SVU-Boat

Recently, I began noticing this sound which appears to be gear/transmission related? It's a low, rubbing or droning noise, noticeable most when I'm bouncing in the 3rd thru 5th gears under almost all circumstances except hard acceleration (but then I can't hear anything but the beautiful engine then). It doesn't really seem to matter whether I'm "in" gear, or the shifter is sitting in neutral. Nor does it appear to matter whether I'm reving the engine moderately or simply coasting in "neutral" or in-gear. It's not evident at first (during the first 10 minutes or so of driving). But thereafter it emerges. I probably should do some more diagnostic isolation to be sure of these occurences (3x with clutch in, gear in, accel, decel, etc.) but I happened to hop on the computer tonight

There aren't any leaks underneath my '86 cabriolet and it's got about 85k miles. In October (about 750 miles ago) I did a complete oil and tranny fluid change w/o issues. I don't otherwise have any difficulties with shifting (other than what's so charmingly idiosyncratic to a 20 y.o. 915 tranny)

Does this phenomena sound familiar to anyone? .. I hope.. or maybe I don't want to know

Peter Zimmermann

Does it get worse while turning left or right, or does it go away when you turn left or right? Forget all about gear selection and accel/decel, what road speed is it the loudest, and does the noise increase as you gain speed?
Pete

carnutzzz

Check obvious stuff first- lug nuts tight?

Ask me how I know!

DGaunt

Oil cooler fan? Just a thought.

SVU-Boat

Ok, I've done some further (amateur) diagnostics.
This front-end droning noise appears loudest around 50 mph (emerging at about 40 and fading past 60). It seems most evident while in 5th gear, regardless of whether in slight accel or coasting. I can't tell if the droning noise would be there in a lower gear (at 50) because the engine noise is too loud.
Oddly (or understandably? to those who've solved this) the droning also drops considerably if I disengage the (4th or 5th) gear.. but is still mildly present while shifter sits in neutral coasting around 50mph too.
I don't notice the noise on turns, and that could be because the speeds are below 20mph.
Do these characteristics help at all?.. I hope :|

r911

What happens if you jack it up and try to move the wheel at 6 & 12 o'clock with your hands?

Peter Zimmermann

SVU: You should inspect your outer front wheel bearings...
Pete

SVU-Boat

I'm leaning toward the bearings now?
I found an "S" curved road which I could take pretty hard at 40 (signs "suggest" 25) and did notice an elevation of this humming/rubbing/droning noise from somewhere in front as I was deep in the turns.

On the jacking up 6/12 o'clock diagnostic, what am I hoping to see .. or not see : |
Thanks so much for the thoughts so far!!
Mike.

Chris M.

I just fixed a similar droning noise on a friend's 87 Carrera. His noise also only began after the car was warmed up but occurred when approaching a stop and went away when the brake pedal was applied. It was only on the right side. Turned out it was a seized piston in the caliper so I rebuilt both fronts and all problems are solved.
Good luck.

c

r911

a droning noise from the front is almost always a wife

- a girlfriend usually makes a higher-pitched whining noise...