Transmission Shudders... Easy Fix?

Thanks Scott

We earlier discussed whether the PO's trans was original or not, I do not recall the answer. I also don't recall if this issue applied to the 4T60E as well as the 4T65E.

As formy original recalling, I guess I was wrong. I thought there was a TSB circa 1997 or 1998 about the '96 4T60E transmission hunting into/out of lockup when cruising in 4th along long road incline at slight (like 3% or 5%) inclination. Some (primarily repair/aftermarket) woud call it "chuggle."

My bad.

Albertj

Thanks Scott.
This also points out that the tranny TSB's are for shifting/engagement conditions, not steady-state driving...

i dont know if this thread follows another,that i cant find,where you "crack" the case and wedge out the solenoid and replace it,and button her back up without removing the tranny. my question is,if thats done,whats to prevent the case gasket from cracking and the tranny having to be removed anyway? from what ive seen,these gaskets are pretty fragile....

robotennis61 wrote:

i dont know if this thread follows another,that i cant find,where you "crack" the case and wedge out the solenoid and replace it,and button her back up without removing the tranny. my question is,if thats done,whats to prevent the case gasket from cracking and the tranny having to be removed anyway? from what ive seen,these gaskets are pretty fragile....

Robo....LINK.
1st page, bottom. Steve took a pic of it for us.

Abaddon wrote:

robotennis61 wrote:

i dont know if this thread follows another,that i cant find,where you "crack" the case and wedge out the solenoid and replace it,and button her back up without removing the tranny. my question is,if thats done,whats to prevent the case gasket from cracking and the tranny having to be removed anyway? from what ive seen,these gaskets are pretty fragile....

Robo....LINK.
1st page, bottom. Steve took a pic of it for us.

thanks. but dont you think the gasket could break? or is it one of those hard plastic types?

This is kind of out of left field, BUT, I also recall the 4T65E had a flash upgrade GM issued to the PCM to correct "deceleration stall." I wonder if that is what is really going on here. With the 4T60E there appears to be no TSB - BUT - I have heard that doing a reflash of the PCM (as if a new PCM was being installed) fixes this kind of problem.

IF curiosity is driving you this LINK may be interesting.

Further thoughts?

Albertj

Not sure about the gasket on a '95 Robo. Sry man

Albert that's interesting, although I think that fix might be a rare one....but possible. That's one of those problems where you do everything you know how to do, and follow every flow chart perfectly, then "try" the reprogram. I've had it happen before, just not with a transmission concern.

I did some more searching for a '96. I found 2 other bulletins regarding something close to this concern. One of them is related to Intermittent neutral or loss of drive from 4th gear. The other is about Torque Converter Replacement. I can't post it, but the very first line of it is this....

The Torque Converter should be replaced under any of the following conditions...
--The vehicle has TCC shudder and/or no TCC apply

Obviously it's considerably longer than that, but I find it funny that it's the first line of it.....

Eldo wrote:

AA wrote:

Quote :

I let off the gas for a tic and then get back on the pedal far enough where the TC will not lock up until I've finished the incline or whatnot.

This is exactly what adjusting the PCM program does, except it happens automatically - you don't have to physically let your foot off the gas.

I still think Rick is describing the same KR symptom that Jason, Scott and I were, not a worn tranny...

BTW, mine did it from the time I bought the car at 69,000 miles.
BTW, again: What does FDR stand for?

I agree with Aaron. If I actually sat down with my PT and played with the tune, I'd be able to augment the TC lockup tables which would make driving the car easier. Will get around to that eventually.


Mark - FDR=final drive ratio

Pretty awesome being able to go 80+mph and only be revving at 2500rpms.

Abaddon wrote:

Not sure about the gasket on a '95 Robo. Sry man

Albert that's interesting, although I think that fix might be a rare one....but possible. That's one of those problems where you do everything you know how to do, and follow every flow chart perfectly, then "try" the reprogram. I've had it happen before, just not with a transmission concern.

I did some more searching for a '96. I found 2 other bulletins regarding something close to this concern. One of them is related to Intermittent neutral or loss of drive from 4th gear. The other is about Torque Converter Replacement. I can't post it, but the very first line of it is this....

The Torque Converter should be replaced under any of the following conditions...
--The vehicle has TCC shudder and/or no TCC apply

Obviously it's considerably longer than that, but I find it funny that it's the first line of it.....

I think this one (the TCC replace TSBs) has to do with the TCC lining glazing (yet one more reason to change the fluid under the severe schedule whether in severe service or not). the TCC lining glazing up can happen. I am not sure if it was a change between carbon fiber and kevlar or different suppliers of supposedly the same lining.

I've also learned of more than one 'chuggle' fixed by simply disconnecting the battery and letting the PCM forget the TCC lockup adjustments, but I think a reflash makes more sense in the long run by resetting everything *and* altering the bounds of adjustment.

We shall see.

