Low speed growl/howl

[Ralph]

For the second time after driving for 30 or more minutes, and pulling into a parking spot, I get a howl (not too loud) from the left front. Some vibration in the steering wheel Hasn’t happened when turning right yet. Wheel hubs are both cool.

Any ideas?

[Gregs672000]

Stock brakes? Maybe some contamination on the inboard side? I've had my nonstock brakes do that after sitting for some time, but it clears up with use. I don't have a dust/grease cover on mine, so the ball joint grease has to be watched. Are the wheel bearings tight or sloppy?

[spl310]

The howl could also be the surge tank venting

[C.Costine]

For the second time after driving for 30 or more minutes, and pulling into a parking spot, I get a howl (not too loud) from the left front. Some vibration in the steering wheel Hasn’t happened when turning right yet. Wheel hubs are both cool.

Any ideas?

Rolling? stopped? running? shut off?

[theunz]

You say the hubs are cool, but have you jacked up the front and checked for play in them? If you are running large tires they may be rubbing on the sway bar at full lock, and it is possible to rub on one side and not the other.

[redroadster]

Backing plate rubbing or gravel caught between it and rotor ? It's the #1 terrible noise complaint
What's a surge tank ? Oh on the carb setup

[Ralph]

For the second time after driving for 30 or more minutes, and pulling into a parking spot, I get a howl (not too loud) from the left front. Some vibration in the steering wheel Hasn’t happened when turning right yet. Wheel hubs are both cool.

Any ideas?

Rolling? Yes
stopped? No
running? Yes
shut off? No

[Ralph]

You say the hubs are cool, but have you jacked up the front and checked for play in them? If you are running large tires they may be rubbing on the sway bar at full lock, and it is possible to rub on one side and not the other.

Will jack it up today and check for play, and will also have a closer look at tire clearance at full lock.

[rwmann]

Now it's looking like lock clearance or debris between backing plate and rotor.

[Ralph]

Doesn’t seem to have any clearance issue when I jacked it up. Got the same noise going straight, at about 20 mph only once while running around today, nothing while parking
I will continue to monitor and note what’s going on right before the noise happens.

Thanks for the help so far

[theunz]

I was at a race recently with a friend who has a Miata. After qualifying he said he was getting a vibration in some of the turns. I detected a very minute bit of play in the bearing. His brother who is a very good mechanic and does the wrenching on the car said that he felt the bearing was fine. We went ahead and changed it anyway and when he went out for the race the the vibration was gone. So with the big sticky slicks the turns with a lot of G’s were causing the vibration that otherwise wasn’t felt. Your hard turns while parking could be putting just enough stress on a slightly worn bearing to do the same thing. Perhaps cleaning, repacking, and tightening the bearing might help. All it costs is time.

[rwmann]

Now looking more like debris floating between backing plate and rotor.

[jrusso07]

Maybe try re-seating the front wheel bearings before pulling the hubs for bearing inspection?