4T65E-HD Transmission Questions

[tony1679]

First off, I am a noob, but I have been lurking BITOG for three years. So I'm far from inexperienced.

This is regarding the Impala in my sig. This transmission has a notoriously high failure rate. I would like opinions on what maintenance schedule I should follow, type of fluid, etc. It calls for Dex VI.

I've had this car for about a year now, and I take extreme care of it. I currently have NO problems whatsoever, but the average life of these transmissions seems to be <100,000 miles. Or perhaps I should say the average mileage of failure is <100,000 miles. I am at 97k. The reason for the high failure rate is a 300+ horsepower 5.3L LS4 hooked up to this transmission that is designed for a V6. To make it worse, it is a FWD setup. So shortly after I bought it, I purchased a handheld tuner to cure a few problems. The main purpose was to turn off the Active Fuel Management (AFM, cylinder deactivation) technology, but also to raise the transmission line pressures and shift points. This has made a noticeable difference for the better. Will the tune and "overly religious maintenance" be enough? Thanks in advance.

 

[rshaw125]

A large fluid cooler?

What was the process for changing the shift points? Mine (V6) always likes to shift up to 4th overdrive as quick as it can. Around town it'll start to lug. Would be nice to tune it to shift up later.

 

[tony1679]

I have thought about the cooler, but not sure if I want to take the plunge.

As far as the shift points, I'm not sure what exactly was done. I know instead of being in OD at around 35 m.p.h. like the stock setting, the tuned setting won't go to OD until about 54. Less shifting, less heat, longer life.

 

[AKhan87]

Yes an ATF cooler should help + 20-30k 1 Drain & Refill intervals with a good ATF, I prefer Amsoil ATF.

Do a used oil analysis of transmission fluid and see the condition of the fluid first in my opinion, being that it is a troublesome transmission

 

[rshaw125]

Originally Posted By: tony1679
I have thought about the cooler, but not sure if I want to take the plunge.

As far as the shift points, I'm not sure what exactly was done. I know instead of being in OD at around 35 m.p.h. like the stock setting, the tuned setting won't go to OD until about 54. Less shifting, less heat, longer life.


Which handheld tuner do you use? I think mine 'lugs' when the torque converter locks up around 30 mph.

 

[tony1679]

Superchips Cortex. The line pressures and shift points are set to the "Superchips" settings.

On a side note, I absolutely love the Cortex, although it is my first tuner. I only wish I could adjust the fan settings with it.

 

[barkingspider]

Transmission cooler is a good idea. If not, then I would change the fluid earlier than what isrecommended in the owners manual, or at least drain and refill regularly. Then just sock away some money every month or so to save for the transmission rebuild just in case.

 

[tony1679]

^This is what I have been doing. So I guess the real question is how much of a PITA is a transmission cooler install? Also what would a good setup cost?

 

[SteveSRT8]

I have put them on trucks and vans for less than 100 bucks.

Go to the junkyard and buy a late model GM truck trans cooler, it'll have a huge readily bendable and drillable bracket on it. It's a nifty flat plate design that cools very well with near zero pressure drop. Brand new they are under a hundred bucks.

Get thee some trans hose and clamps, a couple of zip ties, easy schmeezy...