I know it is hydraulicly operated (pressure) which is controlled by a solenoid in the transmission that recieves its signal from the ECM by grounding the constant input voltage supplied to the solenoid. But, is the pressure applied when the solenoid is activated, or is it relieved? (article about TC's in latest Pop Hot Rod indicated it is relieved) - In other words, is the clutch locked by applying pressure, or relieving it? And, is the pressure sealed between the shaft and converter by polymer o-rings, metal rings, or??? I had a TH350C apart several years ago, but I don't remember what the input shaft looked like, and didn't really understand the operation anyway (I know a converter replacement solved a vibration problem on that car).

I'll be pulling my TC when I switch engines in the next few months. Right now, my TCC doesn't lock, and I have an engine speed-related vibration that seems to be the converter - I'm assuming a converter rebuild or replacement will cure those problems. But, when I pull it, I'd like to know what else to look for while it's apart.

Thanks in advance for any info.

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R. 2.93 limited slip. Cat-back from '91 GTA, Accel HEI SuperCoil. AMSOIL syn lubes bumper-to-bumper. Daily driver, work-in-progress (LG4 w/LB9 block, ZZ3 cam and intake, WP 305 heads ported & polished, TBD headers & hi-flow cat).
57 Bel Air, my 1st car. 0.030 over 396, Weiand Action+, Edelbrock 1901 Q-Jet, Jacobs Omnipack, 1-3/4" headers, TH400 w/TCI Sat Night Special conv & shift kit, 3.08 10-bolt, AMSOIL syn lubes bumper-to-bumper. Best 15.1 @ 5800' Bandimere. Daily driver while Camaro was being put together.

 

Torque Converter Locked:
<img src=http://members.home.com/crussel/camaro/2nd_Gear_TCC_On.gif>

Torque Converter Unlocked:
<img src=http://members.home.com/crussel/camaro/2nd_Gear_TCC_Off.gif>

[This message has been edited by Apeiron (edited January 25, 2001).]

 

I'll have to study that more later (I hear three knocks on the ceiling). But, it looks like the pressure changes location within the convertor when locked vs. unlocked.

Also, the unlocked schematic doesn't show any pressure to the solenoid. ????

Thanks for the response. It's a keeper.

Any info on the TC/shaft sealing?

 

Found a nicer diagram for what you want:

 

The gist of it is when the tcc is unlocked fluid is routed in front of the clutch to hold it off the cover. When the clutch is applied the fluid is directed to the back of the clutch plate to hole it against the cover.

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82 z28 350cid, vortec heads, comp 262h cam, Holley 600cfm carb, 2in twice pipes, MSD ignition, turbo 350 trans, 3.73 posi, manly b&m megashifter

 

But to answer your question....you may not be locking because of a simple wiring problem. Above your brake pedal are 2 switches, one for the brake lights, one for your TCC solenoid / cruise control vacuum release (it is the switch with the vacuum line attached to it).

If the TCC switch is bad, your converter wont lock. I drove around like this for a LONG time before accidentally figuring it out.

With the ignition on and the brake pedal released, you should have voltage to both sides of the switch (purple wire). Pressing the brakepedal releases the switch and cuts the connection...thereby turning off the converter when you hit the brakes. That purple wire goes straight to the + side of the TCC solenoid.

Other problems could be: 1) bad tcc solenoid

2) the computer is not grounding the TCC solenoid at the proper times.

You can test for the computer by manually grounding the TCC negative (tan?) wire after you verify that you are getting power to the positive (purple) one. If it works, you should hear it 'click'. If it does not...you probably found the problem.

The vacuum switch is $13 dollars at the dealer. The solenoid can be had for 20-something at most tranny parts warehouses.

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Mike Metzler (Desert86Roc)
Mike@SpeedworldMotorplex.com [*] Webmaster: SpeedWorldMotorplex.com[*] Click Here For My Racing Page[*]86 IROC 305 TPI (406 build in progress)
ET's @ 1250 ft[*] 14.28 @ 95.461 mph (uncorrected, NOS, no headers)[*] 15.365 @ 86.785 mph (uncorrected, Headers, no NOS)

[This message has been edited by Desert86Roc (edited February 13, 2001).]

 

I had already verified the 12v on the purple wire at the tranny and tried the grounding switch - didn't help. However, I didn't know about the temp switch at the time, and although I'm not completely sure, I believe the trans was cold when I did this stuff. So, I still need to check that, but based on the weird vibration, I'm sure there is something wrong with the convertor, even if there is something else that's keeping it from locking.

Still wondering about the pressure sealing between the input shaft and TC...

 

Not all transmissions have the temperature switch.

 

The seal you are asking about is a special
dark gray o-ring on the input shaft. I was
told by my friend who is the manager of a
transmission shop that the 700-r4 needs the
converter to be locked in overdrive to help
lube the rear planetaries. Is this true??

 

The wiring diagrams I have seen do not have a temp switch... Engine temp is one of the criteria that the ECM uses to ground the circuit, but if you are manually grounding the correct wire, with power to the other, regardless of engine operation you should be able to hear an audible click when the solenoid engages. With the key on & engine off do you have power at the wiring harness before it goes into the trans?

 

I checked for voltage at the transmission connector, purple wire, ignition to "on". I tried the grounding at the ALDL and each of the other two wires in the transmission connector. Same results with all.

I'll have to check the internal transmission circuits some time, probably when I'm doing the engine/TC work.