nowhereguy

I rebuilt a 4l60e, first time. The problem I'm having is if I put it in drive it just slips and wont move but if I start by putting in low is shifts fine. I can shift out of low to drive after maybe 10 mph and it goes thru the gears up and back down unless I make a complete stop then it repeats the problem. Any help would be appriciated, I'm kinda lost

FirstYrLS1Z

iTrader: (4)

https://ls1tech.com/forums/automatic...knows-why.html

nowhereguy

Thank you,
That does sound like the problem I'm having.

silverz28camaro

iTrader: (20)

Did you replace the sprag? If so possibly installed backwards and overruns when it should grab

nowhereguy

I took it back apart today. The sprag turns freely clockwise and locks counter clockwise. I disassembled it and all looks fine. Lost again. Could the low / reverse one down it the bottom cause that? Does anyone know what the line pressures should be?

silverz28camaro

iTrader: (20)

how are you looking at the sprag when bench testing it...if you flip it then it will free spin the opposite way..

with the sungear side facing up the outer race should free spin clockwise as you stated....did you take it apart? a bad spray could slip under engine load but feel fine by hand...take it apart if you havent

also check the forward acc. pison in the valvebody for cracks or pin wear

also make sure that flat manifold pressure switch has all the o-rings that help it seal to the valvebody

mrvedit

Stock line pressure is around 60 in Park/Drive at idle, and around 90+ in Reverse. Pressure will go higher when you give throttle.
With a Boost valve, pressure will typically be 50% higher.

art vandelae

I just rebuilt my daughters 4l60e and I'm having the same exact problem. After doing some research I felt like I must have installed the forward sprag backwards. That seemed like the most probable cause of our problem. Well I just pulled the tranny out and checked my sprag and it was installed correctly.(per ATSG book purchased after the fact) I too disassembled it and it appears to be fine. Have you been able to figure what the problem is yet? I'm at a loss. I did motor swap on her Blazer, the tranny was fine before but since I had the motor out there was no way I was going to put a newer motor in it with a tranny with 175,000 miles. Now I wish I left it alone! No good deed goes unpunished!
This was my 1st 4160e but I did my 4l80e 5 years ago and its still doing great. (probably shouldn't have said that) LOL

art vandelae

Not sure if anyone is still looking at this thread or not but today I checked the lo/rev roller sprag and it is definitely bad! I don't know how it got by me or it may have crapped out during my test drive, but it spins freely both directions. I'll pick up a new one and post my test drive results this weekend weather permitting.

mrvedit

I'm following this thread and finding it very educational; of course I am sorry for your troubles. Sounds like you have figured it out. Good luck and keep us posted.

art vandelae

YES IT CAN!

I just got my daughters 4160e back together and test drove it and it works perfectly! The lo roller sprag was the sob that was the cause of my pain. Glad its all over! Woo Hoo

mrvedit

Thanks for the info and your trouble has my sympathy. I will now be sure to replace the low sprag on every rebuild. (I'll confess I didn't replace it on my 2010 rebuild, but that tran only had 2000 miles on it.)

maddoglou454

27 years of doing this and every once in a while they will drive you crazy. Sometimes everything checks out fine, and it's just a defective sprag and it still looks perfect like it did when you install it. But it sure feels good when you finally fix it and the crazy thing is, it Dyno tested perfect on some occasions. Go figure.