We have been collecting data on the average miles of the first failure of transmissions for a LONG time on this Forum.

jr's3800 and I took this on as a task. The 4T60'* have fewer problems and last an average of 40k miles or so longer than the 65'* before their first problem. Some things were fixed in the design of the 65, but other problems were introduced.




Hey, came across this post with my first transmission problem. I have a 2000 Bonneville SLE, which appears to have the beloved / hated 4t65-E. I had the fluid and filter changed in the trans in the summer (2011) at about 87k miles. Dec. 2011, it started throwing code p1811, and the transmission guy wants to do the rebuild ~ $1800. I may try to upgrade to Dex-VI and install the Transgo shift kit, discussed widely here. I may be fighting the inevitable, but another 6 months before the rebuild would be great. Hope this help your stats.

Moved off a 5 year old thread to it'* own and in correct area.

The P1811 is a long shift. Installing a shift kit can correct this problem by shortening up the shift time. This code starts to show up as the clutches are starting to wear. Try the shift kit. I've fixed several transmissions with that code simply by cleaning up the shift accumulator. And that will be done when you install the shift kit.

Thanks for the advice. I got it done this morning, which took longer than i was hoping. The write-up i used is

"https://www.gmforum.com/showthread.php?t=279684"
(please delete if i cannot post the web address)

It was really helpful. Used the Transgo kit, but i chose not to do the complete job, and take off the side panel. Just the 1-2 and 2-3 accumulators. I picked up Dex-VI at Walmart, $4.17 per quart, here in Michigan. Seems to be running really nicely, and shifts are firm and even. Seems to have worked, starting at 94k miles. I will update, but i just need the trans to make it to the summer.

If anyone is interested, i found write-ups for the shift kit (4t65e mainly) on other sites, but i do not want to offend.

You may be surprised how long your fix lasts. I can't remember exactly, but I think it was 2 years and 60K miles ago I installed the kit, after getting hard shifts. 240K total on 4t65e now and shifting smoother than ever.

Technically P1811 is Max Adapt Shift that puts EPC/PCS pressure to max and shifts harshly. The shift kit helps by reducing the amount of fluid/accumulation before the shift.

The best fix for this issue is to lower the driverside of the trans and change the pcs/epc. A shift kit does alleviate most of the symptoms though.

I ended up researching the 1811 code, but i admit dropping the subframe and replacing the PCS is a bit outside my skill level. Couple days in now with the shift kit, it seems to be driving really nicely.

Another thing i was going to ask about was 4th gear. Before the harsh shifting, etc., I was getting flutter between 3rd and 4th gear. Basically, it was up and down shifting evey half second, after the car was warmed up, and on the road for an hour or so. It happened intermittently, and its hard to reproduce. I know the 4th spindle is weak in the 4t65e, so is it related to that? Any help would be great. Thanks again.

As long as you still have 4th, the hub shouldn't be an issue. some of the issues we experience are ignition related and or TPS/MAF. All three have a huge impact on how the trans acts/shifts and behaves.

Its ironic you brought up ignition, TPS, and MAF. About 8 months ago i had the engine replaced. A mechanic i used to usee (no longer) changed the intake set incorrectly, and a few months later, the main bearings were toast. Got the new engine for free, which was nice, but getting back tot he point. The new engine was a rebuild off a 2003 LeSabre, so some of the electronics might have been replaced. Either way, i still have the problem now. This makes me think its more likely related to the transmission. You make a good point about still having 4th gear though. How does the computer engage each gear, vacuum lines?, im still learning about this car, it is my wifes. Again, thanks for the help.

Does it happen around 45 mph or so? This is the area where 4th gear is used and the torque convert locks up. If the torque converter isn't locking right it will switch back and forth causing a surging.

Now that i think about it, its closer to 65-70 mph. Forgot to include that.