81 differential help
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Intermediate
Joined: Jul 2007
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81 differential help
I have an 81 corvette that when driven awhile (enough for the rearend to heat up) the differential starts to make a "whirring" sound (kinda like when you rube your finger on the top of a wine glass) when I turn corners. The rear end was rebuilt about 25000 miles ago along with all new U-joints. Could it be as easy as changing the the fluid? If it is, what weight of gear oil do I use? Any advice would be appreciated. If someone could tell me where the drain plug is and if I have to take the spare down to get to it? Thanks in advance
Zach
Zach
Last edited by ZAXVETTE; Aug 1, 2007 at 01:19 AM.
Melting Slicks
Joined: Aug 2001
Posts: 3,050
Likes: 124
From: Wichita KS
I have an 81 corvette that when driven awhile (enough for the rearend to heat up) the differential starts to make a "whirring" sound (kinda like when you rube your finger on the top of a wine glass) when I turn corners. The rear end was rebuilt about 25000 miles ago along with all new U-joints. Could it be as easy as changing the the fluid? If it is, what weight of gear oil do I use? Any advice would be appreciated. If someone could tell me where the drain plug is and if I have to take the spare down to get to it? Thanks in advance
Zach
Zach
The noise may be from a lack of Limited-Slip Additive in the differential.
Your 1981 has a "Dana" aluminum rear end (shared with 1980-1982). There is no drain hole. Fluid is removed by siphoning through the fill hole.
After the fluid is removed:
1st. Add 4 ounces of "Rear Axle Limited-Slip Lubricant Additive", Part Number GM1052358.
2nd then fill to the level of the filler plug hole with special gear lubricant GM1052271 or 1052272. The Forum Archives will have lots of threads on lubricants, everybody has an opinion.
The GM gear lube works for me, but in any case, be sure to use 4 ounces of "Rear Axle Limited-Slip Lubricant Additive", Part Number GM1052358.
Melting Slicks
Joined: Mar 2006
Posts: 2,465
Likes: 0
From: Orange Park Fl
These things are known to leak. You might just check and see if it needs topping off. If you are not sure the limited slip additive was used (any repudable shop would know to do this), you'll want to use the additive first to top it off. The GM additive mentioned above seems to be the favorite around here. You'll need a 3/6" allen head socket to take out the plug. You don't have to remove the spare carrier, but it does make things easier (I usually don't). After you get the plug out, stick a finger in the hole. The fluid should be right up to the bottom of the hole. If not, add. When I top mine off, I usually use straight Lucas Heavy Duty Oil Stabilizer. God bless, Sensei
