70 Rear End noise
Hi: I posted recently about howling noise in the rear when basically coasting with a load on the drivetrain. I have not addressed that issue but in the meantime, I replaced the snubber and also the spring bushings only because they looked cracked and the cups looked rusty. I then went for a spin the noise is still there but I swear it is coming from the right rear now. Would a wheel bearing issue cause a similar sound? All was redone 3k miles ago. Moving at speed with the clutch depressed, it is silent. I was confused before and even more so now!
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Re: 70 Rear End noise
I don't understand what you mean by "coasting with a load on the drivetrain". When coasting there is no load on the drivetrain unless you want to include the drag from the rear wheels.
So are you saying that if you lift off the throttle at speed (what range, what gear(s)?) the noise is apparent, but then if you depress the clutch it disappears?
I must have missed your first post, but couldn't find it in the first three pages of threads. Can you post a link to it?
Axle bearing and wheel bearing excessive noise is fairly constant with speed, Ring and Pinion noise can vary with both speed and applied torque while moving forward. It can also occur coasting but is usually much less noticeable.
Back when my '88 MBZ 190E 2.6 special order five-speed was new and I made several trips a year up the nearly dead flat I-5 from southern to northern California the axle would "sing" under "float" conditions. Float is when there is literally no torque being transmitted either way such as a light downgrade when gravity and drag force are essentially equal, and you only need a very slight amount of throttle to maintain speed. The only source of this high frequency noise could have been the ring and pinion gear teeth vibrating back and force within the range of backlash, but I don't know if the backlash was excessive or not enough.
I-5 through the San Joaquin Valley is very flat, but there are enough very slight downgrades that made the axle sing for a good part of the trip, which was very annoying as otherwise the car was nearly quiet as a bank vault, like 67-68 dBA at 70 MPH.
It took two axle replacements from MB USA under warranty to get one that didn't sing, and it's still okay to this day with 87K miles.
Various engine and drivetrain noises can be tough to find and also tough to explain.
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Re: 70 Rear End noise
Well, I figured my description was not a good one. What you describe as float is what I am talking about. It's when you are at a steady speed and are not accelerating but driving at a steady speed and as you say on a slight downgrade you hear it and as soon you would hit an upgrade it will go away. When out of gear and coasting is silent. So frustrating not being able to identify. When I first heard it I thought it was the transmission. I know it sounds crazy that changing the bushings made it sound more from the right rear. That would have had a minuet difference in the angle of the dangle.Comment
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Re: 70 Rear End noise
sounds like gear whine, I would expect an outer axle bearing to be noisy all the time and if noisy you should be able to feel some play in it.
Was the differential rebuilt and new gears installed? New gears may have a whine about 45-50mph. US Gear even wrote a paragraph in their setup sheet stating a certain amount of gear noise is to be expected. They're gone now and all the gears are imported so possibly that is the issue. GM gears were not like this so if they are in the car and noisy they may be worn, but pinion bearing noise is similar.Comment
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Re: 70 Rear End noise
Going to drive it a bit more with someone else listening and then switch out to see if I can determine. It does sound like you described being the pinion not done right or loose. Thanks. Will follow upComment
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