help builders and mechanics...do halfshafts require balancing??

[Whaler]

I am having my halfshafts made ( i think) by my builder, or he has them custom made and has yet to deliver. Anyway I informed him that before I recieve them I wanted to know if they were to be balanced or not.
Telling him that I had my driveshaft balanced by the shop that made it for me,why stop there. The half shafts in effect being 2 more driveshafts in the drivetrain.

He writes me back, telling me its a scam for shops to make money and that driveshafts under 4 feet usually do not require balancing.

I want a second opinion here and don't want to piss him off.

I had the car delivered without halfshafts in it 4 months ago because they were screwing around trying to get these things made. He says it's a custom order for a few cars he made ( mine included) and they are coming from a supplier in the states. So I am not the only customer with an IRS rearend waiting on these shafts form him

Balancing my driveshaft, which I have now installed in the car, cost an additional 40 bucks and I can see where the weights have been tacked on. ( this shaft has a tube length being 13 inches long)

I need input....thanks

Tim

[ERA535]

They do not require balancing.

[Jack21]

If you balance them beforehand, and they don't vibrate afterward, you'll think you wasted money. If you don't balance them, and they do vibrate afterward, you gotta take them back out and balance them.

[Whaler]

"If you balance them beforehand, and they don't vibrate afterward, you'll think you wasted money. If you don't balance them, and they do vibrate afterward, you gotta take them back out and balance them."


You mean

If I don't balance them and they don't vibrate I have saved myself 40 bucks per halfshaft.

I have one answer that says its not required

I have also read that late 60's Corvette half shafts are not balanced at the factory either.

How many auto driveshafts come balanced? It hink the motorsport Mustang driveshaft may now come balanced.

Anyhow thanks for the input guys...anyone else want to throw in a word or two...builders??

I guess my builder is correct.

Tim

[427sharpe]

No balancing required. They will not 'vibrate' like a driveshaft unless they are bent, which a rebuilder will see during assembly.

[Tom Wells]

Whaler,

Remember, the driveshaft turns three to four times as many RPM than the halfshafts do. so the driveshaft may need to be balanced where the halfshafts do not. And in a normal car, the driveshaft is much longer (Cobras excepted, of course ), meaning it needs to be checked for straightness too.

Tom

[Whaler]

Cool
thanks for the answers guys. I phoned the driveshaft shop that made my driveshaft( now that they are open) and they too said they have yet to do any halfshafts for the cobras that they had done driveshafts for.
They have seen and done some corvette halfshafts
He also corrected me on my earlier comment about factory driveshafts generally not being balanced. They are.
He told me to go with it and if I do have problems then look at balance.

Everything I hear is leaning towards it being unnecessary.

I appreciate the help

Tim

[boxhead]

You will need to balance the half shafts if they are a tube style shaft , ie same as tailsaft.
If your half shafts are a solid rod with cv joints ,as in most front wheel drive cars , then you will not need to balance.
I have seen jaguar half shaft that was out of balance because a weight had fallen off.

[niles]

My kit uses shortened(4 in) Alum. 4 in dia tubular shafts from a late model corvette; they were built in Pensacola and were balanced; just like the std Vet shafts are.
gn

[Whaler]

I have an e-mail into the builder
I don't know if mine are solid or tube style....that I will find out

Thanks
Tim

[boxhead]

what is the diameter of your shafts?
if there 1.1/2 inch or less then they will be solid , any larger and they will be tube type.
Generally tube shafts are 4 inches or more.

[niles]

Whaler:
Lot of opinions here.
Lets review some of the engineering going on:
just because they are turning less RPM than a drive shaft; has little do do with vibration; vibrations are noticeable when the imbalance is near the natural or resonant frequency of the system. There will be several different nat. frequencies; usually at mathmatical multiples of one another. Frequently a car has wheel vibs at around 55 mph; slow speed and tire rpm; just a natural freq. on a 15 in tire.
yes, cobras have small, low mass shafts; but a 3 gram imbalance is a much larger percentage imbalance than a 3 gram imbalance of a 30 lb drive shaft.
See the attached: http://www.dennysdriveshaft.com/html..._kit_car.html.
Granted shafts should not have much imbalance; IF! the ends are welded on concentric; but have and end welded on .015 in off center and it will vibrate.
Dennydriveshaft is a High quality cobra shaft maker; and he balances everything!
Don't spend $thousands on a custom high end Cobra and then skimp on essentials like balancing. Bad economics on several fronts; a shaking half shaft can manifest itself in transmission shake or some other symptom; after speeding many hrs and dollars eliminating that only to find the vib. is originating some where else. Old race car proverb; leave nothing unaddressed and nothing to chance; chance will screw you everytime; Chance is Murphy's bad cousin.

gn

[Whaler]

Niles
I am the one insisting on the balance now. I have the car less the halfshafts. I e-mailed my builder and basically said, " hey before you send my half shafts are we going to get them balanced?"
The reply was that they didn't require balanceing, that anything ( with exception ) under 4 feet doesn't require balancing and that no was the answer, bottomline.
So as usual I would think his word as builder was that from God, but now I am getting wiser, I see that it would cost him 40 bucks per side.

I want it done if it needs it, before I get them and put them in

I paid my builder 6000 CDN for the upgrade to IRS, when I had the car built, we better not be fighting over an 80 dollar balance job now...I am still waiting for the shafts???? Why? Well because He went thru a retrofit on the shafts with some supplier out of the states after he saw something he didn't like on a car of his with the motorsport 460 or the bigger engine when its was dragging with slicks.

So here I wait.

Now you know it isn't me cutting corners niles.....thanks.

As I also said earlier, I don't know if we are talking soild or tube axles,,,I have that e-mail in as well.

Tim

[Mike Braddock]

I agree with Niles. I would have them balanced for peace of mind. If you end up with any vibrations when the car is finished and you don't have them balanced, this will nag you to no end until you finally take them back off and have them sent out for balancing. At that point (in time and money) the cost will be more than $80 . Plus, if they don't require balancing, the shop should tell you so and the cost won't be the full $40 per shaft since they don't have to weld on any weights and recheck the balance.

[Whaler]

Hi guys , my builder e-mailed me to tell me I am getting solid crome-moly centershafts with CV-type joints. He again says they don't need balancing.

I will see when we get them and probably have them checked

Tim

[boxhead]

I have never seen a solid shaft with cv joints that needed to be balanced.
As long as it is straight it should be ok.

[Whaler]

lol SO MY BUILDER TELLS ME....

Tim