Noisy Rearend
Thread Starter
Intermediate
Joined: May 2009
Posts: 28
Likes: 2
Noisy Rearend
Bought a 78 this summer. Car runs great, but noticed a whub whub whub sound from the rear after a mile or two.
Thought at first it was a tire rubbing, as the previous owner had 275/60s on the back. Replaced with 255/60 and the sound was still there. Realized it was coming from the rear dif. Drained the fluid and replaced with fresh fluid (synthetic with additive already in it). noticed the sound was much quieter now, but still there.
Talked to the previous owner who told me he had the rear differential rebuilt (4.11), and that they were Richmond Gear straight cut gears, and that he was told they would be noisy by the guy that did the job.
My question is, does this sound legit? Can't imagine straight cut gears in a differential... and wouldn't they just whine then all the time, or would they throb like that?
Thought at first it was a tire rubbing, as the previous owner had 275/60s on the back. Replaced with 255/60 and the sound was still there. Realized it was coming from the rear dif. Drained the fluid and replaced with fresh fluid (synthetic with additive already in it). noticed the sound was much quieter now, but still there.
Talked to the previous owner who told me he had the rear differential rebuilt (4.11), and that they were Richmond Gear straight cut gears, and that he was told they would be noisy by the guy that did the job.
My question is, does this sound legit? Can't imagine straight cut gears in a differential... and wouldn't they just whine then all the time, or would they throb like that?
Safety Car
Joined: Nov 2008
Posts: 3,713
Likes: 550
From: Seattle Washington
No there is no such thing as straight cut gears for Your rear end. Yes aftermarket Gears are known for being more noisy than the OEM. If it sounds as though the previous owner asked the rebuilder about the noise after the rebuild then it probably started as soon as he got it done. Sounds as though there is quite a bit more noise than what there should be, and that a rebuilder has made an excuse for it.
Pro
Joined: May 2013
Posts: 672
Likes: 31
From: Rapid City South Dakota
Bought a 78 this summer. Car runs great, but noticed a whub whub whub sound from the rear after a mile or two.
Thought at first it was a tire rubbing, as the previous owner had 275/60s on the back. Replaced with 255/60 and the sound was still there. Realized it was coming from the rear dif. Drained the fluid and replaced with fresh fluid (synthetic with additive already in it). noticed the sound was much quieter now, but still there.
Talked to the previous owner who told me he had the rear differential rebuilt (4.11), and that they were Richmond Gear straight cut gears, and that he was told they would be noisy by the guy that did the job.
My question is, does this sound legit? Can't imagine straight cut gears in a differential... and wouldn't they just whine then all the time, or would they throb like that?
Thought at first it was a tire rubbing, as the previous owner had 275/60s on the back. Replaced with 255/60 and the sound was still there. Realized it was coming from the rear dif. Drained the fluid and replaced with fresh fluid (synthetic with additive already in it). noticed the sound was much quieter now, but still there.
Talked to the previous owner who told me he had the rear differential rebuilt (4.11), and that they were Richmond Gear straight cut gears, and that he was told they would be noisy by the guy that did the job.
My question is, does this sound legit? Can't imagine straight cut gears in a differential... and wouldn't they just whine then all the time, or would they throb like that?
Thread Starter
Intermediate
Joined: May 2009
Posts: 28
Likes: 2
Still haven't found the source of my rear end noise.
When going about 25MPH and then worse again at 45-50mph a wub wub wub sound come from the rear of the car. Initially I thought it was a bad tire, but that turned out to not be the case. Then I changed all of the u-joints on the drive and half shafts. I eventually realized it was coming form the rear dif. So I bought a brand new rebuilt rear end from Zip Corvette and installed it. Initially the sound went away, so I thought "Awesome" but after a week or two, the sound slowly returned. It gets louder as time goes on. I then took my old differential and had it rebuilt and also put new side yokes on. After replacing the sound was gone... but then again slowly the sound returned... I am stumped and don't know where to look next and was hoping someone could give me some suggestions.
When going about 25MPH and then worse again at 45-50mph a wub wub wub sound come from the rear of the car. Initially I thought it was a bad tire, but that turned out to not be the case. Then I changed all of the u-joints on the drive and half shafts. I eventually realized it was coming form the rear dif. So I bought a brand new rebuilt rear end from Zip Corvette and installed it. Initially the sound went away, so I thought "Awesome" but after a week or two, the sound slowly returned. It gets louder as time goes on. I then took my old differential and had it rebuilt and also put new side yokes on. After replacing the sound was gone... but then again slowly the sound returned... I am stumped and don't know where to look next and was hoping someone could give me some suggestions.
Thread Starter
Intermediate
Joined: May 2009
Posts: 28
Likes: 2
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Thread Starter
Intermediate
Joined: May 2009
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Melting Slicks
Joined: Jul 2006
Posts: 2,277
Likes: 483
From: Salmon Arm, BC
Have you looked at the half shaft ujoints?
How about the rear bearings on the trailing arm, disconnect the half shafts and spin the axle to see if there is any roughness in the bearings.
How about the rear bearings on the trailing arm, disconnect the half shafts and spin the axle to see if there is any roughness in the bearings.