09-07-2017, 07:30 PM
Michael: if you have the HT741 transmission it will lock up in 2nd gear some time after shifting into that gear but before shifting to 3rd. Once it locks up in 2nd it stays locked up until downshifting. 3rd and 4th gear are always in lockup. The shifting sequence is 1st unlocked, 2nd unlocked, 2nd lockup, 3rd lockup, 4th lockup
I suspect your higher temperature is due to the higher load passing through the gears in order to maintain speed against the resistance of the headwind. Even more likely is that the increased load due to headwind increases the engine load and coolant temperature which raises the transmission oil temp as that oil passes through a coil in the bottom of your engine coolant radiator (assuming your coach works the mine does). With that arrangement, any rise in engine coolant temperature will likely cause a rise in transmission oil temp. I've noticed that correlation with mine. A reason for this configuration is to get and keep the fluid warm to reduce viscosity so there is less oil drag in the transmission and ergo better fuel efficiency. What will they think of next?
I suspect your higher temperature is due to the higher load passing through the gears in order to maintain speed against the resistance of the headwind. Even more likely is that the increased load due to headwind increases the engine load and coolant temperature which raises the transmission oil temp as that oil passes through a coil in the bottom of your engine coolant radiator (assuming your coach works the mine does). With that arrangement, any rise in engine coolant temperature will likely cause a rise in transmission oil temp. I've noticed that correlation with mine. A reason for this configuration is to get and keep the fluid warm to reduce viscosity so there is less oil drag in the transmission and ergo better fuel efficiency. What will they think of next?
Jon Kabbe
1993 coach 337 with Civic towed