rear diff droning sound?

[98_Q_silver]

Well I finally was able to replace the new 80/90wt oil with 85/140 tonight and I still have the same droning noise. Absolutely no change at all. While the car was up on jack stands I put the car in neutral and spun the tires by hand. No vibration in the springs like SteveTheTech suggested. I did hear a squeaking sound coming from somewhere. I thought it was one of the rear brake rotors but it just didn't sound like a pad was dragging at all. I crawled up toward the front of the car and spun the tire again. The noise sounds like it's coming from what I am going to call a carrier bearing on the driveshaft. I think I just may have found the source of the droning. Traveling from the diff forward there is a u-joint then driveshaft then u-joint then carrier bearing then driveshaft. I am now suspecting the carrier bearing is on it's way out.

What is that like to replace?? Thoughts...

[qship96]

Give it a few good whacks to redistribute the jizz in there and see if it helps

[98_Q_silver]

Give what a few whacks? I know I am new to this site but that doesn't seem right.

[qship96]

Someone more experienced with this than I will chime in, but it has something to do with freeing up the bearings or such.....may want to try to do a search typing in "driveshaft" into query box

[98_Q_silver]

Did the search and found out that there is a driveshaft balance issue that can cause other problems like a worn out nose bearing in the diff.

[maxnix]

Whacking the U joints can sometimes free them up.

[Q45tech]

Failure to check and keep driveshaft in balance usually causes wear on input bearing in diff. Another owner self inflicted injury.

Based on history of a few hundred Q, the average seems to make 180-220k before needing a diff even with 30k fluid changes.

We replace about 4-5 per year..............harder and harder to find a useful junkyard unit now.

[98_Q_silver]

It's sounding more and more like my diff is on it's way out. That is not good since I just bought this car about 3 weeks ago. I don't think the diff oil has ever been changed. I am still holding out on the drive shaft carrier bearing or the u-joints being bad. I guess I will have to take it in to the experts and let them tell me what is causing the noise.

If I need a new diff, what can I expect to pay for used one with TCS? My car is a '98. At least that is what the title says even though it has the analog odometer.

[SteveTheTech]

I would recommend getting it looked at professionally as most of these parts are pretty expensive.

Here is a pic of a 98 combination meter. Does yours match?

[98_Q_silver]

That's what I have.

I am starting to get a little nervous about this car. I really like it but not at the expense of replacing parts that should last for more than 140,000 miles.

I have owned several vehicles over the years that were rear wheel drive or four wheel drive with well over 140,000 miles and they never had the diff oil replaced. They ran fine. Is it b/c it's a luxury car and it has the TCS and viscous limited slip in it? This car has not been beat on ever. It was owned by a local older couple that bought it with 28,000 miles on it. His wife drove it 25 miles to work every day on the highway. She has since retired and they sold it to get a little Mercedes convertable.

I think I might have made a bad decision buying this car if I am going to have to replace high priced items. I bought it b/c it was a Japanese car that I thought would be very reliable and not have any trouble with it.

[qship96]

All the cheap miles have already been used........should have bought a newer low mile car if you arnt prepared to replace parts as they wear.....afterall you did get a car with 144,000 miles already on it!!!!!

You either buy brand new/few year old car and pay more upfront in the purchase price.....or you buy old, high mile car for low purchase price and expect to spend to replace worn parts......pick your poison as there is no free ride either way

[SteveTheTech]

The car is 10 years old the electronics as well as mechanical components are getting tired and may require replacement for optimum operation. Usefull life is ~100K any more than that and most cars start costing money.

[98_Q_silver]

I really hope that's not true.

I have not bought a used car with less than 100k miles on it for the last 8 years and I have not had any major issues to deal with other than half shafts. Maybe I should have bought another Saab or Audi. I am heading to the Infinity dealer in the morning to hopefully find out what the noise is. So far I am really impressed with this site. Everyone has been very helpful.

I will let you know what I find out.

[qship96]

I really hope that's not true.

I have not bought a used car with less than 100k miles on it for the last 8 years and I have not had any major issues to deal with other than half shafts. Maybe I should have bought another Saab or Audi. I am heading to the Infinity dealer in the morning to hopefully find out what the noise is. So far I am really impressed with this site. Everyone has been very helpful.

I will let you know what I find out.

Quite possibly the reason you had better luck in purchasing used Audi/Saab with over 100,000 miles on them is because alot of their original parts had already worn out and were replaced by previous owner....whereas the typical japanese sedan is still on most of its original parts well past 100,000 miles and problems/wear tend to surface at higher miles.

