an easy task. I'm researching right now to see if adding a trans cooler might help prevent this from happening as it usually only happens when the car gets hot.

http://www.oldsmobileforum.com/forum/showthread.php?t=1471

 

[wgtoys]

I don't know if it is a coincidence or not, but the car is shifting great these days after several thousand miles running with Mobil-1 ATF. For a while the harsh shifting would come and go, but for the last month or more it has been behaving perfectly.

Strange.

 

[Ryan]

Let us know if the harsh shifting goes away... I don't want to pay $700 for someone to replace the Pressure Control Module for it to go bad again in a year. If the synthetic fluid does the trick I will go that route.

 

[wapacz]

may you dislodged some derby that was in the valve body causing problems.