2016 Rear Differential Fluid/Rear Axle Fluid

[powerhaulic]

Why the need for friction modifier in a Limited Slip Differential?

Limited Slip differentials NOT USED IN TRUCKS or SUV'S.

 

To control clutch chatter!

 

Chatter is essentially the build-up and release of energy between the differential clutch packs in a limited slip differential during operation. This phenomenon often occurs when torque is transferred between the clutches or when rotational speeds change. During the stick-slip phase, energy is built up to a point where contact between the clutch plates change between static friction (stick) and dynamic friction (slip), resulting in noticeable vibrations. It is this vibration that causes an audible chatter or ratcheting to be heard within the differential. While certainly an annoying characteristic, there is typically no mechanical damage occurring to the differential. It is most often noticed in parking lots or slow driving while turning where the outside wheel turns faster than the inside wheel.

 

In an effort to control this chatter, friction modifiers are often used. These additives result in a smoother transition between the two states of friction: static and dynamic. Static friction occurs when the clutches physically lock together, while dynamic friction occurs as the clutches are slipping, ergo Limited Slip Differential.

Nicely written

 

Perfectly stated Mike

[Sierra Boy]

 

Want to run Amsoil Severe gear 75/90...how much do I need. About 6 qts to do both

Look up more info >>>>HERE

is the transfer case same fluid? No, use Dexron VI ATF

Also does the rear need posi fluid? No, trucks do not have Posi, Posi it an old Chevy sales name for a limited slip differential which are normally installed in performance cars etc. Trucks and SUV's have a locking rear differential and the use of any limited slip additives can delay the engagement of the locking mechanism and can damage the G80.

Note - G80 is GM's option code for a limited slip and locking rear differential. What is installed depends on the vehicle. Cars get a limited slip, trucks and SUV's get a locking rear differential. The ONLY GM truck to ever get a limited slip was the discontinued QuadraSteer models.

 

Thank you for all the info and time sir!!

 

I'm old school with muscle cars and first GMC new truck so have no clue on fluids levels.

 

Sierra Boy

[tjdriscoll]

Hey Guys,

 

I just came across this thread. I have almost 19k on my 2014 Sierra now. My buddy who builds Jeeps was telling me that you should change the diff fluid every 15k. From what I've read so far here that seems to be the general consensus.

 

I was looking at using either the Mobile 1 synthetic or the Royal Purple equivalent. My truck does not have the rear locker option that I know of so from what I understand the friction additive shouldn't matter to me correct? I'm siding towards the M1 as I've used their products for years on my old truck and was happy with the results. I know that you do pay more for the Royal Purple name...

[tnchevy]

Check in your glove box for G80 and that will tell you if you have a locker or not. I think 15k is a little early myself but it can't hurt anything either. When I changed the fluid in my 2002 at 30k miles (its first change) it leaked from the front diff afterwards and never stopped till I got rid of it with 120k miles. It was not a bad leak and needed about 1/4 of a quart once a year to bring the level back up but it must have had some grime caught up in the seals keeping the fluid in and when I dropped the old fluid out it must have flushed some of that grime out or something.

[Nathan79]

Hey Guys,

 

I just came across this thread. I have almost 19k on my 2014 Sierra now. My buddy who builds Jeeps was telling me that you should change the diff fluid every 15k. From what I've read so far here that seems to be the general consensus.

 

I was looking at using either the Mobile 1 synthetic or the Royal Purple equivalent. My truck does not have the rear locker option that I know of so from what I understand the friction additive shouldn't matter to me correct? I'm siding towards the M1 as I've used their products for years on my old truck and was happy with the results. I know that you do pay more for the Royal Purple name...

M1, Royal Purple, Amsoil. They are all fine. No one knows which is actually better. Run each with confidence.

[mookdoc6]

 

 

 

Check in your glove box for G80 and that will tell you if you have a locker or not. I think 15k is a little early myself but it can't hurt anything either. When I changed the fluid in my 2002 at 30k miles (its first change) it leaked from the front diff afterwards and never stopped till I got rid of it with 120k miles. It was not a bad leak and needed about 1/4 of a quart once a year to bring the level back up but it must have had some grime caught up in the seals keeping the fluid in and when I dropped the old fluid out it must have flushed some of that grime out or something.

That is the only problem with early fluid changes on the diffs. But at least now I know there is a decent gasket with the K2's and reusable so I don't end up like every other prick on the road with the wet spot on the Rear Diff!

[sdeeter19555]

That is the only problem with early fluid changes on the diffs. But at least now I know there is a decent gasket with the K2's and reusable so I don't end up like every other prick on the road with the wet spot on the Rear Diff!

Likely the leak and fluid change were completely unrelated and coincidental.

 

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[Cowpie]

Changing diff lube early should have nothing to do with developing a leak. Have changed out factory fill diff lubes before 10,000 miles for decades. Lube Locker makes a excellent replacement gasket for the earlier diffs that didn't get the same gaskets that are being used now, and no RTV or gasket sealer required. I have reused Lube Locker gaskets on diffs of various OEM brands for all of this century. Nice that I don't have to mess with dong diff pans anymore. Drain and fill plugs on the diff of my 2015 2500 6.0L.

 

On the M1 diff lube, I would recommend that M1 Delvac 75w90. It is not the same as the 75w90 LS version that is pretty common. The Delvac version is definitely intended for heavy duty use and no limited slip modifiers.

[SwampCatRuss]

What is the torque spec for the rear cover bolts ?

[sdeeter19555]

What is the torque spec for the rear cover bolts ?

Not sure, probably somewhere in the 15 INCH-POUND range because of the thin cover and reusable gasket...

 

I do mine by feel, basically snug the bolts with a 1/4" ratchet, too much will warp/distort the cover. I know guys will say that's not the correct way, but it hasn't failed me in 30 years...

 

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[Bobaloo22]

Lots of good info here guys. Thanks!

[last truck]

I have no Idea, but I would like to know too. I would bet it's filled up on the light side. I can only imagine how much crap is in there! I should have taken a picture of my first Crankcase oil @ 1000 miles looked like I had a gone silver mining some even about the size of finger nail clippings? Oh, well I am over it.................

 

sell the truck now if you had chunks in the oil.

[FL335i]

Cover bolts torque spec is 20#.

[sdeeter19555]

Cover bolts torque spec is 20#.

Inch or foot?

 

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[tnchevy]

That is the only problem with early fluid changes on the diffs. But at least now I know there is a decent gasket with the K2's and reusable so I don't end up like every other prick on the road with the wet spot on the Rear Diff!

Mine leaked from the front diff at the seals to the axles shafts, no gasket on the front diff. May have been coincidence but the front diff on my 2002 didn't leak at the axle seals till I changed out the original fluid at 30k miles. The original front diff fluid on that truck was pretty nasty at 30k miles as well.