[jagamajajaran]

First, this is not the normal tire chatter that most everyone already knows about. Here's the situation:

Over the last two days, traveling from Oklahoma to Kentucky, what started as a very slight thumping sound while driving down the highway grew into a louder thumping sound today somewhere in the driver side front wheel area. I need to find a local service department to take it to here in the Bowling Green area, but since I can't attempt to do that until tomorrow, I thought I'd throw it out here for some guesses about what the problem may actually be. Here are the specific symptoms. Keep in mind that they have grown in intensity through the day today.

- When driving in a straight line, I hear a thumping sound that increases in frequency the faster I drive. It sounds like a helicopter in the distance at highway speeds.

- When taking a curve to the left or right, the thumping sound is more intense.

- When braking, the sound goes away and there is no pulsating of the brakes either.

- When making a left hand turn or a right hand turn at a slow turning speed, the thumping sound is very intense.

- There are no foreign objects in the tires.

My inclination is that the problem does not have to do with the tire, but has something to do with the front driver side brake since the sound immediately stops when applying the brakes.

The car now has a little over 5000 miles on it.

Any ideas? Thanks!

 

[jsvette]

Very remote reach Jeremy but I had a similar situation on my 1975 Rolls Corniche that took 6 months to figure out. It turned out that one of the front wheel pistons was slightly seizing because of a constriction caused in one of the brake lines caused by heat. Braking and then stopping forced the piston to retract eliminating the noise.

 

[Milliwatt Rob]

Wheel bearing or brake.

 

[Mobius]

Wheel bearing or brake.

Strong possibilities.

Have you ever had the wheels off? If not torqued properly, lugs will loosen with time and lead to your symptoms.

 

[jagamajajaran]

Very remote reach Jeremy but I had a similar situation on my 1975 Rolls Corniche that took 6 months to figure out. It turned out that one of the front wheel pistons was slightly seizing because of a constriction caused in one of the brake lines caused by heat. Braking and then stopping forced the piston to retract eliminating the noise.

Very interesting...thanks for the reply.

Wheel bearing or brake.

I'm going to find a jack so I can check the bearings.

 

[jagamajajaran]

Strong possibilities.

Have you ever had the wheels off? If not torqued properly, lugs will loosen with time and lead to your symptoms.

Yes...and guess what!? Two loose lug nuts on the front driver side wheel. Going to go find a lug wrench now... Thanks!

 

[jsvette]

Yes...and guess what!? Two loose lug nuts on the front driver side wheel. Going to go find a lug wrench now... Thanks!

Wow, impressive. Sometimes the most basic and obvious is the last place we check. Hope that it.

 

[jagamajajaran]

Wow, impressive. Sometimes the most basic and obvious is the last place we check. Hope that it.

All are tightened up now...feeling stupid that I didn't think of this at first. Duh!

Thanks for the input, everyone!

 

[rdslon01]

Jeremy, loose lug nuts on the driver's side is vandalism, unless you:
a) never had them fully seated in the first place, or
b) drive in reverse, or
c) maybe possibly it might theoretically be able to happen if you repeatedly take many short trips where you accelerate VERY slowly, and HAMMER the brakes, over and over and over and over and over..........

Why do we know this for sure?

With threads on lug nuts which tighten with clockwise motion, when wheels accelerate counterclockwise (driver's side when rolling forward), the inertia of the lugs cause the lugs to get relative clockwise torque applied. That acceleration is due to either a change in RPMs when the car speeds up, or a change in direction (which is constantly happening when the wheel spins). As for the change in direction, the wheel under the lug nut has to travel slightly faster at the outside of the lug nut than the inner side, and this also contributes to a further slight relative clockwise torque on the driver's side lugs as the wheel spins counterclockwise (forward motion for the car on the driver's side).

On the passenger's side, for forward motion of the car, the wheels spin clockwise instead of counterclockwise, yet the lug nuts are still threaded the same way, so everything is backwards there from a torquing perspective. Lug nuts on the passenger's side experience a little bit of relative counterclockwise torque (want to get looser) as you drive.

Now, of course, this torque applied to the lug nuts is very, very slight in either direction. If you never get your wheels firmly seated (both the wheel firmly seated on the car, and the lug nuts firmly seated on the wheel) after the wheel is put on the car, then the ever so slight wobbling of the wheel will overcome the slight torque from the direction of wheel spin, and the lugs can become more loose as you drive regardless of which side they are on. But that is something you should notice at least in the first few hundred miles or so of having a wheel put on, and I assume yours have been on the car much longer than that. Actually, it is always a good idea after putting a wheel on to drive it a few miles, re-torque, then go about your normal routine and drive normally, but after 50 miles or so do a re-torque yet again. At that point the driver's side should definitely be good to go, but the passenger's side, um... well... It doesn't hurt to check that every now and then, even though if the passenger's side is firmly put on and torqued down properly, the slight counterclockwise torque applied to the lug nuts as the wheel accelerates forward should not be able to overcome the friction of the lug nut to the wheel which will counteract the slight loosening torque the lug nut on the passenger's side experiences as you drive. But it never hurts to check the passenger's side periodically regardless of how long the wheel has been on the car.

This is physics guys; this is truth. There is no reason to start saying, "Well, I have driven for 5,000,000 miles and never had a problem..." Good for you. You always had them torqued down really well and the friction held it on for you, even though the passenger's side had a little loosening torque constantly applied while being driven forward while not decelerating. But the loosening torque was there on the passenger's side, and the tightening torque was there on the driver's side nonetheless.

Jeremy, I am glad you have found and fixed the problem!

 

[jagamajajaran]

Very helpful information. I changed the wheels prior to the trip but torqued the lug nuts to 100 ft/lbs. The only thing I did not do was check them after 50 miles of driving, which I know I should have done. But I am 99.99% sure they were all properly seated. I'll keep a closer eye on them now, though.

 

[rdslon01]

Oh, you had the wheels off recently. That explains it then.

Even if all the lug nuts are initially seated at 100 ft*lbs, the wheel itself may not have been completely properly centered and seated on its backside. Drive it a while, and it can work its way loose.

Take care, enjoy your time in the Bluegrass Commonwealth, and be safe.

 

[mjw930]

When they painted your wheels did they mask off the tapered area where the lugnuts seat?

Now we know why they say re-torque after 50 miles . Glad that's all it was, now I'm off to re-torque mine......

 

[Z51Stingray]

When I brought my car home, a little voice told me to check the lugnuts. Mine came from the factory torqued at only 80 ft/lbs.

I retorqued them to the proper 100 ft/lbs.

 

[jagamajajaran]

When they painted your wheels did they mask off the tapered area where the lugnuts seat?

Now we know why they say re-torque after 50 miles . Glad that's all it was, now I'm off to re-torque mine......

Yes...they did. I retorqued all lug nuts last night.

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