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So Friday night I went to the track. I did a burn out in the box, manually shifted from 1-2 in the box, dry hopped and made a pass.
I got back in line, made a adjustment to the tire height with HP Tuners.
Next time hit the box, and same deal, I launched and the truck wouldn't shift into second. It sat on the limiter, so I shifted it up into D and it finally shifted to 3rd and ruined the pass, obviously.
Since then, I thought it was in the tune, but it's not. I have a code of P0701? I think, the Neutral safety/gear selector switch is bad. At first, I didn't believe this to be the issue, now, I don't know. Anyone heard of this causing a issue?
I tried to force 2nd with HP Tuners, but 2nd doesn't work at all. 3rd and 4th work fine, and shift good, and firm, and TCC works fine.
I thought maybe a shift solenoid, but now I don't know. Looking for advice from some guys who have experience.
Since it shifts into all other gears, the shift solenoids should be fine.
A worn band is the most likely culprit; generally you lose 2nd before 4th.
Check the end play of the servo - while holding a ruler near the servo cover, press on the servo cover with a crow bar and estimate how much it moves in
1/16" to 1/8" is spec.
3/16" is worn but 2nd and 4th are likely still working
1/4" is worn out and you likely will lose 2nd and soon 4th.
If worn, lengthening the servo pin will often get you a bit more life out of the trans.
(I have document that many times, but can do it again.)
Is that how the new transmissions work? Wouldn't it still shift into second and slip? I thought about it being worn ( and actually read where you said that before), but I would expect a slip, not a 1st hanging till it hits 23mph and direct shift into 3rd.
I did a bunch of reading on this, but couldn't nail down my issue. Maybe because a lot of people think 2nd was shifting late and really it was shifting into 3rd like mine IDK.
I certainly appreciate any help, obviously I don't understand how these really work, and am trying to learn, and not over complicate this.
Is that how the new transmissions work? Wouldn't it still shift into second and slip? I thought about it being worn ( and actually read where you said that before), but I would expect a slip, not a 1st hanging till it hits 23mph and direct shift into 3rd....
Sorry, I misread your post.
Yes, you are correct - a worn band would slip in 2nd not redline in 1st.
You mention that you cannot command 2nd from HP Tuners. Please give more details:
* If you command 3rd gear and then 2nd, what happens? (Stay in 3rd or shift to 1st? Or free-rev?)
* If you command 1st gear and then 2nd, what happens? (Stay in 1st or free-rev?)
Based on your answers I'll study the hydraulics again, but hopefully your problem is only a stuck valve in the valve body. A bad/clogged shift solenoid is a possibility, but I would then expect problems in 4th gear too.
I understand, and I am not super clear to others when I say things, even though I clearly understand what I am thinking, LOL.
I will give it a try again tomorrow and report back. I do know that before I figured out I didn't have 2nd, when I was on a on ramp, and hit it, it downshifted into 1st, and hit the rev limiter, and stuck there till I backed completely out of it. It was in D4 when this happened.
I do know with HP Tuners, when I was in 1st, and commanded 2nd, it just stayed in 1st, and wouldn't do anything else, no matter how far I stayed in it.
I will check the command 3rd, then 2nd and see what it does.
If the Band cannot stall & hold the Reverse Input Drum stationary, The trans will just stay in 1st gear until 3rd is commanded.
Solenoids are unlikely as both are "On" in 1st & both are "Off" in 3rd.
There is only one band; there is no such thing as an "OD band". The band is applied in 2nd and 4th gear and controlled by the servo which has separate 2nd and 4th gear pistons. (In 4th gear both the 2nd and 4th servo pistons are applied.)
Clinebarger is saying that if the band is not strong enough to hold the combination reverse-input-drum and sun-shell, the trans is in "no mans land" and the trans stays in the mechanically easiest gear which is 1st.
Your symptoms are a bit different than others often reported here - usually people report slippage under high throttle in 2nd gear and you are reported no band application at all in 2nd gear even under light throttle.
In any case the first step is to measure the end play on the servo. If too much you have a worn band.
If within spec, we can consider a valve body problem.
Tearing into it tomorrow to see whats what. Hopefully I can find a specific how to on measuring the end play on the servo.
I thought that band was refereed to as 4th/OD gear band.
Obviously, I know NOTHING about These transmissions, but my history with other transmissions (Ford AOD's) is second gear always slipped, and I can not in my memory, recall ever having a issue like this, just all of a sudden, unless catastrophic failure of hard parts broke.
Ill let you know what I find, and thanks for the help guys!
The band is applied by the 2-4 servo meaning the band is applied in 2nd and 4th. Here are some pictures that may help.
The green arrow is pointing to the 2-4 servo. Push in the servo cover as mrvedit explained above and see how far you can push it in
Here is a picture of the band with the 2-4 servo. The second picture is the servo pin which compresses the band around the reverse input drum. Were the green arrow is pointed is where you would put a small weld if you have excess worn band and want to get a little extra life out of it as explained above.
