one piece shaft

['68 longbed]

just a goofy "want" here but I'd kinda' like to get rid of the two peice drive shaft.

is there a one peice shaft that i can rob off another vehicle that will work with the three speed?

I'm trying to set up to swap motors this weekend and perhaps get a 200r that i have access too, is there a drive shaft that I can rob off another vehicle that will work with that set up?

trying to stay away from cutting a shaft down, or leingthening one. since it makes for a logistic pain right now.

thank you all again for your help. you have saved me a great deal of screwups!

[Longhorn Man]

it can be done, but it could be opening up a huge can of worms.
The industy standard has been no longer than 6 feet long for a drive shaft. It's been that way for ever, up untill recently. now, they are making them out of alluminum and in a huge diameter. (I see them broken all the time)
if you go to a drive shaft shop, most will send you away.
Others, will do it, but charge you a LOT.... and only 1/2 of those places should try it.
The longer the shaft, the more it'll sag. It won't be measurable, but the faster you drive, the more it'll matter, and if you do the overdrive, it'll matter even more since the shaft will be going faster than the crankshaft.
If they do it wrong, it'll not just be out of ballance, but it'll 'whip' ... think of rolling a pushrod on a piece of glass. (best way to find if one is bent) Imagine that push rod has a slight bend in it... just enough to be seen. Now, imagine that as a driveshaft... weighing 25 pounds, and spinning 3000 RPM.
It would shake the truck, it would ruin the seals in the tranny output, and the diff input, and would end up damaging both if left alone long enough, or if it is bad enough, it could damage things quick.
A properly assembled 2 piece is perfectly fine. It can handle more severe angles from the engine to the axle, you can remove just the rear half for towing, which would keep the tranny from barfing all over the place, and with quality components, can handle what ever power you give it, and hold up for many years. Many of these trucks still have the original carrier bearing under them today.

Some will tell you they did it and it's fine. Others will tell you they did it, but had to kill the crossmember to fit the shaft through, others will tell you they did it and it was a waste of money.



I say spend the money elsewhere.

[bad6772]

longhorn, your knowledge and input is valued on this site, at least by me anyways.lol i got a buddy that works at a gm dealership. that has been trying to get me to run a G series van driveshaft for years. its shaft is the correct length and also aliminum?<spelling king> you gave me alot more reasons(other than NO) to tell his A$$ . thanks .........tony

['68 longbed]

makes sense. I hadn't considered the leingth/wieght ratio being that much of an issue.

I like the stick but I'm hoping to milk as much mpg as I can out of the ole girl and hoping to get the gears in the rearend changed in the next few weeks. (thinking 3:55's ) and I have a fairly fresh 200r. but I'm not in love with the overdrive automatics that much.

five speed's with the manual clutch seems to be hard to find. and I'm dreading getting the drive shaft cut. would like to pick one up that I can throw in while i'm doing the swap.

[alfeefish]

I just picked up a one peace out of a 2003 pickup. It is 58 Inches center to center, just what I needed. Now the u-joint will not bolt up to the rear end. Can I change the u-join housing on the rear end from 67 to 2003, Will this work...

[Jim_PA]

Originally Posted by alfeefish

I just picked up a one peace out of a 2003 pickup. It is 58 Inches center to center, just what I needed. Now the u-joint will not bolt up to the rear end. Can I change the u-join housing on the rear end from 67 to 2003, Will this work...

If it exists, I would get a conversion u-joint.

[alfeefish]

Ttt

[bigjimzlll]

On my LWB 67 I went with a 1 piece. To do it I moved the engine back as far as possible. I then used the "long" tailshaft th400. I think the tailshaft is 13" long. I used 4" .140 thick DOM tubing for the shaft. It gets spun to 7500 rpm at 138MPH in the 1/4 mile.
If I were to do it again, A good custom 2 piece would be the ticket.

[Longhorn Man]

jim, you did mention the right way to do it though, esp with the long tranny and the engine set back.

[Orange]

Originally Posted by alfeefish

I just picked up a one peace out of a 2003 pickup. It is 58 Inches center to center, just what I needed. Now the u-joint will not bolt up to the rear end. Can I change the u-join housing on the rear end from 67 to 2003, Will this work...

Originally Posted by Jim_PA

If it exists, I would get a conversion u-joint.

I guess that's pretty much what I have - just made my own.

I had a 1-piece shortened for my truck when I did the 700R4 swap, and bought some new Spicer U-Joints to go with it. The end caps worked great in the shaft girdles, but not the rear end girdles...So I just slid 2 of the end caps off of my old U-joint to use in the rear end sides, and it works great.

You have to have the same diameter U-Joint "ears" or whatever though to do that. (The part the caps slide on).

DLB

[alfeefish]

Yea, mine are different my 2003 u-joint will not fit my 67 rear end.Do they make a universal u-joint?

['68 longbed]

Originally Posted by alfeefish

Ttt

probably a stupid questin but I see this alot and wondering what it is?

[sick69]

ttt= To The Top

[Big D]

Using one from a G-series van sounds like an alternative, Should be plenty of those in the bone yard.

Wonder what the length is on a 70's era full size wagon? They might be harder to find since most ended up as demo derby cars.

[Truckstr]

There's nothing inherently wrong with going to a one-piece driveshaft. BUT both bigjimzilll and Longhorn Man are on the right track. Too long can be a problem, but not simply because of the length. It's in the balance (more difficult to achieve properly on a looong driveshaft), the natural frequency of the driveshaft and a few other factors.

Go to this link and read a little: http://www.wallaceracing.com/driveshaftspeed.htm

One of the biggest factors is the driveshaft's critical speed. That's what makes the driveshaft live or die in a 'hot' vehicle. Exceed the driveshaft's critical speed and things can go boom real quick.

There's a story in a recent issue of one of the car mags I subscribe to (Sorry. Too many to remember which one). A guy had built a hot engine and done some other mods to his truck. He had it on a chassis dyno doing some final tuning. He's spinning the engine up (and wheel speed - chassis dyno, don't ya know) and all of a sudden BOOM. The driveshaft came out. Ruined the transmission and a some other pretty serious damage. Could have hurt somebody. Lucky! Why did it let go? He was spinning the driveshaft up beyond 120+ mph. It was a stock driveshaft designed with a max speed of less than 110mph in mind. His combo and mods had enabled the truck to far exceed what the stock combo would do, i.e., exceed the driveshaft critical speed. Moral: for 'hot' cars/trucks, get a driveshaft designed for the intended useage.