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Camaro Research Group Discussion => General Discussion => Topic started by: hdptsr on December 03, 2010, 07:34:04 AM

Title: factory 1969 12 bolt pinion angle
Post by: hdptsr on December 03, 2010, 07:34:04 AM
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
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on December 03, 2010, 10:59:02 AM
(http://i45.photobucket.com/albums/f58/markx22/1969%20shifter/th_springperch9-17-2010.jpg) (http://s45.photobucket.com/albums/f58/markx22/1969%20shifter/?action=view&current=springperch9-17-2010.jpg)
Title: Re: factory 1969 12 bolt pinion angle
Post by: hdptsr on December 03, 2010, 04:37:07 PM
So the spring perches should be welded on the axle tubes with the pinion pointed down 6 degrees? 
Title: Re: factory 1969 12 bolt pinion angle
Post by: JohnZ on December 03, 2010, 07:13:41 PM
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.
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on December 03, 2010, 07:38:58 PM
(http://i45.photobucket.com/albums/f58/markx22/1969%20shifter/th_12-3-2010pinionangle.jpg) (http://s45.photobucket.com/albums/f58/markx22/1969%20shifter/?action=view&current=12-3-2010pinionangle.jpg)same drawing rotated like John said .
Title: Re: factory 1969 12 bolt pinion angle
Post by: rodent on December 03, 2010, 08:27:47 PM
Spring perches turned inward at 2°
Title: Re: factory 1969 12 bolt pinion angle
Post by: hdptsr on December 03, 2010, 10:21:36 PM
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 :)
Title: Re: factory 1969 12 bolt pinion angle
Post by: KevinW on December 04, 2010, 12:30:27 PM
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.
Title: Re: factory 1969 12 bolt pinion angle
Post by: mopar346 on December 04, 2010, 02:02:28 PM
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
Title: Re: factory 1969 12 bolt pinion angle
Post by: JKZ27 on December 04, 2010, 02:24:16 PM
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
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on December 04, 2010, 03:13:57 PM
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
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on December 04, 2010, 03:17:58 PM
This is the 2 degrees Rodent was talking about .               (http://i45.photobucket.com/albums/f58/markx22/1969%20shifter/th_springperch6-25-2010.jpg) (http://s45.photobucket.com/albums/f58/markx22/1969%20shifter/?action=view&current=springperch6-25-2010.jpg)
Title: Re: factory 1969 12 bolt pinion angle
Post by: mopar346 on December 04, 2010, 03:20:30 PM
Excellent point, that may be the confusion. Up from perch level down from drive line angle.
Title: Re: factory 1969 12 bolt pinion angle
Post by: mopar346 on December 04, 2010, 03:25:13 PM
Good illustrations, out of the Assemble Manual ya'll keep talking about?
Title: Re: factory 1969 12 bolt pinion angle
Post by: mikes 67 on December 04, 2010, 03:26:09 PM
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.
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on December 04, 2010, 05:06:37 PM
I redrew the spring in post 10 . When you set it up just get the 6 degree difference between the pinion and the spring perch as shown in the first drawing . Don't worry about the ground or the car that could vary with ride height . Just make it look like the drawing .(http://i45.photobucket.com/albums/f58/markx22/1969%20shifter/th_12-4-10pinionangle.jpg) (http://s45.photobucket.com/albums/f58/markx22/1969%20shifter/?action=view&current=12-4-10pinionangle.jpg)
Title: Re: factory 1969 12 bolt pinion angle
Post by: hdptsr on December 05, 2010, 09:59:51 PM
Thank you all for your input!  It makes sense to me now.  Even though the perches are welded on the axle tubes at a pinion angle of 6 degrees up, when the rear end is on the springs and installed, it is closer to neutral or 0 degrees.  That last drawing was excellent.  Does the assembly manual show all of this?  I better get me one.  Thanks for saving me tons of time and a headache later on. 
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on December 05, 2010, 10:18:51 PM
No those are my drawings .
Title: Re: factory 1969 12 bolt pinion angle
Post by: KurtS on December 06, 2010, 04:26:29 AM
And they are great drawings Mark! Thanks!
Title: Re: factory 1969 12 bolt pinion angle
Post by: JohnZ on December 06, 2010, 09:54:25 PM
And they are great drawings Mark! Thanks!

Yes, they are! Nice work!
Title: Re: factory 1969 12 bolt pinion angle
Post by: bertfam on January 07, 2011, 05:57:38 PM
Mark, post the pictures again. They're no longer showing up. It's good reference material to have!

Ed
Title: Re: factory 1969 12 bolt pinion angle
Post by: mopar346 on January 08, 2011, 02:45:44 PM
I saved a couple. Here ya go.
Title: Re: factory 1969 12 bolt pinion angle
Post by: mark x22 on January 08, 2011, 03:19:07 PM
mopar346 you might want to delete the first one , the spring is wrong . this one is better .
[Fixed - Kurt]

(http://i45.photobucket.com/albums/f58/markx22/th_springperch6-25-2010.jpg) (http://s45.photobucket.com/albums/f58/markx22/?action=view&current=springperch6-25-2010.jpg)
(http://i45.photobucket.com/albums/f58/markx22/th_12-4-2010pinionangle.jpg) (http://s45.photobucket.com/albums/f58/markx22/?action=view&current=12-4-2010pinionangle.jpg)
(http://i45.photobucket.com/albums/f58/markx22/th_springperch9-17-2010.jpg) (http://s45.photobucket.com/albums/f58/markx22/?action=view&current=springperch9-17-2010.jpg)
Title: Re: factory 1969 12 bolt pinion angle
Post by: bertfam on January 08, 2011, 06:38:58 PM
Perfect. Thanks!

Ed
Title: Re: factory 1969 12 bolt pinion angle
Post by: mopar346 on January 10, 2011, 02:15:34 AM
Thanks for the update.
Title: Re: factory 1969 12 bolt pinion angle
Post by: bcmiller on March 13, 2023, 07:13:25 PM
Did anybody save these images off in large size?