2008 Yukon Denali Transmission Swap

[ford141]

My transmission is on its way out in my 2008 Yukon Denali. For several years it has had a delay going into reverse, and for the past year it has had a flare on the 2-3 shift. Now, for the past month or so it has had a 1-2 second delay and slippage on the 4-5 shift, especially first thing in the morning. I have been letting off the throttle on the 4-5 shift because it feels like it wont catch. I know its days are numbered, it's only a matter of time.

Currently funds are pretty tight, and with 175K on the Yukon, which is only valued at $6-8K, I can't see putting $3k into a new transmission. I'm thinking a used takeout is my best option at $1100-1500. My question is, what years will swap directly into my 08? I've narrowed my search to only Denalis and Cadillacs with the 6.2 6L80e, but can i swap in anything from 07-14? I know the 09-up had DOD, but I'm not sure if that affects the transmission. I've heard there were refinements to the later 6l80s, so I'd prefer newer if I can as long as it will swap directly in and work with my computer.

Any help is appreciated. I'm limping mine along for now but I'm afraid I only have a few months before 5th goes completely.

 

[wjburken]

My transmission is on its way out in my 2008 Yukon Denali. For several years it has had a delay going into reverse, and for the past year it has had a flare on the 2-3 shift. Now, for the past month or so it has had a 1-2 second delay and slippage on the 4-5 shift, especially first thing in the morning. I have been letting off the throttle on the 4-5 shift because it feels like it wont catch. I know its days are numbered, it's only a matter of time.

Currently funds are pretty tight, and with 175K on the Yukon, which is only valued at $6-8K, I can't see putting $3k into a new transmission. I'm thinking a used takeout is my best option at $1100-1500. My question is, what years will swap directly into my 08? I've narrowed my search to only Denalis and Cadillacs with the 6.2 6L80e, but can i swap in anything from 07-14? I know the 09-up had DOD, but I'm not sure if that affects the transmission. I've heard there were refinements to the later 6l80s, so I'd prefer newer if I can as long as it will swap directly in and work with my computer.

Any help is appreciated. I'm limping mine along for now but I'm afraid I only have a few months before 5th goes completely.

I would suggest you find a trusted transmission shop and have them look at it to see if it would make more sense to try and fix what’s wrong with your current transmission. You may find that for about the same money, they can go through your transmission and replace what’s needed and you will know what you versus a used one.

 

[Big Mama]

Others will chime in I believe you have a 6L80E. Try searching for that. I don’t think it changed until 2012 or 13. Have you gotten a quote on doing a rebuild? Don’t throw out the baby with the bath water. Spend to fix it or have car payments. Easy choice if the rest of the rig is good.

 

[ford141]

Yes, I do have the 6L80e. There are technical bulletins everywhere that describe the exact problem that I have, which are delays in reverse engagement, flares in 2-3, and 3-5. All indications are that the rev/3/5 drum is cracked, which is a common issue with 07-08 6l80/6l90 trans. Requires replacement of the drum. I believe paying a shop to remove/tear-down and rebuild my trans will be cost prohibitive for me at this time, which is why I'm considering the used route. If I can swap in a 09-13 trans that would be great, but I don't know if it will swap directly.

https://atracom.blob.core.windows.net/gears/2011/2011-12/2011_12_20.pdf

 

[swathdiver]

My transmission is on its way out in my 2008 Yukon Denali. For several years it has had a delay going into reverse, and for the past year it has had a flare on the 2-3 shift. Now, for the past month or so it has had a 1-2 second delay and slippage on the 4-5 shift, especially first thing in the morning. I have been letting off the throttle on the 4-5 shift because it feels like it wont catch. I know its days are numbered, it's only a matter of time.

Currently funds are pretty tight, and with 175K on the Yukon, which is only valued at $6-8K, I can't see putting $3k into a new transmission. I'm thinking a used takeout is my best option at $1100-1500. My question is, what years will swap directly into my 08? I've narrowed my search to only Denalis and Cadillacs with the 6.2 6L80e, but can i swap in anything from 07-14? I know the 09-up had DOD, but I'm not sure if that affects the transmission. I've heard there were refinements to the later 6l80s, so I'd prefer newer if I can as long as it will swap directly in and work with my computer.

