4t60e TCC problem?

[robertisaar]

just like clutches, lock/unlock, engage/release: every time it does it, it wears it out a little more, and eventually it will fail. granted ~50K miles isn't that much, but who knows how those miles were driven.

EDIT: and removing the PWM wire from the equation will just only allow 100% apply or 100% release, nowhere in between. it's strange that GM decided to use two circuits here, but it works. when the PWM solenoid hits 100%, the on/off solenoid goes on and the PWM probably turns off(i haven't had a need to deteremine if it does or not). and then when it's time for release, the solenoid would power to 100%, the on/off would go off, and the PWM would dial down to 0%.

at least that's what i'm being told from alldata.

[willyman82]

Ive just been visiting all-data also. I understand now what you are saying about cutting the PWM wire. I may do this and see what happens this weekend. A hard lockup and hard unlock may not be so bad to eak out another 50K from this F'in car. Just a bit uncomfortable for the driver to get slamed around. Just so Im straight on this, the ECM modulates the PWM valve to control the presure to the lockup plate in the torque converter, and the other solinoid is just on/off? So the car will remain drivable and wont stall at lights, etc?

[robertisaar]

more or less, that's exactly how i would explain it.

[gpse3400]

Ive just been visiting all-data also. I understand now what you are saying about cutting the PWM wire. I may do this and see what happens this weekend. A hard lockup and hard unlock may not be so bad to eak out another 50K from this F'in car. Just a bit uncomfortable for the driver to get slamed around. Just so Im straight on this, the ECM modulates the PWM valve to control the presure to the lockup plate in the torque converter, and the other solinoid is just on/off? So the car will remain drivable and wont stall at lights, etc?

Its not that bad. But ultimately If you do find it that harsh, you might be able to reign it in with an adjustable modulator if you don't already have one. But as a result, your normall shifting might get alittle mushy.

[willyman82]

This weekend was a bit of a washout because of the rain, but I got some tests done. The solenoids are 22-23 ohms for 1-2, 2-3, TCC and 12 ohms for the TCC PWM solenoid. Temp sensor is about 2K warm and about 7K cold. The vacuum actuator works and gets the same vacuum as I measure at the direct manifold tap (17 inches Hg). I get 11.8V at the common supply to the connector with the engine off and key on.

I clipped the TCC PWM solenoid wire. The lock/unlock feel is much more defined, but it doesnt hold any better than before. The judder is the same as it was when I encounter a small hill on the highway. It seems unlikely that the TCC would be bad from a 51K trans, but I guess its possible. I sure don’t want to pull trans again if that is the case. I think clipping the PWM wire rules out issues with the computer not applying enough pressure to the TCC. Other opinions on that?

Once the weather clears I am going to do a line pressure check using the tap on the top of the trans to see if it is low. I may even run a long piece of brake line into the car to watch the gauge as Im driving and the TCC locks up. Next Ill drop the pan and check the filter. This may sound dumb, but I figured I would do the filter after driving the new trans for a few thousand miles to wash any stuff through so as not to foul up a new filter right away. Wouldn’t the pump make a lot of noise if it was having trouble pulling fluid?

I already pulled the end off the old trans and it doesnt look like a valve body job on this thing would be so bad. Ill just pull the whole driverside suspension and K frame, lower the engine and pull the brain bowl off. Has anyone else done this before?

Thanks,
-William

[3400-95-Modified]

It's not that hard, but you need to catch all the ball bearings that are between the VB and the Channel plate, and put them back where they belong

I would suggest getting a ATSG Book before pulling the VB off, and if your going that far I would also suggest doing the Transgo shift correction kit. It's a $40 kit and worth it to prevent this again.

I just dropped 230 on valves and such for my trans this year, and thats already got the Trans-Go kit.

[willyman82]

Is this the kit? If not, could you please provide the link.

http://www.sonnax.com/instructions/SC-4T60-E-97-IN.pdf

I already have the book on order. What is the correct type of grease to use to hold the check balls in place for re-assembly? I have read everything from bulb grease to petrolium gelly and axle grease. Axle grease seems wrong because I would think that would dammage the clutches.

[3400-95-Modified]

I use Trans assy lube, its a green grease that dissolves with transmission fluid.

That would be the wrong kit since its 97 and up, you want this one.

http://www.transmissionpartsusa.com/TRANSGO_4T60E_Shift_kit_1991_99_p/500-000037936.htm

and you want the assy goo thats on this page. I use the green, but I guess the blue is good too.

http://www.transmissionpartsusa.com/Lubegard_Fluid_Additives_s/6351.htm

You can also buy a new TCC valve from TPA if you wish. I just did, They offer it in reamed size if your bore was destroyed and you have a ream tool, OR just the stock size to help prevent side loading and sticking.

also the SC kits are much more in-depth And require tool kits to install... so the kit is $123, and then the tools are $104. Probably only needed if the trans is worn really bad.

