Question about one piece drive shafts

[widegauge]

Does any one know how far a one piece drive shaft needs to slip in and out of a auto tranny, you know for suspension travel and all. trying to figure out how long of a drive shaft I need for a 460/c-6 swap in a short bed 2wd. found a salvage yard with tons of drive shafts so I was just going to measure them and find one the right length.

[fordman]

not knowing what your yoke size that slips into the tranny is a pain, but to measure a drive shaft you are suppose to measure from center of ujoint to center of ujoint. and then add the yoke for the front. so if anyone would have a yoke laying around he needs this measurement to get the right shaft.

[FORDification]

Most people who need to get a custom driveshaft made will slip the yoke into the end of the transmission until it bottoms out, pull it back out between 3/4" to 1", and then measure from the center of the yoke's U-joint cup to the center of the U-joint cup on the rearend...and then get the driveshaft made to that measurement. Keep in mind that the vehicle needs to be on the ground as it would normally sit with the suspension compressed...you can't have the back end lifted up in the air with a jack.

[widegauge]

so from the truck setting at normal ride hight to being completely bottomed out is only 1" of slip yoke travel? seems like it would go alot farther then that. but that is another problem I had a 360/390 with a auto behind it when I got the truck but I sold some of the parts of the motor and the tranny to recupe some of the money of the truck becouse I knew that I was going to put a big block in it. so when I went and got the c-6 I didnt get a slip yoke.

[390Nut]

Don't mean to sound doom and gloom but it's highly unlikely you'll easily find a driveshaft that works as is, due to your combination. Don't think there were to many shortbed trucks with 460s in them, and their accompanying C6 trannys. Very likely you'll need to get one made, in which case you measure from the end of the tailshaft on the tranny, to the center of the yoke on the rear axle. If you can find one that's too long, then your in business, as it's simple to get one cut down to length.

Find a place that builds custom drivelines, and they'll know how to build it, including the proper yoke/length. Probably be a bit pricy, but it will be completely new with no seal grooves on the yoke, new u-joints, and be balanced as well.

[FORDification]

so from the truck setting at normal ride hight to being completely bottomed out is only 1" of slip yoke travel? seems like it would go alot farther then that. ...

That's correct....you never need more than 1" of travel on the yoke. By the time the up/down suspension motion is transferred to an in/out lateral motion, the amount of travel is pretty small actually, because the suspension travels in an arc (more or less).

[widegauge]

wow I would have never thought that...thats pretty cool, thanks.

[68F250]

There's actually more driveline "stretch" when the suspension is fully drooped, say when you're airborne or on a chassis lift.

I seem to recall you need at least 1 inch of spline engagement or else the driveshaft will vibrate. Good rule of thumb is insert splines until they bottom-out and then pull it out 3/4 to 1 inch. This is with the vehicle on the ground.

[71F100FE]

I went thru this with my Mustang.

The Max amount I would pull out the yoke is 1", preferably 3/4. After you take your measurements be sure to deliver the yoke, U-joints and all to the balancer. That is the best way to get a good balance.

Good luck, Ric.