I have read that a common problem with the 4l60e is that under WOT loads it will not shift from 2 to 3. I have read posts here and elsewhere where the sponsors that are known to build good trannys and know what they are talking about agree with this being a common issue. So, how the hell do you fix it? trans in question is freshly rebuilt with all the goodies inside it.

 

I think you can lower the shift point in the PCM tune.

 

Generally when the trans is in good shape this is caused when the shift point and mph are to close to the rev limiter You should always allow a little more time for the 2-3 shift to occur than the 1-2 shift heres why. The 1-2 shift is a very simple shift fluid is sent to the second servo and the band applies, The 2-3 shift is a bit more complicated fluid is sent to the 3-4 clutch and is also used to release the second servo releasing the band there fore more fluid is needed to complete the shift and it takes a little more time from command to actual shift. So in most cases lowering the 2-3 shift RPM and MPH in tuning will solve the problem barring any mechanical issue. Where you might only need 100 to 200 RPM between command and shift on the 1-2 you might need 300 to 400 rpm for the 2-3 of course this varies according to how much power your actually making. More power may require you to make a greater gap and the RPM will be rising faster where the time required to make the shift is a constant. This also the reason you will hear people say they shift perfect on the 2-3 N/A but when using the bottle cant make the shift. The RPM again would rise much faster.
Of course all of this is assuming you have already had tuning done for the stall you have.
Hope this helps some.

 

It could be the tune, I have my WOT 2-3 shift set for 70 MPH which is about 5600rpm. When I try to go WOT though I see the rev limiter at 6500 and it will only shift if I let off the gas. I can get right back on it then and it doesn't slip, it just won't shift. I had pcmforless do the initial tune but I also have tunercat so I can adjust it at will. It does rev up real fast though, I will try lowering the 2-3 point more and report back. I had this trans rebuilt a few months ago and it is supposed to have all the goodies in it but I really don't have any trust in the place that did it anymore. If it is something in the trans can it be fixed before it hurts anything? I heard you have to use a high rpm slide spring. I don't know if they did or not....

 

I was having the same issue as you, Thought it might be the tuning so I sent my pcm to pcmforless got it back hoping it fixed it, NOPE pulled the tranny and there was a bunch of black clutch residue laying in the pan. So I sent it off to CPT for a race rebuild. My tranny only had 2,000 miles on it. I will never get my tranny built by anyone but CPT from now on.

 

Well, I hope that is not the case with me. The fluid is clean and does not smell burnt at all. I am running a large external cooler that is total overkill for this size trans but it's there anyhow. I still haven't had a chance to lower the shift point yet. I will report when I do.

 

The funny thing was my fluid was not burnt and looked nice and pink too.Thats why I thought I had a tuning issue as well. Pull your pan and see if you have black/grey goo in your pan.

 

Yep sounds like your 4l60e crapped out on you...Talk to Frank at CPT, my trans fluid didnt smell burned and was still red after I drained it but it slips...Would be my 3rd one now, and last after Frank is done with it =)

 

I don't know who built your transmission, but I think they messed up.

Frank
CPT

 

ok I dug back through your post and found this-
Servo upgrade
I am thinking of getting new 2-4 servos for my transmission. My current trans has the following:
1. A valve body reprogramming kit (custom from the builder)
2. Raybestoes Z-PAK with 13 clutches
3. Raybestoes high temp energy clutches throughout the rest of the unit, along with all new steels, bushings, and rings.
4. A .500 boost valve
5. 4140 hardened pump rings
6. Teflon Pump bushing
7. 10 vane pump rotor
8. 29 element sprag
9. Sonnax Wide Open Throttle Valve NOT USED IN 60E
10. Sonnax Sunshell
11. Hardened input shaft and drum.
12. Kevlar band
13. Corvette servo
14. blocked off 1,2,3,4 accumulators VERY BAD IDEA ON THE 1-2

"This unit was bought from a nonsponsor so I won't mention the name, so far it has been great. seems like the 2-3 shift could be a little tighter though and every once in a while I think it slips between shifts. My friends think its in my head and shifts great but I think I need new stuff and trans parts need love too! What does everyone think about getting rid of the corvette servo and replacing it with a fairbanks/sonnax combo? From what I understand the corvette servo is standard on a F-body anyways."

How did you proceed from there You said the 2-3 shift was a little weak Did you try the fairbanks servo as it will lower 2-3 shift accumulation, But unless I am mistaken and you did address this or if the servo had no effect unfortunately I would say you likely have a 3-4 clutch issue and its has or is failing, The ZPACK is and excellent clutch set but there is a bit more to getting it set up correctly than just taking it out of the package, I have found for high performance use even the clearance settings in its own package are not at all ideal and need to be set up differently for performance use. After finding this post I doubt the issue can be solved in tuning I wish I could give you better news

 

I didn't do anything with the servos. I was warned that installing the fairbanks servo would be bad if the bands in my trans did not have reinforced lugs. I tried to find out from the people who built it if they were or not and started to get the run around, thats when I lost faith in them. I asked if it had alto bands or what brands and the only answer I could get was that they used kevlar bands. If it is the trans can it be fixed before it burns anything up? I only have like 2k on it now.

 

Pull the pan. Its easy.

 

Frank, I know CPT didn't build my transmission so it must be junk! I am seeking advice on how to FIX the problem, not how it was not built right and thats why it doesn't work right. And you know who built my transmission, you flamed me for it in earlier posts. If you have nothing constructive to add please refrain from posting period.

Performabuilt- thank you for all the information you have given me so far. You say the servo will shorten the shift, can I use the fairbanks super servo with the stock 4th apply servo or should I get the sonnax servo to go with it? Also if they blocked the accumulators to firm the shift will these make it shift even harder? assuming the 3-4 clutch pack is not fried (I intend on pulling the pan this weekend to see what's in there) can I get another valve body that is done right and fix this? If so can I get it from you and how much?

 

I would suggest first you pull the pan and see whats in it and go from there if you would lke to talk about it when you pull the pan feel free to give me a call

 

First of all, yes, this makes several posts about this same transmission. You had somebody build it that messed it up. The point is, WE didn't build it, so it's hard to tell what they did wrong. You want to attack me for telling the truth?
Do a search to see how many people I've helped on here. You obviously got a warranty with the work, right? Shouldn't your builder be fixing it, then. Have you ever seen one of my customers post on here about how to fix one that we built?
There are several things wrong in that build list. The CORVETTE SERVO is most likely part of your trouble. Next, when you find out that your builder reonstalled the 3-4 load release springs, you will have gound the other.
You want to keep being hard headed. Sometimes it just pays to listen to what someone is telling you. would you like me to tell you that your builder built you a wonderful transmission? If that's what you want to hear than why do you keep posting about problems?
Do your research very well, before you accuse me of not trying to help people on here. You might want to check to how many "hard luck" cases I've knocked money off rebuilds...With unadvertised specials. Hell, I've talked to other transmission builders all over the country helping other members, on here, fix problems.
See, we do many things in our builds to pevent what you're experiencing. It may not be one simple fix. It's not my fault you tried to cut corners.

I tried fixing this transmission in one of your earlier posts, and you jumped at me here, too.
https://www.camaroz28.com/forums/sho...d.php?t=587932

Frank
CPT