Rear diff service

[chevy_man]

Hmmm, never have seen a blow-up with clutches in it. Still doesn't matter, there's a TSB that specifically states NOT to add LSD friction modifier to a G80 rear-end. It shouldn't hurt it, but there's no use spending $12 on a 4oz. tube of shit that you don't need and GM says you shouldn't use.

 

[Vincesrg03]

Mobil 1 75w 90. Its synthetic and has the additive in it. Just did my rear end about 2 weeks ago. Could not believe how the old fluid looked. Like mud. Now Yuk seems to drive smoother. Did front and rear diffs. Front used 80w 90.

 

[91RS]

Hmmm, never have seen a blow-up with clutches in it. Still doesn't matter, there's a TSB that specifically states NOT to add LSD friction modifier to a G80 rear-end. It shouldn't hurt it, but there's no use spending $12 on a 4oz. tube of shit that you don't need and GM says you shouldn't use.

Hmm, not familiar with that bulletin off hand. However, I didn't mean the additional bottle of additive. The tall bottle of GM fluid has a little additive in it (although it doesn't say it on the bottle) for the G80 diffs and the Dexron LS gear oil has much more additive in it for for the posi rear ends in the Corvette or TBSS. However, the tall bottle of fluid is quite expensive and that's why I recommended Royal Purple or Amsoil.

 

[TheFuzz]

I've got some whining going on, so I think it's time to service the diffs and t-case. Gotta get some Mobil 1 gear oil and some smurf fluid and go to town on it one of these days. With 230K on the truck I'm scared to see what the old stuff looks like...I don't know if it's ever been changed! (although I'm really hoping that it has...)

 

[greenhornet]

Me thinks 91RS is right as I just had my diff open and it is the same as my old 76 Chev/2 ton which is a Eaton locking type With clutch discs.The little fly weights are for releasing the locker at about 20 miles per hour,as the think you don't need posi. after that.

 

[Z15]

GM rear wheel drive cars use a G80 Posi, Positration or limited slip differential.

Trucks use a G80 Locking Differential.

When a limited slip is used in a truck its coded G86.

http://www.youtube.com/watch?v=tTGZOJQQBeE&feature=player_embedded#at=15


The bulletin mentioned

#PIP4054C: Eaton Locking Differential Chatter Shudder Noise on Turns - keywords bind grab grind - (Aug 26, 2008)


Subject: Eaton Locking Differential Chatter Shudder Noise on Turns


Models: 2004-2007 Buick Rainier

2000-2009 Cadillac Escalade, ESV, EXT

2002-2009 Chevrolet Avalanche

2004-2009 Chevrolet Colorado

2003-2009 Chevrolet Express

2000-2009 Chevrolet Suburban, Tahoe

2000-2007 Chevrolet Silverado Classic

2007-2009 Chevrolet Silverado

2002-2009 Chevrolet Trailblazer

2004-2009 GMC Canyon

2002-2009 GMC Envoy

2000-2009 GMC Yukon, Yukon Denali, Yukon XL

2000-2007 GMC Sierra Classic

2007-2009 GMC Sierra

2003-2009 GMC Savana

Equipped With a Locking Rear Differential RPO G80

The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Customers may comment on a chatter or shudder from the rear axle on vehicles equipped with an Eaton locking differential. This condition would be noticed in parking lot maneuvers, turning, or during locking differential engagement and may be more noticeable when the differential is hot. Locking differential clutch chatter may be causing this concern.

Note 1: This does not apply to vehicles equipped with RPO QS4 (Quadrasteer) which is part of option package NYS. Quadrasteer vehicles use Dana axles and have a different fluid requirement.

Note 2: This PI does not apply to vehicles equipped with a RPO G86 limited slip differential.

Recommendation/Instructions:
If differential clutch chatter is encountered in a vehicle equipped with an Eaton locking differential, flush, drain and refill the differential with new synthetic fluid, use the fluid part number listed in SI for the vehicle currently being worked on. If the condition returns replace the rear differential clutch plates and refill the differential with new synthetic fluid, use the fluid part number listed in SI for the vehicle currently being worked on. Refer to eSI for clutch plate replacement and set up procedures.

Note 1: Eaton locking differentials used in 10.5" rear axles are equipped with steel clutch plates. It is a design characteristic of these steel clutch plates to exhibit more clutch chatter than other models.

***Important: Installing any friction modifier causes the clutch pack in the locking differential to slip and miss engagement. A fluid flush can often remove debris that is a contributor to clutch chatter. Adding friction modifier additive can cause a loss of locking differential functionality***