drive shaft balancing speed consequence

Hi all!
in a blown alcohol door car application,what is considered to be the minimum speed applied to the driveshaft for balancing?
i had one shortened some time ago by a truck company in France and they balanced it to 2000 rpm.
it worked fine for 5 passes then the tailshaft internals in the transmission began self destroying,me only noticing it through a "grinding" noise when towing back to the pits.
after inspection,was told that it could be the harmonics caused by the low balancing rpm that caused the failure(had no clue of that when had the driveshaft modified,but that definitely makes sens now)
also,for my current application(roughly 1400 hp in a 2400 lb car) what is the most commonly used material for a driveshaft?
forgot to mention:switching from 727 torqueflite(self destroyed) to bruno/3 speed lenco(lesson learned...)
thanks for input
cyril

 

I doubt the balancing speed had anything to do with it. You would have felt a vibration even in a race car. Faster balance speeds are "supposed" to help induce whip into a long driveshaft and hopefully account for it. Chances are the trans was already on the way out. You now have gone the correct route so it is no longer a concern.

 

How do you know the driveshaft shop actually did it correct? I'd be re-mounting the driveshaft and re-checking balance and run out. Probably not a concern, but what are your U-Joint angles like?

 

Hi all and thank you for input!
Mike,now i know where to shop for my next driveshaft!
I must admit that my chassis (ex pro mod from 1997) has seen various trans combinations with previous owners from clutch/lenco To lencodrive that i did not pat attention To the driveshaft angle,but To leave the trans yoke enough travel on the tailshaft.
I am currently putting the bellhousing/Bruno/lenco together so when the time comes to order the new driveshaft i will pay attention To that.
What is the maximum allowed angle with the car standing still?

 

Just curious. Is it worth the extra $$ to go from aluminum to carbon fiber?

 

Randy, depends who is doing the clutch . Carbon is nice but need to be real careful handling it, no dings or it will be expensive. If it's a converter car then its down to money I guess.

 

No one have mentioned the drive shaft length and the drive shaft critical speed.

I am not trying to promote Mark williams parts but they do have a good tech on this topic.

https://www.markwilliams.com/driveshaft-tech.html

 

Very interesting article!
thank you for sharing!