5th Gear or 6th gear on 35J?

[jasonm]

My overdrive switch has 3 options; Overdrive off, 5 gears, or 6 gears. When would I use the "5th gear" option? Wouldn't highway driving be best with 6 gears? Just curious.

[jasonm]

My overdrive switch has 3 options; Overdrive off, 5 gears, or 6 gears. When would I use the "5th gear" option? Wouldn't highway driving be best with 6 gears? Just curious.

[Pusherman]

I don't know your tranny setup, but my advice would be to let the tranny do all the shifting. The only time there may be an exception to this is when you're in hot weather climbing mountains. I know the diesels recommend keeping the engine at 2K RPM's for optimum cooling. Not sure about the gassers, but I'm sure there is a correlation where there is an optimum RPM for cooling when driving in hot temps and climbing mountains.

So check your chassis manual, and see what they recommend under these conditions. Otherwise, let the tranny do its job on its own. Keep it in 6th.

[Paul T]

I use the overdrive switch to "lead" the grade brake so to speak when going down hill in the mountains. Why wait to tap the brake actuating the grade brake when I can just select 5th and then 4th with the overdrive rocker switch. Then if required I can always get on the brake as required. It just seems to give a smother down shift than the grade brake ssystem although the results are exactly the same.

[Pubtym]

I have 2006 35U. I leave overdrive "On" 99% of the time...letting tranny computer do the down & upshifts. When I'm climbing or going repeatedly uphill-then downhill...and I find the tranny repeatedly downshifting to 5th or 4th going uphills...I'll switch the overdrive to lockin 5th maximum until road conditons permit steady 6th gear. Then I'll return to Overdrive "On" again.