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Author Topic:   Driveshaft tubing diameter
posted April 01, 2004 05:43 PM
We were going thru our selection of junkyard driveshafts, choosing one to shorten, when we came across one that was 53" long and a consistent 2.5" diameter. We do not know the origin of this driveshaft. Does anyone know the rules of the road on driveshaft length / RPM / Diameter? It needs to be 49.5" will top out at 6500 rpm. Can I shorten this one and expect it to live? Thanks in advance for the responses.

posted April 01, 2004 05:54 PM
There are no rules of the road on driveshafts. Of course you have to have the right yokes to use the u joints you need but if it fits all is good, smaller diameter is good, and even better if it is thin wall tubing. Other than that shorten it "properly", bolt it in and race. Good luck.

posted April 01, 2004 10:43 PM
The technicle rules to the road on driveshafts are criticle speed, it changes with shaft diameter and or length. Smaller,longer = less speed attainable before failure. I had a shaft come into the cockpit 2.5"x44", called DANA Corp. asked some questions and was informed my shafts criticle speed was 3800 rpm. Leave the pencils alone and get something larger,your elbow and or legs will thank you.

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