1996 Accord Bad Vibration at Wheel Speed

My 96 Accord 5-Speed Manual has recently started an intermitant bad vibration while at highway speeds. It feels mechanical, and seems to starts after driving for a few miles, and feels like bad tire imbalance. The only problem is that you can make the vibration go away entirely by depressing the clutch. Also, the vibration frequency does not change when you shift gears, so it can’t be related to the motor, clutch, or gearbox.

The mechanic says he can’t find anything wrong with the bearings or CV joints.

What do you think?

I fail to see how you can conclude that the problem can’t be related to the motor, clutch, or gearbox if it goes away when you put the clutch in.

The first thing I would do would be to inspect your motor/transmission mounts and give the suspension a good once over… Eliminate the easy things first…

Why not try rotating the tires and seeing if it changes?

They balanced all the tires, even found a slightly bent tire, but all that did was lessen a constant vidration that was already there.

As far as concluding the problem isn’t in the motor or gearbox, I came to that conclusion because the frequency of the vibration remains constant and does not change while I shift gears. The vibration seems to follow along with the speed of the wheel. I’m not a mechanic.

Say it is a motor mount, how much do you expect to spend there?

I should emphasize that the vibration seems to remain at a frequency equal to wheel speed, and does not change when I shift gears. I also meant to write, “bent wheel”, not, “bent tire”

Were all 4 tires replaced at the same time? Years ago, I put 2 new tires on my wife’s 86 Colt and it had a violent shake over 40 mph. Even though the new tires were supposedly the same size (different brand than the originals though) as the old ones, the difference in diameter was enough to cause the vibration. Four new tires solved the problem.

Ed B.

All 4 tires replaced 2 months ago. This symptom first appeared 3 weeks ago and has progressively worsened. The symptom is intermitant, goes away when I depress the clutch, goes away when I let off the gas entirely but worsens when I only slightly let off the gas, physically feels like tire imbalance but sounds more mechanical, and is related to wheel speed and not motor rpm.

There is such a thing as a bad tire even when new. You can try rotating the tires front to back and see if that changes the problem. If it does, it is likely a tire. I’d go back to the tire store and have them rotate them.

or get out your spare and swap it in one at a time.

As a first step in the diagnosis, I’d suggest having the wheels “road force balanced”. That spins the wheels on the machine while they’re being pressed against a spinning drum, simulating the conditions they’re under while actually on the vehicle. That can detect internal tire defects that a regular spin balance cannot.

That test is definitive enough to either find the problem (if it is in the wheels or tires) or clearly eliminate the wheels and tires as a possibility.