4L60E problems

Croatan_Kid

Croatan_Kid

How's your hammer hangin'?
Joined
Nov 4, 2007
Location
New Bern
I just did a full rebuild on a 4L60E for a buddy. He bought the truck from me and I had bought several parts which were included in the sale. The majority of which were transmission rebuild parts and a new torque converter. It was a "Monster in a Box" kit and the converter came from them as well.

Before the rebuild, it had burnt 3rd gear, wouldn't skip it and go to fourth. The band looked fine and so did all of the other clutch packs. Good enough.

I pulled it down, cleaned the hell out of everything, replaced most of the soft parts (seals, o rings, etc), it even got a new valve body! The Monster stuff comes with new sprags, the pump rebuild stuff, and all of the usual upgrade stuff. It all went together as well as I expected, just as they have in the past transmissions I have built. The only difference is this is the first 4L60E I have done, the rest have been 700R4s.

Long story short, filled the converter, put the trans back in the truck after an all-nighter, filled the pan, fired it up and kept adding accordingly. Moment of truth! The truck was on a lift, no tires on it, shifted through all the gears and they worked. So I let it run through the gears. I get up in to third. We throw the tires on it, drop it down and back out.

Once I put it in "D", it won't move. 3 and 2 are the same. I have Reverse and manual 1. I also read a PO748 with my HP Tuners VCM scanner. I tried to use that to command 1st, 2nd, and 3rd gears and nothing wanted to work. It would lock the converter clutch though. If I took off down the road I could get it to jump from 1st to 3rd, but that was it. That made me think it was a band or 2/4 servo problem, but it only works when I pull it down to 1. That would make me think it was a broken sprag, but I just replaced them and check their operation prior to installation.


Any ideas guys? I'm tired of driving 40 miles each way to work on this damn thing, it's really starting to kill my weekends, money, and at this point it's personal. I'm gunna kick this transmissions ass in to submission and it's going to like it. This thing should bark the tires on a WOT 1-2 shift.
 
if it was the input sprag it would still have 3rd and 4th it just wouldn't pull on takeoff in od. if it has third and no fourth it is a band/servo issue (also no second), but still doesn't explain why it will only take off in manual low. the p0748 is a pressure control solenoid code so that could be part of the issue .

was the servo checkball capsule changed or checked?
how many checkballs did you put in the vb?
were the stator bushings ok or did you replace them?
did you replace the input shaft sealing rings?, if so how did you resize them?
 
It called for all of the checkballs to go back in except for two. One on the VB side was to be left out, the other was in the case and under a retainer of sorts. Just to the right of the accumulator bore.

The bushings looked fine, as did the shaft seals.

I guess the first thing I'm going to do is pull the pan for a visual inspection and go from there.
 
I believe i put the input sprag in backwards. The kit came with both sprags. I can see that as an easy mistake to make.
 
I take that back, the reverse roller clutch wasn't grabbing. It was free spinning in both directions. Took it apart, flipped it over, and now it grabs like it's supposed to. That'll damn sure do it. I had actually put the input sprag in correctly.
 
That's what I read everywhere else too. I had the tabs/teeth of the cage upwards (looking down in the trans) like every one I could find online, but it wouldn't grab like it was supposed to. It could spin with the same resistance in either direction, I knew it should be a strong grab and only operate in one direction. Off the top of my head, I don't remember that I actually flipped it over, but I may had had it oriented wrong in the steps/detents in the outer "race". My lack of sleep is catching up to me. It certainly works now though. I realized it was wrong as soon as I noticed I could spin the sunshell either direction with everything prior to it removed.

The guy kept pushing me to get it done with no sleep and got a little ill when I make an "ooops!". I'm sure we both know that lack of attention to detail doesn't mix well with a properly functioning automatic transmission :D It was a fuster cluck. I'm waiting on the "It works!" text and hopefully not the "get back over here" text.
 
Croatan_Kid said:
I take that back, the reverse roller clutch wasn't grabbing. It was free spinning in both directions. Took it apart, flipped it over, and now it grabs like it's supposed to. That'll damn sure do it. I had actually put the input sprag in correctly.
Click to expand...
The first one i ever messed with i took apart and put it back together about 50 times trying to make sure i had it right.

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It had been a while since I was in a GM auto. This was also the only time I got a good rebuild kit that came with all of those parts. Good news is he drove it today and it did great. I still need to go back over and do some tweaking on the shift timing, firmness, and shift points though. I'll probably wind up fine tuning the stock ecm too while I'm there. I'll have to license it anyway with HP Tuners.
 
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