Topic: rear drive shaft after SAS

[phi564]

i've got an '90 ext cab pickup.  i'm fix'n to do an 4" SAS and 4" rear lift with a single case.  right now i have a 2 peice stock rear drive shaft, i was think'n about changing to a single peice w/ a CV.  i know it would be pretty long, so i was just wondering what some other have done.

thanks,
chris

[79coyotefrg]

just make it a 1 piece,  dont  worry about a cv

[blackdiamond]

On my 85 truck I ran the stock rear driveshaft with a 4-1/2 inch lift without any issues.  I suspect you will have more travel, so I would suggest getting it lengthened a bit and calling it good.

[BLACKDOG]

Thats a very long driveshaft.  Remember, the longer they are, the wider they need to be.  If you go to a one peice, you need to make sure the tubing clearances will fit.  When I got my 2 piece made into a 1 piece, the guy had a computer program that showed the torque loads at different lengths with different sizes of tubing.  The stock tubing was too weak to handle the extra length of the driveshaft. 

You can also make some spaces to put in the carrier bearing bracket, to lower that and keep the angles closer to normal for the time being.  Then when(if) you go duals, you can step up to a 1 piece. 

[phi564 [OP]]

i've got a rear drive shaft from an '84 ext cab pickup.  if i did do a one peice i was gonna definately step up the tubing to some sch 40 or something like that.  i didnt really think about it needing to be wider but that is a good point.

if i did keep the two peice and lowered the bearing, do i need to set up my pinion angle as if i had a CV and angle it towards the TC or a regular u-joint shaft and set the angle the same as the TC flange?

thanks for the input

chris

[BLACKDOG]

I read your first post, and thinking about it a little more, you may not even have to put the spacers.  before I went to duals, I had a 2 peice, with no spacer, stock '91 d-shaft, and never had any issues.  I have 63" chevies, and got about 4" out of them, so you're looking at the same thing.  If I did it again, I might at a 2" spacer, just to get a closer to stock angle.  I know DTB has built or is going to build a spacer for his truck for the time being (3rd gen ex cab as well) so you might hit him up for some pics of what he did.  He may already have some up on his Tree hugger thread in Project Buildups.  I don't know, I haven't looked at it for a few days. 



Also, with a two piece driveshaft, by putting a spacer in, you "lengthen" it anyway, by increasing the angle it is at.  If you look at an L vs. a \_  the distance between the two points is farther, due to the angle being increased from 90* to 120* or so.   Hopefully this makes sense?  if not, I can do a diagram on paint when I get home. 

[91 super yoda]

im probably where you are lookin to be. ive got the 4" SAS w/o duals and no spacer on a stock 91 shaft. ive been runnin it like that with no problems. driven on the street at least 3 days a week and wheeled on the weekends. you can add a spacer to make yourself feel better if ya like.

[phi564 [OP]]

91 super yota - do you have any vibes on the road.

thanks for all the info guys!

chris

[91 super yoda]

no, ive never had vibrations from the way its set up. ill probably leave it like it is. dont fix anything thats not broke.