is it possible/what would it take ?

[zach2011]

It's a good idea once your engine goes out, certainly, but if you're just gonna do it for fun then it's too much trouble. BUT, since you're planning on doing this once the 4-speed goes out, I'd say go for it.

 

[wheatswake]

thats my plan i thought alot of others with a 07/08 would agree or at least give them an option when the time comes

 

[zach2011]

You should be able to do it, my dad took his 2008 Denali's 6.0 liter motor and put it in a 96 ford bronco, and got it to work. So putting one in a Tahoe should be very possible.

 

[wheatswake]

You should be able to do it, my dad took his 2008 Denali's 6.0 liter motor and put it in a 96 ford bronco, and got it to work. So putting one in a Tahoe should be very possible.

i was not really wondering anything about a 6.0 liter motor. i was asking about a 6sp transmission on a 5.3 motor for an 07/08 tahoe/yukon. is it possible and what does it take? i would think its possible because they are doing it now in the 2010 if i am not wrong. but no real answers here so far. maybe down the road someone will try it and see what it takes to do it for an 07/08.

 

[badtothe bone]

Someone here is thinking again with 1955 technology.

There are some pretty big reasons for not wanting to swap a 4 speed transmission for the 6 speed transmission, none of which has anything to do with saving money or gas mileage.

The problems you are going to run into, besides the fact that the transmissions are different and the transfer cases are different and the electronics’ are different and the wiring harnesses are different and the mechanicals are different is going to be the price.

The last 4L60E transmission I bought at the junk yard with supposedly 40,000 miles on it, cost me $500

The six speed transmission you are looking at is going to cost $1500

The problem is - it is just too new. There are not a lot of good used units out there to be able to just walk into a junk yard and give them $100 and come home with a good unit. It is going to cost you 4 times as much to take your old transmission out and put the new transmission in. Even then it probably won't work and you are going to have to spend another $1000 on top of that - just to try to upgrade your old vehicle into a newer vehicle.

The six speed transmission has not been out long enough for us to really know what is going to go wrong with it and what it's strong and weak points are. But you will not see any real improvement in gas mileage with that transmission.

The only difference between a 4 speed and a 6 speed is that the 6 speed has more forward gears in it. The final drive gear ratio is the same.

I actually don't see any advantage to the 6 speed, unless you wish to run faster gears, which is the reason they put the 6 speed in the truck in the first place. The lower first gear helps it to pull out. It just offsets the regular 3:73 final drive gear ratio and allows you to run 3:42 or 3:23 gears and yet the truck will still feel like as if it has the deeper gears in it.

The 6 speed transmission does not spend a lot of time in any one gear unless you are puttering around town. Even then, it hunts for the right gear all the time and when the engine starts to lug, it down shifts one or two gears and the engine roars and yet the vehicle is not moving much faster.

It is ok where you have the newer style engine that only runs on 4 cylinders at highway speeds, but for around town, there is no advantage.

Go to a rent a car place and rent a new Chevy Truck, Tahoe or a Avalanche for a weekend or for a week and see if you can feel that there is something of value there before you plan on spending thousands of dollars on something you really don't need.

My guess is, if you keep the fluids and filters changed on the automatic transmission you presently own, it will last as long as the vehicle. There is no expiration date on your old transmission and just because other people has had a problem with them in the past, doesn't mean that you will have a problem with yours.

 

[Zed 71]

It looks like 6-speed issues are now starting to pop up. This is from Fast55s thread in the performance section - keep in mind that the dealer completed the TSB and the issue has not gone away and new ones popped up. Other forums are noting similar problems with the 6-speed and 5.3L; however, I do not think those have TSBs out yet.

Thread->
It just had the "repair" for TSB #09-07-30-004A done. It's specific to the 6 speed trucks with the 6.2, Denali, Escalade or Tahoe. I saw the TSB at the dealer and it's exactly the problem my truck has. On the 2-3 shift, especially before it's completely warmed up, it would almost feel as if it hit neutral for a second. The TSB describes rough shifting or "flair" on the 2-3 shift. Supposedly due to leaking clutch fluid seals on the input shaft. Obviously they had to pull the entire trans/transfer case. Now, even the 1-2 shift seems to have this problem (slight, but there), and the 2-3 shift is even worse. It's not every time it shifts, but at very light throttle, almost every time. This cannot by good for the bands. Do you think programming could help with this? I'm not sure what they intend to do since the TSB work was already done.

 

[wheatswake]

ok i have changed my thinking towards it now. thanks for giving factual reasons for not wanting to do it. some of the things you wrote make alot of sense i.e. 6sp trans is very new(don't know everything about it), so far we have heard it has a tendency to want to change gears alot of the time, the final gear ratio is the same (no gain in mpg most likely). some things might not be to big a deal. maybe down the road they might make plug and play harness unions (like for the stereos now days) to make the 6sp swap out possible (without this its useless to try), i would think 4 or 5 yrs from now one could prob get a good deal on a 6sp and driveshaft(new or salvage) so cost could be around the same amount, no transfer case worries for me (2WD), . i was thinking the advatage would be better mpg (but most likely not) and a tougher trans (since it has been mentioned that they are built better than the 4l60e and everyone knows the 4l60e is not the greatest trans). i will just see when mine eventually goes out (i plan on having my tahoe for a long time), but overall i hear you and agree.

 

[badtothe bone]

It looks like 6-speed issues are now starting to pop up. This is from Fast55s thread in the performance section - keep in mind that the dealer completed the TSB and the issue has not gone away and new ones popped up. Other forums are noting similar problems with the 6-speed and 5.3L; however, I do not think those have TSBs out yet.

Thread->
It just had the "repair" for TSB #09-07-30-004A done. It's specific to the 6 speed trucks with the 6.2, Denali, Escalade or Tahoe. I saw the TSB at the dealer and it's exactly the problem my truck has. On the 2-3 shift, especially before it's completely warmed up, it would almost feel as if it hit neutral for a second. The TSB describes rough shifting or "flair" on the 2-3 shift. Supposedly due to leaking clutch fluid seals on the input shaft. Obviously they had to pull the entire trans/transfer case. Now, even the 1-2 shift seems to have this problem (slight, but there), and the 2-3 shift is even worse. It's not every time it shifts, but at very light throttle, almost every time. This cannot by good for the bands. Do you think programming could help with this? I'm not sure what they intend to do since the TSB work was already done.

The problem is not with the computer software, it is with the seals that they incorporated into the transmission, the change in fluid and the warm up procedure.

With GM's 100,000 mile warranty - who cares how long the transmission lasts, GM will have to pay to fix it the first 100,000 miles and by the time the truck gets 100,000 miles on it, you will probably trade it in on something newer and it will be the next persons problem. I can drive the new Avalanche 20 miles and the transmission temperature might not get above 120*F when it is cold outside.
You need the heat in the transmission to burn off the moisture inside of the transmission.

 

[Zed 71]

The problem is not with the computer software, it is with the seals that they incorporated into the transmission, the change in fluid and the warm up procedure.

Uh, no kidding, that was in the thread.