GQ Auto Lock Up

[GQtdauto]

Not sure if anyone still watching this thread but if there is does anyone know if I can just use a simple lock up in 3rd overdrive only for a 1994 td4.2 with same auto as mentioned .
In other words if I flick a switch in 3rd overdrive can I keep it there as long as I maintain speed .
And how do I wire it up ?

Robert

[ripper]

If I'm understanding your question right, yes, that would be easy. If your trans computer is the same as ours, you'd cut the wire from pin 22 and put your switch in there to feed 12 volts to the torque lock up solenoid.

You should be able to test it by sticking a pin through the wire and seeing if it gets 12 volts when you get up to about 90 km/h.

I don't understand why you'd want to manually do this though? If the trans and computer are working properly it will stay locked up itself if you stay over 90 km/h.
Also without the brake switch and park/neutral cut out you risk frying the trans by forgetting it's locked up.

[GQtdauto]

Thanks for your reply , don't know if my auto is different ratio or diff gears are different but when I'm in OD and motor is cold it takes about 5-6 Klms for the change from 3rd to 4th (od) .
When in this 3rd gear torque converter is locked , revs sit at 2050rpm and speed is about 100 k , peddle response is fantastic if I plant the foot I speed up instantly but as soon as box heats up to normal revs drop to 1700 and peddle response goes .
If I can get it to stay in this third overdrive while on the blacktop it would be ideal , all other driving would just be overdrive off in 3rd but no faster than about 80 ish to keep revs down .
My third gear overdrive off ,rpm 2850 speed 95 k but overdrive on in third and cold 2050 rpm and 100 k .

Thanks for your help with this .

[Winnie]

It's worth keeping in mind that you would use a fair bit more fuel driving in a lower gear on the straight roads.

[GQtdauto]

That's the strange thing with my setup , when in OD and gearbox cold (GQ TD 4.2t) revs are only 2050 at 100 and if I put my foot down the speed increases as much as the revs so torque is locked till box is warm .
When it goes into overdrive revs drop too much and even a slight incline will slow the thing down till I put my foot down raising the rpm but converter slips causing high revs and increased heat problems .
If I could somehow fool the box into thinking it was cold all the time I would be happy but don't know if this is possible or advisable .

[GQtdauto]

Sorry should have made clear 3rd gear overdrive on but locked because box not up to temp yet .

[GQtdauto]

My GQ must have long legs or ratio is way out , in overdrive rpm 1700 at 100 k which is when the box heats up and it changes into fourth .
But I'm going to try the opposite to what has been done to wire 22 and simply cut it run both ends to a switch but not add power and see if that keeps it in third overdrive without changing up to fourth .
Using the pin in wire 22 I get bugger all voltage till it pops into fourth then I get 10 plus volts .

[ripper]

It's normal for it to take a while to warm up enough for it to lock up in 4th.
How accurate is your speedo? Ours is about 10% out (tested with GPS) so 1700 rpm is probably 100 on our speedo but only 90 in reality when the TC (Torque Converter) is locked up in 4th gear.
I suspect your cold 2050rpm is actually 4th gear (OD) before it's warm enough for the TC to lock up. Ours is more like 2500rpm with the TC manually locked in third at normal trans temps.
Cutting the wire will probably do what you want.

[GQtdauto]

Thanks ripper, speedo is out by 10 Ks but I accounted for that ( must do the mod for it on this forum) will cut the wire tomorrow morning and take it for a run if it stays in third overdrive after heating up the tranny I will be happy .
Not sure if the torque lock system you and others have come up with will allow me to lock in 3rd gear od without jumping to fourth .
Don't know if my setup is different to most can only go by observation and the gear to travel on the blacktop is definately 3rd od while cool .
Throttle response is like a manual , rpm is just above 2000 at 100 Ks and like I said after 5-6 Ks it changes to fourth , revs drop to 1700 and even a small incline will slow it down .
I do realise this is different to what most seem to be doing , almost opposite in fact .
Probably doesn't help having 33s and rooftop tent and now I want to pull an 1600 kg camper trailer around as well .

[ripper]

Thinking more, this will do what you want BUT, you run the risk of cooking the auto if you use it too much, and you shouldn't tow your camper trailer in OD.

The factory TC lockup helps the trans run cooler as the TC generates a lot of heat when it's not locked.

We had our auto reco'd a few years ago and the auto shop said not to tow in OD. I asked about a box trailer and they were even hesitant about saying that that would be ok.

Your 33s will be reducing your revs, so 1700 at 100km/h is probably right for OD with the TC locked. We're using 31s.

Our van is about the same weight as your camper and we tow in 3rd with the TC locked. That puts us at about 2500 revs for 100km/h.