4l60e slipping in 3rd and 4th
Thread Starter
TECH Enthusiast
Joined: Apr 2007
Posts: 709
Likes: 2
From: 336 NC
4l60e slipping in 3rd and 4th My 160,000 mile LT1 4l60e is slipping in 3rd slightly. In 4th gear it would not maintain speed. The trans started slipping with no warning while taking off from a light. I was near my home when the slip occurred, so i drove the rest of the way home in 2nd gear. The trans fluid has never been changed since new. My question is.. Could the trans filter be dirty/clogged or should I take the trans and have it rebuilt?
"...... Could the trans filter be dirty/clogged or
should I take the trans and have it rebuilt?"""
^^^^^^^
at 160 k ..."filter be dirty/clogged" ...most likely
at 160 k AND slipping..".should I take the trans and have it rebuilt?.. "
3/4 clutch pack gone... be my guess
would I try filter & fluid ? @ a cost of 38-40.00 per supplies and even @ a small chance of it solving problem, yes I probley try
Johnny
should I take the trans and have it rebuilt?"""
^^^^^^^
at 160 k ..."filter be dirty/clogged" ...most likely
at 160 k AND slipping..".should I take the trans and have it rebuilt?.. "
3/4 clutch pack gone... be my guess
would I try filter & fluid ? @ a cost of 38-40.00 per supplies and even @ a small chance of it solving problem, yes I probley try
Johnny
Joined: Aug 2007
Posts: 24,241
Likes: 89
From: Turnin' Wrenches Infractions: 005
Got a local guy who is looking to get rid of a fresh rebuild 4l60 out of his LT1 car. Might could work out shipping. I have rode in the car since, the trans is legit. The motor spun bearings about 500 miles after the trans was rebuilt 
Send me a pm if you want his screen-name.
Send me a pm if you want his screen-name. 
Teching In
Joined: Jan 2011
Posts: 28
Likes: 0
Typically when you are changing fluid to solve a slip problem it is too late! If a trans is not making third or fourth then it is a 3/4 clutch pack issue. This pack is in the top of the input drum. The 3/4 cluches are well know issue with these transmissions. My suggestion would be to put an upgraded kit in there. A stock 3/4 set has 6 clutches. Raybestos makes whats called a z-pack which alternates steels and cluches on every other side. Also alto makes a kit that has thinner steels and you can fit 9 clutches in there. I typically use the alto kits becuase of price and have seen the z-pack fail alot but also i put a z-pack in my higher hp cars. When building a transmission there is a huge learning curve. These are not like engines where the parts are much more identifiable. I am confident you can rebuild it yourself but take it slow and make sure you buy yourself a book!
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TECH Regular
Joined: Mar 2009
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From: Ricerville
A slipping 3-4 clutch will not, in my experience, set off an SES light. Also, I agree that it's time for a rebuild. Common stock 4L60E/700R4 problem particularly with more than stock horsepower, although it can (and does) happen under stock power as well.
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Teching In
Joined: Jan 2011
Posts: 7
Likes: 0
From: spoakne wa
ya i think its pretty common in the 4l60e. ive had it do that 2 times and it was burnt clutch packs both times. time for rebuild. i would go with a high performance build. my transmission guy had built many of these for race cars and sayd they just dont handle anything over stock power very well.
Staging Lane
Joined: Jan 2014
Posts: 53
Likes: 2
From: Central Tx
how much would it cost for a t56 swap? clutch install, slave cylinder and lines ran as well as new gear box with all the parts sounds like a 3500 dollar job i have a 4l60e and i was looking into maybe doing the same.
i have a 4l60e and i was looking into maybe doing the same. 