Any help is appreciated. I'm limping mine along for now but I'm afraid I only have a few months before 5th goes completely.

Too bad you didn't say something here sooner. More often than not, the first thing these transmission need is their solenoids rebuilt, not a complete overhaul. I would not recommend a junkyard transmission but the improvements came midway through 2009 but that will not affect anything that I'm aware of, the computer is built into the transmission so if you change it, it will have to be programmed to your truck. The tail cone can be swapped to make a RWD trans work for AWD and visa versa.

The shop manual covers those gripes you mentioned, what causes them and how to fix them, AllDataDIY.

 

[ford141]

Too bad you didn't say something here sooner. More often than not, the first thing these transmission need is their solenoids rebuilt, not a complete overhaul. I would not recommend a junkyard transmission but the improvements came midway through 2009 but that will not affect anything that I'm aware of, the computer is built into the transmission so if you change it, it will have to be programmed to your truck. The tail cone can be swapped to make a RWD trans work for AWD and visa versa.

The shop manual covers those gripes you mentioned, what causes them and how to fix them, AllDataDIY.

I've always heard that these transmissions are not real smooth shifting and have some quircks, so I hadn't put much thought into the issues until the 5th gear issue just started to crop up. I've owned it for 5 years and bought it with 125K, and reverse has been slow engaging since then. Thought it was normal. Since the 5th gear issue, I started searching for answers and found the bulletin for 3/5/rev drum issues.

 

[swathdiver]

I've always heard that these transmissions are not real smooth shifting and have some quircks, so I hadn't put much thought into the issues until the 5th gear issue just started to crop up. I've owned it for 5 years and bought it with 125K, and reverse has been slow engaging since then. Thought it was normal. Since the 5th gear issue, I started searching for answers and found the bulletin for 3/5/rev drum issues.

No, that's not been my experience. Mine runs like a top as does most of the other guys here. Also had it tuned along with the engine to perform better. How many times have you serviced the transmission and how old is the fluid in it now?

 

[ford141]

No, that's not been my experience. Mine runs like a top as does most of the other guys here. Also had it tuned along with the engine to perform better. How many times have you serviced the transmission and how old is the fluid in it now?

I don't have the service records from before I bought it, but I changed the fluid/filter at about 170K. Both fluid and filter were clean.

 

[Big Mama]

As James stated I haven’t really heard a lot about trans problems or rough shifting. Unfortunately we never know the history of a used rig in most cases. The only way I’d get one used is with a warranty and have it checked before installing and rebuilding the solenoid mentioned. It’s a bite in the budget but as the truck sits today you won’t get much for it. Tough call to make.

 

[ford141]

So, I think I will try the solenoid rebuild before I give up totally on this trans. Worth a shot for $100. If I can get rid of the delay in the 4-5 shift I'd be happy. Not sure it will fix it but better than swapping the trans.

 

[thompsoj22]

ivs got the same vehicle at 139k miles. trans is still working great but when it starts acting up i intend on rebuilding it myself for approx $2,500 and that will include a new converter/tehcm. The 6L80E is really a rebuilders dream as they are somewhat simple. Just my opinion but dropping the tehcm and installing the "films" on the solenoids is a good idea if you were going to rebuild the trans but not as a cure for your issues. spend the hundred on a "trusted" diagnosis from a "hundreds of good reviews" trans shop. does it act any differently stone cold as opposed to op temp? the shop can diagnose faults/pump pressure but not the cracked/leaking drum which would require the teardown. junkyard trans, unknown condition. your trans has survived 175k miles and still going. i would opt for the rebuild with a solid warranty. anyway, it is no fun to have to deal with major repairs when cash is tight! hang in there.