[TBrack]

Failure to check and keep driveshaft in balance usually causes wear on input bearing in diff. Another owner self inflicted injury.

Based on history of a few hundred Q, the average seems to make 180-220k before needing a diff even with 30k fluid changes.

We replace about 4-5 per year..............harder and harder to find a useful junkyard unit now.

how the heck do you balance a driveshaft?

[bullittandy]

It is much more likely the tires than the differential. Occam's razor-simpler explanation is the better one. My suggestion-buy new tires.

[98_Q_silver]

If the tires are causing the noise problem then wouldn't the noise change when driving on different pavement types? I still have the noise driving on dirt (not that I subject this great car to dirt roads but I had to test the tire theory).

I am going to have someone listen to the drivetrain while it's up on a lift to make sure it's the diff. My guess is that it is. If I need to find a used one, what can I check to make sure sure it's not wasted also? If I spin the axle flanges would I be able to feel any bearing problems? Would there be some backlash in the gears inside that would be excessive? A salvage yard can tell you it has x miles on it. How do you know for sure. Any tell tail signs?

[maxnix]

If the tires are causing the noise problem then wouldn't the noise change when driving on different pavement types? I still have the noise driving on dirt (not that I subject this great car to dirt roads but I had to test the tire theory).

I am going to have someone listen to the drivetrain while it's up on a lift to make sure it's the diff.

Listen to Andy. I thought I had a bad bearing, but it was slight cupping on the inside of all four tires. Lowering springs and a lttle too much camber and crappy Dunlops that were not strong enough.

I won't be surprised if you find nothing like I did when I raised it twice to listen. New tires, no noise.

[98_Q_silver]

I hope you are right. I know my wife would be pleased to hear that it's the tires and not the diff. I will try to get it checked out this week.

[maxnix]

So, out of curiousity, which tires are you running? Miles? Stock suspension?

[oldmako]

My car has an occasional drone as well. (135K) I thought it was the trans or rear but now I'm not so sure.

I changed the rear end fluid with M1. No idea how old the old jizz was but it was clean. M1 in the transmission as well.

Before you freak out and start wrenching, read some of the posts regarding changing out the drive shaft and/or rear diff. Not only will you drop some serious coin, you may end up making things worse in the long run. I'm not too sure that's money well spent.

Mine has gone quiet just as quickly as it began droning. It used to start around 40mph. But the last two months or so it's been quiet. Beyond the fluid change I have done nothing. It may be the quiet before the BFS, but it's quiet.

Got a buddy with a Q?? Try swapping tires one morning and going for a spin before you mess with that shaft or rear end.

You might want to instead spend the money on a new stereo....a really loud one.

[98_Q_silver]

The tires are crappy Bridgestone Insignia SE200. I would guess about 10,000 - 15,000 miles. Never rotated but in fair condition. The fronts had some slight cupping going on so I rotated them. Now that I think of it, the noise is somewhat worse than before I rotated them. Instead of the noise coming on around 40mph it's now at 15mph and above. I am having a hard time believing it's the tires when the noise doesn't change with road surface driven on.

Suspension is all stock.

[maxnix]

The tires are crappy Bridgestone Insignia SE200. I would guess about 10,000 - 15,000 miles. Never rotated but in fair condition. The fronts had some slight cupping going on so I rotated them. Now that I think of it, the noise is somewhat worse than before I rotated them. Instead of the noise coming on around 40mph it's now at 15mph and above. I am having a hard time believing it's the tires when the noise doesn't change with road surface driven on.

I'll give you 3 to 1 odds you have identified your problem. The reason it sounds the same is the cupping is causing the noise and it is the same frequency on every surface at a given speed.

Save your money and get some real good strong tires. Read the tire sticky thread in Infiniti General for some real life testimony. Remember, just because a tire works well on a Miata or a 3er, that doesn't mean it is strong enough for a Q45. Read my review of the Dunlop Direzza DZ 101, a much stronger higher performing tires than your current ones that suffered the same fate.

[98_Q_silver]

Maybe you are right about the tires. I have yet to read any tire posts. These tires would have not been my choice. These tires are S speed rated. Not even close to what should be on this car. I agree with your comment that the tires are not strong enough for the car.

I don't know anybody or have seen another Q driving around here ever. Maybe I should try to hook up with elwesso. He shows that he is from Angola / Anderson. Either place is only an hour drive for me.

[maxnix]

S rated! Don't go until you get new tires that are up to specification!

Seriously, Congress is holding hearings now, so a set of tires is less than the electricity bill for the hearing room.