I'm working on narrowing down a vibration. I usually feel it at about 60 mph. It's subtle, rhythmic, cycles every two seconds. No sounds or clunks or anything. Not in the steering wheel, I feel it in the seat.

I think it's wheel/tire related, but while thinking this through, I started to wonder about the torque tube, and think I have eliminated that.

At speed when the vibration occurs, I push in the clutch, and put the transmission in neutral. This should spin down the torque tube, right?

Clutch is between engine and torque tube, neutral is between torque tube and rear diff. Do I have an accurate understanding in how things are attached to other things?

 

60 MPH vibration is almost always wheel balance (or bent wheel).

 

Thanks, that's what I'm hoping.

 

^^^^^this ^^^^^^^^
Feels just like Shudder, had the same vibration just after installing new tires even though I asked and paid for for road forced balanced . Brought it right back to Discount , took them two more times to get it right . The right rear tire was at the top of the spec, and the other 3 were at the lower end of the spec . When getting done ask for a BULLSEYE balance , right on spec . Also don't discount a bent wheel as that will also cause this harmonic vibration

Dave

 

Found it! Bent rims.

Cheaper to fix than new tires, so i'm not complaining too much.

 

Glad u found it ....

Dave

 

This is a VERY good point. I have been retired since 2012 but used to work at a dealer w/ the latest Hunter Roadforce balancer. Generally the tech selects from initial settings something like, car, truck, big truck. That choice tells the machine how much out of balance is acceptable before it throws a flag up. Don't take these #s as real but a car might be allowed 3/4 ounce. The printout will show zero out of balance if it is out <3/4 oz. The 'acceptable' out of balance is larger for larger vehicles. Makes sense as a huge truck tire/wheel can be further out of balance before it is felt than a car. Bullseye mode shows out of balance down to zero rather than ignoring a small amount. It also prints that on the paper the owner is handed. It takes more time to get to a few grams. I usually added stickon weights less than the machine called for from the first balance. Then I could ad a little more and work my way toward zero. Not only could I add weight carefully, but that weight could be added to one side or the other of where the original weight was placed. I don't remember the details of the road force measuring but whether the machine does it or the tech makes the decision, there can certainly be some slight road force problem that would not be felt. I found very few tire problems causing an excess roadforce readout. It was much more often the result of a bent wheel.

 

Wow ... Thank you for the detailed explanation 👍
I never understood the how and why on the setup the machine

Dave

 

I mount and balance my own tires and use a balancer that is truly archaic compared to that Hunter machine. It is a Coats Micro Precison M-76 bubble balancer. I can get the wheel balanced down to within 7 grams and at this level of precision, there has never been any vibration. Even on wide Corvette tires /wheels, the fact that it cannot do dynamic balancing has also never resulted in any vibration. I use stick on weights and put them in the center of the barrel so I do not induce any dynamic imbalance. The point is that balancing wheels should not be rocket science. You just need the tech to pay attention and do a good job.

 

Assuming a wide-body with OEM wheels, your discovery is ALL TOO COMMON! But, easy to fix... fully forged, quality, aftermarket wheels.

 

I just had the same issue. Was getting vibration at 60+ mph. Took it to the dealer for a road force balance. Found out that I had three bent rims. They were trying to get me to buy replacement wheels from them (of course). I opted to purchase some after market wheels. Looking for something forged. I knew that it was coming eventually as I have heard the horror stories of these wheels and I did buy my Z06 used. Now I know to ask for a bullseye balance as well!!

I really appreciate this community and the vast amounts of knowledge I’m able to glean from so many folks.

 

Not wide-body, just plain ole base model wheels on MN's potholed roads.

This shop https://twincitywheel.com/ is relatively close to me ahd charge $85 a wheel unless it's REALLY bad. I've used them in the past and will likely have them repair these.