 

[ford141]

ivs got the same vehicle at 139k miles. trans is still working great but when it starts acting up i intend on rebuilding it myself for approx $2,500 and that will include a new convertor/tehcm. The 6L80E is really a rebuilders dream as they are somewhat simple. Just my opinion but dropping the tehcm and installing the "films" on the solenoids is a good idea if you were going to rebuild the trans but not as a cure for your issues. spend the hundred on a "trusted" diagnosis from a "hundreds of good reviews" trans shop. does it act any differently stone cold as opposed to op temp? the shop can diagnose faults/pump pressure but not the cracked/leaking drum which would require the teardown. junkyard trans, unknown condition. your trans has survived 175k miles and still going. i would opt for the rebuild with a solid warranty. anyway, it is no fun to have to deal with major repairs when cash is tight! hang in there.

I agree that rebuilding is the best route, and I'd love to do it myself (did the C6 in my street truck 10 years ago, still working great), but I don't have the time to do that with this Yukon since it's my daily. I also don't know of any reputable trans shops around here anymore, most of them have went out of business years ago. I did have the local GM dealer look at it a few years ago for a rough downshift issue that it has always had, and they retuned the software which helped but did not cure the problem. Still to this day (and for the last 50K miles of ownership) it likes to stay locked in 6th when you start up a hill and will start lugging the motor and loosing speed while you roll into the throttle. After loosing some speed, the transmission with abruptly downshift to 4th, which jolts the drivetrain and shakes the whole truck. Doesn't do it all the time, but just when you think it won't, it willl. Never any codes.

As far as the slow 4-5 shift that has just started, it only happens in the morning when the trans is still cold. Usually the trans temp is between 80-100F degrees by that part in my commute. I don't notice it after the trans warms up (although in cold weather it never goes above 120F).

 

[Big Mama]

Eric, does it do the same thing if you shift manually?

 

[ford141]

Eric, does it do the same thing if you shift manually?

Yes it does. I have started shifting manually when I leave in the morning so I can leave it in 4th until I crest the top of the hill and the load lightens. Then I shift into 5th on the downhill. The shift is still delayed but it's easier on the clutches when it finally catches.

 

[tgui]

I'm looking forward to your updates on trying solenoids.

I know you want to save up but a full valve body replacement could be done. Not only solenoids, but seals and other parts in the valve body can go bad.

I'm eyeing something like this from Sonnax

https://www.ebay.com/itm/For-Chevy-...560491&hash=item420da5dc61:g:7WAAAOSwElpd5T74

 

[Derick]

See if you can find a donor truck or van....grab the trans out of it and sell the remainder as a parts vehicle. Might get your money back.

WatchJRGo did that to get a 4l80e that hes putting in this rolls....

 

[thompsoj22]

I agree that rebuilding is the best route, and I'd love to do it myself (did the C6 in my street truck 10 years ago, still working great), but I don't have the time to do that with this Yukon since it's my daily. I also don't know of any reputable trans shops around here anymore, most of them have went out of business years ago. I did have the local GM dealer look at it a few years ago for a rough downshift issue that it has always had, and they retuned the software which helped but did not cure the problem. Still to this day (and for the last 50K miles of ownership) it likes to stay locked in 6th when you start up a hill and will start lugging the motor and loosing speed while you roll into the throttle. After loosing some speed, the transmission with abruptly downshift to 4th, which jolts the drivetrain and shakes the whole truck. Doesn't do it all the time, but just when you think it won't, it willl. Never any codes.

As far as the slow 4-5 shift that has just started, it only happens in the morning when the trans is still cold. Usually the trans temp is between 80-100F degrees by that part in my commute. I don't notice it after the trans warms up (although in cold weather it never goes above 120F).

Now im just guessing, Ill say your converter is failing, If im not mistaken the converter should "unlock" as the rpm drop when climbing, this is a function of the converter and requires no electronics it is simply rpm/load related. you will notice a slight increrase in rpm as it unlocks, if the "lug/hill" continues the computer will initiate a downshift.your converter dosent seem to be unlocking by your decription? If you do the solenoid films you will be removing the tehcm from the trans, there is a filter associated with the tehcm, there maybe debris there causing shift problems. imo your shift problems should be worse as the trans fluid gets to op temp? get back with your results as the info you provide helps others when it is their turn.