Hi all, new to the forum. I'm in the processes of rebuilding a 97 4L60E transmission and looking for good info on air testing before final assembly. I found a lot of good info on this site after spending hours searching the net. I'm very disappointed in the ATSG manual I've been using for this rebuild.

I found this post from clinebarger that sort of covers some of what I'm looking for:
https://ls1tech.com/forums/automatic...l#post19047878

But, I'd like a little more info an exactly what should happen while testing each clutch pack. I air tested the input drum through the holes in the input shaft between each sealing ring and thought it seemed good. Now I want to test the assembly as clinebarger recommends in his post. I have the input drum, reverse input drum, and pump assembled and sitting upside down on the bench. When I put air to the pump ports as identified in that post, I don't feel like I'm getting the correct behavior from the clutch packs.

Since I had so much trouble finding the info I'm looking for, I thought I'd start a new thread where we could identify which ports to test and what behavior should be expected. The post I linked above along with several others are very informative, but don't quite cover what should happen when testing and what should not. If there is already a good thread covering this and I just missed it, feel free to post a link.

Here's what I'm getting when testing mine... I get quite a bit of air leakage from many different places so it is difficult to pinpoint any specific location as a leak test failure so to speak. I realize that there will be some air leakage from multiple places, so if there are any places where air leakage would be a sign of failure, please explain. When I put air to what I believe is supposed to be the 3-4 clutch, I get air leakage out of what I believe is the forward clutch port. The 3-4 clutch pack engages, then the forward clutches apply. When I put air to what I believe is the forward clutch port, I get leakage out of the 3-4 port. The forward clutches apply and the 3-4 clutches do not. Sorry if I'm not explaining very well. I might be able to get a video to show the behavior I'm getting if necessary.

 

Lots of good info in the Sonnax Sure Cure® Kit instructions. Look at page 12 for air testing.

 

Yes, it is normal to have lots of leakage when testing through the pump.
First air is quicker to leak through tiny holes than thick ATF.
Some leakage will occur from between the pump halves.
If you carefully air tested just the input drum and all clutches apply when you air test through the pump, then you are good to go.
The air test through the pump mostly ensures that you didn't ruin one of the teflon rings on the input shaft.

 

bbond105, that Sonnax instruction last page has pretty much exactly what I am looking for as far as how to test through the pump passages. What it doesn't tell is what to check if something seems wrong. For example, it says the 3-4 should not apply when testing the forwards. What if they do? Mine don't, so I'm OK there, but that's the kind of info that would be helpful to people like me that don't really know what they are doing. Since I'm having a hard time finding that kind of info in one place, that is what I was hoping this thread could turn into.

mrvedit, thanks for the reassurance on the air leakage and testing. That does help boost my confidence that things are probably OK.

The one thing I'm still a little unsure about though is the test for the 3-4 clutches. In the Sonnax instructions it says "3-4 clutch: Overrun, no piston movement". I take that to mean when the 3-4 clutch applies, the overrun should not. So what should you check if you think the overrun might be applying? Since the overrun and the forward clutch packs share the same apply plate, I can't tell for sure which one is applying on me. When I just put a little air to that port for the 3-4 test, only the 3-4 clutches apply. But, if I give it more air, then I see the forward clutches apply as well. It could be possible that the overrun clutch is applying and pushing the forwards as well.

I think I'm OK, because in the post I referenced from clinebarger, he mentions when testing the 3-4 "(The Forwards will "soft" apply....Non-Issue)". Is there some way I can make sure the overruns aren't applying as well? In the ATRA manual I have, it mentions that when testing the overrun clutch, you will notice the forward clutches applying as well and that it is perfectly normal. I just like to take my time and make absolutely sure I know things are OK. I can't stand having any potential doubt on things like this.

Thanks for the help!

 

Apply air to the 3-4 Clutches, IF the Overruns are applying.....The Input Sun Gear will be locked in BOTH directions. The Sun Gear HAS to Overrun in one direction with the 3-4's applied! If not.....Suspect a Torn Forward Piston lip seal or a busted piston.

 

Clinebarger:
I hope you are still checking this forum, and I don't mean to resurrect an old, old thread, but it is relevant to my question. I may include too much info here, but I'd want as much information as possible to make a decision, so I'm guessing you would too.
I'm re-manning a '97 4l60e (Z71, PWM edition) and am experiencing what seems like the overrun clutch engaging with 4th gear. 1, 2, and 3 engage nice but when 4th is commanded, it engages, but the engine seems to brake as well as it feels like a giant hand has taken hold of the tailgate and is pulling back on the truck. From what I've read, that appears to be the overrun clutch assembly engaging when it shouldn't. (as soon as it did this while test driving it, I neutralized it because I know the overrun frictions can be damaged very quickly when this happens). When it first went into the vehicle, I had a very similar issue. Before I could get back to the shop, it had lost 2nd and possibly 4th. It would run 1st up to about 4k RPM then shift directly to third and at about 50-60MPH, the TCC would lock, but I don't think 4th ever engaged again. While still installed I tested the band actuator by compressing the apply piston cup. It seemed to not have a bottom so I suspected that the anchor slipped. I opened her up and I replaced the band and the reverse input drum because it was lightly scored and the brand new band was toast. Test drive and I have the problem described. If I keep the selector in D3, the trans works fine through the upshift of 1, 2 and 3, and into the lockup. However, there did not seem to be any manual or commanded downshifts/engine brake until the vehicle was stopped. And of course, no usable 4th. Removed and pulled the entire thing appart down to a bare case again. Realized that I inadvertently compressed the incorrect input drum spring-pack above the apply piston. So I put the right one in. Also, the forward/overrun clutches seemed to have excessive clearance. However, none of the frictions were damaged and neither were any of the steels or pressure plates/wavy plate. I scrapped all of them and repacked the set to specs. That should be adequate background info.
I've read how to bench test the input drum assembly and I'm stuck on the input sun gear. In a thread I read where you said that when the 3/4 clutches are applied, the forward and overrun should remain free and the sun gear should overrun in one direction and lock in the other. But you said that about the forward pack as well.

""Apply air to the Forward Clutch feed hole on the Pump Cover, The Input Sun Gear should Overrun in 1 direction, & Lock in the other direction.
Apply air to the 3-4 Clutch, Again, The Input Sun gear should overrun in 1 direction, (The Forwards will "soft" apply....Non-Issue).""

I've been doing this for 30+ years and have never had to do a full test and have never had to test the movement/locking of the input sun. When I apply the forward clutch via the pump port, the sun gear locks solid. NO movement whatsoever. With the 3/4 activated via the pump port, the pack compresses and the sun can be spun in one direction, but not in the other. I have always considered that a passed test. Am I correct in thinking this way or should the sun overrun with the forwards engaged as well, such as the other thread stated? TBH, I have a difficult time understanding why the sun would be able to overrun the same way during both test operations. To me that would seem counterproductive.
Thank you for taking the time to read this epic and offer advice.
Fred