Today I took the car out for a drive and I was messing around, and I came up on a yellow light -- so I'm cruising around 50-55, so I get on it to make it through the light. The Z28 revs up, and then bounces off the rev-limiter.

"WTF Mate?!"

I'm quite concerned with what just happened. I slow down to a stop light (still in gear) and I notice the idle isn't what it usually is in gear at a stop light. I give it gas to roll off, and it acts like it is out of gear. I have to put it in 2nd to roll off the light.

Long story short, after talking to multiple techs and F-Body enthusiasts, the verdict is basically the tranny has taken a ****. It comes down to being my fault because of using synthetic ATF on a 32,000 mile 11 year old transmission. That + spirited driving for a year = 4L60E taking a **** on me at 59,000 miles.

SO -- at first I was hoping it was a shift solenoid (hopefully 1-2), but basically the GM Drivetrain tech said because on a downshift it free-revs, basically means the clutch disengage/re-engage isn't working because of there not being enough line pressure, basically being caused by a mechanical issue somewhere.

Gonna diagnose it when I have the time (classes are killing me) but I just wanted some votes on what you guys would do, worse case scenario.

 

No opinions?
Options?

 

If i remember correctly, the 4L60 has 5 clutchpacks and 2 sprag assemblies. The one clutchpack that holds in all forward gears is the "Forward" clutch. If you're bouncing off the limiter when going WOT in any gear, that clutchpack may be the main issue.

[EDIT] Just found my manual. "A" means solenoid A, and "B" means for the other. Here's the breakdown of what each gear needs on, off, or applied:

1st: Both A and B on, forward clutch, forward sprag, and lo/roller clutch
2nd: A off, B on, forward clutch, forward sprag, and 2-4 band
3rd: Both A and B off, forward clutch, forward sprag, and 3-4 clutchpack
4th: A on, B off, forward clutch, 3-4 clutchpack, and 2-4 band
(if you are in D, 2, or 1 on the shifter, and not "circle D" (overdrive mode), then the overrun clutch holds in all of gears 1 through 3)

Reverse: Both A and B on, reverse input clutch, and lo/reverse clutch

In short it's going to need a rebuild, but i hope this can give you an idea of what to look out for. When you rebuild i suggest running, at minumum, all raybestos or borg warner clutch packs, upgraded sprag (29 element), red eagle 2-4 band, high output slide spring for the pump (and all new pump parts while at it), .480 or .500 boost valve, and a new pressure switch assembly. Make sure your builder uses these at a minumum, even if you have to go out and buy these parts yourself and take them to him/her. And add a 28k GVWR transmission cooler afterwards (keep that fluid cool and it'll last a lot longer).

Hope this helps

 

So possibly a complete rebuild isn't in order? Any links to where I can find more info?

Thanks

 

Hey i edited my other post, sorry for taking so long (i'm a slow typer, lol).

I would get it completely rebuilt. Sounds like a sales moniker, but i assure you that you'll be much happier with the trans afterwards especially with the parts i mentioned above. It'll shift faster and firmer, and will last longer. I'm not a stickler for adding brand new parts into a trans with old ones because once you upgrade or renew some parts, others will fail. With 60k miles many parts are beginning to wear appreciably, so replace all the friction parts.

 

I complete agree. Do it once do it right. I've already got a tranny cooler on it -- I'm going to most likely be pulling it within the week. I greatly appreciate the info. Thanks again!

 

No problem. Here's a good place to buy the parts you may need: http://www.4l60-e.com/ . I don't suggest you let them build the tranny though, they have a bad track record with the better business bureau. But the parts and prices are very reasonable.

Hopefully "Probuiltautomatics" (Dana) will chime in here, he's a very well known builder of 4l60/700r4s and posts here quite often.

 

I need more information on this, as to what forward gears you have and if you still have reverse, etc., but once you get it apart, then you can see what happened. I can help you out on what to do to make this a very strong & reliable unit.

 

Sitting at a stop with it in gear [D] (/w overdrive) it will just rev up like it isn't in gear. With it in [d] (/wo overdrive) it will rev up like it isn't in gear either. Put it in [2] and it obviously goes into gear and you can roll off. Once moving over 30mph, I can shift it up into [d] and once around 40ish I can shift it into [D].

I still have reverse, and I can still use my 1st as well. When slowing down to a stop light with it in [D] you can notice the tranny downshifts as the speed decreases, but once it has to go into 1st (in [D]) the idle goes back up as if it were in neutral, and when you give it gas it just revs up freely.

 

Pro Built Automatics -- Any other input?