4l60
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
Tell us more about what year, model and mileage you are thinking of.
I would avoid anything '94 or '95 as IMHO those were the alpha-test and beta-test years.
Over 400 crank HP you probably want a performance rebuild, especially if over 100,000 miles. A stock 4L65E from 2003+ can handle 450 crank HP.
I would avoid anything '94 or '95 as IMHO those were the alpha-test and beta-test years.
Over 400 crank HP you probably want a performance rebuild, especially if over 100,000 miles. A stock 4L65E from 2003+ can handle 450 crank HP.
TECH Junkie
Joined: Jul 2015
Posts: 3,012
Likes: 48
plenty of them survive just fine right into high mileage. I think its when you go beyond bolt ons that its time to think about upgrades. Theres guys running tens on stock trannys I am sure but that is asking for trouble , 12's not a problem at all I think its how deep in the 11's you go that is the threshold for reliability of breaking hard parts and slipping clutches.
They will of course last longer if you add a cooler and a couple minor upgrades shift kit , upgraded servo etc.. they also prefer to be slightly overfilled and left in OD vs. manually shifting when drag racing.
They will of course last longer if you add a cooler and a couple minor upgrades shift kit , upgraded servo etc.. they also prefer to be slightly overfilled and left in OD vs. manually shifting when drag racing.
Moderator
Joined: Aug 2010
Posts: 7,323
Likes: 529
From: Ann Arbor, MI
The 4L65E was used in the 6650 lb 400HP Hummer 2. I could not find many complaints about transmission problems in the H2. A few where the radiator had an internal leak which mixed engine coolant into the trans fluid.
Many of the common failure points were greatly improved in 2003 for use with the more powerful LS2 engine.
Many of the common failure points were greatly improved in 2003 for use with the more powerful LS2 engine.
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The 4L60E can be built to handle some big power this fact, We and other have many many units out there to prove it, As for the large number of 4L60E ISSUES in this forum take with a grain of salt, Bear in mind the 4l60e if the most common GM trans in both the CAR and TRUCK world of GM and also that people mostly post when they have an issue no one post to tell how well their trans work or it quiet rare.
Now if you have a sock 4l60e and think your going to long term make 600 rwhp with it and really run it GOOD LUCK WITH THAT and I will say same with even the stock 4L80E.
Truth is Transmissions do not make the car go faster so people 1 hate spending money on them, 2 do not do it till they absolutely have to, Can not blame them after all a new turbo or spray is far more fun , But a decent Built trans is a necessity to get that power from the engine to the wheels.
Now if you have a sock 4l60e and think your going to long term make 600 rwhp with it and really run it GOOD LUCK WITH THAT and I will say same with even the stock 4L80E.
Truth is Transmissions do not make the car go faster so people 1 hate spending money on them, 2 do not do it till they absolutely have to, Can not blame them after all a new turbo or spray is far more fun , But a decent Built trans is a necessity to get that power from the engine to the wheels.
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Launching!
Joined: Feb 2015
Posts: 203
Likes: 6
If the trans is in good shape when you buy the car, there are some nice budget upgrades that can be done to make it live a long time with decent power. 400 wheel or so I would say.
big cooler
good shift kit such as sonnax performance pack or trans go HD2
sonnax HD 2-3 shift valve
aluminum accum pistons
dex VI fluid flush
There are other things that you can do as well, but these are some of the basics that can be done without pulling the trans. They add quite a bit of durability to the trans.
For what its worth, mine lasted quite a while behind a HCI LQ4 6.0. Many many many passes at the track. All i had was a big cooler.
big cooler
good shift kit such as sonnax performance pack or trans go HD2
sonnax HD 2-3 shift valve
aluminum accum pistons
dex VI fluid flush
There are other things that you can do as well, but these are some of the basics that can be done without pulling the trans. They add quite a bit of durability to the trans.
For what its worth, mine lasted quite a while behind a HCI LQ4 6.0. Many many many passes at the track. All i had was a big cooler.