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2006 4L60E... engine braking and 1-2 shift

483 Views 1 Reply 2 Participants Last post by  1979Malibu
First question: My 06 Express Van doesn't seem to have much engine braking. Is that something that is part of the software, or something about the hydraulics? Is there a fix for it? I don't need anything crazy, but it just seems to drop RPMs off-throttle a lot more than what I would expect from the normal TC stall/slip.

Second: Am I correct that the 1-2 shift is controlled by the servo, the solenoid, and the valve it controls? My 1-2 shift is sluggish. You can feel it start the shift, then it sometimes takes a second or so for it to "settle" into second. No other slipping and the RPMs don't flare, but I gotta think that the 2nd clutches are taking a lot of extra heat, especially when towing the boat (3500 lbs-ish). Important side note... I've never noticed the delayed shift happen when in tow/haul mode. I'm just trying to fix it while it's still a valve body/servo issue and before it's a fried clutch issue. Right now it feels very much like a hydraulic issue and not a clutch issue.

I've been considering a valve body/shift kit anyway, so adding a corvette servo would just be a small bag of quarters, just wanted to be sure that I'm barking up the right tree. Thoughts?
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1979 Chevrolet Malibu 496-TH400-9" (cruiser). 1992 Chevrolet S10 355-700r4-7.625" (daily driver).
494 Posts
It won't have engine braking in OD as the overrun clutches don't (and shouldn't) apply there. Your foot off the gas would likely activate the lock up in the torque converter and cause the RPM to drop.

2nd gear is a band (also called the 2-4 band) that applies to the reverse input drum. It releases as the 3rd gear clutch is activated and then reapplies for 4th gear (OD) while the 3rd gear clutch (also called the 3-4 clutch) stays applied. The drum and the band see some wear with use.

As you suggested a number of things happen for the 1-2 shift. When you're towing, the extra throttle might make the shift happen with more pressure and cover up the delay you may have at light throttle???

The kit in the link along with the Corvette servo should do your 4l60e some nice benefits. The instructions indicate how and where to tighten up the clearance for that 2-4 band. The Corvette servo helps with 2nd gear apply and helps the 2-3 shift improve.

Stay on the conservative side with the hole sizes (in the directions with the kit) and you should be good. It has been a while since I got into a 4l60e and I'm sure I'm leaving something out. If any of this is incorrect, hopefully one of the far more knowledgeable folks can chime in.
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