Duramax with Hydra-Matic a good combo?
i am used to the duramax and Allison combo in my 2005 Silverado and love it. I need more passenger room. I'm looking at a 2008 express with the duramax hydramatic combo. I know it's not as good as ...
Forum Discussion
I maintain a large fleet of delivery trucks, 29 of which are equipped with LS engines and 6L90E transmissions.
The basic design flaw with the 6L90E is the control unit is part of the valve body.
Think about it, every computer or controller you have has passive or active cooling, whether it's the fan in your PC or the fuel lines running through the ECM on a Detroit Series 60.
The TCM in every 6L90 lives (or dies) in an environment that is 160F at best and can go much higher under load with the converter unlocked.
I have replaced 8 of my 29 transmissions so far, 1 for a broken park pawl (driver abuse). and 7 catastrophically failed when the TCM shorted and engaged an additional solenoid. Visualize a trans brake applied at 60 mph, you get a pan full of large broken pieces. And a tow bill.
I have about 35 older trucks with LS power and 4L80E transmissions, they will give you a slip code when they are worn out, and in our application that's usually around 200k miles. And they just need an overhaul kit, not a lot of hard parts.
Here are the miles at which my 6l90E's failed.
68,574, pan full of metal
72,873, pan full of metal
79,874, happened at idle, had to be towed, conflict between 2 gears but no pan full of metal.
89,533, park pawl driver abuse
129,747, pan full of metal
134,558, pan full of metal
153,484, pan full of metal
186,264, pan full of metal.
To be perfectly fair I still have 21 running with OEM transmission with some approaching 200k miles, I am just alarmed at the high percentage which have failed in such a spectacular and expensive manner.
I also have numerous Allisons behind both Cummins B series diesel and LS gas power, this is by far the best transmission we use, typically going 300-400k miles without issue.
The basic design flaw with the 6L90E is the control unit is part of the valve body.
Think about it, every computer or controller you have has passive or active cooling, whether it's the fan in your PC or the fuel lines running through the ECM on a Detroit Series 60.
The TCM in every 6L90 lives (or dies) in an environment that is 160F at best and can go much higher under load with the converter unlocked.
I have replaced 8 of my 29 transmissions so far, 1 for a broken park pawl (driver abuse). and 7 catastrophically failed when the TCM shorted and engaged an additional solenoid. Visualize a trans brake applied at 60 mph, you get a pan full of large broken pieces. And a tow bill.
I have about 35 older trucks with LS power and 4L80E transmissions, they will give you a slip code when they are worn out, and in our application that's usually around 200k miles. And they just need an overhaul kit, not a lot of hard parts.
Here are the miles at which my 6l90E's failed.
68,574, pan full of metal
72,873, pan full of metal
79,874, happened at idle, had to be towed, conflict between 2 gears but no pan full of metal.
89,533, park pawl driver abuse
129,747, pan full of metal
134,558, pan full of metal
153,484, pan full of metal
186,264, pan full of metal.
To be perfectly fair I still have 21 running with OEM transmission with some approaching 200k miles, I am just alarmed at the high percentage which have failed in such a spectacular and expensive manner.
I also have numerous Allisons behind both Cummins B series diesel and LS gas power, this is by far the best transmission we use, typically going 300-400k miles without issue.
