New DEXRONŽ LS gear oil Cures Rear End Noise?
01-18-2008, 02:11 PM
#1
Burning Brakes
Thread Starter
New DEXRONŽ LS gear oil Cures Rear End Noise?
Any one tried the new lube yet? Guess I better return my 2 tubes of additive.
Document ID# 2048181
2008 Chevrolet Corvette
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)
Models: 2004-2008 Cadillac XLR (Including V-Series and Export)
2005-2008 Chevrolet Corvette (Including Z06 and Export)
This bulletin is being revised to change the fluid recommendation and to remove the requirement of adding friction modifier. Please discard Corporate Bulletin Number 07-04-20-002 (Section 04 -- Driveline/Axle).
Condition
Some customers may comment on a clunk and/or chatter type noise from the rear of the vehicle while making turns.
Cause
This condition may be caused by slip/stick of the posi-traction clutch plates due to insufficient limited-slip axle additive. As plates slip and stick, a jumping or jerking feel occurs accompanied by a clunk noise.
Correction
Important: DO NOT remove the differential cover from the rear or the two sides. It is not necessary to flush the old fluid from the differential.
Drain and refill the rear differential fluid using the procedure listed below.
Draining Procedure
Raise and support the vehicle.
Clean any dirt from around the differential drain plug.
If not equipped with a differential cooler, remove the drain plug (1) and washer (2) from the differential.
If equipped with a differential cooler:
4.1. Using a bent tip screwdriver, remove the quick connect fitting retaining ring (3) from the quick connect fitting (4) and discard the retaining ring.
4.2. Remove the differential cooler inlet pipe from the differential nut.
Drain the fluid.
Filling Procedure
If not equipped with a differential cooler, install the drain plug (1) and washer (2) to the differential.
Tighten
Tighten the differential drain plug to 35 Nˇm (26 lb ft).
If equipped with a differential cooler:
2.1. Install a new retaining ring.
2.2. Connect the differential cooler pump inlet pipe (2) to the differential. A distinct snap should be heard or felt when assembling the cooler pipe to the fitting.
2.3. To ensure the cooler line is properly installed, give the cooler pipe a gentle pull.
Clean any dirt from around the differential fill plug.
Remove the fill plug and washer from the differential.
Important: DO NOT add any limited-slip additive (friction modifier). With this new fluid (Dexron LS Gear Oil 75W-90) it is no longer required to add friction modifier. If friction modifier is added, it will cause the fluid to lose some of it's friction reducing properties as well as reducing seal life.
Fill the differential with the new DEXRONŽ LS gear oil, P/N 88862624 (Canadian P/N 88862625). Refer to the table listed below for lubrication specifications.
Check the fluid level to ensure it is even with the bottom of the fill plug hole to no lower than 6 mm (0.25 in) below the opening.
Install the fill plug and washer to the differential.
Tighten
Tighten the differential fill plug to 35 Nˇm (26 lb ft).
Important: Steps 8-13 are for vehicles equipped with the differential cooling system. For vehicles not equipped with the cooling system, proceed to step 14.
Raise the vehicle so the wheels are about a foot off the floor. Make sure the wheels can spin freely without obstruction from the hoist or any nearby items.
Start the vehicle and put the transmission in second gear. Slowly accelerate to 10 mph and hold this speed for one minute.
Turn the vehicle off .
Raise the vehicle.
Check the fluid level in the differential. Add fluid until the recommended level is reached.
Lower the vehicle.
Once the differential fluid has been changed, the vehicle must be driven in 8-10 tight figure eight maneuvers to heat the fluid and allow the fluid to be worked into the clutch plates.
Document ID# 2048181
2008 Chevrolet Corvette
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)
Models: 2004-2008 Cadillac XLR (Including V-Series and Export)
2005-2008 Chevrolet Corvette (Including Z06 and Export)
This bulletin is being revised to change the fluid recommendation and to remove the requirement of adding friction modifier. Please discard Corporate Bulletin Number 07-04-20-002 (Section 04 -- Driveline/Axle).
