CorsePerVita

Having a hell of a time telling.

I'm starting to thing more towards mainshaft but I want to bounce it off those of you that have had one go out or heard it. It COULD be a rear wheel bearing too! Posting to bounce off opinions.

- At about 45mph I start getting a howling, no doubt it is a bearing.
- The pitch raises as the speed raises
- I can only reproduce it in 4th or 5th, at the same speed
- It doesn't do it in any other lower gears, however, i heard a similar noise upon decel in 2nd at just a hair under 2krpm
- Coming from the rear from what i can tell.

Reason i am confused is because it only is prevalent at about 45, definitely coming from the rear. I only hear it up till about 65 then it's almost gone, but i can hear a very high pitched whine still but it's very faint. If I stomp the gas it's more prevalent. Quite literally the faster you go in 5th, the higher pitched it gets. Sort of like if you sped a top up, faster and faster, it whines faster and faster. Strange thing is it sounds ALMOST the same in 4th as it does in 5th at the same speed. I can't tell but the tone sounds /about/ the same. If it is different isn't not by much, this is why I am not sure.

I also hear it on decel, though it's a different tone.

I almost never hear it in any other gear but this morning caught it once in 2nd gear at a decel but it was for maybe a second and a half, very short time.

My understanding is that a mainshaft bearing would make noise through ALL gears, am i correct? And under load or decel? Not just 4th or 5th at highway speed?

I suppose process of elimination I could do the rear wheel bearings, but I hate throwing money at things as the fix and prefer to diagnose them. I planned on taking my car on a trip here soon but until I know the issue I refuse to since I do not want a major failure 3 hours from home.

Sysgen

If you go up to 50 lets say and put it in neutral and press the clutch, does the sound go away? You'll have your answer once you try. If the sound goes away then it's the Torque Tube bearings. You can also lift the car and check if there is some play in the wheel.

CorsePerVita

sound goes away, yes. so you don't think it's mainshaft, its TT bearings? i was wondering... it also mimicks any sort of lash (such as if you let off the gas hard at highway speed, that brief, whine whine whinnnnnnnnneeeeeee on decel).

I can deal with TT bearings. Much more so than mainshaft bearings. So that is pretty relieving. It has sounded like rattling pissed off bearings in a coffee can for a while... now this...

guess it's time to do the TT.

Landseer

The new Black Sea Constantine's are the only way to go. (But I think you already know that.)

I have rear left bearing going bad on a 928. Its most noticeable on acceleration on a steep windy uphil, as I turn right.

CorsePerVita

thanks landseer - i'm assuming you must have seen the posts i replied to over on 928 forum then lol.

most definitely isn't a wheel bearing then, was hard to tell since a rear wheel bearing would be slightly different than front. spoke to a few other people who believe it's torque tube as well since it goes away soon as the clutch is pressed. might just do the clutch while i'm down there too.

StoogeMoe

Howling in rear?
Solution - remove werewolf from hatch.

CorsePerVita

Not aware of any werewolves. Ex wife moved to another state years ago! No demonic creatures left that I'm aware of.

limerocket

Sounds more like the ring & pinion to me, especially considering the accel/decel transients you describe. If it were TT/mainshaft bearings, you would be able to isolate that by engine speed and load in most any gear since they both spin at crank speed. A failed clutch disc can create funny resonances as well, but you would certainly hear an on/off clunk.