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4.10/4l80e with 33" tires - rpm at 70mph?

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Old 11-12-2013, 03:29 PM
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Originally Posted by Vortec350ss
Has the truck been tuned for the bigger tires? If not then actual tire size is irrelevant when looking at speedo and tach.

70 MPH with the stock 245's and 4.10's that 2400RPM sounds right. You may actually be traveling closer to 75 MPH when your speedo is reading 70. Your gas mileage seems and sounds off first and foremost because those tires dont help, but your speedo is probably slightly off, making mileage seem off as well.
This^^^
Old 11-12-2013, 03:43 PM
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nope not tuned. still doesnt answer why the RPM doesnt flare when i tap the brake to unlock the converter...
Old 11-12-2013, 03:49 PM
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are you on cruise?

If not the 80e unlocks as soon as you let off the gas, which would also be before you hit the brake unless you drive with 2 feet. If you are on cruise then it may flare just a tad, but you wouldn't hear/see that unless you have a loud exhaust, and it was under a little bit of throttle, like accelerating slowly or going uphill.
Old 11-12-2013, 04:08 PM
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Originally Posted by Vortec350ss
are you on cruise?

If not the 80e unlocks as soon as you let off the gas, which would also be before you hit the brake unless you drive with 2 feet. If you are on cruise then it may flare just a tad, but you wouldn't hear/see that unless you have a loud exhaust, and it was under a little bit of throttle, like accelerating slowly or going uphill.
So are you saying that with cruise control on, the 80E segment won't unlock the converter at low/zero TP%? But with cruise control off it will unlock at low/zero TP%?
Old 11-12-2013, 05:05 PM
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to check the converter, i get the truck running a constant 70mph and reach up with my left foot and tap the brake without lifing my foot off of the accelerator at all.
Old 11-12-2013, 05:11 PM
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When it unlocks I would expect you see a slight surge in RPM in that case.

Are you sure the converter is locking, or is that what you are trying to figure out?


And Ferocity, I think the transmission will behave the same but you rarely see no throttle under cruise compared to normal driving.
Old 11-12-2013, 05:16 PM
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i'm trying to figure out if it is locking. i guess i just need to get it over to charlie to see. this is my first 80e so i'm not 100% sure on how they act.
Old 11-12-2013, 05:26 PM
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You should be able to tell if its locked when you are on the highway. Without taking your foot off the gas just press it progressively more and more... RPM shouldn't move until it hits a point where it commands to unlock and probably a gear change.

On the flip side if you let your foot off the gas to make sure its unlocked and then get into it again you should see RPM move a little before it locks again.
Old 11-12-2013, 05:30 PM
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With my 80e I cant see the RPMs change at all either when I tap the brake, and I can see it unlocking with with hp tuners.

Nothing at all like the 60..felt like it went up 500 rpm.
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