Clunk! Even after nickel plated slip yoke

[Burrito]

I had the slip yoke replaced with the nickel plated slip yoke on my pickup, but still have the clunk at stop and start of motion. What's the deal?

 

2001 Chevy Silverado 2500HD 6.0 4x4

[Big Joe]

I have the same truck and was experiencing the same noise. Mine seemed to be comming from the rearend. Talked with a buddy of mine who also has same truck and he said he had to change the oil in the rearend and that will stop it. I had the dealer do that the next time in for service and never have had the noise again.

[sleepur606]

I'm pretty sure replacing the differential fluid will help you out a great deal. I replaced the fluid on my 2002 with Royal Purple 75-90. It's got the limited slip additive which I think the HD with lockers don't need, but it can't hurt it. My clunking went away after 18 months of owning the truck and I haven't heard it since.

[Burrito]

You guys were right. I just changed the rear differential oil with Royal Purple 75w-90. Drove around the block a few times, and no clunk. I am so happy about this. I've been annoyed by that clunk for a while. The job wasn't that hard either. I drained the fluid, took off the cover, cleaned off the metal shavings, put a new gasket on, and filled it back up. I'm working on the front differential now. The oil is draining as we speak.

 

Both the dealership and Napa said synthetic was not necessary for front differential. Why is this?

[dewfpo]

Both the dealership and Napa said synthetic was not necessary for front differential.  Why is this?

 

<{POST_SNAPBACK}>

 

 

 

It's not required for the front diff by the manufacturer because it is rarely used and doesn't get anywhere as abused as the rear differential. When using 4WD the torque load is split between the two axles, when in 2WD is all goes to the rear. That's why the front diff is a lighter duty unit than the rear diff. But using a synthetic lubricant is always a good idea.

 

DEWFPO

[Billdog350]

Both the dealership and Napa said synthetic was not necessary for front differential. Why is this?

 

<{POST_SNAPBACK}>

 

 

 

It's not required for the front diff by the manufacturer because it is rarely used and doesn't get anywhere as abused as the rear differential. When using 4WD the torque load is split between the two axles, when in 2WD is all goes to the rear. That's why the front diff is a lighter duty unit than the rear diff. But using a synthetic lubricant is always a good idea.

 

DEWFPO

 

I know I'm pulling this thread back from the dead, but I was wondering if going to Mobil 1 synthetic gear lube (or similar) will cause any issues with my factory posi rear. From all of these threads it sounds like it won't, but I wanted to make sure. Also, I have seen people say that I won't need the limited slip additive from GM if I go with synthetic, is there truth to this?

[icecoldtexan]

Both the dealership and Napa said synthetic was not necessary for front differential. Why is this?

 

<{POST_SNAPBACK}>

 

 

 

It's not required for the front diff by the manufacturer because it is rarely used and doesn't get anywhere as abused as the rear differential. When using 4WD the torque load is split between the two axles, when in 2WD is all goes to the rear. That's why the front diff is a lighter duty unit than the rear diff. But using a synthetic lubricant is always a good idea.

 

DEWFPO

 

I know I'm pulling this thread back from the dead, but I was wondering if going to Mobil 1 synthetic gear lube (or similar) will cause any issues with my factory posi rear. From all of these threads it sounds like it won't, but I wanted to make sure. Also, I have seen people say that I won't need the limited slip additive from GM if I go with synthetic, is there truth to this?

 

 

I have been using Mobil1 75w90 synthetic in my rear and front diff on my '01 2500HD since new and have had zero issues.

[Billdog350]

Also, what about using 75w-140? I just bought some Wal-Mart synthetic but they only had it in 75w-140 but I'm thinking I need to return it and find synthetic elsewhere in 75w-90. The GM manual also says 75w-90 so I think I know the answer.

[99silverado1500]

I know i shouldnt be responding to a old topic that was re brought up, but is this what were talking about http://www.royalpurple.com/prodsa/mgeara.html in 75w90? If thats what it is, whats the average cost of the stuff do a complete change out on the rear?