Albertj

Quote :

I've also learned of more than one 'chuggle' fixed by simply disconnecting the battery and letting the PCM forget the TCC lockup adjustments, but I think a reflash makes more sense in the long run by resetting everything *and* altering the bounds of adjustment.

This may have in fact happened, but for some other reason. I don't see how the PCM could forget the TCC lock-up values. Disconnecting the PCM may reset fuel trims and DTCs, but if it changed the program I'd be very surprised.

AA wrote:

Quote :

I've also learned of more than one 'chuggle' fixed by simply disconnecting the battery and letting the PCM forget the TCC lockup adjustments, but I think a reflash makes more sense in the long run by resetting everything *and* altering the bounds of adjustment.

This may have in fact happened, but for some other reason. I don't see how the PCM could forget the TCC lock-up values. Disconnecting the PCM may reset fuel trims and DTCs, but if it changed the program I'd be very surprised.

Reflash woud update the program. Disconnecting the PCM will not. PCM won't forget the TCC lockup values but will reload the base tables I understand.

Albertj

Eldo wrote:

Is it possible that what you're feeling is 'surging' and not 'shuddering'?

It sounds to me like you're describing something that my car has always done, except that it's the engine, not the tranny.

My car will shift into OD and lock up the TCC at 42MPH. At any speed from there up to 50+MPH, if I take a moderate hill and "drive for economy", my engine will surge from the 'lugging' of the engine and the spurts of knock that make the PCM yank out a bunch of timing, then restore it, then yank it again. Something that someone else might describe as shudder...

If I lean into it harder and provide Power Enrichment, or tap the brake or release & reapply the throttle to disengage the clutch, the problem disappears. Before I opened up my intake & exhaust plumbing, it would even do it at higher speeds on one certain hill on the freeway.

I have Californicated 91-octane swill, so I wasn't surprised - this symptom will also disappear when I mix up a tank of 93.

Does this sound like it might be what you're experiencing? Also, what octane are you running?

So did you find a permanent solution in your case Mark?

Well I suppose you could say that... Especially because I have an L67 in the land of piss-water 91-octane, I just don't lug my motor on those uphill areas. As I posted, the problem is not as constant since I opened up my downpipe and my intake tubes - and when I mix a tank of 93-octane I have no problem at all!

Thus, I just tap the brake or go "up-fast-down" on the gas pedal to release the TCC when I'm in one of those overly economical lugging modes...

DEMonte1997 wrote:

As was said, if your car is on an incline going about 41 to even 50mph and the TC is locked, you'll get some surging on a worn trans. If it's stuttering/bucking really bad, I assume worn or malfunctioning TCC solonoid. These cars (esp the L67 powered ones) have a pretty crazy FDR which causes a lot of load on the motor when the TC initially locks in 4th gear. If you're on a decent incline, it will cause this surging. I've noticed this in 5 3800 powered cars to date. My solution? I let off the gas for a tic and then get back on the pedal far enough where the TC will not lock up until I've finished the incline or whatnot.

A fluid change couldn't hurt as well for the time being unless it's bad enough where you think parts need to be changed.

HTH

I think I'm having this problem on my 95 series I. I noticed after I get to 45-50 the car shifts and then starts bucking wildly until I let go of the gas pedal and then it goes back to normal for a few seconds until the gear shifts and then it starts doing that again. Is this the TCC solenoid?

sniperdude wrote:

DEMonte1997 wrote:

As was said, if your car is on an incline going about 41 to even 50mph and the TC is locked, you'll get some surging on a worn trans. If it's stuttering/bucking really bad, I assume worn or malfunctioning TCC solonoid. These cars (esp the L67 powered ones) have a pretty crazy FDR which causes a lot of load on the motor when the TC initially locks in 4th gear. If you're on a decent incline, it will cause this surging. I've noticed this in 5 3800 powered cars to date. My solution? I let off the gas for a tic and then get back on the pedal far enough where the TC will not lock up until I've finished the incline or whatnot.

A fluid change couldn't hurt as well for the time being unless it's bad enough where you think parts need to be changed.

HTH

I think I'm having this problem on my 95 series I. I noticed after I get to 45-50 the car shifts and then starts bucking wildly until I let go of the gas pedal and then it goes back to normal for a few seconds until the gear shifts and then it starts doing that again. Is this the TCC solenoid?

If you tap on the brake pedal (while holding your other foot steadily on the gas) does the bucking stop? tapping the brake pedal should release the TCC. I had this bucking only under medium throttle in 4th in my '94 Regal (3800) and it was a cracked spark plug. Don't rule out a misfire as the root cause - the bucking is a symptom.

Typically the TCC will either lock or it won't, which is why I bring up the importance of making sure it's not a misfire.

Hey Derek, I just tested that out on the way to the dealership.

Tapped the brake pedal while holding the gas down and the car stopped bucking.

It's the same effect as letting off the accelerator.

The car has a bad misfire condition as well, which is getting checked out at the dealer right now.

So the misfire could be the cause of the bucking, which you are feeling when the TCC is locked... see if it continues after the misfire is taken care of.