Video: GM 5.3 flexing under load - is this normal?

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I’ve been chasing what has felt like movement in the driveline on my 2008 Suburban 5.3 with the 4L60E. I thought I had it licked after replacing the driver’s side motor mount last week. Now, it feels like the movement has returned, though not as bad as before. I just took this video (link below) of the engine moving up on the drivers side under load. Wondering if you all would take a look and let me know if you think this is normal. Again, the mount on this side is one week old. It’s OEM ACDelco FWIW.

If the mount is bad, I have to figure out if it was a lemon or if something is going on that is breaking that mount on that side. Thanks a lot. This is driving me crazy.

https://youtu.be/8A92zWaaPcE
 
Motor mounts should be replaced in pairs. But some movement is normal.

I'd be more worried about that awful buzzing sound.
 
IS YOUR TRANSMISSION MOUNT TIGHT? IT WORKS IN CONJUNCTION WITH THE ENGINE MOUNTS. SOME FLEXING IS NORMAL.
 
Yes. I did the transmission mount before I checked motor mount. It’s two weeks old. Changing it cut down on what I felt. That’s what led me to keep looking when I ended up finding the failed motor mount.

Again, what I’m feeling is only on shifts. And really only on the 2-3 shift. Im starting to wonder if something is amiss inside the transmission and while new mounts have helped lessen it’s effects, mounts are not the root issue.
 
Seems more mounts from that side are for sale on eBay …

Clinebarger should know …
 
Originally Posted By: 4WD
Seems more mounts from that side are for sale on eBay …

Clinebarger should know …


The GMT900 platform is known for left motor mount (Torque side) failure.....Which is odd as the GMT800 platform used a very similar mount.
They usually rip apart when they fail & the engine will move A LOT more than in the video.

I would suspect a "sticky" Slip Yoke, I really need to know if your truck is 4wd or not??
 
Thanks.

It is a 4wd. The yoke was the first thing I did, but only did it with ATF. (Apparently grease on the yoke in this application is a no no?). It didn’t change anything, but using ATF, I didn’t really expect it to. Part of me wants to do it with grease and see if that works, and then plan on doing the transfer case drain/refill.
 
It "only" happening on the 2-3 shift is interesting. Just so you know.....The 2-3 shift on a 4L60E will NEVER be perfectly "clean".

The 2nd Clutch (2/4 Band) has to be pushed OFF while at the same time the 3rd Clutch (3/4 Clutch) comes ON. This is Impossible to accomplish in a perfectly choreographed manner.
As the frictions wear.....The "Timing" can change.

On a good unit.....The 2nd Clutch coming Off & the 3rd Clutch coming On will Overlap ever so slightly.....Which in actuality is a 2nd-4th-3rd shift, But it's in 4th for such a small time on a good unit you can barely tell.

On a unit on the way-out, Heavily worn-out, Or built/modified with mismatched components....The 2nd Clutch will push off before the 3rd Clutch can come On, This will feel like a slip or as we call it a "Cut-Loose". In actuality...It's shifting 2nd-1st-3rd.

The 4L60E & derivatives NEVER used "Shift Timing Corrections" or "Adaptive Shift Strategies" to help mask friction wear like GM Transaxle units (4T65E etc) Because, Well.....It doesn't work on this unit!!

I don't even want to plant the seed that this is a transmission issue!! Maybe taking it to a good transmission technician for a test drive would be the best coarse of action.
 
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Originally Posted By: HawkeyeScott
Thanks.

It is a 4wd. The yoke was the first thing I did, but only did it with ATF. (Apparently grease on the yoke in this application is a no no?). It didn’t change anything, but using ATF, I didn’t really expect it to. Part of me wants to do it with grease and see if that works, and then plan on doing the transfer case drain/refill.


The 4wd Yoke gets a healthy supply of splash lube when the truck is moving, I have never personally seen wiping some ATF on the splines do any good. The 2wd trucks have a sleeve, The ATF in the trans cannot lube the splines.....Being the reason you can use grease.

For testing purposes.....You can absolutely use some grease on the splines!

In the end of all this mess, With GM issuing SEVERAL TSB's......The Slip Yokes were the problem all along. Not that we in the industry didn't figure that out years before.

IF you do come to a conclusion that the slip yoke IS the issue.....Buy a Chromoly Sonnax slip yoke, Cheaper & better quality than the "updated" GM slip yokes.
 
