Overdrive
February 29th, 2012, 11:44 AM
#1
CF Beginner
Thread Starter
Join Date: Feb 2012
Posts: 18
Likes: 0
Received 0 Likes
on
0 Posts
Overdrive
What is your opinion of driving in Overdrive?
It had been well over a decade since I have been in a car with the OD option on the tree.
I kind of remember in our old Bronco we would only use it at highway speeds but it has been so long I just don't remember.
To me it would seem if OD puts you in a higher gear it would be more stress on parts at lower speeds. Now that my suburban gives me that option again I am wondering if it cool to keep it in overdrive at all times without any worry...
It had been well over a decade since I have been in a car with the OD option on the tree.
I kind of remember in our old Bronco we would only use it at highway speeds but it has been so long I just don't remember.
To me it would seem if OD puts you in a higher gear it would be more stress on parts at lower speeds. Now that my suburban gives me that option again I am wondering if it cool to keep it in overdrive at all times without any worry...
February 29th, 2012, 11:54 AM
#2
the world has change quite a bit since your old bronco...
Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway. When it is switched on, an automatic transmission can shift into overdrive mode after a certain speed is reached (usually 70+ km/h [40-45 mph or more] depending on the load). When it is off, the automatic transmission shifting is limited to the lower gears. For an automatic transmission, it is almost always best to select overdrive and allow the transmission to control engagement of the overdrive. (It may be necessary to switch it off if the vehicle is being operated in a mountainous area or when towing a trailer.) With a manual transmission, overdrive should usually be selected when the average speed is above 70 km/h (40-45 mph).
Overdrive (mechanics) - Wikipedia, the free encyclopedia
Generally speaking, overdrive is the highest gear in the transmission. Overdrive allows the engine to operate at a lower RPM for a given road speed. This allows the vehicle to achieve better fuel efficiency, and often quieter operation on the highway. When it is switched on, an automatic transmission can shift into overdrive mode after a certain speed is reached (usually 70+ km/h [40-45 mph or more] depending on the load). When it is off, the automatic transmission shifting is limited to the lower gears. For an automatic transmission, it is almost always best to select overdrive and allow the transmission to control engagement of the overdrive. (It may be necessary to switch it off if the vehicle is being operated in a mountainous area or when towing a trailer.) With a manual transmission, overdrive should usually be selected when the average speed is above 70 km/h (40-45 mph).
Overdrive (mechanics) - Wikipedia, the free encyclopedia
February 29th, 2012, 2:16 PM
#4
CF Junior Member
Join Date: Feb 2012
Posts: 48
Likes: 0
Received 0 Likes
on
0 Posts
If I was driving around in an '88 anything, I would add a transmission temperature gauge. Much of the improvement in transmission reliability in recent years is because of more cooling and smarter heat management due to computerization. $0.02.
February 29th, 2012, 5:45 PM
#6
CF Junior Member
Join Date: Feb 2012
Posts: 48
Likes: 0
Received 0 Likes
on
0 Posts
Not an "additive" but if you have an auxiliary transmission cooler, you probably won't have heat problems with it. You will run into torque limits first (which you can obviously work through with axle gearing.)
Pop open the hood and see if your transmission oil line is plumbed up to a small radiator next to the main water radiator (or in front of it.) If so, you already have an aux cooler. From there the trans oil might also be plumbed through the main radiator. If you don't have either of these things, adding a cooler will take some work and hours at a transmission shop. If you have one or the other, you can always upgrade your transmission cooler to a bigger size if you want to, change to electric fan to move more air if you want, etc.
Main thing to do if you notice high trans temp is slow down. If you have a trans cooler, also shift to a lower gear, because higher RPM on the input side of the transmission will cause it to pump more oil up to the cooler.
For some transmissions you can also get aftermarket oil pans that are deeper, and have metal fins on them, to make them a better heat sink. Without a cooler up by the radiator, the main way a transmission gets rid of heat is bleeding it off through the surface area of its oil pan, underneath the vehicle.
Hope this helps!
Pop open the hood and see if your transmission oil line is plumbed up to a small radiator next to the main water radiator (or in front of it.) If so, you already have an aux cooler. From there the trans oil might also be plumbed through the main radiator. If you don't have either of these things, adding a cooler will take some work and hours at a transmission shop. If you have one or the other, you can always upgrade your transmission cooler to a bigger size if you want to, change to electric fan to move more air if you want, etc.
Main thing to do if you notice high trans temp is slow down. If you have a trans cooler, also shift to a lower gear, because higher RPM on the input side of the transmission will cause it to pump more oil up to the cooler.
For some transmissions you can also get aftermarket oil pans that are deeper, and have metal fins on them, to make them a better heat sink. Without a cooler up by the radiator, the main way a transmission gets rid of heat is bleeding it off through the surface area of its oil pan, underneath the vehicle.
Hope this helps!
Last edited by jeffsw6; February 29th, 2012 at 5:55 PM.
Thread
Thread Starter
Forum
Replies
Last Post
snake91876
Tahoe & Suburban
3
October 13th, 2012 3:41 PM
