I know there are a few super smart trans guys here so thought I’d ask some questions about my trans having low pressure. I’ve rebuilt (successfully haha) numerous 60e’s for my swaps and projects over the years, a few holding up to decent power adders in drag racing applications, but this one transmission has kept me on my toes.

I got it a few years back as a core with the typical 3-4 problem, so I completely went through it like usual with all new bushings/bearings, clutches steels, tighter 3-4 clearance, correct band clearance, and the TransGo HD2 kit with corresponding (and slightly modified) hole sizes to what I’m doing. As I said, I’ve been perfecting my art (not a pro by any means) but it lost 3-4 within about 4000 miles. I got it back, went through it and added a new pump because it showed some wear and put it in my turbo Yukon. Right off the bat, the shifts were perfect for what I wanted, but it had no lockup. I could toggle it on HPTuners and hear it, but no actual lockup would happen. At this point, I dropped the pan, checked the solenoid and valve with no luck. I put it back together and it still didn’t work so I turned lockup off in the tune to make it to the weekend to pull it out without something unexpected happening. Well yesterday I got curious while I was logging and commanded lockup, and it worked! So I pulled over and set the lockup tables back to what I wanted and took off but completely lost 3-4. Also, when I pulled up at home in d2, the converter locked on its own and killed the engine when I came to a stop, but I couldn’t replicate it.

Something seemed very off so I pulled it in the garage to pull it out and I normally disconnect the cooler hose to let the pump move the majority of the fluid out if I’m about to pull it anyways, and the flow was extremely low compared to what it should be and didn’t move more in reverse or with throttle. I didn’t put a gauge on it because it was very obvious at this point. I tore it all back down and the 3-4 clutch pack is still almost exactly what I set it at with no signs of wear.

Some things I’ve done over the two rebuilds are: re-seat the capsule in the case, air checked everything separate and as an assembly, replace all electronics, boost valve, replace Teflon’s both times, swapped input drums, and verify position of all valves and springs in valve body.

The reason I’m posting, is to see if there is something I’m missing so I know to check it in future builds because I’ve been searching all over the place with no similar situations, leaving me to just think it’s cursed haha.

 

I'd suggest getting a pressure gauge on this to see what it's doing.
You say you added a new pump. New as in never before used or new reconditioned? Did you check all of the valve bores for wear?
Did you replace the harness?
Are the replacement electronics of good quality/name? Borg Warner, AC Delco, or Rostra?
Could be one or more valve bores in valve body worn out. Lots of info here: Sonnax GM 4L60-E Transmission
Are you confident the converter you're using is good?
Can you monitor the trans being commanded to lock up and shift into third gear?

Don't suppose you know if the issues you're having now were occurring before you rebuilt it?

 

Thanks for the reply, to answer your questions:

I normally put my gauge on ones I rebuild before and after, but this one I had no history or way of testing before tearing it down. I didn’t put the gauge on it before I pulled it because I was pretty upset in the moment and just wanted it out.
Remanufactured pump
Ac delco parts with new harness
I cleaned and checked the valve bores to the best of my ability by using light and making sure the valves moved freely and the bores looked round still
I used the converter in my nitrous Blazer for a month while I was waiting on the 80e converter, so I knew it was good
I monitored the PCM commanding the shift and lockup
And finally, I had no idea if the problems were there when I got it

 

I've definitely been in your shoes. These things can really frustrate one to no ends.
I've had plenty of reman pumps with worn bores in them. Never assume the part your getting is in good condition w/o checking it. Ask me how I know.
If I were to assume everything external from the trans is functioning correctly and because you've swapped the pump I'd probably be looking at the valve body.
From your description it doesn't sound like you checked the bores for wear? Only visually.
I'd clean the pump and VB (so no trans fluid is in them) and start taking things apart and checking the valve bores. Depending on options you have to grab the valve, I like using two straight picks on either side of a valve or small needle nose pliers.
Check the pressure regulator valve and converter clutch valve bores in the pump for wear.
The VB may be more difficult for you to remedy since many of the Sonnax fixes require tooling to ream the existing valve bore. Probably simpler to swap the valve body with another one though for me it would be nice to ID the problem before you do so.

Did you happen to try disconnecting the trans harness and see if you had 3rd then? You should only have 3rd and reverse when the harness is disconnected.

An unknown trans can be difficult to figure out. You don't know what problems it had and who may have put mismatched parts into it before it came to you.

 

Need to vacuum check your VB and pump.

 

I was a little vague, but I did check the bores with the valves in for movement and used a light for some backlight around the valve in the bore (the best I could) to check for out of round and gouging. I did this on the pump and valve body. I disconnected the plug and it definitely wasn’t third, felt more like first, but it was only in the garage because I didn’t want to drive any more on it.

I just finished going through the valve body and pump again and I may have had the HD 2-3 shift valve backwards, but I’m unsure if it turned and rolled on my bench while I was moving stuff around. I’m a little skeptical that it was backwards because all up and down shifts were spot on until the tc started randomly working again.

I’m putting a Sonnax o-ring style boost valve in to see if that changes anything for me as well. I’m kind of at a loss if this doesn’t fix it, but once it’s back in I’ll report back with line pressures and the actual solution. Everything was still super clean inside and clutch packs were all very close to what I set them up at, so it’s pushing me toward epc (although I’d think it would default to higher pressure) or the pump/boost valve.

