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Discussion Starter · #1 · (Edited)
I rebuilt the 4L60E tranny in my 96 suburban about 1 1/2 years ago. Followed the ATSG Manual using a quality rebuild kit. Made a few performance mods. Shift kit, New Converter, etc. "Seemed" to run fine for a year or so, although I never pushed it very hard. Currently it shifts 1st, 2nd, and reverse but sometimes ( more often than not ) when it shifts to 3rd there is nothing there. as if it goes into neutral. The truck has 4.88 gears and 37" tires. The speedometer works but is not calibrated for the gear/tire mods. Also the gear selection indicator lights don't always work or don't work correctly. Does this look like a minor electrical/servo/calibration problem or is it more likely a major internal issue?
 

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I rebuilt the 4L60E tranny in my 96 suburban about 1 1/2 years ago. Followed the ATSG Manual using a quality rebuild kit. Made a few performance mods. Shift kit, New Converter, etc. "Seemed" to run fine for a year or so, although I never pushed it very hard. Currently it shifts 1st, 2nd, and reverse but sometimes ( more often than not ) when it shifts to 3rd there is nothing there. as if it goes into neutral. The truck has 4.88 gears and 37" tires. The speedometer works but is not calibrated for the gear/tire mods. Also the gear selection indicator lights don't always work or don't work correctly. Does this look like a minor electrical/servo/calibration problem or is it more likely a major internal issue?
Have you pulled the valve body to ensure all the valves are moving without obstruction? Sometimes, even the smallest bit of debris can keep the tranny from shifting.
 

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Thanks for the reply. I haven't started working on it yet. Trying to figure out what the most likely issues are before tearing into it. Doesn't seem like there would be a problem related to debris unless something is going wrong internally. I drove it some this weekend and found that when I take it really easy, it wont engage 3rd at all. But when I accelerate more agressively it will shift. Although it doesn't feel right. Llike it doesn't want to stay engaged. Thinking I might take it to a shop and have an experienced trans guy take it for a drive.
 

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Thanks for the reply. I haven't started working on it yet. Trying to figure out what the most likely issues are before tearing into it. Doesn't seem like there would be a problem related to debris unless something is going wrong internally. I drove it some this weekend and found that when I take it really easy, it wont engage 3rd at all. But when I accelerate more agressively it will shift. Although it doesn't feel right. Llike it doesn't want to stay engaged. Thinking I might take it to a shop and have an experienced trans guy take it for a drive.
Well, I'm no expert, however, when you put it that way, it brings me back to my first statement about the valve body. Transmission fluid pressure increases when you're driving more aggressive. At least, thinking of physics here. So it makes sense. Something is sticking in the valve body. Whether it be a valve or faulty check ball...
 

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Thanks again. That's pretty easy to look at. At least I know what I'll be doing my next day off.
You say you rebuilt it yourself, so you should know how much of a mess those check balls can be. It's much different when the tranny is installed when you pull the valve body off, rather then when the tranny is upside down on a bench. Just remember to be easy when you take the valve body off, and if you decide to pull the separator plate, which is recommended since you'll be breaking the gasket bond when you take it off, be sure to let the separator plate down as gently as possible to keep those check balls in their proper locations. I would inspect the plate to see if there are any burrs where the balls seat, and also check to see if the valves are moving as they should. Good luck with it.
 

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Line Pressure/ Burnt clutches?

Sounds like a leak to me in the 3/4 area, pistons might be ok - their is an o ring in the input drum that needs replaced and oftern gets overlooked in which can cause a major leak, the input drums are also know for being cracked. Clutches might be smoked. Install a line pressure gauge and check pressure. Does it work cold and go away hot? Fluid level? Etc?

Sounds like an internal leak or burnt 3/4 clutch pack.
 
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