2011 Denali front diff mount issue - SOLVED

[Familyman2112]

I have had an intermittent clunk/thud coming from the front of my 2011 Yukon Denali with 120k. I replaced the driver side engine mount a couple years ago shortly after buying the vehicle. That fixed the clunk I was experiencing at the time. Replacing the mounts is a royal PITA by the way. However the latest clunk would happen during acceleration and/or deceleration. After doing much research, I decided to replace the front differential mounts. I have yet to drive the vehicle after replacing the mounts, I’ll update later, I finally finished the job at about 1:30 this morning. The real purpose for this post is to let people know what they may encounter with this job. The front two mounting bolts as well as the two 21mm nuts and two bolts that hold the diff to the mounts come off like a dream. However, the two rear bolts were spawn of satan. Both were completely rusted to the bushings and without a cutting torch be prepared for a long day. After many hours of MAP heat, PB blaster, impact drive, long breaker bar, air chisel, 6 pound mallet and drive drift, etc., they both finally came out. Before you start the job you may want to buy two new bolts to replace the nasty rusty ones that you will be beating out. It was necessary to have someone up top with the impact and about 20 inches of extensions while I was underneath holding the bushing plates with very large channel locks. Then it is just PB, heat, chisel and banging for a long time. The bushings will catch on fire and they will drop very hot rubber droppings… Going back together was pretty straight forward. The front driver side bolt is kind of a pain to get back into the hole from underneath, it is relatively accessible from the engine compartment. Have the person who who put the bolt in put a ratchet on it while you impact the nut from the bottom. The rest of the bolts are doable from underneath. The frame bolt heads are 15mm and the nuts are 18mm.
Final thought for anyone who is going to do this, you may as well replace your CV axles while you’re there. You do need to unbolt both from the differential to get the mounts done.

 

[SpareParts]

I found them not to bad to change. I have changed two sets on different Yukon's.
Had my son on top holding the bolts with a long extension and ratchet. I ran the impact wrench underneath.
I can't remember for sure but i don't think i took the axles loose either.
Anyway, At least you got it done and no need to worry about them anymore!

 

[Joseph Garcia]

I have had an intermittent clunk/thud coming from the front of my 2011 Yukon Denali with 120k. I replaced the driver side engine mount a couple years ago shortly after buying the vehicle. That fixed the clunk I was experiencing at the time. Replacing the mounts is a royal PITA by the way. However the latest clunk would happen during acceleration and/or deceleration. After doing much research, I decided to replace the front differential mounts. I have yet to drive the vehicle after replacing the mounts, I’ll update later, I finally finished the job at about 1:30 this morning. The real purpose for this post is to let people know what they may encounter with this job. The front two mounting bolts as well as the two 21mm nuts and two bolts that hold the diff to the mounts come off like a dream. However, the two rear bolts were spawn of satan. Both were completely rusted to the bushings and without a cutting torch be prepared for a long day. After many hours of MAP heat, PB blaster, impact drive, long breaker bar, air chisel, 6 pound mallet and drive drift, etc., they both finally came out. Before you start the job you may want to buy two new bolts to replace the nasty rusty ones that you will be beating out. It was necessary to have someone up top with the impact and about 20 inches of extensions while I was underneath holding the bushing plates with very large channel locks. Then it is just PB, heat, chisel and banging for a long time. The bushings will catch on fire and they will drop very hot rubber droppings… Going back together was pretty straight forward. The front driver side bolt is kind of a pain to get back into the hole from underneath, it is relatively accessible from the engine compartment. Have the person who who put the bolt in put a ratchet on it while you impact the nut from the bottom. The rest of the bolts are doable from underneath. The frame bolt heads are 15mm and the nuts are 18mm.
Final thought for anyone who is going to do this, you may as well replace your CV axles while you’re there. You do need to unbolt both from the differential to get the mounts done.

Glad that you took care of the worn bushings, and sorry that it was such a PIA. I had to replace mine, and I'm sure that the clunk will go away when you drive the truck.

 

[donjetman]

I didn't have any problem when I replaced my diff mounts. My Denali doesn't have any rust. I've had my front diff out several times over the yrs.

https://www.tahoeyukonforum.com/threads/front-differential-mounts.120260/page-3#post-1677117

 

[Familyman2112]

OMG, what a difference! The clunk is gone. I had to have a second transmission (in two years) put in last year. Unfortunately soon after an intermittent noticeable clunk when shifting from reverse to drive. I assumed something was amiss with the trans, but they checked it out. Of course it didn’t happen for them… New diff mounts, no more shift clunk! Score

I am going to comment on another post I read about the plug-in to the OBD to bypass the AFM, absolutely wish I would have come across that sooner. Driving at 85-90 on the highway and she was purring along, no vibration or weird rpm. I drove over 500 miles and it was an absolute pleasure. New diff mounts, AFM bypass, repaired driver’s side seat cooler, replaced the passenger side seat control, drain and flush diffs and transfer case! Now if I could get the cruise control working again, I would be tickled pink.

