Jeep SRT trans oddity

[0x64]

Trying to help a friend out of state. My time is limited with him as I am not in state much. I didn't get to drive and verify this last time I was up as it was raining. So this is his description.

After and only after startup when you drive off. As soon as it reaches 20mph you feel the transmission/transfer case lock. After that truck is normal. Only does when key is cycled and first drive off.

Any ideas? File attached.

ORIGINAL.hpt

[B00STJUNKY]

Trying to help a friend out of state. My time is limited with him as I am not in state much. I didn't get to drive and verify this last time I was up as it was raining. So this is his description.



Any ideas? File attached.

ORIGINAL.hpt

WK1? If so, I would suggest replacing the transfer case fluid. I just faced a similar issue with this in my 06 Jeep SRT8. I would get the clunk after start-up and it would occur around the same MPH. I would also get a rhythmic thudding/clunking in high gear and heavy load (full throttle going up a hill). I was beginning to think my transmission was on its way out, but I eventually tried disabling the T-Case by pulling the electric actuator motor, and after doing that, no more clunking. So, on a whim, and without much hope for it making any improvement, I changed the T-Case fluid, and everything suddenly felt fine.

Apparently these T-Cases (NV146) are super sensitive to having clean fluid in them. The fluid is expensive (to the tune of about $50/quart, and you'll need to buy 2 quarts), but it could prove to be the fix.

[0x64]

WK1? If so, I would suggest replacing the transfer case fluid. I just faced a similar issue with this in my 06 Jeep SRT8. I would get the clunk after start-up and it would occur around the same MPH. I would also get a rhythmic thudding/clunking in high gear and heavy load (full throttle going up a hill). I was beginning to think my transmission was on its way out, but I eventually tried disabling the T-Case by pulling the electric actuator motor, and after doing that, no more clunking. So, on a whim, and without much hope for it making any improvement, I changed the T-Case fluid, and everything suddenly felt fine.

Apparently these T-Cases (NV146) are super sensitive to having clean fluid in them. The fluid is expensive (to the tune of about $50/quart, and you'll need to buy 2 quarts), but it could prove to be the fix.

Thank you. I should have specified. It's a 2007 SRT-8 I told him it sounded like something fluid related but being it goes away after that initial drive I wanted to post and see if others have ran into this.

[B00STJUNKY]

Thank you. I should have specified. It's a 2007 SRT-8 I told him it sounded like something fluid related but being it goes away after that initial drive I wanted to post and see if others have ran into this.

Yeah, the NV146 was used from 2006 to 2010. So, that would include your friend's Jeep. Have him also measure the circumference of his tires and compare front to rears. There is a 3% tolerance on tire size that you should stay within. My tires measured out to have about 1.5% difference front to rear. The clunk or thud that he's feeling is the drivetrain building up a bind while the clutches in the T-Case are engaged, and from what I can figure based on what I've seen and what your friend is seeing, there must be a self-diagnostics test being run after a key-on cycle to make sure the 4-wheel drive system is functioning as it should, and that this self-test is being done at about 20mph. The larger the difference in tire size front to rear, the more aggressive the bind and the resulting clunk/thud will be.

Make sure he knows not to try and substitute some other fluid in his T-Case, and also have him look up the proper fill procedure. It isn't supposed to be filled to the point of spilling out of the fill plug, the level should be a certain distance below the fill plug.