2k RPM whine

[rrubel]

In the last couple weeks (most noticeably after my track day), I've been hearing a whine or resonance or something similar at pretty much exactly 2000 RPM. Doesn't appear to matter what gear I'm in, but I do have to be giving the car gas. 2K coasting is quiet, passing back through 2K while decelerating is quiet.

Any clues? I thought for a while it might be exhaust, but I can't pinpoint anything. I'm hoping against hope that it's not the rear end. It's hard to tell from inside the cabin where the noise is coming from, and I haven't been able to recruit an assistant to rev and watch the tach while I'm listening in the garage.

Thanks...
[RICHR]

 

[Ken]

Rich, I had a similar resonating vibration (although mine occured through a range of rpms) that I could not track down. When I finally pulled the L-98 I noticed the outer ring of the torsion damper had slipped towards the timing chain cover, so much that it was almost touching the cover. It was probably way out of balance by that time. :eyerole

That might be the answer to your question. :confused

Good luck.

_ken

 

[rrubel]

Ok... that's one thing I can easily check tomorrow. The car's up on blocks right now (doing the rest of the rear swaybar and control arm bushings with urethane) so I can't drive it, but visual checks are a different matter.
Thanks!
[RICHR]

 

[BigRed]

We're not talking about rear end whine are we?

Other than than Id suggest Fan (Front of engine) but we are electric so..

 

[rrubel]

BigRed, I'm not sure... it's hard to pinpoint where the noise is coming from, and I haven't been able to check for it when stopped. I'm pretty sure that if I coast in neutral and keep the engine at 2k, even though the car is slowing down I still hear it.
[RICHR]

 

[BigRed]

Kind of far fetched but had you have the car of a hoist? Try it and gas it a bit.

If that doesn't work (no weight on rear) Can you do it at real low speed so that a friend can use a bike or a quiet car to help you diagnose the exact location?

Hearing noises from the cab is so decieving, its very hard to pinpoint. (Harder when your pushing a L98 with flowin muff's heh)

Is it a WHINE or more of a squeak? (this is gonna sound dumb but) Whirr whirr whirr or chickchickchick.

:L

If it is the whine I would look at the rear end, wheel bearing, condition/brand of tire. One other thing I don't know where our fuel pump is could it be back there whining?

If its squeakin good luck! :L Hard to find but usually cheap.

But you said you noticed it AFTER racing it. Did you do hard burnouts? This could lead to rear end or tire dmg.

 

[WhalePirot]

So, the first question is; Is the whine tied to engine or car speed?
If car, is it only on decel or accel?
Does it come even with the radio off?

 

[rrubel]

Well, I thought I'd made that clear in the initial post, but as I looked it over again I realized I didn't.

The whine is at 2k RPM regardless of car speed, though it's most noticeable at highway speeds (then again, I tend to not drive at 2k for long periods of time other than in 4th OD). If I slack off the gas it goes away (mostly). If I keep the tach at 2k and the car in neutral (coasting), regardless of speed, I can hear it. It gets louder as I approach 2k from the bottom, so at 2100 to 2150 it's ramping up.

However... as I thought about it more, it crossed my mind that it's more like a resonance than a true whine (I have a rear-end whine in my Outback; this isn't really the same sound). This is why I first thought maybe exhaust or something.

I have the back of the car on stands right now, but there's no wheels and half the suspension's missing so I'd be afraid to run it. I did take a quick look at the exhaust at the rear (had to drop the mufflers to take out the swaybar - is there an easier way???) but didn't see anything obvious.

Thanks.
[RICHR]

 

[Eagle85C4]

Air pump?
Alternator?
Water pump?
Tranny?
Throwout bearing?

Because it is rpm related it has to be something that is spinning at speed, tires and drive line don't turn that fast....
I would think if you have someone hold it at 2k then poke around under the hood you might find it...just a thought. Good Luck Rich....

BTW on redoing the bushings did you get a kit or just get what you need. After hearing about you doing yours and a few others on here I am considering replacing all of them on my 85 while it is in the garage for the winter. Lord knows it could probably use it. I believe in preventative maintenance, what was the old saying..."an ounce of prevention is worth a pound of cure..."

 

[rrubel]

Alternator, water pump, throwout bearing all have less than 3k miles on them. Air pump - no clue. Tranny - god, I hope not, though it'd be an excuse to wedge a 6-speed in there.

WRT the bushings, I bought a bunch of separate sets. I got a couple from someone on CorvetteForum and the rest from Suspension Restoration. The full kits came with more than I planned on replacing, so it would have been a waste of $$.

I'm doing front and rear sway bars, front and rear control arms (right now only top arms in rear; bottom are a &*(^&(&* to remove), diff->spindle arm, and one other I can't remember off the top of my head at the rear.

Also would have done shocks except the TPIS ones I have came with urethane bushings already.

A word of advice - the front A-arms are a right royal pain. My mechanic went through all sorts of contortions to get them in. Most of the others are easier, though a few on the rear sway bar require a press.

[RICHR]