 

[Joseph Garcia]

OMG, what a difference! The clunk is gone. I had to have a second transmission (in two years) put in last year. Unfortunately soon after an intermittent noticeable clunk when shifting from reverse to drive. I assumed something was amiss with the trans, but they checked it out. Of course it didn’t happen for them… New diff mounts, no more shift clunk! Score

I am going to comment on another post I read about the plug-in to the OBD to bypass the AFM, absolutely wish I would have come across that sooner. Driving at 85-90 on the highway and she was purring along, no vibration or weird rpm. I drove over 500 miles and it was an absolute pleasure. New diff mounts, AFM bypass, repaired driver’s side seat cooler, replaced the passenger side seat control, drain and flush diffs and transfer case! Now if I could get the cruise control working again, I would be tickled pink.

Yes, I fully agree with you on the elimination of the clunk. Nice!

 

[alvocado]

I have had an intermittent clunk/thud coming from the front of my 2011 Yukon Denali with 120k. I replaced the driver side engine mount a couple years ago shortly after buying the vehicle. That fixed the clunk I was experiencing at the time. Replacing the mounts is a royal PITA by the way. However the latest clunk would happen during acceleration and/or deceleration. After doing much research, I decided to replace the front differential mounts. I have yet to drive the vehicle after replacing the mounts, I’ll update later, I finally finished the job at about 1:30 this morning. The real purpose for this post is to let people know what they may encounter with this job. The front two mounting bolts as well as the two 21mm nuts and two bolts that hold the diff to the mounts come off like a dream. However, the two rear bolts were spawn of satan. Both were completely rusted to the bushings and without a cutting torch be prepared for a long day. After many hours of MAP heat, PB blaster, impact drive, long breaker bar, air chisel, 6 pound mallet and drive drift, etc., they both finally came out. Before you start the job you may want to buy two new bolts to replace the nasty rusty ones that you will be beating out. It was necessary to have someone up top with the impact and about 20 inches of extensions while I was underneath holding the bushing plates with very large channel locks. Then it is just PB, heat, chisel and banging for a long time. The bushings will catch on fire and they will drop very hot rubber droppings… Going back together was pretty straight forward. The front driver side bolt is kind of a pain to get back into the hole from underneath, it is relatively accessible from the engine compartment. Have the person who who put the bolt in put a ratchet on it while you impact the nut from the bottom. The rest of the bolts are doable from underneath. The frame bolt heads are 15mm and the nuts are 18mm.
Final thought for anyone who is going to do this, you may as well replace your CV axles while you’re there. You do need to unbolt both from the differential to get the mounts done.

@Familyman2112 do you have the part numbers or specs for the mount bolts? I have both mounts on order and it sounds like a good idea to have new bolts in hand.

 

[alpha_omega]

CV Axle/Intermediate Shaft - 84842044

Front Axle Vent Valve - 12471619

Front Differential Carrier Mount -

• Front LH Mount - 23104736
• Front RH Mount - 23104735

Front Differential Carrier Bolt -

• LH (M12x1.75x45.8) - 11519538
• RH (M12x1.75x95) - 11561577

 

[rdezs]

OMG, what a difference! The clunk is gone. I had to have a second transmission (in two years) put in last year. Unfortunately soon after an intermittent noticeable clunk when shifting from reverse to drive. I assumed something was amiss with the trans, but they checked it out. Of course it didn’t happen for them… New diff mounts, no more shift clunk! Score

I am going to comment on another post I read about the plug-in to the OBD to bypass the AFM, absolutely wish I would have come across that sooner. Driving at 85-90 on the highway and she was purring along, no vibration or weird rpm. I drove over 500 miles and it was an absolute pleasure. New diff mounts, AFM bypass, repaired driver’s side seat cooler, replaced the passenger side seat control, drain and flush diffs and transfer case! Now if I could get the cruise control working again, I would be tickled pink.

90% of the time the issue with the cruise control is the switch up above your brake pedal.... Right where it connects to the push rod for the power brakes. Technically it's called a brake light switch, but if you take your old one apart you'll find like five or six different things that it switches. The ECM wants to know when the brakes are pushed down.... Let's see, for the brake lights themselves, second to activate a solenoid so you can take it out of park, 3rd to deactivate the cruise control when you touch the brake.... No idea on the other two or three. I will speculate the maybe one goes to the ABS module, one to the body control module and one of the ECM.

 

[rdezs]

...... Yet another example of how complicated things have become and reduced reliability. That old 65 mustang only had one wire going to the switch.

 

[MWD_CTSV]

At 225K miles, my 2011 started the front diff cluck as well. I just replaced the mounts and was surprised that only one of the four bushing was damaged (drivers front). That is a lot of clunk for such a small bushing that was partially torn but the rubber was still intact. Even the decel 2-1 shift would be annoyingly clunky sometimes.

Thankful for a relatively easy fix.

 

[petethepug]

Replaced both those dog bone mounts with the MOOG brand @ 180k when trans was being replaced on our 09 Esky.

The truck had the thunk after letting off the gas and making its first corner every day. The really strange thing the Indi found was one of the bolts had lost half its diameter rubbing inside the bushing.

At 191k now with a completely rebuilt front end, new z95 on all 4 corners. It’s quiet, solid, comfy and tied into the drive line better than new.