4L60E delayed 2-3 shift after WOT application?

[Bill 1960]

Hey, all, I am experiencing a delayed upshift from 2-3, but only after a significant period of WOT. I'll try to describe how it behaves:

Normal throttle, say up to 70%, shifts as expected.

Brief application of WOT, shifts down, shifts back up quickly as soon as I let off.

Sustained WOT, as in from a stop OR if I get into it at around MPH and hold it down to 65-70, it will hang in 2nd gear. Let off the throttle by half or so and I don't get the expected upshift. Let off the gas completely or nearly so and it will shift up to 3rd. This would be like your typical freeway merge where you goose it agressively to get up to traffic speed.

And if I just do a WOT run from a dead stop and wind it out, it will shift 2-3 normally at around 5600 RPM. Of course I'm at 80 mph by then, so doesn't apply to most situations, but it does demonstrate the trans will shift at governed RPM from 2-3.

Any theories on the cause and correction? Is this a software or a hardware problem? Or is it normal?
Vehicle is a 2008 SSV (last year of the 4 speed). Only 60k miles, but 10,000 hours, so it spent a lot of time either idling or crawling through the bush (it was operated by the Border Patrol). Carfax says the transmission was "checked" at 34k miles, 8 years ago.

My plans in the near term include changing the fluid and filter, and probably do the servo upgrade with the Corvette servo and perhaps the Sonnax 4th gear servo as well. Is it likely there's just a sticky valve or servo etc. that may be remedied by performing these maintenance items?
Any advice or recommendations is much appreciated.

About my intended use- I'll be lifting and running 33-35" tires, and maybe at times towing a trailer. Those two things make me think the servo upgrades would be a good investment.

(Note to mods; although my truck is a 2008, I placed this in the 200-2006 section because I expect there are more experts on 4L60E here. Please move it if that's not OK)

 

[JonnyTahoe]

I have had the same issue once in a while. I never go more than 5k rpms and have only held it to the floor a few times till it shifts. 10,000 HRS that is more than my Tahoe with 295k.

 

[JonnyTahoe]

Hey, all, I am experiencing a delayed upshift from 2-3, but only after a significant period of WOT. I'll try to describe how it behaves:

Normal throttle, say up to 70%, shifts as expected.

Brief application of WOT, shifts down, shifts back up quickly as soon as I let off.

Sustained WOT, as in from a stop OR if I get into it at around MPH and hold it down to 65-70, it will hang in 2nd gear. Let off the throttle by half or so and I don't get the expected upshift. Let off the gas completely or nearly so and it will shift up to 3rd. This would be like your typical freeway merge where you goose it agressively to get up to traffic speed.

And if I just do a WOT run from a dead stop and wind it out, it will shift 2-3 normally at around 5600 RPM. Of course I'm at 80 mph by then, so doesn't apply to most situations, but it does demonstrate the trans will shift at governed RPM from 2-3.

Any theories on the cause and correction? Is this a software or a hardware problem? Or is it normal?
Vehicle is a 2008 SSV (last year of the 4 speed). Only 60k miles, but 10,000 hours, so it spent a lot of time either idling or crawling through the bush (it was operated by the Border Patrol). Carfax says the transmission was "checked" at 34k miles, 8 years ago.

My plans in the near term include changing the fluid and filter, and probably do the servo upgrade with the Corvette servo and perhaps the Sonnax 4th gear servo as well. Is it likely there's just a sticky valve or servo etc. that may be remedied by performing these maintenance items?
Any advice or recommendations is much appreciated.

About my intended use- I'll be lifting and running 33-35" tires, and maybe at times towing a trailer. Those two things make me think the servo upgrades would be a good investment.

(Note to mods; although my truck is a 2008, I placed this in the 200-2006 section because I expect there are more experts on 4L60E here. Please move it if that's not OK)

What Border was the truck being used at ? That motor has seen lots of heat hopefully they were good with timely oil changes. Post some pics of this truck we want to see it.

 

[Bill 1960]

@jonnytahoe it was a Texas truck from the day it was built in the Arlington plant. There’s some pics here:
https://www.tahoeyukonforum.com/threads/2008-ssv-help-empty-my-wallet.123587/page-2#post-1520269

The engine seems well cared for, fluids all looked good, no blow by, runs quiet.

