factory 1969 12 bolt pinion angle

[hdptsr]

I have a 1969 SS (350 300HP) car with a factory 12 bolt.  The owner prior to me changed the multi leaf perches to mono.  I want to weld multi perches back on however would like to know the correct pinion angle that the spring perches were welded to the axle tubes at the factory.  With the spring perches level what is the correct down angle in degrees of the pinion? (out of the car) Thanks Joe

[mark x22]

[hdptsr]

So the spring perches should be welded on the axle tubes with the pinion pointed down 6 degrees? 

[JohnZ]

So the spring perches should be welded on the axle tubes with the pinion pointed down 6 degrees? 

With the spring mating surface on the perches horizontal, the pinion centerline should be 6* UP from horizontal.

[mark x22]

same drawing rotated like John said .

[rodent]

Spring perches turned inward at 2°

[hdptsr]

Man I am really confused about what pinion angle I should weld the spring perches on.  I emailed Moser and they said 6 degrees down (negative) then I e-mailed Currie rear ends and this was his reply.... he asys 5 degrees up (positive was the way they came from the factory

Darrell Schwaiger" <darrell@currieenterprises.com>  No vehicle (besides some very odd Dodge cars) had the pinion pointed towards the floor from level. The transmissions are going to be higher than the rearend, it needs to point upward. The numbers I gave you are the numbers we build all of our axles to for that vehicle.

Somebody please straighten me out on this so I can get to welding

[KevinW]

Just go find a junk chevy rear from the mid 70s to compare.  The pinion angles are all the same mono or multi for that era.

[mopar346]

It is defintiely up, although I could not have quoted the degree with out researching it. They have posted a technical drawing from I'm sure a factory source, so I would believe it just based on what I know. If you think about it as you excellerate the pinion goes up to essentially align the drive line. Consider any ride heigth over stock you are going to have as well to ensure nothing changes. They do make degreed shims in I think 2 and 4 degrees in the case that you get it off a little you can correct it with out cutting and rewelding. I use to use these shims to prelaod my J bolt bars fort 2 degrees.

I usually jig everything up on tires and all to ensure angles and centering is correct, once I have everything like I want it I tack it in place and then pull it and weld everything.

And don't be talking about old Dodge cars.

Good luck

[JKZ27]

Also consider the mounting point on the leaf spring. I think when the axle is mounted on the springs, it actually puts the pinion closer to level when the perches are welded with the pinion up about 6*. So, the down position would seem wrong to me. When power is applied to the axle, it tends to rotate so the pinion moves up.

John

[mark x22]

With the pinion level which also puts the rear cover mounting surface 90 degrees straight up , the spring perch's point down in the front 6 degrees like the drawings show . With your first question with the perch's level the pinion goes up 6 degrees in the front like in the second drawing

[mark x22]

This is the 2 degrees Rodent was talking about .               

[mopar346]

Excellent point, that may be the confusion. Up from perch level down from drive line angle.

[mopar346]

Good illustrations, out of the Assemble Manual ya'll keep talking about?

[mikes 67]

The springs do not sit level in the car. If you measure from the ground up to the front eye of the spring, then measure from the ground up to the rear eye of the spring  you will find the rear sits about 7 inches higher.
  The correct way to set the pinion angle is with the rear end in the car.  Set jack stands under the rear springs so they are holding all the weight of the car,set your new perches on the springs then set your axle housing on the perches.  using an angle finder measure the angle of the output of the transmission then set the pinion angle a couple of degees down from that. Center the housing from side to side and tack the new perches in place, then remove the rear end and finish welding out in the open.
   I hope this helps,  Mike.