RPM & gearing question
#16
02-15-2012, 09:18 PM
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Scanner confirmed no torque converter slip.
In stock tune and light to moderate acceleration, the TC will normally lock up just prior to the 3-4 shift, with a 3.73 gear that would be about 38 mph in many cases.
If you have AE or can find someone that does, then go for a test drive while monitoring the following values:
You can then watch the shift solenoids to see when the next gear is selected. You can watch TCCM to see when the PCM is asking the TC to lock up and finally you can watch the slip value to see if it's actually locked.
Some scanners might not have the TC slip actual as a choice. The work around is to select
If you watch those two values then you can confirm the TC is locking up when the numbers are about the same. It's normal to see a 3-5 rpm variation while monitoring...
If you have AE or can find someone that does, then go for a test drive while monitoring the following values:
- Shift Solenoid 1
- Shift Solenoid 2
- Torque Converter Clutch-Modulated
- Torque Converter Slip Actual
You can then watch the shift solenoids to see when the next gear is selected. You can watch TCCM to see when the PCM is asking the TC to lock up and finally you can watch the slip value to see if it's actually locked.
Some scanners might not have the TC slip actual as a choice. The work around is to select
- Engine RPM
- Turbine Input Speed Sensor
If you watch those two values then you can confirm the TC is locking up when the numbers are about the same. It's normal to see a 3-5 rpm variation while monitoring...
#18
02-15-2012, 11:02 PM
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#19
02-16-2012, 12:45 AM
I would imagine so!
There has to be something that has changed in the driveline to be running those RPMs at that speed. If you're convinced it's not in the TC, then it has to be either the transmission or the diff. Is it possible your rear diff is geared differently than the dana 50 that failed on you? Maybe having different gearing caused the failure?
On a separate note, Greg, I love the new signature picture!
There has to be something that has changed in the driveline to be running those RPMs at that speed. If you're convinced it's not in the TC, then it has to be either the transmission or the diff. Is it possible your rear diff is geared differently than the dana 50 that failed on you? Maybe having different gearing caused the failure?
On a separate note, Greg, I love the new signature picture!
#20
02-16-2012, 01:34 PM
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I just replaced the transmission 3 weeks ago with no change. I verified 3.73 gears in the rear by counting driveshaft rotations, but was unable to verify the front. I will probably just end up replacing the rear diff with 4.10, but with these increased rpms I would be At 2300 rpms at 65 mph.
#21
02-16-2012, 02:10 PM
Hmmm....I am stumped. I hope you figure it out and we all can learn from this experience. 
Thanks. I was probably inspired by your sig photo...
A nice background of greenery is scarce in my area so the best I could do it get one of the mountain ranges in the shot. 
I was never very successful with that method. I've always had to pull the cover, count the teeth on the ring gear and divide by the tooth count on the pinion gear. Then there will be no doubt what gear you have.
Thanks. I was probably inspired by your sig photo...
A nice background of greenery is scarce in my area so the best I could do it get one of the mountain ranges in the shot. I was never very successful with that method. I've always had to pull the cover, count the teeth on the ring gear and divide by the tooth count on the pinion gear. Then there will be no doubt what gear you have.
#22
02-16-2012, 02:11 PM
I just replaced the transmission 3 weeks ago with no change. I verified 3.73 gears in the rear by counting driveshaft rotations, but was unable to verify the front. I will probably just end up replacing the rear diff with 4.10, but with these increased rpms I would be At 2300 rpms at 65 mph.
#23
02-16-2012, 02:41 PM
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#24
02-16-2012, 08:39 PM
Senior User
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02-20-2012, 09:18 PM
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#27
02-20-2012, 11:30 PM
Chet
#29
02-20-2012, 11:53 PM
#30
02-21-2012, 01:46 AM
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