[willyman82]

Hi All,
I have been studying the hydraulic circuits in the manual for this trans. I think there might be a leak at the TCC apply valve between the 2nd feed circuit and the exhaust port (top of the valve). This would explain a weak lockup and eventually no lockup (as was the case with the last transmission). In comparing all the differential pressures in the valve body, this point has the highest differential pressure and therefore would be the most likely to fail. Also, it is the narrowest so any leak past the seal would not be slowed by boundary condition turbulence as it would in the other valves. The leak could certainly be elsewhere, but this reeks of a bad design and is highly suspect. My fiance has decreed that I wont be taking the valve body apart until I can prove my theory by taking apart the old trans valve body and examining the TCC control valve seal...in the summer. Since I need a car before then I did a few experiments.

First experiment: I disconnected the vacuum regulator on the side of the trans to command max hydraulic pressure. Oh boy shifts are firm! TCC seems to hold a bit harder in OD but still shudders on hills.

Second experiment: I disconnected the PWM solenoid for the TCC with the vacuum regulator still disconnected. This gives max feed pressure to Apply circuit and the valve will stroke further because the 2nd circuit has higher pressure than before. I was unable to recreate the shudder problem with these two changes.

Obviously the car still is not drivable like this, so I came up with a circuit that does two things. When in 4th gear as commanded by the PCM (Sol A - ON / Sol B - OFF) and the TCC solenoid is turned on, a circuit will enable a vacuum control valve on the vacuum modulator (vent modulator vacuum to atmosphere) and disable the PWM solenoid. So when on the highway and the PCM commands the TCC to lockup, it will go to max pressure with no PWM control of the TCC. Otherwise it will drive like normal around town and still have PWM TCC control when in 3rd.

Can anyone find a fault with this as a temporary fix? Could anything be damaged by running continuously at maximum pressure (not shifting just constant)? Is there any chance of blowing something apart internally or can the trans handle this?

Thanks,
-William

[3400-95-Modified]

Hi All,
I have been studying the hydraulic circuits in the manual for this trans. I think there might be a leak at the TCC apply valve between the 2nd feed circuit and the exhaust port (top of the valve)

This is probably why they have come out with this valve to fix it. I ordered this along with the anti stick 1-2 2-3 3-4 and the 4-3 3-2 valves... and line pressure boost vavles and such. Same as I did with my first trans and I really liked the shifts after doing that.



The new TCC valves sold to replace the fully steel ones have a teflon seal at the end.

Unless this is not the area you are speaking of.

[willyman82]

3400-95-Modified: Did you increase your line pressure by changing the regulator springs? If so what did you increase it to? Im trying to get an idea of what the trans can handle...

That valve is exactly what I am talking about. Problem is my fiance wont let me do a valve body rebuild until the summer when the weather is better and we have more time. I already did the trans swap and that took way longer than it should have because I threw out my back doing it.

NEWS! I verified that the old transmission is code WFW and the new one is a WFW also. Phew! Now I just need to make it work until I can fix the valve body. I dont know much about GM platforms, but the Acheiva (donor) was a type N and my Corsica is a type L from what I can gather. The WFW only went in those two types. Other 3100 drivetrains with the 4T60E in other platforms got different transmission codes.

Thanks,
-William

[3400-95-Modified]

I've used up to 99 buick transmissions in Beretta's... The only change is the final drive, the torque converter and a few internal hard part upgrades. So having an exact WFW is not necessary, but does make it easier. To make a newer 99 one work, I've had to swap the side cover, and the tone ring on the differential to keep the speedo right. This works on 94-95's since they use speed to shift, on a 96 it will throw a code unless you fix the gear ratio multipler telling it your are running a 1:1 chain vs the .89:1

I am usng the adjustable vac modulator for upping the line pressure some, and I also shimmed my accumulator springs to put more preload on that. I don't have the tools to check the line pressure so I am not sure how high it is... I know its no where near pegged or at the limit. I will typically adjust it and keep my eye on the trans temp to ensure I'm not stressing the pump and generating a bunch of heat... As of right now I think it was staying under 190*f driving around town... I do not live in a city so I do not know how it would respond under those conditions.

I'll be posting pictures soon in my Performance 4t60e thread showing whats coming out of my car as well as what I'm putting in it. I'm going to be tearing into it tonight and I hope to get all the valves that I ordered this week.

Here is the list of valves that I bought from TPUSA

[IsaacHayes]

Willy, have you already built the circuit? Could you post the diagram if you have drawn one out? Sounds interesting. If you do run a solenoid to vent the modulator, make sure there is a check valve before the vent so it doesn't create a vacuum leak and possibly a filter on it to keep dirt from going into the modulator/engine.

If you have a laptop and an ALDL cable, I have a TunerPro RT definition to scan the 94-95 V6/4T60-e engines. You can see TCC slippage, trans temp, etc etc. and log and datalog it in real time...

I believe the trans is also controlled based on MAP load too.

[robertisaar]

I believe the trans is also controlled based on MAP load too.

there is a way to test that....

you'll run a bit rich though.

[3400-95-Modified]

I believe the trans is also controlled based on MAP load too.

In what regard?

Pressure is controlled ONLY by engine vac and the vac modulator... The rest is electronic shift control.

Are you referring to shift logic and TCC lock up and unlock procedures?