Outer Limits 4x4 Board

Tech time guys. I have a little question concerning this on the electrical section. Correct me if I`m wrong. It is not advisable on Td42 auto to swith off the lockup as when O/D is on and no lock up you will overheat unit. So why then if you sit in third with no O/D on does the transmission not overheat ?

Also if I fit lock up switch and am then able to lock convertor in third I must always go into O/D with Convertor locked or if it isn`t I must do it
myself after flicking switch on gearstick. This sound about right?

Alex

Alex, I use a manual lockup switch on my GQ TB42e for towing our caravan.
As a general rule I tow in 3rd gear with the T/convertor locked and if it's flat or downhill I'll use 4th gear but if I have it locked in 3rd gear I'll unlock it 1st then press the switch to get 4th gear. If you don't unlock it you will get a harsh gearchange from 3rd to 4th.
As for auto temps, your auto will run hotter in 3rd with no lock up but when your convertor is locked the temp will drop significantly.
Recently over Xmas we were towing our van (approx 1.7-1.8 tonnes) in 38C degree heat and my auto temps never went over 85C (2nd & 3rd gear unlocked) towing up hills. My cruising temps with the T/C locked were 50-55C.
Please note though, I use 2 front mounted auto trans coolers and do not the radiator trans coolers at all.
Prior to going to front mount coolers I would see temps of 100-110 C regularly.
If you haven't got a trans temp gauge I would highly recommend it to you as I feel it's the best way of monitoring just how hard your auto is working under different conditions.
Regards Andrew.

I have a manual shift conversion on my auto and have just had it stripped down after 12 months competition etc. It has had TD42 with 21 psi, intercooled etc etc. I don't use the lock up at all, and do not even have the option of using it.
The only reason for getting it stripped was to get the shafts changed to suit the VH45. Talking to the guys who did the work, they were very suprised at the condition of the trans. There was no wear and no signs of overheating etc. ie no problems at all. Take into account that for stage starts or attcking a bog/ hill I'll stand on the brake then the throttle. It would get about 14psi at close to 2000rpm before the wheels truned. And still no overheating or damage. Run synthetic fluid, a big cooler and keep the motor running at 2000ish rpm and the trans is plenty strong and will last really well.
I'm so happy with it, it is getting used behind my new motor and that will have over 500hp.

Thanks guys. Are we really saying that you can run in fourth unlocked as long as you are not loading the set up......... ie no trailer flat ground or downhill ? I just need a simple switch diagram....one switch one relay.

Alex

What we're saying is use the right gear and it doesn't make that much difference. Yes locking it will reduce the temp, but have the revs slightly higher will also to this.