Think I need front diff work

[Apach 031]

Hey folks. I've been investigating a newish clunk coming from the front end. 08 Denali 6 2 AWD. It's not the engine or diff mounts, already replaced those last year getting rid of the last clunk. It makes a big clunk when going into gear, or when I decelerate and then jump back on the accelerator, but it's worst when shifting down for passing. Feels exactly like a bad motor mount (and yes, I checked to make sure the new one isn't broken ). Dug out the GoPro and laid it under the front diff, while I shifted back and forth from drive to reverse. I'm getting between an eighth and a quarter of a turn rotation on the pinion as it engages. This seems pretty excessive to me. What do you all think.

I should mention, when I replaced the diff mounts last year, I tried to do a diff service, but the plugs are seized in hard. I even hit em with a torch. Which probably didn't help the fluid inside. Finally gave up. Oops.

I tried to attach the video file, but it's too large.

 

[Geotrash]

Hey folks. I've been investigating a newish clunk coming from the front end. 08 Denali 6 2 AWD. It's not the engine or diff mounts, already replaced those last year getting rid of the last clunk. It makes a big clunk when going into gear, or when I decelerate and then jump back on the accelerator, but it's worst when shifting down for passing. Feels exactly like a bad motor mount (and yes, I checked to make sure the new one isn't broken ). Dug out the GoPro and laid it under the front diff, while I shifted back and forth from drive to reverse. I'm getting between an eighth and a quarter of a turn rotation on the pinion as it engages. This seems pretty excessive to me. What do you all think.

I should mention, when I replaced the diff mounts last year, I tried to do a diff service, but the plugs are seized in hard. I even hit em with a torch. Which probably didn't help the fluid inside. Finally gave up. Oops.

I tried to attach the video file, but it's too large.

That's way too much play. I would wager that something inside there is busted. Nice job on the sleuthing work and telling us what you've already done.

BTW - for the front diff fluid, having a good local shop do it it money well spent. They have usually done so many that they have their technique down to a science, and they always seem to stock replacement plugs for when they booger one up.

 

[Joseph Garcia]

I just replaced my front differential, but it wasn't making a clunk. I heard a metallic whirring sound from it, whenever I put my foot to the gas, even slightly. When the shop took it out and opened it up, there were metallic shards all over the place.

I also had the situation where my shop could not loosen the fill plug.

 

[swathdiver]

I tried to attach the video file, but it's too large.

Upload to YouTube and link to it here.

 

[Apach 031]

Upload to YouTube and link to it here.

Good idea. I'll give it a try tonight.

 

[Apach 031]

That was easier than I thought. Here it is:

 

[Dustin Jackson]

Look at your diff moving up and down man, either the diff mount bushings are shot or that thing isn't bolted in all the way. Don't know if that's the cause of your problem but that don't look right to me.

 

[B-train]

That's a lot of play for sure. I know rear axles will have a small amount of driveline slack to take up, but that does seem excessive. Makes me wonder about my 2008 now because I have a similar noise that you described......usually when passing and a downshift, or off and back on the gas semi-aggressively.

I was under the impression that maybe there was slack in the transfer case chain that was causing it, but maybe I need to crawl under with a video as well :/

 

[Apach 031]

Look at your diff moving up and down man, either the diff mount bushings are shot or that thing isn't bolted in all the way. Don't know if that's the cause of your problem but that don't look right to me.

Hey, you're right! It's actually back and forth, because the camera is lying on the ground looking up. But ya, the whole diff seems to be sliding back and forth, especially in the right side. I was so busy looking at the excess rotation, I missed the diff movement. And those mounts don't have more than about 5000 miles on them. Guess I have some homework to do on the weekend. Excellent catch Dustin!

 

[swathdiver]

That was easier than I thought. Here it is:

Hey Pete did you check out that FRAM oil filter? LOL @PG01

Not making fun of you @Apach 031, Pete and I used FRAM filters for years without issue but "they" say your engine will self destruct using them.

To my way of thinking, your front differential and engine are moving around way too much.

 

[PG01]

Hey Pete did you check out that FRAM oil filter? LOL @PG01

Not making fun of you @Apach 031, Pete and I used FRAM filters for years without issue but "they" say your engine will self destruct using them.

To my way of thinking, your front differential and engine are moving around way too much.

Lol… first thing I noticed….loved the ‘grip’ on them when they came out…

 

[Apach 031]

Quick update. Crawled under and checked the torque on all of the diff mounts bolts last night. Everything is still tight. The rubber bushings still look intact on the insulated mounts. I'll have to get it on jacks with a pry bar this weekend and have a better look.

Lol, you busted me on the filter. Walmart was having a sale.

 

[89Suburban]

That was easier than I thought. Here it is:

WOW lol

 

[Apach 031]

As a follow up...it was the driver's side front diff mount. Should have posted this earlier, but I got caught up dealing with some electrical problems (see my other post, lol) .The rubber bushings were so worn, I could turn them by hand. It was allowing the axle to wrap up, and making it look like there was play in the pinion. These were Moog units that I put in less than a year ago. Only about 10k miles, and easy miles at that. Lesson learned, genuine GM was used the second time.

 

[Geotrash]

As a follow up...it was the driver's side front diff mount. Should have posted this earlier, but I got caught up dealing with some electrical problems (see my other post, lol) .The rubber bushings were so worn, I could turn them by hand. It was allowing the axle to wrap up, and making it look like there was play in the pinion. These were Moog units that I put in less than a year ago. Only about 10k miles, and easy miles at that. Lesson learned, genuine GM was used the second time.

Yikes. Yes, Moog has gone to shit over the last 5 years. I have Moog lower ball joints on my '07 that are only 4 years old and the rubber dust boots are disintegrating. I'm pi$$ed.