From top to bottom in this picture. Top is the pump. Middle is the reverse input drum in which the 2-4 band wraps around and locks that drum from spinning in 2nd and 4th. Bottom is your input drum which this is where you will find your overrun clutches, forward clutch pack and 3-4 clutch pack
Here is a simple schematics picture of what is and is not applied depending on gear selected and which gear you are in when in D
If the transmission were out, there are ways to accurately measure the servo end play, although I think most mechanics just eyeball it.
With the trans in the car you have to estimate it.
Use a crow bar to press on the servo cover a few times to un-stick it and get used to the movement; it takes about 50 lbs of pressure to move it. Do not remove the cover.
Then figure out how to hold a short 6" ruler next to the servo cover so that you can estimate how much it moves when you press on it with the crow bar.
Yes, it is unusual to have a sudden complete failure like this where you completely and only lose 2nd gear (and especially not 4th gear too). Things like the 2nd gear servo piston seal, 3-2 downshift solenoid and 3-2 downshift valve could cause your symptoms, but they are unlikely to fail because you are running at WOT.
Is this a stock trans or a performance built one?
EDIT: Thanks for the excellent pictures and explanation 98CayenneT/A.
I know this might sound like a dumb question, but I am guessing your saying to check that, with the engine off, and this is a non running amount of movement to check?
If so, it sure doesn't feel like 50#'s of pressure, more like 10, and yeah if that is the case, I would guess I have 1/4". It feels like it is moving the entire range. Thought I would start there since this seems like the easiest place to start on my situation.
Correct - you check the servo end play withe the everything off.
1/4" of free play indicates your band is worn out.
Maybe its not 50 lbs, but it sure is more than 10 lbs; makes me think the return spring is missing which may have contributed to premature wear on the band.
If you are not up for removing and rebuilding the trans now, you might consider lengthening the servo pin for perhaps a bit more life out of the band.
Besides welding a blob on your existing pin, I think that GM also sells a longer servo pin. Or you can buy the Sonnax 2nd gear billet servo piston which comes with a very long pin; this only makes sense if you want to upgrade the servo.
The HD2 kit also includes two servo shims which will tighten the clearance.
OK, quick update. I did what I HATE to do. I changed 2 things at once. I changed out the gear selector switch, and I pulled the pin out for the band and added right at .100 on it.
ONE of these fixed it. My guess is, it was the .100 on the pin. I can;t believe there is that much movement on this, even now. Guess it's time to make a decision, rebuild a 60, or rebuild and fit a 80.
I may do both, as a friend of mine gets my older, left over parts in order to help him build a project, and he will be needing a decent 60 in the future, so we will see.
By "gear selector switch" do you mean the electric box outside the trans on the shift rod or the "manifold pressure switch" bolted to the valve body?
The electric box definitely didn't make a difference because it only signals Park/Neutral for the starter safety feature and Reverse for the backup lights.
The manifold pressure switch does signal which gear the shifter is in, but a problem with it is not consistent with your symptoms. However some of the strangest problems reported here were due to a bad pressure switch. (Which is trivial to replace.)
Therefore, I'm confident that welding a .100 blob to your servo pin is what restored 2nd gear. I have heard of some people getting another 10,000 miles out of their trans, but for others it was less.
Lots of info and help here on either rebuilding your 4L60E or swapping to a 4L80E.
If the plans are for 550+ HP, I would suggest the 4L80E as the more economic and long-term reliable choice.
Thanks for the response. Yes, the gear selector switch/neutral safety switch is what I replaced. Speaking of that, I have a question on that. Can those be swapped back and forth on the older style, and newer style? The reason I as is what is coming next. I have a 2004 4L65E and it has the newer style selector switch. I will need to swap that to the older style to work on my truck. My guess is, it's no big deal, but again, I know NOTHING about these, as I demonstrated.
So on to the news. I ended up by just luck, picking up a 2004 4L65E from a Denalli 6.0 4x4. It has been rebuilt at some point. It is painted, and written on the pump. The fluid looked near new, and as I press on the servo cover, it barley moves (now that I know this trick) LOL.
My other question is, how do I know if it has a Corvette Servo? I don't plan on keeping this in my truck for more than a year, but I may throw a few cheap upgrades on it. I was thinking a Corvette servo if it doesn't have one, and maybe the Sonnax 2-3 shift valve, and a TransGo HD shift kit?
I will have it all apart to swap it to a 2wd trans and fingers crossed its as nice as I think. Any suggestions?
BTW, yes, I think I will be over 550 once I hang the turbo. My guess is I am around 410 now based on mph/et.
Well, it was a short lived "fix". Driving today about 40mph, and all of a sudden, it was like it was tossed into neutral. I have been being VERY easy on it, but I guess the pump took a **** or something, because I lost EVERYTHING.
Time to swap the shaft in the other trans, and get it in for a temporary trans, until I get my 80E swap together and built.
Sorry to hear that.
If you lost all forward gears and reverse, then the pump is the likely culprit.
First confirm that you have Park to rule out a drivetrain/u-joint problem.
Also, we have had cases where all three converter bolts has come loose.
10-06-2016, 09:28 PM
4L60 lost 2nd gear/ wont shift into 2nd 
