[Hwyhogg]

Quick question guys. I had my drive shaft shortened. I gave them the measurement from the rearend yoke midpoint to the transmission output shaft and the measurement of the output shaft to the transmission housing. I installed the shaft today and there is about 1.5" of the shaft showing at the transmission tail...is this enough? too much? The shop was referred to me by serveral local speed shops.....I'm just making sure all is okay before I fire the beast up and put some torque to it!
thanks again,
James

[ericnova72]

Have you got the vehicle sitting on the rear suspension, so that it is compressed to it's normal ride height?? If not the yoke will go into the trans some when you do.

How long is your slip yoke??, Or how much is in the trans??

[S10xGN]

I had a car like that once, lots of vibration at speed but never broke or came apart. Sounds like you need a shaft about 3/4" longer. Definitely don't "stress" it or you'll risk twisting the output shaft splines in the trans...

Russ

[techinspector1]

With the car's weight on the tires, you should be able to take the rear u-joint loose and push the driveshaft forward about 3/4 of an inch until the yoke bottoms out. Any less than that and you risk bottoming the yoke on bumps. Any more than that and there is insufficient spline engagement to transfer power.

[Hwyhogg]

Well, the weight is on the wheels, and I figure I'm within several hundred pounds of the final weight. I will have a couple buddies get in the truck to simulate the finished interior,seats, etc. I doubt that will significantly change the position. I re-measured the showing shaft and it is 1 3/8". So I guess the shaft is too short Suppose I'll have to get a new one Maybe lowering the truck would help?
thanks for the help guys.

[THERACER]

i think it may also depend on how much the spline is in the tranny also.
someone correct me if im out in left field . LOL

[geezer69]

just how much spline is needed?

[delawarebill]

the way i did mine and was recommended is..
put the d/s into the tranny, pull back one inch and measure the center to center of the ujoints. of course the rear of the d/s will on the floor so u measure as close as u can at the rear ujoint of the 3rd member. bill

[geezer69]

we had one built just a while back.havent drove it on the street yet but it looks like it sticks out too dang far to me.im glad i read this info.thanks for bringin this up hwydogg and for the answers, cool.

[KMatch]

The length in question isn't excessive as it sits, but another measurement will be needed with the suspension at full droop. This will decrease the spline contact - by how much is the question.

[Hwyhogg]

Well, I'm gonna pull the shaft out and try to see how much splined surface is in the tranny. I definitely won't do anything else until the car is complete, ie. fenders, hood, seats. I'm just a little itchy to get the ol' gal to move on her own instead of pushing in and out of the garage. I read the same thing about pulling the shaft out an inch then measuring; I assumed an inch was the target length of play. Nonetheless, I'm still 3/8" longer than that inch . I am concerned because, though it's not a drag truck, it will have over 500 lbs of torque and I would like to have as much spline contact as possible....

[327NUT]

My Cadillac T400 has 3" of spline area on the rear output shaft. If you can, pull the tail shaft housing and take a look, then you'll know just how much splined area you have to work with.

[timothale]

on one of my swaps I used a Ford C 6 Yoke into a GM trans to match up drive shaft pieces, the C 6 was longer, had about 3 in with no splines, I chucked it into the lathe , shortened and deburred it. It made the drive shaft easier , Ford U joints, the same at each end. I always go to the drive shaft rack in the shop with a tape measure and dial calipers first, then to the wrecking yard , I have found a lot of factory made shafts that will work. Some truck 2 piece shafts are short enough

[techinspector1]

Originally Posted by Hwyhogg

Well, I'm gonna pull the shaft out and try to see how much splined surface is in the tranny.

You're makin' this way too difficult. Push the yoke into the tailshaft housing until the yoke bottoms. Pull it out 3/4". That's where you want the finished product.

[KMatch]

Originally Posted by techinspector1

You're makin' this way too difficult. Push the yoke into the tailshaft housing until the yoke bottoms. Pull it out 3/4". That's where you want the finished product.

True, that's the goal, but the question is "how much out of spec before being concerned?". I'd hate to think I replaced a driveshaft that was 5/8" or so too short when it wasn't an issue. Does anyone know the tolerance?