I recently rebuilt my 4L60E. After getting it installed, I took it for a test drive and the first three gears shift perfectly, however it will not go into overdrive. I dont think it is slipping it just never even attempts to go. I plan on making a test box with 3 LEDs and piggy backing off the wires coing from the computer to verify that it is sending the proper signal for shifting and TCC lockup. If all of that looks im assuming there will be something in the valve body or servo. I installed the Trans-Go SK kit and used Sonnax pinless accumulators. I also used the sonnax servo release check valve kit. My question is do these parts work together or could that be what is causing my problems? Hoping somebody may have ran into this issue before and has some words of advice. Thanks

 

The Sonnax servo release check valve does not work well with the TransGo kit, but I don't think that is your problem.

Did you measure the 2-4 servo apply pin travel. Too much travel could cause the band not to fully apply.

 

Make sure you didnt get the hole in the case where the pan rail is covered up. You wont have OD if you did

 

Any chance you have the outer part of the second servo flipped. This will cause no 4th and will the inner servo ring missing or damaged?

 

the computer is commanding everything it should so that part looks ok. No I did not measure pin travel since I was reusing the stock pin but I will certainly check it out. I’m going to pull the pan back off and make sure I didn’t cover that hole up. I didn’t use silicone so I shouldn’t have to worry about that but the gasket could have. I’m pretty sure I put everything back right in the servo but I have been wrong before so I will pull that and check it as well. I also didn’t mention that i swapped to a corvette servo piston while I had it out and rebuilding. I don’t know if that would cause some problems or not

 

I just have seen alot of people flip that and it will stop 4th also the inner servo seal missing or damaged will have same effect ,

 

Over 90% of my builds require a longer pin than what the OE one was. I'm not sure why but it seems that the aftermarket bands are built to a 1/16" longer spec than the OE bands. Maybe it's me because I like the clearance around .100
Did you Air test the 2nd & 4th apply? You can look at pin travel through the 4th apply hole after the case is all loaded up

 

FranksCustomTrans:
thank you for the information. It is entirely possible that I have something flipped around so I will definitely check it out.

Tranzman:
I was sure that I air checked everything but now that you said that im not sure if I checked the 2 & 4 apply. I know for a fact I checked all the clutches before I put them in the case. I’m currently taking the valve body back out but I had to let it cool from my test drive earlier. I will post results when I get it all checked

 

Ok got the valve body off and when you air check the 2nd feed hole the pin moves and the band tightens up. Same thing with the 4th apply hole and the exhaust hole. So it appears that is working.

 

What air pressure are you using? I air test with 40PSI. If you are using 125 or more it may work. I would air test the VB 4th shift valve while it's off. It will need 80psi to move it. I have a Sonnax vacuum test plate that I use on the VB for shift valve and such. Then I would be looking at the 4th piston seal.

https://www.sonnax.com/parts/3043-test-plate-kit

 

It was at 40. I pulled the servo and there is no fluid on the cap side of it. So I’m assuming that means something is not actuating and letting fluid get there. If I understand correctly, fluid goes through the hole in the pin and out the back of it to apply pressure for 4th right? I guess I have valve body issues

 

Yes sounds like 3-4 shift or more likely the 3-4 relay valve which is more common I have noted, Between it and the sequence valve they cover a lot of area more places to bind up..

 

That is correct on both questions. That is also why I suggested to air test the 3-4 shift valve for movement. If you can't air test at least pick it to make sure it moves. Use a dull pocket screwdriver, the valves may be aluminum and could nick easily. That will make things worse.
I'll see if I can't forward the 4th gear oil circuit for you to study. That will help you find it.

 

Thanks that would be helpful. I don’t have a way to air check at the moment so I will try to move them with a screwdriver. I know everything moved freely when I put it together on the rebuild but something may have happened. I read a thread on here where some guy found the hole in the plate was to small and he made it bigger. Unfortunately I don’t have my old separator plate to compare. I believe the wrong year plate was sent to him but mine is correct according to the part number. It’s the trans go plate

 

Here is a section from my GM tech guide hope it helps

 

$1 says the 4-3 relay valve in the valve body is flipped backwards.
Results in a no 4th scenario as being described.
It's very easy to get that valve flipped around. There is 1 land that is smaller diameter that needs to be inboard. But it's possible and easy to assemble with the small land outboard which will cause no 4th.

 

That is very likely. This is the first trans I’ve attempted a rebuild on so I’m not very familiar with any of it but trying to learn. Hopefully this coming weekend I will get time to tear it apart and see. My kids put a damper on the amount of free time I have lol

 

Saw the very same question over in the Transmission Brotherhood today... Guess what? @MaroonMonsterLS1 the 3-4 relay was backwards!!! So you were spot on there. Mark Pucinelli of TransGo posted a picture of the 3-4 relay and 4-3 sequence valve line up. The OP just confirmed the problem & the fix!!!

 

That is what it was. Finally got time to check and it was installed backwards. Flipped it around and now I have 4th. I appreciate everybody’s help on this

 

You owe @MaroonMonsterLS1 $1