 

I was actually looking for a vacuum setup to add to my trans rebuild box, sounds like it’s time to commit.

 

Sonnax

 

Cool, that’s the one I’ll get. Thanks!

 

MaroonMonsterLS1 has a thread on how to build your own vacuum tester on the cheap.

 

Here's MaroonMonster's cheap, but effective vacuum setup.
https://ls1tech.com/forums/automatic...alve-body.html

 

Solid thread! Thanks for that and this transmission aside, I feel that it will pay itself off.

 

Finally got it figured out, I had a couple of things going on that contributed to the weird problems. I got the trans back in after I went through it (waiting on the vacuum setup) and it felt perfect for a day and then it had sloppy shifts all around. Gauge showed 50psi at idle in all gears with no rise, and 98 in reverse. I checked for leaks on the gauge connection and then restarted it, this gave me about 70 at idle and about 160 in reverse (just shutting it off and back on) with a rise on throttle.

I went down a rabbit hole of swapping valve bodies, removing the vette servo/super hold 4th, swapping boost valves (thinking I had the short one maybe), and was ready to chock it up as a loss when I figured I’d swap the separator plate thinking maybe I overdid the band release hole. When I pulled it out, the screens were clogged with gunk and made me sit there under the Yukon for a few minutes thinking wtf because it was spotless when I rebuilt it. This is where the lockup issue comes into play, I believe that the converter sitting for a few years (sealed) was dirtier than I thought, and when it finally locked up randomly, it sent junk all through the trans. When I put the trans back in, I had blown out the cooler lines completely with air and brake cleaner until it was good, but didn’t look at what came out because it was in the waste jug. This is also why I didn’t have much cooler flow (makes sense now). After the leaning everything and flushing the trans a ton, it shifts perfect. I’ve got a new converter on the way because I’m building the original Yukon trans up to replace the one that’s in it because I feel uneasy about longevity after seeing what was in the screens and how many times it flared trying to get it fixed.

now, the 3-4 issue, while I was cleaning the garage and throwing junk away, I looked at the 3-4 piston and the rubber was separating, but only if you pulled on it. Super easy to miss but I tried to air test it in a drum and sure enough, complete blow out. It was new when I built it and I used the whiz wheel like usual but I’m guessing it had a defect.

in summary, don’t trust a used converter that has sat for years regardless of how flawless you remember it being (I knew better too haha). Check cooler flow on both sides to see if it’s clogged. Pull on the rubber on new pistons for piece of mind during assembly. And last, use a pressure gauge on every step of troubleshooting.

I’ve e always been so lucky with my builds to have minimal troubleshooting, but this one really put me to the test and improved my knowledge!

 

Did you aircheck 3/4 piston the first time around?

 

Yeah, checked out fine

 

Hmmm
A converter can sit for years and still be ok. Sounds like the one you had just had a problem. Makes sense on the lock up issue and the cooler flow.

What is the whiz wheel?

If the rubber on the 3/4 piston was separating on the molded piston you should change all of them and all of the lip seals/seals in the trans. Did you put some kind of additive into the fluid to cause this? I've never seen that. I've pulled apart I don't know how many units with 200k+ miles and probably could have reused pistons. Something wrong here. Wondering if this is why the lock up clutch in the converter failed.

When you find a good converter builder stay with them. When I first started building/working at shops, we went through several companies until I found one that did it right and still use them today 25yrs later.

If you keep doing trans work trust me, you will run across things like this that you will pound you head against the wall trying to figure it out. I've been doing this for 30 yrs and I learned new things about 400's over the last month I never knew.

 

Its just the little green lip tool, I wasn’t sure what it’s called. And I’ve never seen that either, I haven’t done near as many as you, but I couldn’t find a single case of it. Every rebuild I do, I change all of them regardless of how they look. I’m also assuming the trans or converter had issues last time it was used too. The lockup is working flawlessly, I loaded it up on the interstate with boost and the slip rpm was between -1 and 2 the entire time. I always use precision or FTI on my race builds, I took this one as a trade from a friend for some fbody parts so figured I’d run it.

I was VERY frustrated today before I got it all lined out. I was pricing out replacement transmissions and was ready to give up on this for a while haha. It all seems to add up and like I said, I learned some lessons that will help me out in the future and dove deeper into my hydraulic circuit books than I have in a long time. I was out in the garage until 1 going back over my work and swapping the performance parts out one at a time.

thanks for all of the help! I knew I was coming to the right spot to bounce ideas!

 

Stop using that junk tool. Get this not necessarily from this place but this is what you want:Universal Transmission Lip Seal Tool / Installer - Blade Style - Spring Steel | eBay When you get it make sure you use some sand paper to get rid of any sharp edges other wise you'll cut lip seals

I had asked you about the converter and you said it was good. Sounds like you got it second hand from someone. It's just something like this that's not worth it to me. I'd rather spend the money (customers or otherwise) on a new converter then worry about the history of one. If it fails the whole unit comes out and has to be cleaned etc. I HATE doing things twice and you look like a . . . .

I'm glad you got it figured out and let us know what you found.

 

I have one of those tools as well, I like the green one in there because it’s a quick roll and done. The converter was new when I got it from him and I ran it in my blazer for a little bit.

 

I like my lip wizard also, I sometimes use a normal tool like was posted above, and sometimes both at the same time. Just depends on the situation lol