My 2003 Honda Element sometimes generates a vibration that feels just like driving down a washboard dirt road. You know one that the ridges are very close together. This only happens around 40 MPH with a load on the engine. At first I thought it was a wheel, tire or suspension issue. But I can make it stop instantly by pushing or releasing the gas pedal. So this leads me to think it is transmission related. This is a automatic.
I would like to see the car sometime but would not feel right about passing on this problem without knowing the cost to fix it.
I presume you have a bad tie rod end that is causing the vibrations.
It is sloppy and hitting just the right bump in the road gets it moving a few degrees left then back right…over and over, until you step on the gas and the increase in power gets it back rolling along with the other wheel.
I’d set it looked at soon, because if the tei rod end gives out, you could lose control.
If you mean “under load - vibrate, not under lead - no vibrate,” it’s likely a front drive-shaft (axle) inner CV joint. This would mean an axle replacement (or two).
My first guess would be an engine operating problem. When was the last tuneup?
My second guess would be an inner CV joint.
Both can be checked by any competent shop.
I’ve also seen a tire act like this. Fortunately, that too can be checked by any shop that has a road-force balancing machine.
But Yosemite is right… you should get this looked at. It could be something dangerous, and it never hurts to err on the side of safety.
Aged fluid can certainly cause a torque converter shudder that is similar to the rumble strip effect due to those wake up grooves cut on the sides of the highway. Right around 40 to 50 MPH is usually where this problem manifests itself.
I agree with ok4450 that this problem is much more likely to be a case of torque converter shudder than a front-end problem or a tire problem. The speed and the circumstances mentioned by the OP make that a very strong probability.
My advice is to have the trans fluid & filter changed (by an independent trans shop), using ONLY genuine Honda fluid. Even if the OP has to go to the Honda dealership to buy the fluid and bring it to the trans shop, this is a very important thing to do.