Thread: Replace ZF6 HP26 with HP28 TRANSMISSION

always let gearbox do its own thing
it is normally in 5th (about 1800rpm)- will sometimes go into 6th if a bit downhill.

hi Terry
thanks for your comments
leave box in normal mode
box shows no sign of wanting to shift up - can manually shift up but smallest increase in load causes it to shift back down.
dont understand why 5th would cause more load - need a certain amount of output torque from gearbox to keep van & car moving (to overcome rolling resistance etc). With higher gear reduction in 5th gear versus 6th gear this means less torque at torque converter = less load on torque converter.(this is from my engineering background).
Have towed at higher speeds & gearbox stays in 5th but I am retired & in no hurry plus get better fuel consumption.

But I am also interested in your experience re 6th gear - even when not towing, car lightly loaded & level road it does not want to go into 6th in normal mode - have to manually force it up. Have complained to dealer before but "no errors"

Also find box very slow to downshift on steeper hills when towing - revs drop to around 2000rpm or less, car is slowing, flat out accelerator & box does not want to shift down (eventually does just as I am thinking of a manual down shift before we stall)

car is a 2.7l disco 3 SE

very interested in your experience.

regards, Dennis