This message is for COWPIE1 or anybody else with info regarding a GLIDER TRUCK..=)

Not familiar with that bulletin, but I have run in 16th regularly, in cold and hot weather, under everything from deadhead to 80,000 gross. Either my temp gauge is wrong, or they are full of buffalo bagels. On a hot summer day, crawling around with 46K in the box, running in direct drive (16th) on my 18 spd, the temp barely even approaches 150F. And that is when really working it hard. Most times, it barely moves the needle off of the bottom 110F. Not sure how others might see this, but seems like the trans is running cool enough to not be a problem running in direct. Once I get high or low of direct, I do see some temp rise a little. Once I get back into running direct, I see temps lower back down.

Actually, more work (i.e. heat buildup) occurs in the overdrives (and somewhat also in the gears below direct). There is a lot more going on and a lot more gears being used. Direct is a simple input shaft to output shaft connection. A lot less wear and tear, and a lot more efficient. Seems strange the Senior Engineer from Eaton would have stated all of this at the 2011 MATS Eaton booth if it were not true. The comments he made is part of the reason I spec'd mine the way I did. Not the only reason, but it was a deciding factor.

 

I'm sorry I did put 16 but I meant 17. The way it reads is top gear basically with the thumb control in low position. Like you I can't see any ill effects and wouldn't think much of it but it came from eaton. I also know that a lot of stuff works that isn't supposed to so I thought I would try to get some input from some one who has tried it.

 

Seems somewhat strange even 17th would be a problem. In days gone by, many 13's and 18's could be had as single overdrives, which basically is what is going on by running in 17th. From a lot of comments, write-ups, and other things transmission related, it seems like many folks have problems getting their minds around the idea that one does not have to run in the top hole all the time. Even with my 2013 Silverado pickup with it's 6 speed trans, I rarely am in the top hole with it either. It has a manual mode button similar to those on auto shift semi truck transmissions, that lets me select, up or down, the gear I want to use. I use it primarily in the 1st overdrive (5th) without using the 2nd overdrive (6th). This keeps it in the best power band of the engine for what I normally do where I live and use it. I have a temp gauge on the display for it, and temps are no more than any other time. But that is probably and unrealistic comparison since those are different transmission technologies.

There are so many situations that crop up, that even with traditional rear gearing and using 13's and 18's, that using the top hole just will not work well. Those situations may be longer in duration than a few minutes. The transmission manufacturers take that into account. There is not one gear in the entire spread that could not be used for extended periods. All the gears are made of the same metallurgy. Some selections may raise the temps a little, but if the temps are getting to be problematic, time to check the trans cooler.

 

Mines got the water cooler, so its always matched with the coolant. I couldnt tell you if it makes more heat in one gear more than another. The only great gain to this is for winter warm up. Sometimes hauling heavy on back roads I dont even see overdrive for hours.

 

Well thats what I was thinking. All the 9 series transmissions actually have underdrive in the back box, the overdrive is achieved in the front. They claim that running thru the aux is causing the heat. My trans is a double over with way to much motor in front of it. It does have the cooling lube pump but still the back box is over instead of under and was designed to be ran thru the aux. The 9 series is set up so much better as far as lube and cooling than what I run, plus since the aux is an under instead of over I think that would be less heat in itself. It did say extended use but as Cetane posted I would call hours at a time on a two lane heavy loaded extended use. It doesn't make since to me which is why I wanted to ask if any one had noticed any problems. If it wouldn't have said eaton on it I wouldn't have thought much of it, actually I don't now hearing real world reports. I am fixing to do some thing different with my trans just not sure what is how I ran across the bulletin and why I asked. Thanks to both of yall.

 

Another aspect to think of about if there is a possibility of issues with running, say, 17th all the time. There is nothing in Eaton's literature when you buy the trans, that this can be a problem. I don't dispute a bulletin that might have made the rounds, but the owners manual does not address the problem at all. And it should have by now with new transmissions if it was a problem. They still have the same warranty, and even still honor extending the warranty 50% if you stick with synthetics in the trans. Never any mention or hint in Eaton's owners manual that there are condition regarding the warranty based on what gears you use frequently.