Differential advice needed
Thread Starter
Cruising
Joined: Jul 2006
Posts: 12
Likes: 0
From: Seeley Lake Montana
Differential advice needed
My car is a '79 L82 4 speed with 25,000 actual miles. I have what I assume is a ring and pinion noise. Anytime the throttle is in a cruising position (low torque on rear end) I hear an oscillating noise that I think is rear end gears (in gears 2,3,4). Open or close the throttle and the noise goes away. Trying to describe the noise in written words is impossible, but an attempt would be: rngrngrng...I'm the second owner of this car and I don't know if it's always sounded like this. My feeling is to change the diff fluid and drive it. Any advice appreciated.
Drifting
Joined: Jan 2001
Posts: 1,841
Likes: 3
From: Halifax, NS, Canada
That is a pretty low mileage car to develop differential problems. I would be inclined to look else where for the problem first. May even be something as simple as a tire causing the noise you hear. I would check the rear trailing arms, u joints, brake discs before I would tear into the differential.
Tech Contributor
Joined: Aug 1999
Posts: 15,166
Likes: 3,968
From: Connecticut, USA
Possibly other areas but the late 70's diff's had some production issues. Could be bad bearing or gear set. If you hear it under load may be in gears. Pop it out of gear when you hear it to see if it's still there.
Thread Starter
Cruising
Joined: Jul 2006
Posts: 12
Likes: 0
From: Seeley Lake Montana
Thanks for the inputs. I put new tires on it last summer and checked u-joints and wheel bearings for play. Every thing was fine. I drove it about two weeks ago but didn't pop it out of gear, and since it snowed 4" last night, it will probably be another couple of weeks before it is driven again. I did notice, however, that when pulling moderately in 3rd everything was quiet until I reduced the throttle to maintain speed at a steady level. Same thing on the highway in 4th. Open the throttle to pass-quiet again. Close the throttle to slow down-quiet again. Thanks again to everyone. My goal here is for this to be reliable enough for 3000 miles a summer (summers are short in Montana). I'm very close to 64, so every summer is important.
Racer
Joined: Jul 2007
Posts: 397
Likes: 0
From: Warren IL
Drain the fluid into a clean drain pan. If it has a very metallic look to it, then you know it has a problem.
You can't look at mileage of a car and say something is unlikely to go wrong. If that was the case I would be out of a job! I regularly am rebuilding diffs and transmissions in cars under 3 years old and less than 36,000 miles.
You can't look at mileage of a car and say something is unlikely to go wrong. If that was the case I would be out of a job! I regularly am rebuilding diffs and transmissions in cars under 3 years old and less than 36,000 miles.