Condition
Some customers may comment on a clunk and/or chatter type noise from the rear of the vehicle while making turns.
Cause
This condition may be caused by slip/stick of the posi-traction clutch plates due to insufficient limited-slip axle additive. As plates slip and stick, a jumping or jerking feel occurs accompanied by a clunk noise.
Correction
Important: DO NOT remove the differential cover from the rear or the two sides. It is not necessary to flush the old fluid from the differential.
Drain and refill the rear differential fluid using the procedure listed below.
Draining Procedure
Raise and support the vehicle.
Clean any dirt from around the differential drain plug.
If not equipped with a differential cooler, remove the drain plug (1) and washer (2) from the differential.
If equipped with a differential cooler:
4.1. Using a bent tip screwdriver, remove the quick connect fitting retaining ring (3) from the quick connect fitting (4) and discard the retaining ring.
4.2. Remove the differential cooler inlet pipe from the differential nut.
Drain the fluid.
Filling Procedure
If not equipped with a differential cooler, install the drain plug (1) and washer (2) to the differential.
Tighten
Tighten the differential drain plug to 35 Nˇm (26 lb ft).
If equipped with a differential cooler:
2.1. Install a new retaining ring.
2.2. Connect the differential cooler pump inlet pipe (2) to the differential. A distinct snap should be heard or felt when assembling the cooler pipe to the fitting.
2.3. To ensure the cooler line is properly installed, give the cooler pipe a gentle pull.
Clean any dirt from around the differential fill plug.
Remove the fill plug and washer from the differential.
Important: DO NOT add any limited-slip additive (friction modifier). With this new fluid (Dexron LS Gear Oil 75W-90) it is no longer required to add friction modifier. If friction modifier is added, it will cause the fluid to lose some of it's friction reducing properties as well as reducing seal life.
Fill the differential with the new DEXRONŽ LS gear oil, P/N 88862624 (Canadian P/N 88862625). Refer to the table listed below for lubrication specifications.
Check the fluid level to ensure it is even with the bottom of the fill plug hole to no lower than 6 mm (0.25 in) below the opening.
Install the fill plug and washer to the differential.
Tighten
Tighten the differential fill plug to 35 Nˇm (26 lb ft).
Important: Steps 8-13 are for vehicles equipped with the differential cooling system. For vehicles not equipped with the cooling system, proceed to step 14.
Raise the vehicle so the wheels are about a foot off the floor. Make sure the wheels can spin freely without obstruction from the hoist or any nearby items.
Start the vehicle and put the transmission in second gear. Slowly accelerate to 10 mph and hold this speed for one minute.
Turn the vehicle off .
Raise the vehicle.
Check the fluid level in the differential. Add fluid until the recommended level is reached.
Lower the vehicle.
Once the differential fluid has been changed, the vehicle must be driven in 8-10 tight figure eight maneuvers to heat the fluid and allow the fluid to be worked into the clutch plates.
01-18-2008, 02:17 PM
#2
Race Director
The AMSOIL Severe Gear 75W90 I changed to 3 months ago in my DD to solve the chatter problem is still keeping it quiet so I have no intention to change again to the new Dexron LS.
01-18-2008, 02:27 PM
#4
Burning Brakes
Thread Starter
Well I won't be trying it for awhile. The GM dealer wants $21/qt but its too new for them to stock so I'd have to buy a case of 12 if they order it. But then they would sell it to me for $14.22/qt. May have to share a case.
01-18-2008, 10:00 PM
#7
Premium Supporting Vendor
Ouch... and people complain that AMSOIL is too expensive. At least $14 per quart is more reasonable. You'd think the dealership would need the rest of the case for other cars and give you the lower price. 
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C66 Racing #66 NASA ST2, SCCA T2
AMSOIL Dealer (Forum Vendor)
AMSOIL Ordering Information (Retail sales using reference #1206638 benefit the forum.)
