[Ted's37]

I have a 700r4 in my street rod. The torque converter quit locking up on me.
The problem isn't electrical. The solinoid energizews when the 12vdc is applied. I did replace the solinoid. It has been locking up fine all summer, now all of the sudden no lock up.

Any suggestions

Thanks

[chevota'54]

Hi Ted, names Charles. Do you have switch on the in the dash area to manualy ingauge the lock-up?

[Ted's37]

Yes I have a switch. The solinoid is energising, the 4th. pressure switch is good.

[SSedan64]

Only leaves the actual TCC in the Converter or TCC apply valve in the Pump.

TCC = TorqueConverterClutch

[Ted's37]

Which is the most likely to fail, the TCC or the valve?

Thanks for your responce

[Crosley]

Originally Posted by Ted's37

Which is the most likely to fail, the TCC or the valve?

Thanks for your responce

Either can fail. the valve in the pump may be stuck.

Installing a check ball in the end of the solenoid , then re-install the l/up solenoid back into the pump... this will cause the converter clutch to lock up with the shift to 2nd gear if the converter lock up is operating correctly.

With the check ball in place, the solenoid is effectively closed full time to move the l/up valve in the pump.

[Ted's37]

Thanks, I will try that and see what happens.

[Ted's37]

Crosley, I put the check ball in the solinoid and tested on the jack stands. When it shifted to 2nd. the rpm when way down, indicated to me that it locked up. When I put the brake on to put it in park the engine stalled. I did this 2-3 times wuth the same results. Before I put the solinoid in I pushed on the apply valve. it wasn't stuck and seem to work freely.

What do you think

Thanks

Ted

[Crosley]

Originally Posted by Ted's37

Crosley, I put the check ball in the solinoid and tested on the jack stands. When it shifted to 2nd. the rpm when way down, indicated to me that it locked up. When I put the brake on to put it in park the engine stalled. I did this 2-3 times wuth the same results. Before I put the solinoid in I pushed on the apply valve. it wasn't stuck and seem to work freely.

What do you think

Thanks

Ted

I think your test indicates the hydraulic system in the pump and converter are working for converter clutch lockup. Unless when the trans is fully warmed up , there is a hydraulic failure via an internal leak.

The test results point to the problem you experience is in the area of the solenoid, switches, wires and voltage/power source.

[Ted's37]

Crosley, I rechecked the circuitry, Everthing checked out. I went ahead and replaced the solinoid. I wired a direct ground to pin 4 and switched 12vdc to pin A. This eliminated the 4th. gear pressure switch. You could hear the solinoid energize when the engine wasn't running and the switch was turned on. When I went out for a test drive the only time the converter would attempt to lock up would be around 40-45mph, 1900rpm. In order to get it to lock up I would have to level out the acceleration or let up on the throttle. Then it would it would not stay locked up, it would go in and out. If I depressed on the throttle it would stay unlocked. It didn't matter if the fluid was hot or cold.
What do you think.
I appreciate your replys.
Ted

[SSedan64]

Do you also have a Vacuum Switch installed in the circuit?
Sounds like it's disengaging Lockup too early. It may be adjustable.

[Ted's37]

Yes, I have a vacuum switch, but I have bypassed it and the 4th. gear pressure switch in order to troubleshoot this problem.
Thanks for your come back. Any other suggestions would be appreciated,

[motosyco]

sounds like the convertor to me just because your engine stalled at idle doesnt mean the clutch can handle a hi torque load in your description that your only feeling lockup when you back off the throttle did you open up the old filter when you had pan off look for green clutch dust in the folds

[Ted's37]

No, I didn't think about tearing the filter apart. There was no green in the pan. When I take the pan off again, I will look for that.

I have a 200 -4r lock up converter that I know works. Could it be used in the 700 to see if it is the converter or not.

Thanks for your feed back

Ted

[SSedan64]

All 200-4R Converters have a 27-Spline Turbine.
Early 700-R4's up to late 84 had 27-Spline Input Shaft, after that, 85, they switched to 30-Spline.
So if your 700-R4 has a 27-Spline Input Shaft it will work.
Example Pic >> 700R4 Transmission Parts Torque converters
Converter Parts >> Torque Converters Explained - TCI® Auto