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I know this is going to sound crazy but here goes, i have a 08 dually with a 6 speed. bone stock:( with 6K miles and it hasnt pulled any trailer yet

The problem is i decided to shift the truck manually and i noticed as i went thru the gears all shift were done right away, then when i shifted from 4th to 5th the tranny shifted and as the rpm started to go up again it shifted again by itself, then as the rpm went up again i was able to shift to 6th by myself.

I tried this 5 or 6 times and it does it everytime. Has anyone had this problem, or is it normal?

Do i have a magical 7 speed:ro)... i doubt it
 

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No, that's just the torque converter locking, it feels an aweful lot like a shift though doesn't it??
When you do that with it in Tow/Haul mode you'll feel the same thing as you get halfway or so into second gear.
 

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I agree with the others, it sure feels like it's shifting but I'll bet it's the
Torque converter locking up. If you keep trying to count all of those shifts it will make you crazy. Just drive it and have fun.:driver:
 

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Glad to help!! You'll also notice a 'roar' in the morning drive for a few blocks or so, then it disappears, it's the engine fan helping warm the motor up (creating drag with the fan) so that's normal also.
 

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awsome i didnt know this either felt like it was messing up around 5-6 great info... i do need to replace my fuel filter though thats next on the list
 

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It's funny how the TC lockup in 5th feels like it shifts again but when it locks up in 2nd if you're in tow/haul it is no where near as drastic a change.
 

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It's funny how the TC lockup in 5th feels like it shifts again but when it locks up in 2nd if you're in tow/haul it is no where near as drastic a change.
the higher the gear, the more load on the converter and it has more stall rpm. so you've got more rpm difference in 5th vs 2nd.
 

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Torque converter lockup...

Very useful info guys, I had my truck in the shop and told them to check out the tranny also because of that same thing, felt like 5th gear shifted twice, the second time at 48mph... I had it down to the "T". They said they couldn't get it to do it even though I could everytime... Glad to know it's not my tranny and most of them do do that. Here's my new question... I noticed this morning that when I got on the interstate (only 2 miles after starting it up) when my truck (it was cold in Texas, 29 degrees...) shifted into 6th and I set my cruise to 70 mph it was reving at 2000 instead of the normal 1800 and I checked to make sure it was in 6th, which it was. Then after about .5 - 1 mile it felt like a slight shift and the rpm's went down to it's ordinary 1800. Could this also be the torque converter locking in when it's cold or something like that?
 

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the trans does not lock up the converter (even if the normal lockup conditions/circumstances are met) until the trans fluid temp is above 80* IIRC.
 

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i will sometimes get 3-4 miles down the road in the winter before the torque converter will lock in. at 60 mph i'll be running about 2000 rpms, and as soon as it locks once the fluid is warmed up it drops back down to 1700.

if you start your truck to let it warm up, will the fluid warm up any faster if you put the parking brake on and put your tranny in neutral? we do that on our combine with a hydrostatic transmission just to circulate the fluid before we get it in and start running when its cold.
 

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Good morning,
Would this explain why when I am pulling, sometimes the tranny sounds like it is stuck in passing gear when I pull a hill? I have to get out of the throttle to get it to quiet down. 2001 stock 2500 hd
 

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ive counted 8 shifts (or thats what i thought they were) with it in manual.. :lol:
 

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Thanks

Lots of thanks guys... I was getting ready to send it into the dealer and starting to cuss the allison... Glad to know that's what it's supposed to do!!!!!
 

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yaa they take a little while to lock up when the motor is cold... it's supposed to help the motor warm up faster... but it also wastes more fuel.
 

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Glad to help!! You'll also notice a 'roar' in the morning drive for a few blocks or so, then it disappears, it's the engine fan helping warm the motor up (creating drag with the fan) so that's normal also.

Does this roar get louder as you accelerate then slowly go away?
 

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... I noticed this morning that when I got on the interstate (only 2 miles after starting it up) when my truck (it was cold in Texas, 29 degrees...) shifted into 6th and I set my cruise to 70 mph it was reving at 2000 instead of the normal 1800 and I checked to make sure it was in 6th, which it was. Then after about .5 - 1 mile it felt like a slight shift and the rpm's went down to it's ordinary 1800. Could this also be the torque converter locking in when it's cold or something like that?
Most electronic trans's monitor fluid temp and adjust shift strategies until the fluid reaches what is considered safe operating temp. This is done to manage torque load until the trans warms up. You should only notice that until warmed up
 
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