Stock driveshaft question?

[96gt4.6]

Hey guys, I know i'm going to get flamed for asking or even CONSIDERING this.....but I thought maybe someone has attempted this before me.

My '79 Malibu has a rather small driveshaft (in my opinion) for the power i'm making. I've yet to take the car to the dragstrip, but will be doing so in a couple of weeks. I do plan on replacing the shaft, just not in the next two weeks and with only 2 races left this year, I really want to get some passes on the new combo before the year closes out for good.

My stock driveshaft appears to be slightly larger than 2 1/4" at best. It's rather tiny.

Anyone have some experience as to just how far HP or maybe 60' wise you can push the stocker?

My combo is a turbocharged GEN 4 6.0L LS motor on 9psi (currently). Estimated 550+ RWHP.

https://www.youtube.com/watch?v=RcJWwyoceDY&list=UUr7LaomBm-XfDG53sCh6tcw

I'm just not sure how it will do on a sticky track with drag radials launching on boost....

 

[lilbowtie]

Do some reading on Drive Shaft Critical RPM. It will give you the info you need when buying a new shaft. PST (precision shaft technologies) has a chart on their site. Also make sure your rear bushings (if you run then) are tight. I personally wouldn't run that shaft.

 

[96gt4.6]

Thank you. I most certainly plan on getting rid of it for an aftermarket piece very soon. I might just take it easy on the launch and see how it goes. I've had the car under many hard throttle top end pulls for tuning purposes.....although I cringe each time!

 

[lilbowtie]

The shaft will take the power. Critical Speed is the RPM at which the driveshaft is computer projected to bend or whip. Exceeding Critical Speed can produce vibrations that can result in driveshaft failure. I wish the guy that built mine would have known more. I lost 2 shafts one in the burn-out box and another after letting off in the traps. This may change your mind -

 

[96gt4.6]

^ Wow....that is bad! Ya......think twice is an understatement!

 

[96gt4.6]

What kind of trap/ET/60' was this car running at the time?

 

[lilbowtie]

The first time I got away kinda lucky - It broke on the top end, the front piece w/ the help of the driveshaft loop slipped out and exited, the rear broke the universal and did the same w/ some damage to the tunnel. The second time (couple year old 3" shaft) was in the water box just about to let go of the brake when hell broke loose - pieces were flying everywhere thank God no one was hurt. Besides the obvious damage the headers were trashed, flex plate bent, and the rear broke 2 teeth. Drive shaft loop did it's thing but there was pieces in the back seat. 11.20's car, 1.48 60's 117 in the traps