04 Yukon xl AWD NR4 10mph clunk/jolt/bind

[Anaconda88]

New to forum hoping somebody can help offer some guidance to solving the issue.2004 Yukon xl AWD 153k . When slowing down once you hit 10mph has a chunk/bind/jolt through the drivetrain that feels like excessive back lash. I rebuilt the front diff as the good old locking tabs for adjusters were broken off with carrier bearing destruction . Rear diff with in spec. Installed new VB with solenoids. New accumulators including the sonnax 1-2 pinless. That seemed to reduce the issue by 40-50% sometimes it won’t do it other times it will . I replaced all the servo seals with the viton D rings . I suspect even tho the t case fluid looks spotless it possible has a stretched chain. Transmission flawless other then a harsh shift into reverse. Tested the trans harness everything checks out .

 

[Joseph Garcia]

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.

Let's ping @NickTransmissions, as he is our resident transmission expert, and he will chime in with his thoughts and perspectives.

 

[Anaconda88]

New to forum hoping somebody can help offer some guidance to solving the issue.2004 Yukon xl AWD 153k . When slowing down once you hit 10mph has a chunk/bind/jolt through the drivetrain that feels like excessive back lash. I rebuilt the front diff as the good old locking tabs for adjusters were broken off with carrier bearing destruction . Rear diff with in spec. Installed new VB with solenoids. New accumulators including the sonnax 1-2 pinless. That seemed to reduce the issue by 40-50% sometimes it won’t do it other times it will . I replaced all the servo seals with the viton D rings . I suspect even tho the t case fluid looks spotless it possible has a stretched chain. Transmission flawless other then a harsh shift into reverse. Tested the trans harness everything checks out .

Thank you for warm welcome !

Welcome to the Forum from NH.

Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.

I hope that you will become a participating member in the Forum's discussions.

Pics of the truck, please.

I cannot personally assist you with your issue, but other members of this Forum much more knowledgeable than me in this area will chime in.

Let's ping @NickTransmissions, as he is our resident transmission expert, and he will chime in with his thoughts and perspectives.

Thanks for the warm welcome. My wife and I have 3 2nd gen’s and 1 3rd! I’m here to help as well

 

[NickTransmissions]

New to forum hoping somebody can help offer some guidance to solving the issue.2004 Yukon xl AWD 153k . When slowing down once you hit 10mph has a chunk/bind/jolt through the drivetrain that feels like excessive back lash. I rebuilt the front diff as the good old locking tabs for adjusters were broken off with carrier bearing destruction . Rear diff with in spec. Installed new VB with solenoids. New accumulators including the sonnax 1-2 pinless. That seemed to reduce the issue by 40-50% sometimes it won’t do it other times it will . I replaced all the servo seals with the viton D rings . I suspect even tho the t case fluid looks spotless it possible has a stretched chain. Transmission flawless other then a harsh shift into reverse. Tested the trans harness everything checks out .

Hard shift into reverse may be due to a removed low/reverse check ball which is common practice for those units. Your clunck/bind condition may be worn T-case chain as you suspect...I am not familiar with T-cases as I've only rebuilt a handful but the NP246 chains can wear. I believe you can put the vehicle up on all four jack stands, place both Trans and Tcase in neutral and spin the front drive shaft to see how long it takes the rear drive shaft to start spinning or vise versa...If it takes more than a couple sec then that would indicate a worn T-case chain.

All 4L60Es have somewhat of a harsh 2-1 clunk which is caused by the low roller clutch grabbing in 1st from 2nd and center support reacting with the anticlunk spring. If you have some sort of bind at the 2-1, that would indicate the servo release timing is off and band is still partially arresting the drum when the low roller one-way clutch grabs and starts holding.

 

[Anaconda88]

Hard shift into reverse may be due to a removed low/reverse check ball which is common practice for those units. Your clunck/bind condition may be worn T-case chain as you suspect...I am not familiar with T-cases as I've only rebuilt a handful but the NP246 chains can wear. I believe you can put the vehicle up on all four jack stands, place both Trans and Tcase in neutral and spin the front drive shaft to see how long it takes the rear drive shaft to start spinning or vise versa...If it takes more than a couple sec then that would indicate a worn T-case chain.

