one piece or two piece driveshaft
 

OK. I know this has been hashed on the board a few times, but I can't remember what the advice has been regarding going with a one piece or two piece driveshaft. And with seach down....well here is the question again.

I'm putting a 700R4 trans in the 70 Chev pickup. It has a two piece driveshaft now. Should I have that one modified or switch it over to a one piece?

I have the driveshaft out of the 85 Sub that I used for a engine/trans donor. Is this driveshaft going to be long enough to use for a start? I'm guessing it is going to be too short.

Thanks for the advice so far on this project!
Mike

A one piece will prevent carrier bearing failiure, since you won't have a carrier bearing, lol. And, next time you replace U-joints, you will only have 2 instead of 3, which will save alot of hassle.

It will cost more to have a 1 piece made than shortening the 2 piece. If you don't want to spend the extra money, get your current shaft shortned, install good-quality U-joints and a carrier bearing, and it should last quite a while before needing attention again.

or these...


http://www.iedls.com/bearings.html

http://www.iedls.com/twopiece.html

I have a question too...
 

I apologize also if this has been covered before, but since we're on the subject...

Does anyone know if there is any power gain or performance difference between the 1 pc. and 2 pc. drive shafts? I always assumed the single shaft was stronger since it didn't have to go through a carrier bearing, But that the 2 pc. was more economical since it spins on a less stressful axis. In other words, the 1 pc shafts are more likely to develop vibration and balance problems.

Am I on to something in this line of thinking, or is it all just a myth?

The main problem with a one piece shaft is they length. Most places will refuse to make a shaft over 6 foot long, and some of the shops who do it...shouldn't
Basicly, the shaft gets too long to support its own weight, and it starts to 'whip' as it spins.

Longhornmail,
Any idea how long the drive shaft would be with the 700R4 installed? It is going to be a couple of weeks before I have the engine and trans installed, but would like to try to reach a decision before then. Right now, I'm leaning to keeping the two piece. Looks like it could be less hassle.

Any idea if the Sub driveshaft would be long enough for a start point on a one piece?
Thanks
Mike

Probably the best place to start would be to measure the length of your current trans and your new 700R4. That will give you a fair idea how much shorter your drive shafts will have to be. As for using the burb shaft I don't know the length but unless its over 4" in dia. I wouldn't consider using it for the reasons Andy stated.

I have 2 piece and have never had a problem. Stay with the 2 piece.

i have a 2 piece on my low 12 second truck

This may only hold so much water, but I figure if the technology is still good enough for the newest trucks on the market, it is okay for my 34 yr old truck.

I am unable to tell you...I haven't seen my tranny coparison sheet in ages.
Sorry.