Noisy rear end

tacosteve

Member
So I’ve got a noisy rear end, and this time it’s not from the Taco Bell. (Though I haven’t totally ruled it out). I changed my fluid and all was well. Recently when the truck is cold it starts off a little shaky and slightly noisy. After it warms up it’s fine. So I’d like to know what you guys recommend for diff fluid and what weight do y’all use with success.
 
So I’ve got a noisy rear end, and this time it’s not from the Taco Bell. (Though I haven’t totally ruled it out). I changed my fluid and all was well. Recently when the truck is cold it starts off a little shaky and slightly noisy. After it warms up it’s fine. So I’d like to know what you guys recommend for diff fluid and what weight do y’all use with success.

07 Sport, right? Did you use friction modifier in the diff fluid?
 
07 Sport, right? Did you use friction modifier in the diff fluid?

Yes I did. I at first put Mobil one synthetic in at first. Then I was told that those difs don’t like synthetic for some reason. So I changed it to Castrol and added friction modifier. Yes it’s a sport 4wd.
 
Yes I did. I at first put Mobil one synthetic in at first. Then I was told that those difs don’t like synthetic for some reason. So I changed it to Castrol and added friction modifier. Yes it’s a sport 4wd.

Synthetic is fine in the diffs. You may just need more friction modifier. Not sure how much you put in originally.
 
I was under my truck a few weeks back and happened to accidentally hit the rear driveshaft with a wrench as I was getting out. It had quite a ring to it, which is strange because there should be a piece of corrugated cardboard running the length of the driveshaft to stop such noise. I don't know if the factory has gone to another product to reduce the resonance, if so, it doesn't work as well as the cardboard, and may well be amplifying the noise from the rear axle gears.
 
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