Slip yoke/shudder

[draper11]

My wife had to drive my 2011 Tahoe for a week when hers was in the shop. She complained of issues. When I drove it again, the transmission was sticking on shift and it had some serious rear end shudders and shakes.

I worked on the following:

-Dropped drive shaft and replaced universal joints
-drained tranny fluid and replaced filter
-replaced throttle position sensor
-cleaned MAF
-changed accelerator pedal sensor
-determined that driver side motor mount was bad and replaced

This helped somewhat.

Ordered a new yoke and GM grease and this seemed to help for a week or so (have done twice). I’ve also changed out a gallon of tranny fluid each time I’ve done this and added Shudder fix. Grease is spun out or washed out when I’ve regressed. Yoke sticking and shudder around 1500 rpm between 30-45 miles an hour seems to get better for a short while when I do this.

An additional problem is this: I hear a deep rumbling sound at low speed without braking or turning. It sounds like a torquing almost bass drumming sound and I think it is coming from the rear.

Questions: what is out of tolerance causing the driveshaft/yoke to slip/stick now? Can
the rumbling noise be from the rear differential (gears or bearings) which has also contributed to my issue with yoke stick and rear shudder? Fluid level back there is fine. There does seem to be some evidence of fluid getting past seals but level looks sufficient. How much could the torque converter be influencing these issues?

Also, I have replaced water pump, thermostat, belts, pulleys, alternator, heater hose connections, valve cover gaskets, and front sway bar bushings. I’m not sure how much damage was caused by the broken motor mount or simply by age (190,000) but a lot seemed to go fast.

Thanks for suggestions. If I knew a good local mechanic that wanted to tackle this, I’d take to them.

I’m thinking I’ll add something inside the yoke next time like a cut length of rubber hose. I’d sure like to correct other underlying issues and keep putting miles on this car.

 

[Geotrash]

My wife had to drive my 2011 Tahoe for a week when hers was in the shop. She complained of issues. When I drove it again, the transmission was sticking on shift and it had some serious rear end shudders and shakes.

I worked on the following:

-Dropped drive shaft and replaced universal joints
-drained tranny fluid and replaced filter
-replaced throttle position sensor
-cleaned MAF
-changed accelerator pedal sensor
-determined that driver side motor mount was bad and replaced

This helped somewhat.

Ordered a new yoke and GM grease and this seemed to help for a week or so (have done twice). I’ve also changed out a gallon of tranny fluid each time I’ve done this and added Shudder fix. Grease is spun out or washed out when I’ve regressed. Yoke sticking and shudder around 1500 rpm between 30-45 miles an hour seems to get better for a short while when I do this.

An additional problem is this: I hear a deep rumbling sound at low speed without braking or turning. It sounds like a torquing almost bass drumming sound and I think it is coming from the rear.

Questions: what is out of tolerance causing the driveshaft/yoke to slip/stick now? Can
the rumbling noise be from the rear differential (gears or bearings) which has also contributed to my issue with yoke stick and rear shudder? Fluid level back there is fine. There does seem to be some evidence of fluid getting past seals but level looks sufficient. How much could the torque converter be influencing these issues?

Also, I have replaced water pump, thermostat, belts, pulleys, alternator, heater hose connections, valve cover gaskets, and front sway bar bushings. I’m not sure how much damage was caused by the broken motor mount or simply by age (190,000) but a lot seemed to go fast.

Thanks for suggestions. If I knew a good local mechanic that wanted to tackle this, I’d take to them.

I’m thinking I’ll add something inside the yoke next time like a cut length of rubber hose. I’d sure like to correct other underlying issues and keep putting miles on this car.

How many miles on it?

The only way I know to accurately diagnose something like this is to take it to a shop that has a set of chassis ears. They mount to various points beneath the car during a test drive and can pinpoint precisely where a sound or vibration is coming from.

Yes, you could have a bearing going out in your rear diff. You could also have a torque converter in your 6L80 starting to fail. What you're describing is one of the symptoms of that and it's a common failure point on that transmission. It could also be a combination of these plus more.

If it were my truck, I'd pay the $200 diagnostic fee and have a shop put a set of chassis ears on it to give me a definitive diagnosis.

 

[draper11]

How many miles on it?

The only way I know to accurately diagnose something like this is to take it to a shop that has a set of chassis ears. They mount to various points beneath the car during a test drive and can pinpoint precisely where a sound or vibration is coming from.

Yes, you could have a bearing going out in your rear diff. You could also have a torque converter in your 6L80 starting to fail. What you're describing is one of the symptoms of that and it's a common failure point on that transmission. It could also be a combination of these plus more.

If it were my truck, I'd pay the $200 diagnostic fee and have a shop put a set of chassis ears on it to give me a definitive diagnosis.

Thanks. 190,000 miles.

 

[Geotrash]

Thanks. 190,000 miles.

Ah, I see now that the mileage was buried in the post and I missed it. Sorry.

A few more thoughts: The deep rumbling sound, if it is indeed coming from the rear, could be either the pinion bearing or a carrier/axle bearing. The way to tell the difference is to listen to the frequency of the grumble. Is it the same frequency as wheel rotation or as driveshaft rotation? If the former, then I would suspect carrier/axle bearings. If the latter, I would suspect the pinion bearing. A torque converter sound would be at the frequency of crankshaft rotation.

if you don't have a shop nearby to take it to with chassis ears, then I would get the rear axle off the ground on safety stands and rotate the wheels. Use a mechanics stethoscope to listen to wheel bearings and to several points around the differential while an assistant rotates a wheel. If you don't find anything conclusive, then I would do the same set of exercises with the front wheels off the ground and listening to the front differential and bearings. Sometimes these sounds masquerade as coming from the rear, but are actually from the front.

 

[donjetman]

If original? frt differential mounts (GM# 23104736 & 23104735) will need replacing.