Driveshaft vibration

67camaroracer · 09-30-2009, 02:01 PM

66 Chevelle 396ci 500 horse 7000 rpm max with a turbo 400 tranny. 12 bolt chevy rear
58" long 3.5 inch aluminum driveshaft that has been balanced a few times. Still have a vibration and have been told that we need to run a carbon fiber shaft because of length and the critical speed. Does anybody have a better idea that may work for our street and strip application without spending $1300.
Thanks in advance for any and all info.
David

Tom Goldman · 09-30-2009, 02:44 PM

I had a similar problem on a car I built with a 3 1/2" 57" shaft. ......I was advised that it was right at the critical legnth for that diameter@ 7000 rpm........The less expensive solution ,if you have the room ,is to go to a 4" diameter shaft. ....I believe the critical speed on a 4" 57" shaft is closer to 7600rpm .....I did find I could tune the vibration out to a slightly different rpm by altering the pinion angle,altho that is only a crutch for the real problem. .........Not saying other shafts are'nt as good,but I've had better luck with Mark Williams shafts ,than other brands..........try this link for more info http://www.markwilliams.com/driveshafttech.aspx .........Tom

gmonde · 09-30-2009, 07:41 PM

try a hose clamp with a small 3/8 washer around the drive shaft and run it up on jack stands and keep rotating the clamp and weight until it smooths out ,,,now in most cases by bringing it up to 2500-3000 rpm free wheeling in high gear,the vibration will be evident (no need to bring it up to any higher than that) it worked in several applications ,,,,i have a 53" drive shaft and have gone thru a few companys and ony one got it right the first time gmonde

Rick Kagawa · 10-01-2009, 06:20 PM

The closest guess I can post is that you have too small a drive shaft. I drive a 1970 Chevelle with a L78 in stock. I clear the traps at about 7700. I originally had Strange Engineering build me a drive shaft. I always had a vibration at the top end. I could never figure out what it was. I broke a pinion in the burn out and it turned the drive shaft into a pretzel.

I started to look for another drive shaft I looked into Mark Williams drive shaft. I was never really happy with the Strange drive shaft. They sent it to me and it wasn't the length that I had ordered. I had it shortened and the shop had to also rebalance it because it was out of balance from the factory. It was a 3 1/2" in diameter.

When I called Mark Williams they said that the old one was too small. It causing whipping of the drive shaft and stresses the U joints. I got a 4" diameter one. When I ran it for the first time the vibration had disappeared. The diameter of the drive shaft is determined by the length and the RPM at which it will be run.

I hope this helps.

Rick Kagawa

09-30-2009, 02:01 PM	#1
67camaroracer Junior Member Join Date: Oct 2007 Location: Ct Posts: 32 Likes: 0 Liked 0 Times in 0 Posts	Driveshaft vibration 66 Chevelle 396ci 500 horse 7000 rpm max with a turbo 400 tranny. 12 bolt chevy rear 58" long 3.5 inch aluminum driveshaft that has been balanced a few times. Still have a vibration and have been told that we need to run a carbon fiber shaft because of length and the critical speed. Does anybody have a better idea that may work for our street and strip application without spending $1300. Thanks in advance for any and all info. David

09-30-2009, 02:44 PM	#2
Tom Goldman VIP Member Join Date: Jan 2003 Location: Allentown,PA Posts: 2,437 Likes: 778 Liked 702 Times in 205 Posts	Re: Driveshaft vibration I had a similar problem on a car I built with a 3 1/2" 57" shaft. ......I was advised that it was right at the critical legnth for that diameter@ 7000 rpm........The less expensive solution ,if you have the room ,is to go to a 4" diameter shaft. ....I believe the critical speed on a 4" 57" shaft is closer to 7600rpm .....I did find I could tune the vibration out to a slightly different rpm by altering the pinion angle,altho that is only a crutch for the real problem. .........Not saying other shafts are'nt as good,but I've had better luck with Mark Williams shafts ,than other brands..........try this link for more info http://www.markwilliams.com/driveshafttech.aspx .........Tom __________________ Tom Goldman 1500 SG , 1506 STK Last edited by Tom Goldman; 09-30-2009 at 02:47 PM.

09-30-2009, 07:41 PM	#3
gmonde Senior Member Join Date: Nov 2007 Posts: 615 Likes: 56 Liked 166 Times in 59 Posts	Re: Driveshaft vibration try a hose clamp with a small 3/8 washer around the drive shaft and run it up on jack stands and keep rotating the clamp and weight until it smooths out ,,,now in most cases by bringing it up to 2500-3000 rpm free wheeling in high gear,the vibration will be evident (no need to bring it up to any higher than that) it worked in several applications ,,,,i have a 53" drive shaft and have gone thru a few companys and ony one got it right the first time gmonde

10-01-2009, 06:20 PM	#4
Rick Kagawa Junior Member Join Date: Apr 2008 Posts: 31 Likes: 1 Liked 3 Times in 1 Post	Re: Driveshaft vibration The closest guess I can post is that you have too small a drive shaft. I drive a 1970 Chevelle with a L78 in stock. I clear the traps at about 7700. I originally had Strange Engineering build me a drive shaft. I always had a vibration at the top end. I could never figure out what it was. I broke a pinion in the burn out and it turned the drive shaft into a pretzel. I started to look for another drive shaft I looked into Mark Williams drive shaft. I was never really happy with the Strange drive shaft. They sent it to me and it wasn't the length that I had ordered. I had it shortened and the shop had to also rebalance it because it was out of balance from the factory. It was a 3 1/2" in diameter. When I called Mark Williams they said that the old one was too small. It causing whipping of the drive shaft and stresses the U joints. I got a 4" diameter one. When I ran it for the first time the vibration had disappeared. The diameter of the drive shaft is determined by the length and the RPM at which it will be run. I hope this helps. Rick Kagawa