Pinion angle with 2 piece driveshaft.

[javajoe79]

 I wanted to get some opinions on this subject. What is optimal for the salt? Will it effect hook up?
Some details are 9", 4 link suspension with bags, 2 piece driveshaft.  Thanks for any info on this.

[Ron Gibson]

Pinion angle is determined by the angle of the drive shaft. The U-joint angle needs to be the same (within about a degree and half) on both ends of  the drive shaft.

Ron

[SPARKY]

U-joints do not know where they are, they just want to work a little to stay happy--remember the angle difference can be a 360 deg cone up down or side ways they don't care

[Gwillard]

Here's some good info. http://www.4crawler.com/4x4/CheapTricks/Driveline-101.shtml

[Ron Gibson]

According to the chart, you might want to keep the angles low at the rpms we run.

Ron

[javajoe79]

 Ok so as it sits now, the first half of the driveshaft is down about 2* from the angle of the engine/trans.

 Then with the truck at ride height the second part of the shaft is about at 6* down total or 4* down from the angle of the first shaft.

 So from what I gather from this link, inland empire who we got the shaft from

http://www.iedls.com/asp/admin/getFile.asp?RID=10&TID=28&FN=PDF

for smoothest operation, our pinion angle should be up the same angle that the first part of the driveshaft is down because the angle of the first shaft becomes the engine/trans angle that you would use to setup a single piece shaft.

Right??

So that would mean that we want our pinion angle at 2* up from horizontal right?

Now if you ask a drag racer they will tell you that with our rear suspension, a 4 link with poly bushings, we need to have the pinion angled down 2* to allow it to return to the proper angle when under load and it also effects traction. Does this apply on the salt?

Also would you put the pinion angle 2* below my angle as it sits, or 2* below horizontal?

[SPARKY]

IF The Trans is 0 and the pinion 0 then the drive shaft angle needs to be less than 3 I run an OD  and my drive shaft speed is around  8500 rpm so I try to keep mine between 1 and 2 deg. --- this means they do not line up in a straight line  my tran is slightly " OFF center"

[javajoe79]

 Ok let me change the numbers I put up earlier. The angle gauge we used was funky and I switched to a real nice one that I didn't have with me last time.

 These measurements are take with the truck at ride height.

First driveshaft runs 2* below horizontal from the trans.

The pinion is at 2* above horizontal

The second driveshaft runs UPHILL to the pinion at about 3*

 We can easily shim the carrier bearing in between the two halves of the driveshaft to make the first shaft run uphill from the trans and then make the second shaft run downhill to the pinion. I believe we had it that way to begin with but in all the times things have been on and off the truck, one of the shims is now missing.

  So with another shim in place we will be able set the pinion down 2* like is common.

However I still would like some feedback on pinion angle under load. On the salt, I am just assuming it won't see as much load as on a drag strip for example. So should I set the pinion angle down any further to allow it to return to 2* under load or should I leave it at 2*?

Thanks

 

[Gwillard]

The way I used to set up two-piece driveshafts was to set the pinion so it was parallel with the output shaft of the tranny, then point it 1-2 degrees nose down from there. That put the u-joints in phase and all the parts got along happily. You do need a slight angle to keep the joints lubed properly, but only about 1/2 degree.

[Interested Observer]

Javajoe,
Per your second set of dimensions, it appears that with the pinion shaft inclined 2 degrees above horizontal, it is parallel to the first section of driveshaft coming from the transmission at 2 degrees below horizontal, and therefore the operating angles of the u-joints on each end of the second section of shafting are equal, which is what you want for a constant speed ratio across the shaft (assuming the yokes on the shaft are phased in the same plane). 

You could also achieve about the same thing by angling the pinion down by about 2 degrees, but in this case the relative location of the u-joint centers enters into it, since it is not the inclination angle of the shaft and pinion that you want to match, it is the angle of operation of the two joints, which may be different depending on the vertical location of the joints. 

Properly set up, the second option is probably superior for joint durability since the joints would be operating at about 2 degrees deflection instead of about 5 degrees.

Caveat:  You have not stated the inclination of the transmission output shaft.  If it is parallel to the first driveshaft section, everything is fine, as above.  If not, the operating angle of the first u-joint will introduce speed variations into the system.

If you really want to get into the technical issues, suggest obtaining the following SAE paper:       http://papers.sae.org/660413/

It would probably be best to adjust the 4-bar linkage to minimize squat and keep the axle where you want it located.

[javajoe79]

Thanks for info bystander. It helps. I think I have a good grasp on it but it's just good to hear confirmation

[hotrod]

Don't forget that if your car changes ride height or attitude at speed, you want the U-joints at ideal angle at that ride height and attitude, not when the car is sitting on the starting line.

If you design a little adjust-ability into the suspension and engine/transmission location mounts it helps to get things sorted out.

When I was in my teens I muched a bunch of U-joints behind a '58 Chrysler Hemi, before I figured out U-joint angle was important.
I got real good at replacing them until I discovered axle spring pad wedges  (leaf spring rear suspension).

Larry

[javajoe79]

Yeah we have full adjustability of trans and bearing placement as well as pinion angle. Good thing is the pinion angle stays constant throughout the rear suspensions range. Also we are looking at adding a ride height controller to our air bag system so it will maintain our desired ride height at speed.

[WhizzbangK.C.]

Here's a link to a document by the most experienced folks in the world as far as multi-section drive shafts are concerned. Might help some, maybe. 

 http://www2.dana.com/pdf/J3311-1-HVTSS.PDF

[CoolRide]

Here's a link to a document by the most experienced folks in the world as far as multi-section drive shafts are concerned. Might help some, maybe. 

 http://www2.dana.com/pdf/J3311-1-HVTSS.PDF

Thats a great link!
Lots of info I had never thought about, thanks!

Sammy