4T65E 3rd-4th behavior / shift kit?

[RnR]

Well as of late I've had a (fortunate) need to do a daily commute again, and this has brought a shift issue to my attention.

It centers around that 3rd-4th gear transition, and if it occurs around 50 mph or below, it's smooth, but should it be much above 50 mph or during aggressive (for me at least) acceleration, it gets hard and shuddery, if you know what I mean. This behavior has been noted before and after the most recent fluid exchange using MaxLife Dex/Merc.

Is this something that could be addressed by changing some common parts (say, with a partial shift kit) during a pan drop?

 

[Steve S]

Is the problem when the torque convertor locks up?

 

[sciphi]

Does it get shuddery when accelerating hard from a dead stop? And does it not do that from a stop when you're lighter on the throttle?

 

[RnR]

Originally Posted By: Steve S
Is the problem when the torque convertor locks up?
Oh boy, not knowing what a torque converter is or how it should act... I feel like a deer in the headlights.

 

[RnR]

Originally Posted By: sciphi
Does it get shuddery when accelerating hard from a dead stop? And does it not do that from a stop when you're lighter on the throttle?
I try never to accelerate hard PERIOD. But it'll come on if I'm merging into highway traffic, or similar get-up-and-go situations. So the condition will more likely appear when it is "pushed". I.E. when that shift point occurs at a higher speed/revs.

 

[Letter_K]

Might want to PM Trav if he doesn't come by. He seems to know a lot about this unit. Not sure if 3-4 is accessable from just dropping the pan. I know 1-2 is and I think 2-3 is too.

Again, going by memmory, but Torque converter locks on 2, 3, and 4 with this transmission. So it's not just a overdrive lock-up.

The more you push the unit, the firmer the shifts should be, but if you think it isn't normal, it probably isn't normal. Is this the Grand Prix you have listed in your sig with 216k? I take it this is the original transmission?

 

[sciphi]

My Buick used to have a wicked shudder shifting from 4-3 on steep uphills, and back into 4 from 3 when under load back when I first got the car. New ATF and an Auto-RX dose made it go away, and it hasn't been back in 50k miles. Likely it was just old ATF and 4th gear clutches that hadn't been used in forever since my car was driven once every blue moon by a senior who never got it above 30 mph.

Is this on the 216k mile GP in your signature? It could be the 4th gear input shaft is finally giving up the ghost. Those will eventually strip out on every single non-rebuilt 1998-2003 4T65 since GM didn't harden the shaft until MY 2004 4T65's. The teeth on the shaft just wear away a little bit on every 3-4 shift until the shaft is smooth. Then you'll lose 4th gear completely.

The input shaft is a worst-case scenario. More than likely it's needing a bit of cleaning with ARX or Seafoam TransTune.

EDIT: TCC lockup doesn't happen until 3rd on this transmission. My TCC will lock hard and fast at 30 mph in 3rd, and unlock at 29 mph in 3rd. The RPM's jump up by 300 RPM when this happens.

 

[RnR]

Originally Posted By: Letter_K
Is this the Grand Prix you have listed in your sig with 216k? I take it this is the original transmission?
That's the one.

 

[T-Keith]

4th gear engaged by a hob shaft out that goes through the sprockets to the far left side of the transmission. It is not uncommon for the splines to wear and eventually break, leaving you without overdrive. You could be seeing this happening, or at the least it could be making it worse.

Unfortunately all of the solenoids you could replace, and the 3-4 boost valve from the shift kit are under the transaxle's side cover, which is not accessible without dropping the subframe out of the car. You could get the transgo shift kit and replace the components under the pan, but I don't think these have anything to do with overdrive.

I think short of taking the side cover off and doing a proper shift kit and 4th gear clutch hub replacement,(did this on my wife's Park Ave, this spring) all you can do is go easy on it and keep changing the fluid regularly. Another possibility is AutoRX?

 

[Trav]

Try 2 bottles of lubeguard red. As someone pointed out the 4th gear input shaft is not hardened on this unit till late 2003 and is a prone to failure.
The 3-4 accumulator is not accessible from the pan and will require more work than a unit with over 200k on it is worth as there are lots of other parts that will be worn to the point of needing replacement also.

Try the lubeguard if it doesn't help get a nice rebuilt unit from triple edge and have it installed by a independent garage, these units are superior to common tranny shop rehashes.

 

[sciphi]

Seconded on the Triple Edge Performance transmissions. I've not heard a bad thing about them.

 

[RnR]

Inquiry to Triple Edge is in work, and I'll give a bottle of LG Red (or maybe some ARx) a go as well.

OT: As I just put a bottle of Lubegard's Platinum in last weekend, would (1) additional bottle of Red be roughly equivalent to (2) bottles of Red?

 

[EricF]

http://tripleedgeperformance.com/New_Home_Page.html

1 bottle of Lubegard Red = 2 1/2 bottles of lubegard platnum.

 

[Trav]

RnR 1 bottle of red will do fine. I don't think i would put ARX in the unit, not because i believe it doesn't work on the contrary many users claim good results in transmissions and PS units, it because of the chemistry and Lubeguard maybe incompatible.

If the car is in good shape the engine is a real workhorse that has a lot of life left in it a rebuilt tranny is only 3-4 new car payments so it pays for itself in a short time.
I have used Triple Edge units both stock and HD an they perform worlds better than a stock rebuild. Dave uses some pretty cool mods like lip seals, hardened shaft and some other modified parts even on a stock rebuild that you just don't get on from a "normal" tranny shop. The HD units are bullet proof and only requires a different r/side cv axle the l/side is the same to fit perfectly. The diff is much stronger on the HD unit.

 

[RnR]

Originally Posted By: EricF
1 bottle of Lubegard Red = 2 1/2 bottles of lubegard platnum.
Wow, that caught me by surprise...

 

[RnR]

Originally Posted By: Trav
If the car is in good shape the engine is a real workhorse that has a lot of life left in it a rebuilt tranny is only 3-4 new car payments so it pays for itself in a short time.
This car has the rusty rocker panels on it, so I don't think getting the HD is really worthwhile. But based on what you and others have said, Dave does indeed produce a very worthy standard rebuild option that I'll likely pursue. Just wish I had a spare vehicle to facilitate cost effective transport. That's life...

TY for the info, guys!

 

[FL_Rob]

Max-life + Z-max in a trans thats now spec'd for DEX6 maybe more than your problem ,at this point, a complete fluid change to DEX 6 is warranted ,and get the transmission back to factory spec before talk of a new trans.

 

[GMorg]

Did the issue arise before or after Z-max was added? Was the Z-max an attempted remedy for this problem or another problem, or was it added on whim?

 

[RnR]

I've been running zMAX as well as LG Red for the better part of a year now. However I've only recently been doing a fairly tough daily commute, during which I've noticed this particular issue to make itself known.

The additives had not been used to specifically address it however.

Who knows... maybe it was triggered by technician test drives as the car has seen some work in the last 45-60 days: brake & gas line replacement, LIM gasket and upper plenum retrofit as well as front brakes and rotors. That means several uncontrolled vehicle "tests" during which anything may have happened.