Furioso

Annoying intermittent vibration felt in shifter when in gear. 5 seconds vibration, 5 seconds gone.
At all speeds.
Vanishes when I put in clutch.
This is a new problem, as I've had the car for 2 years.
Replaced U-joints and rear bearings. 6 month old tires all around.
Maddening. Please help me diagnose.
Thank you so much.
~Ricardo Furioso
ps-I've read about 15 "vibration" threads, and haven't found this particular annoyance.

Kevova

Clutch, flywheel, input shaft. Do you feel vibration anywhere other than shifter?

ben dover

How about clutch engaged, shifter in neutral?

Furioso

Good question. Will check. Thanks.
The weird thing is I don't have to be doing anything to have it start and stop. Feels like a bad bearing.

Furioso

The vibration is most strongly felt in the shifter.
But it of course you can feel it throughout the car.
It disappears when rolling in neutral.
It recedes almost completely, but not quite, when the clutch is depressed.
And my Corvette failed Californicate smog test today.
So I'm kind of depressed as well.
Thanks again for your wise counsel, oh Forum Graybeards.

~ Rich

65Z01

So does it continuously "cycle", like 5sec On, 5sec Off, 5sec On, etc.?

WhiteC1

With it cycling on and off, could it be the A/C compressor? Make sure your A/C is off and see if it still vibrates. With the clutch depressed, engine (A/C) vibrations wouldn't transfer through the transmission to the shifter. Just a thought.

Regards,
John

ben dover

So probably not input shaft bearing, just a guess but I'd check cluster gear shaft bearings.

Furioso

Yes, it cycles on and off.
Like a bad bearing somewhere.
It's not the AC.
It's in the driveline, I'm pretty sure.
Pilot bearing?
I know for sure it'll be a PITA to diagnose.
And probably expensive to fix.
Thank you for your continued support and suggestions.
~ Rich

Furioso

It stops when I turn off AC.
Mechanic thinks it's motor mounts.
How can I tell?
Thank you so much.
-Rich

SJW

There's a clue. I'd carefully inspect everything associated with the compressor, particularly all mounting brackets (look for cracks), loose/broken/missing bolts, etc.

Live well,

SJW

Furioso

Thank you so much.
We'll look into that.
Can you also tell me how to tell if it's motor mounts?
r

SJW

I think the odds are exceedingly slim that this problem is related to motor mounts. IMHO, it's be a waste of time to look for it there, at least until you've inspected many other candidates first.

Check the A/C compressor mounting brackets, bolts, etc, and check to be sure the belt tensioner is doing its job properly.

Live well.

SJW

RUU

Compressor cycling? Low freon? Especially with the "5 seconds on 5 seconds off" description.