Driveshaft Balance

[8secDuster]

I noticed this while doing my original (Coupe) inventory, that the driveshaft did not show any indication of being balanced. (Added or removed weight)
I know sometimes some driveshaft will take very little, or no weight at all.
I would also assume the shaft manufacture would check balance before shipping.
Now that my transmission is on order, and closer to installing it, I thought I would ask the question...

Has anyone had a vibration issue and had to have their DS balanced? Or had it balanced proactively? Or had it checked and it was fine?

Thanks

[RoadRacer]

Never noticed any vibration ¯\_(ツ)_/¯

[Rsnake]

Great thread as I have wondered about this as well. Since mine spins fast doing 160+ mph I am going to have it checked when I pull it to replace the rear seal on the trans which is leaking.
Give me a couple of weeks as the Nevada Open road challenge is this weekend.

[ggunter]

Not all drive shafts have balance weights. If it is a small amount of imbalance, they use a torch on the heavy spot, and it thins the metal to bring it in balance. I watched an old guy at the drive shaft shop who was heating a spot on the shaft with a torch and asked him why he was doing that, and he told me he was adjusting the balance and then showed me before and after on the balance meter. Didn't know they could do that.

[8secDuster]

Not all drive shafts have balance weights. If it is a small amount of imbalance, they use a torch on the heavy spot, and it thins the metal to bring it in balance. I watched an old guy at the drive shaft shop who was heating a spot on the shaft with a torch and asked him why he was doing that, and he told me he was adjusting the balance and then showed me before and after on the balance meter. Didn't know they could do that.

That is pretty cool.

But, for peace of mind, I decided to drop it off at our local DS shop, CCI Driveline & Fabrication and have it checked.
Turns out it needed 67 Grams of weight added. 50 on one side, 17 on the other.
Now, I don't know if you will feel a little over 2 oz's, seems like a lot, but I feel better about dropping it off and having them spin it.
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213771

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[Presdough]

I don't think theyre long enough to cause a vibration as that is usually caused by the tube "jump roping". I've had mine to 133 on the drag strip and upwards of 150 at an undisclosed location with no vibration...

[8secDuster]

I don't think theyre long enough to cause a vibration as that is usually caused by the tube "jump roping". I've had mine to 133 on the drag strip and upwards of 150 at an undisclosed location with no vibration...

That's probably very true, and why they are not balanced when received.
However, where it is located in relationship to my gluteus maximus, it was $50 well spent IMO.

[AC Bill]

Mine was built at a pro driveshaft shop, so I hope like heck they checked it's balance.
Certainly couldn't hurt to have it done..

[PNWTim]

That's probably very true, and why they are not balanced when received.
However, where it is located in relationship to my gluteus maximus, it was $50 well spent IMO.

Anything to smooth the driveline is a good idea and 2 oz is quite a bit. $50 is cheap.

[ggunter]

2 oz. is a lot on a short shaft like these. I can almost guarantee there was a bit of buzz going on in the seat of your pants. Having dealt with driveline vibrations for years in heavy trucks, I learned a ton of info from the engineers at Mack Trucks on driveline vibrations and harmonics. Here are a couple of interesting links to driveline non uniform velocity. part one and two. https://www.youtube.com/watch?v=BaeUR0lt7JM https://www.youtube.com/watch?v=p8Nf92heksA Also there are things like first order, second order, and third order vibrations from different parts of the drivetrain which can carry through to different areas and cause vibration.

[ggunter]

Here is a link to you tube that explains 1st, 2nd and 3rd order vibration. https://www.youtube.com/watch?v=GKXzG2g3nCo&t=334s

[8secDuster]

[QUOTE=ggunter;581333]2 oz. is a lot on a short shaft like these. I can almost guarantee there was a bit of buzz going on in the seat of your pants. Having dealt with driveline vibrations for years in heavy trucks, I learned a ton of info from the engineers at Mack Trucks on driveline vibrations and harmonics. Here are a couple of interesting links to driveline non uniform velocity. part one and two. https://www.youtube.com/watch?v=BaeUR0lt7JM https://www.youtube.com/watch?v=p8Nf92heksA Also there are things like first order, second order, and third order vibrations from different parts of the drivetrain which can carry through to different areas and cause vibration.[/QUOTE

I haven't driven the car yet, so not sure if there was a vibration. The 68 Barracuda 340 I restored was 100% original and un-molested. That driveshaft was un-balanced and it drove fine.
With this car having a couple hundred horsepower more than that car, and the driveshaft being a foot away from me, I was just trying to be proactive before it was installed.
However, to your earlier point, when I removed the old black paint, to repaint it, I did notice what appeared to be a "Hot Spot" on one end of the tube. So maybe there was some sort of quick, old school balance that took place?
Interesting videos, thanks.

[Rsnake]

So I went and did it. After seeing the 2oz of weight on 8secDuster's driveshaft I dropped mine off of a local driveshaft shop.
I also decided to install two new u joints as the ones in the shaft were unmarked and not sure of brand so went with high end units for peace of mind.
I did feel vibration over 160mph and I calculated the shaft is spinning near 8000 rpm give or take. When I picked it up the owner said at 2400 rpm's his
high speed balance machine was shaking and wondered who built this POS driveshaft. He put two weights on it and spun it to 8000 rpm and all good now.
I think all the type 65's who do the Silver State will be getting driveshafts checked. Here are photos of the new weights.
214446214447

[bishes]

What ujoints did you use?

[Rsnake]

Spicer 1330SPL non greasable

[bishes]

Thanks, I'll look at those and consider replacing mine.

[8secDuster]

Wow!
Good deal RSnake.
Glad it's right now.

[Rsnake]

Took the car out on the highway and the gear shifter has no vibration now. Always had something at highway speed and now it has no vibration.

[8secDuster]

Nice
I should have put some Spicer's in mine while it was there....

[Skuzzy]

Well dang it. Now I have to find a driveshaft balance shop. Another to-do item. I am losing the race!