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Jim Caughlin · 05-09-2018, 11:07 AM

I have a 3" alum driveshaft that was built by Inland Empire, I cross the finishline at 9400 RPM and have relatively low HP. Interestingly, I was able to test duplicate steel (13#) and the alum one (10#) on back to back runs, zero performance difference. Actually, I can't say that I saw any noticeable performance improvement from any of the lightweight parts that I incorporated over the years (alum spool, lightened ring gear, gundrilled axles, etc), go figure...

One other note on going to a 3" alum driveshaft, don't forget about resonance / critical speed, it isn't purely a matter of strength. I believe there is a chart on the Mark Williams site that lists length vs RPM for different driveshafts.

Jim Caughlin
SS 6019

05-09-2018, 11:07 AM	#2
Jim Caughlin Senior Member Join Date: Mar 2002 Location: Woodburn, Or Posts: 635 Likes: 70 Liked 693 Times in 208 Posts	Re: 3" aluminum driveshaft I have a 3" alum driveshaft that was built by Inland Empire, I cross the finishline at 9400 RPM and have relatively low HP. Interestingly, I was able to test duplicate steel (13#) and the alum one (10#) on back to back runs, zero performance difference. Actually, I can't say that I saw any noticeable performance improvement from any of the lightweight parts that I incorporated over the years (alum spool, lightened ring gear, gundrilled axles, etc), go figure... One other note on going to a 3" alum driveshaft, don't forget about resonance / critical speed, it isn't purely a matter of strength. I believe there is a chart on the Mark Williams site that lists length vs RPM for different driveshafts. Jim Caughlin SS 6019