Cruise control
- Thread starter Larry
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NoDak
Senior Member
Larry said:
i will try to explain why this happens. when the CC detects 2-3mph difference from the set speed, it will drop out of OD and go into 4th to speed back up to the set point (mind you this is the easy version to get back to the set point, the bad version is when it drops down to 3rd). once it gets back to the set speed, it will go back into OD. since your on a long grade, as soon at it get back to the set speed, it will start losing speed again. and the cycle repeats.
this will only happen on long decent grades. on steeper grades it will drop down to 4th or 3rd and stay there till you get over the hill or on lesser grades the engine will maintain speed above the OD cutout point.
CC wasnt meant to hold speed on grade, only for relatively flat roads. you can use CC to hold speed on a grade, but it will kill your mpg in the process. best to use your foot or put it into a gear suitable for the grade.
Cruise Control
Good explanation. And when you say "best to use your foot" you might also add "safer," that is, if one is into long transmission life. It is a given that the higher the transmission gear, the weaker the gear, by virtue of ratio alone. There is no quicker way to smoke a nice trans, than by letting overdrive do the work on uphills. Lock it in 4th; [3rd if steep enough & lugging is eminent] your MPG may suffer, but compare that meager expense to a complete rebuild.
Now, for flat land use, I know these gear ratios are dictated, in large part, for MPG, not common sense. I have never thought it can be doing a trans any good to drive around town @ 30 MPH in 5th gear. It's just too tall, also pronounced WEAK. I keep mine in 4th, until I get up to about 40. I defer to those who are more technical / knowledgable; am I FOS? :dunno:
Good explanation. And when you say "best to use your foot" you might also add "safer," that is, if one is into long transmission life. It is a given that the higher the transmission gear, the weaker the gear, by virtue of ratio alone. There is no quicker way to smoke a nice trans, than by letting overdrive do the work on uphills. Lock it in 4th; [3rd if steep enough & lugging is eminent] your MPG may suffer, but compare that meager expense to a complete rebuild.
Now, for flat land use, I know these gear ratios are dictated, in large part, for MPG, not common sense. I have never thought it can be doing a trans any good to drive around town @ 30 MPH in 5th gear. It's just too tall, also pronounced WEAK. I keep mine in 4th, until I get up to about 40. I defer to those who are more technical / knowledgable; am I FOS? :dunno:
