Vibration issue Car vibrates when moving, it has been balanced and aligned but problem persists. Am told it could be the propshaft. What could it be and what needs fixing.

You haven't said what make and model of car it is.

On a rear wheel drive car a worn universal joint in the driveshaft (propshaft) can cause the symptoms you describe. It's sometimes referred to as a 'yoke'.

Wear causes the universal joint/propshaft to be out of line/balance and causes the vibration when the car is moving. Another symptom is a 'clunk' when the car engages gear. That clunk noise is also caused by wear.

You can check it quite easily. get underneath the car, grip the propshaft and try and turn it clockwise/anti clockwise. If there's any movement - it's worn.

The link below is of generic images

propshaft universal joint Google Search

If it is a rear wheel drive, check the propshaft bolts and u joints

Because one or both of the front wheels are out of balance.
1. You need to have the front wheel/tire package rebalanced by a competent balancer. Go to a good tire retailer. They have the equipment to do the re-balancing for you. Don't go to the cheapest shop you can find and hope they will do a great balance job for you.
2. If you still have the vibration after re-balancing (assuming it is done well) you will either have a faulty tire or tires (out of round or a heavy spot in the tire) or there is a problem with one or both of the wheels. If either of the front wheels have been slightly bent out of shape from abuse you will get a vibration in the front end of the car and in that event the wheel needs to be replaced. If you have a cheap brand of tires fitted to the car and the re-balancing does not solve the vibration problem I would suspect the tires first. Cheap tires will typically give you problems like this if you buy them but better brands can have tire faults also.

3. Do not let someone tell you that a front wheel alignment will solve a balance problem with the wheels/tires. It will not because the vibration is caused by the rotating wheel and tire. By all means have a wheel alignment done again - because you need to do this on the car about every 10-12000 miles in any event - but doing this will not solve a balance issue.

4. If you want to run a test before doing any work have the rear wheels on both sides moved to the front of the car and the fronts to the rear. Then check if you still have exactly the same vibration. If not then you know where the problem is. If you still get exactly the same vibration or a similar front vibration with the rear wheels fitted on the front, then the balance on the rear wheels/tires will need to be checked and re-done as well.

Having an alignment done usually only corrects the car pulling to one side. Check the rear tires for balance and wear. You may also want to have them rotated to the front to see if the vibration also moves to the front.

Check transmission fluid in g/box is not burnt Re: Jeff

If it is fitted with propshaft you can check the balancing. Some vehicles are fitted with 2 propshafts that is linked in the center with a center carrier bearing. Check if it is tight and not worn and aligned.

Hm. I had an irritating vibration at highway speed with tires that came with my car. I had the balance checked and it was determined that there was an out of round tire. I replaced the tires, had them spin balanced, and the rims were perfect. After that, the vibration at highway speed went away.

Tires are the most common problem for vibration at various speeds.

Where did you buy your tires or have them spin balanced?

get tires spin balanced on a force variation tire/wheel balancer. Hard to find a shop with one but worth it. It can chek for excessive force variations in tire that other machines can't. It's a Hunter 9700 machine in the USA.

alignment issues , bad tire, or a balance issue

have the steering rack checked for excess play, also have all the front end bushing checked, this is a common cause of this type of problem, it is the front end that is doing it, finding the worn part(s) is the job that needs to be done to correct this.