4L60E rebuild, no 3rd gear
 

Hi There:
For the first time I rebuilt a 4l60e (2001 suburban 1500 4X4) which had failed 3,4 gears. I watched a lot of videos and I followed transmission bench rebuild videos mainly for the rebuild. I was very confident that I followed the instruction to the point. I replaced the sun gear as well the shift solenoids.
Long story short, I took the the truck for a less than a mile test drive on our private road, I didn't notice if it shifted to the 3rd or no since I was going slow and trying to listen for any explosion! when I got back, I noticed the huge transmission fluid puddle under the truck. The cooler return line has popped out and tranny was drained. There was this slight hot/burning smell. I popped the line back in (double and triple checked it again), filled the tranny again, went through all the gears few times while stationary and took it for another test drive. It does not shift to 3rd. It doesn't even try. Did I burn the 3rd and 4th? Is there anything else I can check? does less than few minutes will ruin the clutches?
Thanks for the help.
I guess I have to add this: there was a lot of fluid leaked on the exhaust pipes and I am hoping the burned smell was from that.

Re: 4L60E rebuild, no 3rd gear
 

sound like u riped one of the orings on the back pf the pump stator going in and you have no fuilded going to 3rd

Re: 4L60E rebuild, no 3rd gear
 

Okay, that still means I have pull everything apart :(
I was hoping I don't have to do that.

Re: 4L60E rebuild, no 3rd gear
 

No 3rd or 4th....

Bad sprag unit
or
Burned up 3/4 clutch pack
or
BOTH !

Did you have the convertor replaced or flushed during the build?


:chevy::chevy::chevy:

Re: 4L60E rebuild, no 3rd gear
 

I did flush the converter. Basically I flipped it and let it drain over night.

Re: 4L60E rebuild, no 3rd gear
 

Convertors are a haven for all types of contamination when a trans dies....

Flipping it and letting it drain will do zero to remove these contaminants....

The lockup clutch face surface cannot be checked for damage....
The internal components cannot be checked for damage...
The contamination residue including metal dust and clutch dust cannot be removed...

The burnt oil on the ground would most likely be a direct oil dump from the convertor....

Sorry to say this but IMHO...pull the trans, send the convertor out to be split and overhauled...do not accept having it flushed...

Then pull the trans back down..It will need to be fully dismantled and everything cleaned up, resealed and reassembled...

Change the sprag out to a BW late style...

As a heads up, there are several write ups on our forums especially detailed ones by "clinebarger"...who in my mind is the best trans guy I have ever seen....he does it right first time for a reason...its the right thing to do...

Hope this hasnt been to harsh a response....there is no easy fix for this...

:chevy::chevy::chevy:

Re: 4L60E rebuild, no 3rd gear
 

When the 3-4 Clutches are smoked.....But you still have 3rd Clutch apply circuit integrity......

*3rd clutch apply oil knocks the 2-4 Band off via the 3rd clutch accumulator behind the 2nd apply piston.
*With no 3-4 clutch holding ability.....The trans will now be in 1st gear causing a big Flare.

If it just stays in 2nd gear.....That could be a 3rd Clutch apply circuit integrity issue, Like a big leak.

Re: 4L60E rebuild, no 3rd gear
 

Not at all. I appreciate the info.

Re: 4L60E rebuild, no 3rd gear
 

Absolutely CORRECT !!!!

Re: 4L60E rebuild, no 3rd gear
 

Okay, I pulled the transmission again and took it apart and looked for any broken seal or other things. I took the input drum and put it back together with new sprag although the old one still looked okay to me. Since the all other parts were new including the pistons, I test fit them for being snug when put together, I put everything together. When I pressure test the input drum using air compressor setting at 40 PSI, I get a leak which comes from the hole the center of input shaft inside the drum (there are 4 holes, 3 seems to have a ball in them and one without it) when I test 3-4 clutch (the hole closer to drum, at the same time I am blocking the release hole on the side). The forward clutch and over run clutches seals very well.
I thought I may have damaged the pistons when I installed them. I took the drum apart and installed new set on pistons. The same result :(
Is the drum bad? I don't see any visual defects.
I appreciate any help.

Re: 4L60E rebuild, no 3rd gear
 

The open hole at the end of the Input/Turbine Shaft is the Lube Feed hole that feeds the Output Shaft than onto the Geartrian.

There shouldn't be any cross leaks between it & the 3-4 Piston feed hole.

Lube is fed from the cooler return through the pump, Then through the stator support, Then through the hole in the picture. Then travels through the Input Shaft to the open hole at the end.

https://i.imgur.com/uyTONPQ.jpg

Re: 4L60E rebuild, no 3rd gear
 

If it in fact has a cross leak between the lube circuit & the 3-4 circuit....I'd almost have to be the Input Shaft.

I have never ran across this before & I'm assuming you're air checking the drum by itself?

Re: 4L60E rebuild, no 3rd gear
 

I am very new at this and in fact, this is my first automatic rebuild. So, what I have done is based on my reading and online videos.
When I pressure check, I put my air gun nozzle in that hole in the picture, I block the hole on the drum's body with my finger and based on what I have researched, the 3-4 clutch should hold the pressure with no leak, but I get the leak from the drum and when I hold my hand over the input shaft inside the drum, I feel the air.
I am sorry but I don't know the exact science (the flow) of the system. So, I need a new drum or is it possible that I am installing something the wrong way?! It seems very straight forward process in the videos!

Re: 4L60E rebuild, no 3rd gear
 

The 3rd apply circuit could be leaking around the splines of the Input Drum-Input Shaft interface giving the false sense that it's leaking out the lube hole.

Re: 4L60E rebuild, no 3rd gear
 

What would be the cause of that? And, can it be fixed?

Re: 4L60E rebuild, no 3rd gear
 

A new or good used Input Drum would be the fix, The cause is either fatigue or a crack in the drum.

You can lightly smack the drum with a 3/8" extension & it will Ring very clearly like a bell if it's not cracked.

Re: 4L60E rebuild, no 3rd gear
 

You didn't forget the green o-ring in the bottom of the input drum did you?

Re: 4L60E rebuild, no 3rd gear
 

No, I did not forget. I guess that would make it easier.

Re: 4L60E rebuild, no 3rd gear
 

Okay,
I took the tranny off and remove the input drum. I got a different input drum (used but tested one, whatever that means, with all new seals already installed), disassembled and reassembled the new drum with new sprag, tested and this time there was no air leak on any of the clutch packs when I use 40psi air pressure. I did not touch anything else in tanny since I though there is no need for it.
Pu things back together and put the tranny in the truck with fresh fluid, no 3rd!!!
This time, it is shifting hard from 1st to second while before, the shift from 1st to 2nd was very smooth.
This seemed very clear process but now it feels so confusing! What am I missing?
Is there an illustrated reference book for 4L60e? Could it be wiring, that I am connecting the wires wrong on transfer case? But the transfer case is not suppose to be engaged in 2wd mode??!!
Thanks

Re: 4L60E rebuild, no 3rd gear
 

Two different occasions I had 4L60e brought to me that had been "rebuilt" but didn't shift (no codes). In both cases the shift solenoids were not fully inserted and the retaining clips were in the o-ring groove.

No grooving inside the stator support?