Hey guys, I think we messed up. We welded new perches on my buddy's 12 bolt for his 69 BB ragtop. We installed them with a 4 degree down angle (like we thought it should be). We installed new multileafs and the axle.
Now that it's installed, the pinion angle is about 15-20 degrees down! http://www.camaros.net/forum/eek.gif
The driveshaft is binding bad enough to make the front of the differential jump up.
It looks like we need to shim it up about 12-15 degrees. Can this be done safely? That seem like a lot of shims...I'm thinking about 3/4 inch thick it front to real thin if back to make it work. Does anyone make shims like this?

On the bright side, the 4 leafs from classic (made by eaton) fit perfect. Got them from Matt's Classic Bowtie. The ride height is perfect. It is about 12 3/4 inches from centerline of the hub to bottom of the fender lip. We wanted to keep it about 1 inch lower than stock and it worked. Haven't driven it yet (obviously) but they seem pretty soft as well. Supposed to be a 126# rate spring, just like the stock mono leaf. http://www.camaros.net/forum/biggrin.gif

Thanks for any advice.

joe

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69 Rat-Infested Resti-Clone
WCA Member
Badboatdude@CS.com
69 Pics http://hobbystage.net/camaro/joeg/index.html

[This message has been edited by Joe G (edited 03-26-2002).]

i would re-weld the perches- but set the angle with the rear bolted in and supporting the weight of the car.

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1971 Nova(looks like 69 camaro from underneath!)
355sb, vortec heads, HOT cam,T-10 tranny, 3.70 gears 16X8" IROC wheels. 12" Corvette brakes on the way.
see pics here http://community.webshots.com/user/novaderrik

I don't see how any pinion is pointing down with the engine supposed to point down about 3 to 5 degrees....which translates into the pinion pointing up, always!

Go to www.iedls.com (http://www.iedls.com) for help!

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STEVE JACK
ConceptOne Pulleys and Brackets

Not always. Drag cars are generally set up with a 3* negative engine angle to promote better weight transfer. We do this by using tall trans mounts an/or short engine mounts. This setup requires that the pinion tip down a few degrees towards the ground.

Here's another link:
http://www.hotrodheaven.com/tech/chassis/engineangle.htm

Joe G, You definitely want to grind off those welds and reset the pinion angle with the rear end in the car, sitting at normal ride height. 12* is way too much angle to make up with shims etc..!

Joe, I can get you the perch to pinion angle off a Camaro rear end I have here.
I have a GM racing brochure drawing that shows four degrees, thirty minutes UP angle of the pinion when the perch is level.
I would re-do it.
David

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Check my web page for First Gen Camaro suspension info:
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67 RS 327 original owner. 69 Camaro Vintage Racer, 65 Lola T-70 Chev SB Can-Am Vintage Racer

Thanks, guys. We had the 4 degree thing right; just the wrong way!

From what I've read from doing a search, it seems that the 4 degree down angle is what the final installation should be, right? Although even that does jive with keeping the yoke in parallel with the tranny outpu shaft. That would make it 2-4 degrees up, as SJ has said.

What's wierd is that the perches line up with the weld marks from the original perchs that had been removed previously. The 12 bolt is a 69 3.31 posi by the stampings.

Guess our old brains don't work as well as they used too.

Thanks again.

joe

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69 Rat-Infested Resti-Clone
WCA Member
Badboatdude@CS.com
69 Pics http://hobbystage.net/camaro/joeg/index.html

[This message has been edited by Joe G (edited 03-26-2002).]

I've never heard of pinion angle up, unless you're referring to a lifted 4X4. All drag cars should be 4 degrees down in front because at launch, the pinion wants to jump up. That's why drag cars run a pinion snubber. I agree with rewelding the perches.

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70 & 1/2 RS
SB406 & M20 4spd
9" rear

70 Malibu 350/TH400

Gold member #103
Driveline Technician

http://www.geocities.com/carguy63/

[This message has been edited by Scooter (edited 03-26-2002).]

I measured my 10 bolt old rearend pinion angle to copy on the new 8.5 rearend perches. When the perches level it is 5 degrees up.I beleive when it is installed on the car it becomes negatif angle because how it is positioned on the leaf springs and tork of the engine make it allmost 0 angle when you are driving.
I think best think like novaderrik said to put it on the car and weld it to the desired angle.

[This message has been edited by ismail (edited 03-26-2002).]

Thanks for all the help, guys. We got the new perches on. Used the old 10 bolt as a pattern. It was 7 degrees up angle. Installed the 12 bolt and all is well. No vibration and the 3.31 posi really woke up the 396! http://www.camaros.net/forum/biggrin.gif http://www.camaros.net/forum/biggrin.gif

Thanks again

joe

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69 Rat-Infested Resti-Clone
WCA Member
Badboatdude@CS.com
69 Pics http://hobbystage.net/camaro/joeg/index.html

I wanted to resurrect this old thread to clarify things for me. The 7 degree up angle that is discussed....this means that if I have the spring perches on the bottom of the axle and level (parallel to the ground) that the yoke should be pointing up 7 degrees, correct? Then mounting it in the car actually causes it to point down a few degrees?

I have the same problem as Joe and wanted to verify before fixing it.

Thanks,
Brian