Very helpful. Thanks a lot.

Clinebarger, so you’re not concerned about grease on a slip yoke ‘contamintaing’ the ATF in the transfer case? It looks like the splines reach into the case to the point they’re swimming in Dexron.
 
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Originally Posted By: HawkeyeScott
Very helpful. Thanks a lot.

Clinebarger, so you’re not concerned about grease on a slip yoke ‘contamintaing’ the ATF in the transfer case? It looks like the splines reach into the case to the point they’re swimming in Dexron.


Not for testing purposes & you don't want to use alot of grease either.

The fluid level is well below the output shaft in the T-Case, But it IS spray lubed buy the lube pump. The contamination issue has to do with the Wet Clutch in Part-Time Auto/Active transfer cases.
 
I’m afraid I have the Auto 4WD feature. Still a good idea to at least test with some grease? Thanks again.
 
Originally Posted By: HawkeyeScott
I’m afraid I have the Auto 4WD feature. Still a good idea to at least test with some grease? Thanks again.


It will be fine for such a short time.
 
Just greased up the slip yoke and reinstalled. Unfortunately, no improvement in the condition.

That means addressing the slip yoke, u joints, tranny mount and one motor mount hasn’t fixed this oddball feeling I have when the truck shifts. Is it time to focus on the tranny? Could anything in the differential be failing and produce this issue?

(Here is my original description of the issue from a month ago)

https://www.bobistheoilguy.com/forums/ub...iss#Post4688632
 
Originally Posted By: HawkeyeScott
Just greased up the slip yoke and reinstalled. Unfortunately, no improvement in the condition.

That means addressing the slip yoke, u joints, tranny mount and one motor mount hasn’t fixed this oddball feeling I have when the truck shifts. Is it time to focus on the tranny? Could anything in the differential be failing and produce this issue?

(Here is my original description of the issue from a month ago)

https://www.bobistheoilguy.com/forums/ub...iss#Post4688632


You need to find a good technician! If your in/near the DFW area.....I will be glad to look at it!
 
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Driver's side mount always goes bad on the 4wd models, and the video of your new mount looks like it has normal movement. A soft 2-3 shift could be a leaky accumulator.
 
Originally Posted By: eyeofthetiger
Driver's side mount always goes bad on the 4wd models, and the video of your new mount looks like it has normal movement. A soft 2-3 shift could be a leaky accumulator.


700R4/4L60E units do not have a 3rd Clutch Accumulator in the traditional sense, The 3rd clutch uses the back side of the 2nd apply servo for accumulation at the same time knocking the 2/4 Band off. This is why using a Corvette 2nd Servo piston will firm up the 1-2 & 2-3 shifts.

A major leak in the 3rd Clutch Circuit will quickly cause the 3/4 frictions to burn up.
 
Originally Posted By: clinebarger
Originally Posted By: eyeofthetiger
Driver's side mount always goes bad on the 4wd models, and the video of your new mount looks like it has normal movement. A soft 2-3 shift could be a leaky accumulator.


700R4/4L60E units do not have a 3rd Clutch Accumulator in the traditional sense, The 3rd clutch uses the back side of the 2nd apply servo for accumulation at the same time knocking the 2/4 Band off. This is why using a Corvette 2nd Servo piston will firm up the 1-2 & 2-3 shifts.

A major leak in the 3rd Clutch Circuit will quickly cause the 3/4 frictions to burn up.


Could it be the checkball behind the servo assmebly that is leaking or stuck?
 
Originally Posted By: eyeofthetiger
Originally Posted By: clinebarger
Originally Posted By: eyeofthetiger
Driver's side mount always goes bad on the 4wd models, and the video of your new mount looks like it has normal movement. A soft 2-3 shift could be a leaky accumulator.


700R4/4L60E units do not have a 3rd Clutch Accumulator in the traditional sense, The 3rd clutch uses the back side of the 2nd apply servo for accumulation at the same time knocking the 2/4 Band off. This is why using a Corvette 2nd Servo piston will firm up the 1-2 & 2-3 shifts.

A major leak in the 3rd Clutch Circuit will quickly cause the 3/4 frictions to burn up.


Could it be the checkball behind the servo assmebly that is leaking or stuck?


No
 
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