AMSOIL Preferred Customer Program (Members buy at Wholesale - a savings of about 25%)
AMSOIL Catalog
01-19-2008, 03:52 AM
#9
Le Mans Master
Member Since: Jan 2005
Location: Thousand Oaks California
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What a deal!
Last edited by calemasters; 01-19-2008 at 05:57 AM.
01-19-2008, 06:00 AM
#10
Melting Slicks
03-10-2008, 11:22 PM
#12
Burning Brakes
Found this thread with the search tool. I was planning to schedule a visit to my dealer for this very problem.......clunking and jerking in the rear end while making tight turns. I wonder if they do this fluid change as a warranty item?
03-11-2008, 02:38 PM
#14
The updated bulletin came out in Jan. with the new part number, and I think production cars would have already had it installed by then. By the time a bulletin comes out, production will usually have already had it.
03-14-2008, 12:09 AM
#16
Melting Slicks
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I had the new lub put in my vert... didn't solve my problem.
But I can say it was much improved over the previous GM diff fluid to solve this issue.
My clunk occurs primarily at low speed- particularly if you come on or off the gas pedal [throttle] at 11- 12mph and bang! With the new fluid it is a hard felt clunking sound to a pop. Additionally besides the 1-2 up or down shift, you can also experience this going to/from 3rd to 4th. Intermitently you will also get a delay before it finds gear. I'm certain I've got a tranny problem or the diff shaft is getting stuck .. sumpthing going on and it's just bad. Convincing GM of this is another issue. But I will endeavor to keep trying.
Document ID# 2048181
2008 Chevrolet Corvette
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)
But I can say it was much improved over the previous GM diff fluid to solve this issue.
My clunk occurs primarily at low speed- particularly if you come on or off the gas pedal [throttle] at 11- 12mph and bang! With the new fluid it is a hard felt clunking sound to a pop. Additionally besides the 1-2 up or down shift, you can also experience this going to/from 3rd to 4th. Intermitently you will also get a delay before it finds gear. I'm certain I've got a tranny problem or the diff shaft is getting stuck .. sumpthing going on and it's just bad. Convincing GM of this is another issue. But I will endeavor to keep trying.
Document ID# 2048181
2008 Chevrolet Corvette
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)
03-14-2008, 10:53 AM
#18
I had the new lub put in my vert... didn't solve my problem.
But I can say it was much improved over the previous GM diff fluid to solve this issue.
My clunk occurs primarily at low speed- particularly if you come on or off the gas pedal [throttle] at 11- 12mph and bang! With the new fluid it is a hard felt clunking sound to a pop. Additionally besides the 1-2 up or down shift, you can also experience this going to/from 3rd to 4th. Intermitently you will also get a delay before it finds gear. I'm certain I've got a tranny problem or the diff shaft is getting stuck .. sumpthing going on and it's just bad. Convincing GM of this is another issue. But I will endeavor to keep trying.
Document ID# 2048181
2008 Chevrolet Corvette
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)
But I can say it was much improved over the previous GM diff fluid to solve this issue.
My clunk occurs primarily at low speed- particularly if you come on or off the gas pedal [throttle] at 11- 12mph and bang! With the new fluid it is a hard felt clunking sound to a pop. Additionally besides the 1-2 up or down shift, you can also experience this going to/from 3rd to 4th. Intermitently you will also get a delay before it finds gear. I'm certain I've got a tranny problem or the diff shaft is getting stuck .. sumpthing going on and it's just bad. Convincing GM of this is another issue. But I will endeavor to keep trying.
Document ID# 2048181
2008 Chevrolet Corvette
Subject: Rear Axle Clunk and/or Chatter Type Noise on Turns (Drain/Refill Rear Differential Fluid) #07-04-20-002A - (01/09/2008)
That doesn't sound like what the fluid update will fix. Almost always the complaint is at very slow speeds, less then 5mph, and it feels like the diff. is binding up, car doesn't want to roll. You could have excessive backlash in the diff. for a clunk but if it is slow to find the gears, or is at the 3-4 shift point, it sounds like a trans. issue.
