JrRifleCoach

What directly controls the lockup clutches in the torque converter.

We know there is an electric circuit. But is the clutch manipulated by fluid pressure? Or controlled by an electric clutch?

Thanks JRC

383vett

The lockup clutches are kept apart by tranny fluid in the converter. When 12 volts are supplied to the lockup solenoid in the tranny, fluid is exhausted from the torque converter (through the opening in the input shaft) allowing the clutch faces to contact.

JrRifleCoach

Ahhhhhh. SO if the solenoid is "soft" and not closing off the port fully when oil pressure increases, the TC clutch can release.(?)

383vett

If the solenoid is not closing the port, fluid is exhausting out of the converter and will cause the converter to lock up when not wanted.

JrRifleCoach

What is happening as I roll in throttle lightly, lets say 55-60 mph, the torque converter unlocks. Enough throttle to maintain speed over a slight rise in the road. In the past this was not a problem and the TC stayed locked.

383vett

Converter clutch might be shot.

aboatguy

The T.C. clutches are not that stout.

pricesgarage

the thottle position sensor could be bad also it will cause the converter to lock and unlock intermittanly there also a valve in the pump that applies the lock up when the soleniod is activated but most likely a tps aslo chect engine coolent temp sensor

JrRifleCoach

Checking the TPS right now

383vett - New converter from PDQ (Sacramento)

...TPS was at .48 adjusted to .54. followed the voltage with an analog gauge.
Voltage was linear with no bumps or voids.

All works well when cold. Car pulls hard and shifts are crisp.
Everything goes to he11 once the temp is up.

I'm out cruising at 55mph, trans in forth (OD) TC locked (I think)
Little by little the tach starts to rise and speed slowly starts to drop.
I even got the UpShift to lite!

Got a lot of troubleshooting ahead.
Might be a TC, Pump or valve body...

Too much fun!

pricesgarage

hmm next step un hook the lock up drive it verfiy its not overdrive slipping

T. Wayne Nelson

AND, they sluff off clutch material if they are built by TCI destroying the trans.

383vett

Intercept the tcc wires going into the tranny (either at the tranny or out of the ecu). Hook them up to a weitch in the cockpit. You will have full control over converter lockup. Get up to speed, lock the converter up and see if rpms and speed vary.

JrRifleCoach

Therein lies one of the problems.
TC locks OK when cold. Hot, the lock is "soft" or non existent.
I've watched the signal from DataMaster.

Cliff Harris

The pump pressure in the trans tends to drop as the fluid warms up and thins out.

You can raise the pump pressure with a kit. You can install it by just dropping the pan. Higher pump pressure will give your TC a better grip and help the rest of the friction surfaces in the trans live longer. Slippage equals death in these transmissions.

...And adjust your TV cable. It directly affects pressures in your trans.

JrRifleCoach

Will be hooking up a GM trans press gauge tool to record main, 2nd & 3rd gear pressures.

BTW This is a freshly overhauled trans. Gonna have to come out again....

pricesgarage

checkj with a company called sonnax they have a louck up valve that has a teflon seal in it can be changed in the car

Cliff Harris

If you drive around with the trans pressure gauge hooked up, make sure it doesn't get close to the exhaust system.

I had the gauge tied up pretty well so it wasn't moving around. The hose was touching the shield on the exhaust manifold but I figured that was OK. I was wrong. When the hose burst and sprayed trans fluid all over the place it caught on fire. It was pretty entertaining to watch the flames coming out from under the car as I was going down the road. Good thing I carry a fire extinguisher...

JrRifleCoach

Price - already have the Sonnax big servos installed. This trans pulls hard when cold. It falls apart when op temp reached.

Cliff - advise taken.

mistaben

what does the kit cost?

mistaben

lets say this happens at around 4000RPM and you get an engine RPM rise to 4500RPM...

would that be the transmission slipping or the torque converter disengaging... ?