Rear Noise

[vettn71]

When I took my 90 out this morning I noticed that at 50 mph or higher there seems to be a slight vibration and a low "rumble" type sound. Nothing very clear, more like an under tone to the tire noise. It doesn't change when the clutch is pushed in, and under 50 it doesn't seem to be evident. I checked the bearings by jacking the car up and moving the tire with my hands at 3 & 9 and then at 6 & 12, but didn't feel any movement. Tried moving the half shafts and driveshaft, but didn't feel any play there, either. Tires are almost new and haven't had any issues with them. Any ideas?

Jim

[Jagdpanzer]

Had a similar experience after putting on a new set of GY D3s couple of years back. Turned out to be the tire balancing. Had the everything road-force balanced on a Hunter GSP9700 machine http://www.gsp9700.com/
at a local tire shop and that solved it.

[rhipsher]

I've had the same damn thing I start to hear it from 68mph to 80mph. It's definitely speed related. It almost sounds like the tire roar of a big knobby tire on a 4X4. I thought it might be the drive shaft being out of balance. All my ujoints are brand new Splicers so I knew it wasn't them. And I got a four point alignment and that didn't take care of it. So I've just learned to live with it.

[USAFPILOT]

I was always told that a noise like that from the back of the car would be the rear end. I wonder?

[rhipsher]

Originally Posted by USAFPILOT

I was always told that a noise like that from the back of the car would be the rear end. I wonder?

Yeah but which part of the rear end would make a noise like that. I've thought of everything. Rear gears maybe? Wheel bearings? Tire balance? drive shaft balance? I gave up along time ago trying to pinpoint that noise and the cause. I just can't afford to throw money at it by replacing everything that it could be. I'm waiting for somebody to chime in and say they had the same problem and found what the cause was. This is the first time I've ever seen a post addressing this. I thought I was the only one. It doesn't seem to affect the drive ability. It's just kind of annoying.

[tomtom72]

You are sure that the fluid level is okay in the rear & trans? You don't think that this is a bad case of exhaust resonance, or something loose in the exhaust system? Or maybe the spare tire carrier is loose, or the jack is loose? The tires are okay, you didn't loose a weight off of a wheel or have a flat spot or a belt go bad?

I hate to say this but if it's not the rear hub bearings, and you are sure that all the u-joints are good on the 1/2 shafts and the drive shaft joints also.....then it only leaves the stub axles, carrier side bearings and pinion bearings.

Other than that I'm stumped. Usually a low pitch rumble is either the u-joint needles in the first stages of failure, or the rear bearings going south, usually the axle bearings make noise like that.

I wonder if those teflon washers used in the rear hubs could make this symptom if they wear excessively?

[rhipsher]

Originally Posted by tomtom72

You are sure that the fluid level is okay in the rear & trans? You don't think that this is a bad case of exhaust resonance, or something loose in the exhaust system? Or maybe the spare tire carrier is loose, or the jack is loose? The tires are okay, you didn't loose a weight off of a wheel or have a flat spot or a belt go bad?

I hate to say this but if it's not the rear hub bearings, and you are sure that all the u-joints are good on the 1/2 shafts and the drive shaft joints also.....then it only leaves the stub axles, carrier side bearings and pinion bearings.

Other than that I'm stumped. Usually a low pitch rumble is either the u-joint needles in the first stages of failure, or the rear bearings going south, usually the axle bearings make noise like that.

I wonder if those teflon washers used in the rear hubs could make this symptom if they wear excessively?

I removed the spare and jack for wieght reduction. All the ujoints are brand new. Trans fluid is full. Not sure about the rear diff fluid. My wheel bearings have a little play in them but I don't think they would make a roaring noise. When I'm at 80mph I can put the car in neutral and as it coast down to around 68mph the roar pitch start to go down and gets quieter kinda like a single engine air plane dive bombing. It's tire rotation speed related not rpm related.