The best answer depends on how and why the flywheel became out of balance. Most shops will not allow you to supply your own parts, and this is exactly the reason why. When they order and pay for the parts, they make a small profit on them, just like at any other store, and in return they assume the responsibility if a part is defective or wrong. If they damage it, they are responsible for obtaining a replacement at their cost. This is exactly the same as going to a restaurant. If you bring your own food and ask them to cook it, then you don't like something, they did what you asked and are not obligated to take on the responsibility for the quality of the food.
In this case the mechanic provided the service you requested, and you paid for that service. There's no denying a problem developed, but since they didn't sell you a flywheel and make a profit on it, they aren't obligated to warranty its condition. Now that the job needs to be done again, they can't charge you for anything that was related to a mistake they made. It sounds like they didn't make a mistake, so when you requested them to do the second service, just like ordering a second meal at the restaurant, you are obligated to pay for what you asked for.
Now, there are some qualifiers that need to be considered. There are times when a shop will actually ask you to provide parts, but that is not common. Typically it's when a rare or hard-to-find item is needed. Someone at the shop has to do the research and put in the time to locate those parts and get them picked up. That takes a lot of resources that they have to charge someone for. Then, if that rare part is not of suitable quality, who pays for the time it takes to find another one? This is where they may leave that up to you to save you some money.
The next consideration is what happened to the flywheel? I have a friend with a body shop who specializes in rebuilding smashed one and two-year-old Dodge trucks. I've helped him on a few and I know the flywheels on the diesels are really massive and heavy. The only thing I can think of, if you have the old one to look at, is if there was a balancing weight that got knocked off when it was being machined. If it can be shown where a weight was on it before, you would be justified in not paying for the second service. The issue would be between the shop and the machine shop that resurfaced the flywheel. Evidence of a missing weight would be a large spot weld that has nothing attached to it, or a space that's missing paint where the weight used to be.
It's common to find a lot of hairline cracks on the flywheel's friction surface. Those are harmless, but you don't want to see chunks broken out and missing. When there are hot spots, that area is real hard and the cutting bit will skip over them. Some people will try to grind those areas down so they don't cause a chatter as the clutch is engaging. That shouldn't be noticeable as far as a vibration because the amount of metal removed is so small.
The shop has to take your word that there was no vibration before they worked on the truck. The fact they accepted less than they asked for suggests they believed you, and while they don't believe they did anything wrong, they are acknowledging a second service shouldn't have been needed. The shop owner has to pay his mechanic for the second service. The mechanic is usually obligated to fix his mistakes at no cost to you or the shop owner, but I can't imagine what mistake he could have made.
By the way, even with no transfer case to remove, removing the transmission is a big job. I would have expected them to charge you considerably more for the first service. If the job was done in a reasonable amount of time and they kept your truck clean, it sounds like you were dealing with some reputable people.
Wednesday, September 23rd, 2015 AT 8:35 PM