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Jon, read!

Ok, so anyhow, I just picked up a '96 Monte Carlo Z34. Transmission is a 4T60-E.

The issue is this.

1. When the gear selector is in O/D, it has a hard time with the 1-2 shift. It basically slips into Neutral is how it feels.

2. If you put the car in D instead of O/D, it handles the 1-2 shift just fine. It only occurs in O/D. This has me a LITTLE puzzled,but I have an idea what the issue may be.

I did a fluid and filter change on the trans today. Old stuff was definitely worn out, but didn't smell burnt. Pan looked great actually inside. I was a little shocked. Less stuff on the magnet and pan bottom than my 240,000 mile Achieva when I did it's fluid/filter change about 15k ago. About half actually, and the Achieva trans was in terrific shape too.

So, I'm wondering if this is maybe a shift solenoid issue? O/D solenoid? Valve body pressure issue?

I need some help on this one transmission guys. I can get around an auto trans just fine for the most part, but I tend to shy away from most things automatic, so I need input from you auto trans guys , especially the 4t60-E guys.

Well seeing as you're not throwing a P1870 code that leads me away from thinking it's a solenoid issue.

The cable from the shifter to the transmission to select the gears could be out of adjustment, but I doubt it! More than likely you have a line pressure issue.

Check this out...
http://www.sonnax.com/publications/tran ... g-pin-wear

That could be one of the issues which he could check by just dropping the accumulator setup, aka EASY to trouble shoot, but then after that if its low line pressure then there are quite a few fixes for the valve body alone that could cause this type of shifting issue. Fluid is diverted differently depending on being in D and O/D by the shift shaft and SCD does bring up a good point to ensure that the shifter notches on the inside shifter are adjusted properly and lined up with the notches that are in the trans as well. The cable has a pull up plastic U that allows you to adjust the cable when in Park.

This is actually something that I was thinking that I may need, but I may just have a 2nd clutch pack thats too loose for what I'm doing. You could be having shift flare, but since it only does it when in OD and not D I would definately look at the cable first then move on from there. I'll grab my book tomorrow to explain a bit more on the difference of operation of D and OD, I can't remember it off the top of my head.

http://www.sonnax.com/system/announcement/84754-40K.pdf

And remember the trans could be nice and clean because someone just did a fluid change not that long ago...

As far as all the other fixes...

http://www.sonnax.com/product-lines/tra ... nit%5D=232

I have every one of the shift valves they offer as well as the Hi Ratio Boost valves... Thats another one I'm not positive on and wondering if I should try the Low Ratio ones. High ratio was used on the quads and 4 cylinders with the 4t60e, the low ratio was used on 3.1's and 3.4's and so on. I'm not sure if the high low ratio corresponds to gear ratio, because if it does then I need and have the right ones.

Now that you mention it, the shifter is kinda "stiff" when shifting into any gear. I wondered about the cables, but thought more to the TV cable maybe needing adjustment?

Think maybe I just need to adjust my shifter cables?

There is no TV cable, it's all electronic kickdowns. what you need to do is get the main cable adjusted properly since it is only one.

I'm going to check and see if I can find pics of when I did it.

here is the cable adjuster part.



wedge in a small scredriver and get it to lift,



Pull it all the way up like this.



Make sure the cable is pushed in as far as it can go, Park is the lever facing toward the firewall, so make sure thats positioned in the right spot too.

Sweet! Thank you very much Jon. I'll give that a shot tomorrow when I do the adapter to upper plenum gasket. The TDC is a BIG motor and really crammed into this engine bay, so the stuff I have to move to do the gasket will give me easier access to the cable. I appreciate the help man.

You're pretty much my go to guy on the 4t60-e stuff!

I'll let you know if this works or not. If not, I guess we go from there.

I guess I get no thanks!

Jon, thanks for elaborating on my reply with all the details and pics! I could have gave a description of what to do with the cable, but without pics included, it would have been rather useless. I tend to be much better at hands-on when it comes to showing somebody how to do something as opposed to putting it down on paper anyway (it runs in the family). I figured you would chime in, so I purposely stayed vague with my reply.

Good luck SGR! I hope it's a simple fix!!!!!!

I actually ended up removing the upper plenum to get to the adapter gasket as it was DEFinitely the easier route to get there. New gasket is in and I studied how to get to that cable from above on this car and with that monster motor and all it's parts crammed in there, yeah.....


Simply put? No fucking way.

I'll have to see if I can get at it from the bottom or something.


I appreciate EVERYONE'S help. Thanks. Still not finished with this problem until it's fixed, it just may be a day or so.

Just for shits and giggles I bought and added a bottle of Lucas Transmission Treatment today. After siphoning out 1/2 a quart to make room, I added it,let it idle for awhile and took it for a drive. PERFECT 1-2 shift the first three times. Then back to slipping into Neutral. This is all while selector is in O/D.

So, I went back to Drive and it's shifting fine as it always has been, but actually a LITTLE smoother shifts while in Drive on the 1-2. It's always shifted into 2nd while the selector is in D without falling into neutral , but seemed like it "rode" the shift. Now it's smoother.

I came back, let it idle awhile longer and went again, again with the shifter in O/D. Strangest thing..... It shifted PERFECTLY again on 1-2 shift for about the first three shifts.

Wtf?? Any ideas?

Tranny is wore out? lol

That's pretty much the conclusion I'm coming to. Probably reefed on too hard it's whole life.

Sounds like it is an internal issue then and the oil is masking it unfortunately.