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Is My TorqShift a 5 Speed or 6 Speed?

 
  #31  
Old 06-06-2018, 09:28 PM
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Originally Posted by Furian View Post
Hey Guys,

I've recently been driving my 2005 F350 5.4L 4.10 w/ automatic transmission to determine my highway MPG (baseline) before installing a few aftermarket goodies. My truck is 100% stock and only has 26K miles on the clock. On Christmas Eve, I drove 263 miles to drop off a few gifts to friends and determined that I'm getting 11.82 highway MPG. Now, while driving the truck up the mountain to my ex-girlfriends house, I notice that the transmission was constantly shifting from what I thought was 5th gear to 4th gear. On really steep grades, it shifted to what I thought was 3rd gear. Note that my speed at this point was only 60 MPH. I decided to "verify" the gear and manually dropped the transmission lever to 3rd expecting no change in RPM's. Was I surprised! The tach jumped to 4,600 RPM's which means that the transmission was actually in 4th gear... hum. I was confused at this point. How could the transmission downshift two times and still be in 4th gear? The roads were wet and foggy so I couldn't pay too much attention to the RPM's while driving...

So today, I take another road trip to check both the highway MPG and the function of the transmission on more level ground. I drive 145 miles and get 12.36 highway MPG. At 70 MPH, the transmission has the following RPM's at select gears:

4th Gear: 3,100 RPM's 4th Gear or Drive (1:1 ratio)
5th Gear: 2,400 RPM's 5th Gear or Overdrive (.71:1) Torque converter unlocked
6th Gear: 2,100 RPM's 5th Gear torque converter locked

When I'm in what I'm calling 6th gear, I can let off the gas pedal and the transmission will shift from 2,100 RPM's to 2,400 RPM's (torque converter is unlocking but it's still in the same gear) and if I press the gas pedal again it will continue to accelerate from the 2,400 RPM point. Once the desired speed (70 MPH) is achieved, the transmission will shift back to the 2,100 RPM point.(torque converter is locking) As noted above, if I press the gas pedal hard enough, it will go into 4th gear turning 3,100 RPM's. I did not "verify" 3rd gear like before because I was sure that the engine would be over 5,000 RPM's at 70 MPH. I didn't want to potentially damage either the engine or transmission.

My questions are:

1. Does the TorqShift transmission actually have 6 gears or does it have some sort of hybrid 5th gear?

2. Could the transmission be the cause of my less than desirable 12 highway MPG?

Around town, I can drive at 45 MPH and the transmission is only turning 1,300 RPM's. Is this consistent with your trucks?

Thanks for your help...
Replies are in Red. That seems like normal operation for your transmission, the 5r110 does have 6 gear ratios but only 5 are used at one time, one is just a different ratio for 4th gear (If I remember right) when the transmission is cold.
 
  #32  
Old 06-07-2018, 06:30 AM
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Originally Posted by RVK View Post
I found this posting (see below) which explains why when I'm towing with F250 6.0, the transmission switches gears from 3 to 5th gear and skips 4th gear. Has any one experienced the same issue?
The reason it skips fourth gear is that fourth gear has a ratio of 1.09:1. Fifth gear has a ratio of 1:1. There is no reason to use both gears, the difference in ratios is too small. This isn't an issue, this is the way the transmission is designed to operate. Another way to tell that this isn't your problem is that the ratio in third gear is identical to the 4R100's second gear (used in your buddy's 7.3L) and fifth gear is identical to the 4R100's third gear. Shifting 3-5 in the 5R110W is exactly the same as shifting 2-3 in the older transmission.

Originally Posted by RVK View Post
I'm wondering has anyone changed the gear ratio fro 373 to 410 and has it improve towing up a grade?
That will help a little bit. The difference between those ratios is about 10%. So at the same speed you'll be turning about 200 RPM more.

Originally Posted by RVK View Post
The issue is while towing up grade the engine while be turning at 2100 RPM at 45 MPH in 3rd gear. When when I ease off the pedal because of the rpm the transmission will shift to 5th gear
And yes, that's your issue. You are backing out of the throttle for no apparent reason. If you'd just keep your foot in it and let it work like it was designed it will climb the grade like it was designed to do.

I've climbed with my foot on the floor with a 6.0L truck and a 5R110W for nine miles. It was an F-550 grossing 30,000 pounds. The truck was fully instrumented so that I could monitor everything going on. It did fine. You will, too. My work associate was in an F-250 loaded to max GCWR (I frget that number, he loaded it) and it did fine, too, and left me a couple miles behind.

Originally Posted by RVK View Post
It frustrating on a long haul to be bouncing in and out of gears on a long haul. And even more frustrating when my buddy with a 7.3 cruses past me at 50 MPH laughing.
That's because your buddy knows to keep his foot in it and let it do it's job. If you drive the 6.0L the way it was designed to be driven it will run away and hide from a stock 7.3L
 
 
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