someotherguy
Truly Awesome
@NickTransmissions - sorry gang for the GMT800-related question but I've got 2 of 'em here and 1 has been giving me fits from the beginning. Bought a 2006 Silverado SS (RWD) LQ9 6.0 / 4L65E from the salvage auction back in late 2015. 80K miles when I bought it, hit in the rear, running and driving.
Gonna write a short novel and apologies in advance, there's a lot to unpack and I may have forgotten some details.
Noticed right away: ridiculously hard 1-2 shift, I mean, gonna break stuff hard. Took it to my local guy and he figured accumulator piston leaking or spring broken. Pulled the valve body and no evidence of problems there but he felt like maybe it had the wrong spring so he changed it. Found the typical check ball worn through the separator plate so he replaced that. New filter and back together. Still has a really firm 1-2 shift but no longer neck-snapping.
Couple years later the transmission croaks, IIRC first time around it was the sun shell grenaded. Lots of ugly noises. He built it for me and all was well for a while.
About a year later? I'm doing about 70 on the freeway and I'm almost home from work, notice the tach jump up a little bit like the converter unlocked. I go ahead and exit and baby it home (another 8 miles surface streets) and when I get to the house it's like the trans is binding up - doesn't really want to go forward very well, and almost won't reverse at all, like it's engaging several gears at once. Take it back to him and he tore it all down and didn't notice any real cause of failure until he saw some play in one of the drums - forgive me, direct drum? I'm no trans expert. He gets it all back together and again, it's fine for a while.
I've lost track now of what the third failure was (I think 3/4 clutches, started slipping on the freeway?) but he built it again. Mind you this guy has been building transmissions for me since the 80's and he's always been top notch, never had an issue with his work until THIS truck. This ongoing ordeal is pretty concerning but he's warrantied the work every time as he stands behind his work, plus we're old friends, but I'm worried it's gonna strain the relationship each time I have to go back.
So he's built the trans again, and it's fine for a while, until one cold morning I'm leaving work and get on the freeway and it flares up for a moment, couldn't even tell you what gear it was in at the time, I was dead tired and just getting started on a long trip home. Babied it home and it didn't happen again but I've been scared to mash the pedal ever since. It's been OK for months until the other day it acted up again but a little different, like it flared on the 1-2 just at part throttle at a gas station and kind of lingered like it wasn't in a gear for a moment, then it was OK. I checked the fluid and it was about 1.5 quarts low, looked OK. I don't see ANY evidence of leaks, pan is still dry, etc. but I added fluid til it shows full at the hot mark.
What the hell is going on with this transmission? The LQ9 is stock, not cammed or anything, but one big question mark is the tune. Since the truck came from the auction it's not like I have any history on what the previous owners have done with it. I really feel like I'm having an unreasonable amount of trouble with this transmission for a stock application that sees just daily driver usage, it's not like I'm street racing people with it. For comparison's sake, I got my wife practically the same exact truck (another 2006 Silverado SS) and the shifts on it are far, far tamer than my truck.
Any ideas? Thanks!
Richard
Gonna write a short novel and apologies in advance, there's a lot to unpack and I may have forgotten some details.
Noticed right away: ridiculously hard 1-2 shift, I mean, gonna break stuff hard. Took it to my local guy and he figured accumulator piston leaking or spring broken. Pulled the valve body and no evidence of problems there but he felt like maybe it had the wrong spring so he changed it. Found the typical check ball worn through the separator plate so he replaced that. New filter and back together. Still has a really firm 1-2 shift but no longer neck-snapping.
Couple years later the transmission croaks, IIRC first time around it was the sun shell grenaded. Lots of ugly noises. He built it for me and all was well for a while.
About a year later? I'm doing about 70 on the freeway and I'm almost home from work, notice the tach jump up a little bit like the converter unlocked. I go ahead and exit and baby it home (another 8 miles surface streets) and when I get to the house it's like the trans is binding up - doesn't really want to go forward very well, and almost won't reverse at all, like it's engaging several gears at once. Take it back to him and he tore it all down and didn't notice any real cause of failure until he saw some play in one of the drums - forgive me, direct drum? I'm no trans expert. He gets it all back together and again, it's fine for a while.
I've lost track now of what the third failure was (I think 3/4 clutches, started slipping on the freeway?) but he built it again. Mind you this guy has been building transmissions for me since the 80's and he's always been top notch, never had an issue with his work until THIS truck. This ongoing ordeal is pretty concerning but he's warrantied the work every time as he stands behind his work, plus we're old friends, but I'm worried it's gonna strain the relationship each time I have to go back.
So he's built the trans again, and it's fine for a while, until one cold morning I'm leaving work and get on the freeway and it flares up for a moment, couldn't even tell you what gear it was in at the time, I was dead tired and just getting started on a long trip home. Babied it home and it didn't happen again but I've been scared to mash the pedal ever since. It's been OK for months until the other day it acted up again but a little different, like it flared on the 1-2 just at part throttle at a gas station and kind of lingered like it wasn't in a gear for a moment, then it was OK. I checked the fluid and it was about 1.5 quarts low, looked OK. I don't see ANY evidence of leaks, pan is still dry, etc. but I added fluid til it shows full at the hot mark.
What the hell is going on with this transmission? The LQ9 is stock, not cammed or anything, but one big question mark is the tune. Since the truck came from the auction it's not like I have any history on what the previous owners have done with it. I really feel like I'm having an unreasonable amount of trouble with this transmission for a stock application that sees just daily driver usage, it's not like I'm street racing people with it. For comparison's sake, I got my wife practically the same exact truck (another 2006 Silverado SS) and the shifts on it are far, far tamer than my truck.
Any ideas? Thanks!
Richard