Transmission issue?

[Brandon67cummins99]

Hello, I’m new to this forum and couldn’t find anything about this, I have a 2012 Cummins 200k miles. Keep in mind the truck as never been tuned in anyway. It’s completely stock and has been its whole life. Another note is the truck has not pulled any crazy loads. But next summer I’m taking 2 horses and a small trailer from NY-AZ.
Every gear shifts great, nice and quick shifts... until it shifts from 4th-5th and then the Rpms jump about 100-200 before it gets into 5th gear. It’s only when I’m on the gas at all. If I let off before it shift it just takes a second or 2 longer to shift but it doesn’t increase in Rpms when I’m not on the gas. And 5th-6th is nice and smooth. Please let me know what you think, I’m aware it’s high mileage. I’m towing my horses from NY-AZ in about a year. Thanks Again! I have a video of it if you want to send me your email I can send it to you.

 

[AHutson]

Does the rpm come back down after jumping up on the 4th to 5th shift?

 

[Brandon67cummins99]

Does the rpm come back down after jumping up on the 4th to 5th shift?

Yes it does, I have a video of exactly what it does. My email is --admin
note: use conversation system to exchange emails if you want to email me and I’ll reply with the video. I’m just worried and hope is nothing serious. Thanks!

 

[Brandon67cummins99]

Does the rpm come back down after jumping up on the 4th to 5th shift?

Yes once it gets into 5th gear it’s perfectly fine and then it shifts into 6th gear nicely.

 

[AHutson]

That's normal. Mine does it as well. What is happening is the torque convertor clutch unlocks, shifts, re-locks. The only shift it will stay locked is 5th to 6th. I wouldn't take my foot out of it when pulling and it's shifting, mine seems to get confused when you do this and doesn't seem to appreciate it.

 

[Brandon67cummins99]

That's normal. Mine does it as well. What is happening is the torque convertor clutch unlocks, shifts, re-locks. The only shift it will stay locked is 5th to 6th. I wouldn't take my foot out of it when pulling and it's shifting, mine seems to get confused when you do this and doesn't seem to appreciate it.

So if 5th-6th is the only shift it stays locked in then shouldn’t every other shift rev a little bit? Or only just 4th to 5th. Just trying to educate myself best as possible.

 

[AHutson]

It's speed dependent more than gear dependent on when this occurs. The torque convertor doesn't actually lock till you go over 30 mph. If you let off it and let the exhaust brake take over it will bump/rev itself a tiny bit on downshifts. I tow on some grades, mine will lock in 3rd and hold with exhaust brake if it needs it. This transmission is constantly adapting to the driver based on how it's driven. If you have an Edge insight monitor or something like it you can have it show what gear it's in and when it's locked.

 

[Brandon67cummins99]

It's speed dependent more than gear dependent on when this occurs. The torque convertor doesn't actually lock till you go over 30 mph. If you let off it and let the exhaust brake take over it will bump/rev itself a tiny bit on downshifts. I tow on some grades, mine will lock in 3rd and hold with exhaust brake if it needs it. This transmission is constantly adapting to the driver based on how it's driven. If you have an Edge insight monitor or something like it you can have it show what gear it's in and when it's locked.

thanks for the help, hoping your right I’m sure you are, I’m new to this truck, I have the video if you want to email me and I’ll reply with the video of it shifting. Brandon2002must @ Gmail . Com

 

[AHutson]

You're welcome, glad to help. If it had something bad going on it would likely trip the check engine light, or be shuddering on shifts. If you can find a way to post the video or link it to here others will be able to help if it is doing something odd.

 

[Brandon67cummins99]

You're welcome, glad to help. If it had something bad going on it would likely trip the check engine light, or be shuddering on shifts. If you can find a way to post the video or link it to here others will be able to help if it is doing something odd.

I have the link for it on YouTube, at 2000rpms is when it shifts and then you can see the Rpms jump about 100-200 before it goes into 5th gear. If you turn your volume up you can actually hear it as well.

 

[AHutson]

That's the same thing mine does on those shifts. Normal for the 68rfe. When you're towing you will likely notice it doing it more often in other gears as well. Chrysler set it up the programming this way to keep wild drivers from breaking it, the truck won't actually let you have all it's power till it's locked up. My wife forgets this with mine when she gets on the freeway at times. Her reaction is entertaining when she wonders why everyone is slowing down, then checks her speed.

 

[Brandon67cummins99]

That's the same thing mine does on those shifts. Normal for the 68rfe. When you're towing you will likely notice it doing it more often in other gears as well. Chrysler set it up the programming this way to keep wild drivers from breaking it, the truck won't actually let you have all it's power till it's locked up. My wife forgets this with mine when she gets on the freeway at times. Her reaction is entertaining when she wonders why everyone is slowing down, then checks her speed.

Haha gotcha, well thanks again. Feel relieved... those transmissions can’t be cheap to rebuild!