Tahoe kind of "chugs" to a stop...

[KMeloney]

Hey all,

I've documented here how I don't like the way the new 6-speed behaves. I get some flaring in the rpms when coming to a stop -- and then there's the hunting for the correct gear sometimes, etc.

Lately, it feels as though the truck does some "chugging" at, say, 25 mph or so, and down from there when coming to a stop. With the flaring in the rpms, and sometime an audible "clunk" when it downshifts, I'm wondering if what I'm sensing is slop in the DRIVETRAIN.

I've read about people having u-joints replaced, as well as having shafts/yokes greased -- but it sounds as though many of those trucks were earlier year trucks, and with higher mileage. Mine's an '09, and I have @ 27,000 miles on the truck.

I'm hyper-aware of this feeling, and I really don't think the truck should be performing like this. Rather than just take it to the dealer and have them tell me that they can't duplicate the scenario, I thought I'd get some input here first.

That, and if you all could give me a primer on what greasing the slip yoke and replacing u-joints should solve, I'd appreciate it.

Thanks, folks.

 

[Modded]

There is a TSB for slack in the drive train that causes slight chugging and a pretty audible clunk when coming to a stop. I took mine in for it almost 3 years ago and it was fixed.

 

[KMeloney]

Modded-- any idea where I can find a complete TSB number and description of it so I can take it with me to the dealership?

Also, I've experienced the ol' "feels like you get run into in the rear" slip when stopped at a light. Is this part of the same issue? Is there a TSB for that, too

Thanks!!


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[InTruckDesign]

Kirk, have you taken the tahoe in recently?? If not I would check with the service dept. and see if there is an update that hasn't been flashed into the tcm. What you are experiencing with the flaring when coming to a stop was an issue with the 6-spds when they first were released, seems that they have fixed it on the most current tahoes(or at least the ones I have driven) The clunk when downshifting is no doubt driveline slop, it happens as more miles get put on and parts wear in. The fix is for them to grease the slip-yoke, basically packing it with grease to take up the slop.

 

[Fast55]

Basically, the six speed sucks. I'm on my second one. It's the main reason I haven't done a blower. I'm pretty tight with my dealer, but they gag at the thought of 500+ HP and 500+ ft./lb attached to one. Maybe when the warranty is up if I don't get bored with it.

 

[KMeloney]

Thanks, guys.

ITD -- I tried a year ago to have the 6-speed checked into, but they tech thought it was pretty normal. It's gotten a lot worse, though, and so I need to take it back and insist that it be fixed.

Fast -- I agree on the 6-speed. I hate it. How is it that you're on your second? What happened to the first, and how did you have it replaced? Thanks!

 

[Fast55]

Within 3K miles I started having very pronounced flairing. A couple of times it practically went into neutral on the 2-3 shift. For whatever reason, it seemed to really screw up on the first pass through the gears after a hot shutoff, for say, stopping for gas. So bad I got out of the throttle once or twice. There is a TSB for that, its 09-07-30-004A to replace some seals. If anything, I thought it was worse when they were done. I kept bugging them and was able to demonstrate the problem to the SM so they finally replaced the entire trans. It's better, but even after several tuning files from BB, it's not great. The last set of files from Justin are the best so far though. The clunk in the rear when coming to a stop is an easy fix, just lube the slip yoke splines.

 

[Zed 71]

Basically, the six speed sucks. I'm on my second one. It's the main reason I haven't done a blower. I'm pretty tight with my dealer, but they gag at the thought of 500+ HP and 500+ ft./lb attached to one. Maybe when the warranty is up if I don't get bored with it.

This is the first 6L80E failure that I have read. Please provide more info, just curious.

Thanks!

 

[Fast55]

There never was a complete "failure". It just shifted like shit and 3-4 dealer flashes and the TSB did nothing to fix it. It would shift OK at WOT (very slow soft shifts while stock), but at part throttle accelerating normally, (99.9% of your driving), it would really slip or "flair" on the 2-3 shift about 30-40% of the time, and even on the 3-4 shift on a few rare occassions. Even the replacement trans does it, but it's not too often. The Black Bear TCM programming has helped, but never made things "right". It always seems to shift just a little too early, too late, too soft, etc. More than anything, it's just not consistent.