I have a 4l60 behind a 450 rwhp LS2.The trans I bought from a performance trans builder it’s what they call a level 3 that is supposed to be good for 600hp 600tq. The motor and trans are new in a 3300 pound 65 Olds 442 ground up build. The trans has about 300 easy miles as most were from my tuner tuning the car and trying to get my 3200 FTI converter to lock up. The converter would lock up for about 1-2 seconds then unlock so my tuner made it so the the converter wouldn’t try and lock up while I was trying to figure that out. I took it to a local trans shop and the said it could be leaking past a seal or a solenoid.
I drove the car a couple times to work out some bugs as everything is custom and new before I pulled trans to look inside. I was on my way to buy a lift to make it easier to pull the trans and when I was leaving the stop sign it was like my trans was stuck in a higher gear then smartened up and shifted properly not that I thought it ever shifted properly. I only drove about 10 miles then when I was leaving the lift store I put it in reverse and it was like it was stuck in forward and reverse at the same time. I drove it home and it was shifting but seamed like it was now slipping a little. I pulled the dip stick and the oil was black and smelled like clutch. The oil was clean befit left and the trans was never over 170 degrees.
The converter was cut apart and it’s like new so would anyone know what might be the cause of my problem. I have had my trans at a shop for over 3 months now and they haven’t looked at it yet. There are not anyone who builds performance 4l60’’s where I live so I want to order the best parts so I don’t have to pull the trans out again. I would rather over build and pend the money now than lose another summer as I already spent 9 years building my car.

 

Contact Dana at Pro Built Automatics, he will hook you up with everything you will need. He also gives great tech support.

 

sounds like an internal leak. valve body/or valve body screw/screws not tightened. o ring left out or cut. where are you located?

edit. Nevermind, I see you are in cali. too far for me to help you.

 

The transmission shop finally took my transmission apart today and they said the 3 4 clutch pack was burnt and looks like it was stuck in 3rd gear that's why it seemed like I was in forward when I put it in reverse. They said the clutches looked they were cheaper clutches and some of the parts had pitting and scarring where they should have been sealing. They said what they have seen shouldn't have anything to do with the converter to lock up so I will make sure everything is new and not cheep parts. I am going to call Dan at Pro Built and see if he has a kit the replace most of the parts I need to build a good transmission.I am also going to try and get the 4l79 drum with the clutches and sonnax input shaft. If anyone thinks I should do anything different please let me know.



I live in western Canada so everything I get is shipped out of the U.S. and shipping charges in Canada are crazy expensive and the Canadian dollar sucks so I want to build this transmission for the last time.We also dont have alot of people with LS knowledge in my city so i get lots of information off this site. Thank you for the replies and the help.

 

The guy at Pro Built Automatics is Dana, sorry for my misspelling, I corrected it. The 4l79 drum is a good piece as for the Sonnax input shaft, the output shaft will break before the input shaft will, and at your power level I don't think either is needed. There are several build threads on here, Kfxguy and 98CayenneT/A both have good ones. Read those and come back with any questions you may have. Any advice form MaroonMonsterLS1 and Vorteciroc would be good to follow.

 

As for the input shaft breaking, it is very rare. As for the output shaft. Take a stock one the has the 6 line ID on the end of the output shaft, and have it cryoed. Or look for the output shaft that has the 3 line ID on the end of the output shaft, and use it as is. All 4L60E output shaft since the beginning until 2006 were the 6 line ID shaft. Both were available from around 2006 and later. The 3 line ID shaft is found on 4L75E, and were found on other 4L60E's occasionally. The best input shaft is found on 4L75E and has a 1 wide groove ID (not machined) on it in the middle of the shaft. And the shaft is blacker in color from what I have seen. You could cryo the input shaft that does not have the 1 wide groove ID, and have it cryoed. I have never had a reason to cryo the input shaft. As I have never seen one twist or break. As long as you do not have a "way too firm" shift, or shifting it while the torque converter is locked up. You should not have the need for the aftermarket output shaft, if you follow the above recommendations.