All 4L60Es have somewhat of a harsh 2-1 clunk which is caused by the low roller clutch grabbing in 1st from 2nd and center support reacting with the anticlunk spring. If you have some sort of bind at the 2-1, that would indicate the servo release timing is off and band is still partially arresting the drum when the low roller one-way clutch grabs and starts holding.

Thank you for response. I drained the t case fluid out stick my bore camera in. From what I can see has a little slack but nothing offensive that I can see by any means. What’s odd is with the new valve body (reman) it no longer does it everytime but sure does it enough. It’s a pretty good clunk. When I replaced the 2-4 servo seals last weekend there was a little wear pin to piston surface . Would upgrading that servo with upgraded models be worth a shot? I see they have different length pins. Mine has 2 groves. Driving me crazy last bug to get worked out of this truck! My wife bought on eBay and we were hosed! Had 4psi oil pressure at idle -front diff whipped with a ton of other issues! I’ve replaced so much to make this truck right just need this last issue resolved !

 

[Anaconda88]

Today I installed the Trans go . 500 boost valve. So far so good! When you slow down to 10mph it it’s barely noticeable. Or sometimes don’t feel anything. Seems to go into reverse faster -shifts better and just feels better. For $35 I will likely install in the rest of my 4l60-65es . I’m on about the 3rd time with the pan down changing parts and new fluid in the 11k miles we have driven her. Each time the magnet has plenty of slime not sure if it’s cleaning out still or does have a pressure issue causing wear! First time I dropped pan I added 16oz of hot shots shift restore (love this stuff). I’m working backwards here should have had a pressure gauge on first ! I’ll keep forum updated as I will get to the bottom of it !

 

[Tonyrodz]

Today I installed the Trans go . 500 boost valve. So far so good! When you slow down to 10mph it it’s barely noticeable. Or sometimes don’t feel anything. Seems to go into reverse faster -shifts better and just feels better. For $35 I will likely install in the rest of my 4l60-65es . I’m on about the 3rd time with the pan down changing parts and new fluid in the 11k miles we have driven her. Each time the magnet has plenty of slime not sure if it’s cleaning out still or does have a pressure issue causing wear! First time I dropped pan I added 16oz of hot shots shift restore (love this stuff). I’m working backwards here should have had a pressure gauge on first ! I’ll keep forum updated as I will get to the bottom of it !

What's this hot shots stuff?

 

[Anaconda88]

What's this hot shots stuff?ch

What's this hot shots stuff?

Check out the hot shots secrets website. (Amazon usually has the best prices on their products they are amazing! I started using them first in my 5.9 Cummins that led me to try in the gm vortec stuff! Everything I put the shift restore in yielded performance results . Also it will clean your transmission like it’s brand new . I also use the stiction eliminator-gasoline extreme and for the Cummins the diesel extreme -EDT. Their assembly lube is great as well . I encourage everyone to use some stiction eliminator in their vortec! If anyone is interested I can list my results with the stiction ! Every high mileage vortec I used it in yielding higher oil pressure with in a week! Most USA oils just don’t have enough detergents!

 

[Anaconda88]

When I dropped the pan this time I bought this new gasket. I’ve been using the Oem gm gaskets but they rip everytime on this trans for some reason! This was on sale $32 Amazon and it’s an excellent thick reusable gasket! Highly recommend it ! It’s about 3/16 thick very stout gasket!

 

[Anaconda88]

Update about 2 weeks ago I dropped the pan again and installed the trans go -PR. Pressure regulator valve in the pump as after I installed the boost valve I asked myself why did I not install both ! The old PR valve showed plenty of wear . You see the new trans go pr valve to the right . Seems to fully of solved my issue now . Right after the install the reverse shift was about half of the intensity it was but not as soft as the rest of our transmissions. My wife drives it daily to work 100 miles a day . I had to move it other day and shocked when I put into reverse she was soft as could be !