transmission question

[caldwell]

When I am driving on level ground with speed control on my transmission sounds like it is shifting up and down. Sounds like it is down shifting. When I get to an overpass it really digs down. and smooths out before it get to the top of the rise. Since I am new to this this has not been my experience with other transmissions. I have a 2003 Holiday Rambler on workhorse chassis.Please help

[Skip426]

caldwell, do you notice an RPM change that goes with the sound ? One very common area of concern as far as a change of sound , is the cycling of the thermostatic radiator fan. Some people even say the trans is starting to slip, because the noise change is so noticable.For economy the rad fan doesn't always turn at engine RPM. Every time the air temp at the hub of the rad fan reaches a set point the fan speed increases, and so will the noise. If you have the noise and no RPM change, it's just the rad fan doing it's job. Outside air temp, Air conditioning on, and hills will increase the frequency of the sound/cycle. When the rad fan is at full engine RPM it can use up to 20 hp, depending on engine rpm.