AnswerID: 231469 Submitted: Tuesday, Apr 03, 2007 at 18:07
RobAck
replied:
The issue of ascents and descents in auto 4WD is not well understood nor well trained. Two issues are involved, apart from selecting the correct range, which would normally be LOW. As well drive the auto exactly the same way you would a manual and by this I mean using the same gear selection, so 2nd going up hills to reduce wheel slip and 1st going down hill to maximise engine braking.
But auto trans behave differently wth different manufacturers with some holding the selected gear and others continually kicking up or down. But this issue can be driven around with training.
Firstly you need to lock the torque converter into L. To do this select L just before you crest the hill so it is actually driving in that gear before you go down hill. If you make the selection on the way down it will take up to a vehicle length before the converter locks and that can not be a comfortable feeling at all.
Secondly their is a poorly understood technique called brake throttle modulation. Explaining it is difficult and training it is a touch harder but this technique applies to both manuals and auto's for a wide range of driving conditions. But as has been explained the technique relies on gentle pressure on the brake, using the left foot, and driving against that resistance and using enough revs to remain above the torque converters stall point.
Landcruiser 100 5 speed auto and Prado 5 speed auto are virtually the same transmission and the low range reduction in L is very good and well beyond the cotnrol provided by the older 4 speeders.
I know as I train on this stuff all the time and own an auto VX Prado V6 which gets used hard all the time as a training vehicle.
What I do suggest is joining a club and getting some of the training I have described above.
Regards
RobA
Reply 9 of 9