Note: Also posted in the Drivetrain forum.

First, I need to give the history of my transmissions before I go into the symptoms. My '94 Z28 A4 had 120k miles when I bought it, and in less than a year the transmission blew. It would not shift from 2nd to 3rd at WOT, it would just bounce off the rev limiter until I let off. So, I took it to a very reputable local transmission shop, which rebuilt and seriously beefed my 4L60E and added a 2000 stall converter and a TransGo shift kit.

Here I am now, a year an a half later, and my...transmission?...is acting up again. About 90-95% of the time when the car is at WOT and shifts from 1st to 2nd, I get a BAD, BAD grinding and it shakes the ENTIRE car. It feels as if the vibration is concentrated towards the back of the center console and towards the rear of the car. Whenever this happens, my ABS INOP light comes on until the car is shut off and turned on again.

Once in a while, the car will shift fine and kick sideways into 2nd like it should, but that has become very rare. Now, I've had the stock 3.23 rear swapped for another stock 3.23 rear (long story), but the same problem happened before and after the rear was swapped.

Does anyone have the lightest idea what's happening? It's a hard thing to describe, but the car violently shakes and feels like it grinds it's way into gear almost, the shift is slowed up during this.

Is my ABS kicking in for some reason? Should I pull the ABS fuse and see if this fixes it? Thanks in advance.

 

i would go ahead and pull the ABS fuse and see what that does.
dont have a clue what it could be, have you had the cars computer tuned at all have you switched gears?

why dont you take it to the trans shop aging and tell them what is happing?

 

Had almost the same noise but my tranny mount went out. it would shutter but sound like it was hitting the underneath of my car just an idea.

 

I forgot to add that I took it back to the shop and they said that the transmission is "fine" and the problem is "probably rear or suspension related." Warranty was one year, I'm long past that.

The PCM is tuned by PCMforless, but the rear is a stock rear...I'm going to have him burn me another program to see if that changes anything. Worth a shot.

 

bumped...need help bad.

 

I know exactly the problem you are having with the trans not shifting at wot. It's most likely the 3/4 clutch pack or possibly the 2/4 band. One way to help is put in 1/2 quart more trans fluid in it. It won't hurt it like other transmissions ie turbo 350/400. The extra fluid will not build up pressure in the converter like other turbo trans'. There are 3 guys at the track running 4L60E's and all three including me tried the added 1/2 quart and it worked. Make sure your TV cable is adjusted correctly too.
I was talking with a guy who has a 4L60 in an Impala SS. He said after 20 runs, his was banging the rev limiter on the 2-3 shift. This was after a full re-build using the red 3/4 clutch pack and kevlar band. After adding 1/2 quart of extra fluid, it started shifting properly again. So far, he has 12 more runs on it with no problems. He is putting some strain on the trans though with a 383 and 3600 stall.

 

I might add fluid just to see, but the problem you describe is not what's happening. When my trans blew out the first time, that's exactly what it did during the 2-3 shift, peg rev limiter and not shift, as I explained in the first post. Now, its completely different symptoms.

 

ooops,
sorry. Yea, I would unplug the fuse for the ABS as well. I've never heard of this problem however.

 

not to jack his thread but could the tps have an affect on wot shifting? after my head n cam swap and tuning mine wont shift at wot. regular driving it shifts fine never slips or anything like that. but if you floor it it wont shift. even if youre cruising along and stomp it and it drops down and when it gets ready to shift back out it wont. if i back off the gas a little it will shift but i cant win any races like that.

 

It shouldnt, my tranny did that right before it blew last time though.

I pulled the ABS sensor and it still does it.

 

EDIT: bleh, i got confused reading your post. So the CURRENT problem is that sometimes you get a bad grinding vibration behind console? Tried checking out your tranny mount since???

 

Tranny mount is still good, i think it's internal...

 

Damn That Sux!!!
My Tranny Was Rebuilt About 1 1/2 Years Ago With 120k Miles And It
Stopped Shifting Into Overdrive And One Day I Was Making A Left And Gave It Gas And When It Was Downshifting Into 1st It Made A Loud Grinding Sound And I T Was At 5krpms Going 10mph. Got It Rebuilt And Added A B&m Shift Kit And 1 1/2yrs Later I Am Starting To Get Trouble Again.

Sometimes When I Give It Gas From The Start It Will Shift Fine
And Firmly From 1st Into 2nd But Wont Go Into 3rd So I Got To Pop It In Neutral And Back Into O-drive And It Shift....
Good Luck

 

similar problem happened last time mine blew, wouldnt shift into 3rd at WOT.

 

Can Tranny Fluid Cause This Problem?