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edubois 01-30-2003 02:41 PM

Driveshaft length and balance
If a driveshaft has to be cut and rebalanced, how should the measurement be taken to get the exact length and fit? Only needs to be and inch or two shorter. I am replacing a Powerglide with a TH400 in a 71 Chevelle.

Seon 01-30-2003 03:19 PM

If your drive shaft was already on the car with the powerglide and you change the transmission to a 400, just measure the length of the powerglide and the measurement of the 400. Then cut the drive shaft using the difference of the two lengths. BTW measure from the flange of the transmission where it bolts to the engine to the end of the tailshaft.

[ January 30, 2003: Message edited by: Seon ]</p>

onebadmerc 01-31-2003 02:19 PM

Take your yoke off of the driveshaft, slide it into the transmission all the way then pull it back out 1/4 to 1/2 inch. Then take your tape and measure fron the center of the U joint cap in the yoke to the center of where the other U joint cap sits in the rearend. Make sure all four of your tires are on the ground when measuring, the way it will be when your driving it, or your measurement will be off.

dmorris1200 01-31-2003 02:56 PM

If I remember correctly I slid mine out about an inch and measured. No problems so far.

onebadmerc 01-31-2003 03:36 PM

I might be wrong on the 1/4 to 1/2 figure, too think about it I think the driveshaft shop told me 1/2 to 1 inch. It has been a year since I had the driveshaft shortened and my memory isn't as good as it use to be. I am sorry if I gave you the wrong measurements edubois.

dmorris1200 01-31-2003 04:42 PM

I don't know what the 'text book' measurement would be. I'm not even sure how I did it was right, but it's working. I measured how far out the yoke was from bottoming out with the 8-inch rear still in the car ( which was about an inch) and then set the yoke the same and measured for the 9-inch rear. So far so good. :D

TurboS10 01-31-2003 05:20 PM

If you slid the yolk all the way in the transmission and measure from the center of the yolk cap to the center of the rear cap and give this to your driveshaft shop, they will add the correct slide clearance. That said, most of them use 1".


edubois 02-01-2003 12:00 PM

Thanks everybody, good info...

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