Thread: Torque converter lock up / stall

I was having a think-out-loud on the P38 forum about something similar the other day. I'm no expert on the topic, so guru's correct me if I'm wrong, but there is a lockup plate within the system that does this magic job! Triggered from the transmission ECU, it'll lock up based on a preset speed or gear, and when conditions are right (ie temp not too cold and throttle load not too high).

The P38 Rangie when driven what I would say normally, sits between 2,000 and 2,250rpm at stall and locks up at 60km/h (sometimes earlier if your ECU learns that you drive for economy). I too believe that 2,250rpm is too high for the 4.6 V8 in a P38 as maximum torque is at 2,600rpm, so you are never far from having balls ready to get-up when you plant the foot. It should be stalling around 1,800rpm (and I'm sure the TD5 is much the same as it's max torque is around 2,000rpm).

I enquired about tapping into the signal wire from the ECU and putting a manual lockup switch in to override the computer. I'm sure it can be done and would make it easier on the motor.

Cheers
Keithy

The lockup on the bosch vehicles seems to happen at lower revs than gems. The earliest mine will lockup is at 68kph. Where my brothers d2 v8 locks up at 57.

Interestingly the ashcroft website lists a lower stall convertor as an upgrade for the td5 - they put the 4.6 tc in.
The td5 is different to drive - I suppose it's just getting used to it.

Not sure exactly what activates lock-up, but with regard to stall speed, a low-stall torque convertor dramatically improves engine braking in low range, which is a definite upgrade for off-road driving.

It is electronically controlled (solenoid) and for TD5 about 80 kmph is correct for 4th lockup (and will then unlock somewhere about 70 or higher in individual cars).
You can get an over-ride system - see here (second part)

The 4speed discovery is a ZF4hp22/24 , We have available a compushift that will control all shift characteristics for the Full Electronic version (ie No TV Cable ).
I am unsure of the year that this changes so you would need to check.
Cost would be around $1700.00 plus fitting

We also have available a lock-up switch for the electronic units that can control lock-up apply in all gears.
Wholesale Automatic Transmissions
Cost $ 325.00 plus $25.00 freight

That's not bad, I'd like to get more info off Rodney about it.

Just a quick note.

In the ZF4HP22EH - Disco 2 the lockup solenoid is powered to turn the Converter lock OFF.

So cutting power to the solenoid turns the converter lock ON.

After the Stupid Nissan Auto the ZF is great and not considering a manual over ride, but this is what I have the parts for.

Lockup Trans Switch

Thanks. Good information will have a think about what to do. I take it that the trans controller can not be configured in standard form, and requires the link posted to have control of shifting patterns.