Q: Vehicle runs rough and has a knocking sounds. Could it be the transmission?

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Runs rough after 45mph, makes a clicking sound kinda like knock when slowing down and it also vibrates. What can it be?

My car has 135000 miles.
My car has an automatic transmission.

Hi and thanks for contacting Your Mechanic. Check your drive train in the front, you could have a wheel bearing going out. The reason it stops making noise when you accelerate is because torque is applied on the bearing and forcing it to tighten up. You can check the bearing out by jacking up the vehicle and taking a large pry bar and lifting up on the wheels. If the wheel moves but not the suspension, then the bearings are worn out and need replaced. If nothing is wrong with the wheel bearings, suspension, or steering components, then the transmission could have an issue with the thrust bearing inside it. There may be too much clearance on the thrust bearing causing the final drive to move while descending. The only fix to this is repair or replace the transmission. If you need further assistance with your vehicle, then seek out a professional, such as one from Your Mechanic, to help you with the ticking noise and vibrations while descending from road speeds.

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