Was I ripped off/scammed by this shop?

[Osker]

Hey folks,

My friend and I have swapped a 350 TBI engine and tranny into an old ’71 GMC pickup truck. Because of this, we needed to get the driveshaft shortened 3.5 in in order to fit.

It is a single piece aluminum driveshaft, and we took it to a driveline shop to get it done. I said I wanted only two things done – shortened 3.5 in, and balanced. The next morning I got a call from them saying that the U-joints needed to be replaced. Now I know the U-joints are in good condition, and there is nothing wrong with the driveshaft apart from being too long. The joints were smooth, did not bind, were silent, and I’m quite certain they didn’t create any vibrations when the pickup was in use. I asked what was wrong with them and the guy put me on hold and said he would go ask. He told me that the ones I had on were crunchy (exact word he used), and that I would need to replace them with new ones for a good balance.

I didn’t buy the crunchy part because I knew they weren’t, but I’m no expert and didn’t know if it was true that U-joints generally needed to be replaced to achieve a good balance on a driveshaft. I had a bad feeling the whole time, but decided to do it in good faith – which I deeply regret now.

The shop is local and has great reviews online. However, it is also a fact that not all reviewers/customers are knowledgeable and would even know it if they there were ripped off.

Someone knowledgeable please tell me if U-joints on a driveshaft that are seemingly in excellent condition need to be replaced with new ones for a good balance, so I can at least be wiser of one more thing in the future If I need to do this again. I don’t know how the actual balancing job is done apart from the driveshaft being put onto a machine, and spun through an RPM range to check for vibrations.

Hindsight is 20/20. I should have just said no and told them to balance with the current U-joints. There’s nothing I can tell the shop now, the job is probably already done. I just hope the sticker shock won’t be too bad. 🙁

Topic

[Erin]

Probably NOT scammed.
If the driveshaft had to be shortened by 3.5 inches, it will be working at a greater angle than before shortening. The old U-joints may not have been good for this under daily use. U-joints and inboard CV joints (on half shafts) are good for only so much of an angle before causing binding, which I guess is what he meant by “crunchy”.

I could be wrong about all this but one thing is for sure – when doing any kind of serious mod to a vehicle, several other things surrounding it also need to be modded to accommodate.

I think if you have enough knowledge to do major engine work, you will probably understand when he explains why the old ones were bad.

[Author]

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