 

[BentleyArnage]

The weak sister called the 3-4 clutch has excessive clearance. This was the norm from the factory. You need a serious update to the 3-4 clutch pack. 8-9 frictions, kolene steels and a .030 clearance. If you're going to abuse the shit out of it, get the 4L79 3-4 drum that uses turbo 350 clutches and its bolted together. Big bucks, but it's a one time thing.

 

[Bill 1960]

Next week it goes in the tranny shop for diagnosis and service. I’ll report back what they find. Hopefully it’s repairable without pulling it out. It’s been slowly getting worse.

I did get the service records from Chevrolet. Reverse / low clutches replaced at 34k under warranty. Considering the mileage and hours on the unit, first gear is probably where it spent most of it’s time. The positive takeaway is the fluid has less than 30k on it, so that’s not been neglected.

In the spirit of being prepared for come what may, if it needs an overhaul, how many would have an independent shop do the work vs go to the dealership? My understanding is GM reman carry a 3 year warranty coast to coast. Considering we roam the country traveling the chances of being home for any follow up / warranty work is slim. A guarantee from an independent shop in FL is not worth much in TX.

 

[Bill 1960]

Independent transmission shop says it needs a rebuild based on some clutch debris in the pan. Not too confident in their diagnosis, it feels a bit like they’re just giving me a default outcome without really getting into the particulars of the reluctance to up shift. Once it shifts, it doesn’t slip in any gear.

It’s going to the dealership for a second opinion. If they confirm it I’ll have a GM reman put in. Three years/ 100k for about $3k installed.

The independent guys offered me several options; if they did it in house it would start at $1700 with a 12 month warranty. And go up from there to be the same price as GM for the same trans; so may as well have GM do the whole job if it comes to that.

 

[Bill 1960]

Final outcome is to replace with a reman from the GM dealer. Not too happy to do this at 61k miles, but it is what it is.

I don’t get the impression that either shop that’s seen it is interested in a repair per se. All they want to do is exchange the whole unit. If I were in their shoes I’d probably do the same. Maximize the profit and pass the risks off to the reman suppliers.

 

[sonic_the_hedgeh]

Hey, all, I am experiencing a delayed upshift from 2-3, but only after a significant period of WOT. I'll try to describe how it behaves:

Normal throttle, say up to 70%, shifts as expected.

Brief application of WOT, shifts down, shifts back up quickly as soon as I let off.

Sustained WOT, as in from a stop OR if I get into it at around MPH and hold it down to 65-70, it will hang in 2nd gear. Let off the throttle by half or so and I don't get the expected upshift. Let off the gas completely or nearly so and it will shift up to 3rd. This would be like your typical freeway merge where you goose it agressively to get up to traffic speed.

And if I just do a WOT run from a dead stop and wind it out, it will shift 2-3 normally at around 5600 RPM. Of course I'm at 80 mph by then, so doesn't apply to most situations, but it does demonstrate the trans will shift at governed RPM from 2-3.

Any theories on the cause and correction? Is this a software or a hardware problem? Or is it normal?
Vehicle is a 2008 SSV (last year of the 4 speed). Only 60k miles, but 10,000 hours, so it spent a lot of time either idling or crawling through the bush (it was operated by the Border Patrol). Carfax says the transmission was "checked" at 34k miles, 8 years ago.

My plans in the near term include changing the fluid and filter, and probably do the servo upgrade with the Corvette servo and perhaps the Sonnax 4th gear servo as well. Is it likely there's just a sticky valve or servo etc. that may be remedied by performing these maintenance items?
Any advice or recommendations is much appreciated.

About my intended use- I'll be lifting and running 33-35" tires, and maybe at times towing a trailer. Those two things make me think the servo upgrades would be a good investment.

(Note to mods; although my truck is a 2008, I placed this in the 200-2006 section because I expect there are more experts on 4L60E here. Please move it if that's not OK)

I have a 2004 gmc yukon denali xl with a 4l65e. It is very similar. I have about the same problem if I let off the throttle it shifts fine. So I ordered a transgo kit to fix the problem.

Today I went to a trans shop and they had a guy from the shop test drive with me. He said you don't have a second gear bands must be worn out. Yet all I know is it cannot shift into second gear. Plus on this forum there was at least one person with the same symptoms as me and it fixed the shifting fine.

Any ideas? The guy that was with me said they wouldn't install a kit like this because I would burn out the bottom of the trans.

He said I need a rebuild. Yet I have doubts since another 2 people I did see had problems like this and the transgo kit fixed it.

Any ideas? He could not confirm why it can't shift into second. There are possibilities but this is an Allison and I hope I can get this kit installed to find out.

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