Centering the rear end and setting pinion angle

[Chryco Psycho]

you have to have opposite  but equal angles , so if the trans is 1* down the diff should be 1* up to match , or better a bit low so it will climb under power

[PlumCrazyChris]

you have to have opposite  but equal angles , so if the trans is 1* down the diff should be 1* up to match , or better a bit low so it will climb under power

That is opposite of what I have heard before.

It seems to make sense, and I understand that is how cars are from the factory,  but all diagrams I've seen show if the trans is down, the diff should be down the same amount for a performance leaf spring car.

Is what I'm saying wrong?  Please let me know before I start welding on my car.

[cuda346pk]

you have to have opposite  but equal angles , so if the trans is 1* down the diff should be 1* up to match , or better a bit low so it will climb under power

Thats why I was figuring to put tranny at 0 to 1* down and the pinion at 1* down expecting it to climb to match the tranny at 0 or 1. Am I missing something?

[Chryco Psycho]

should be close 

[cuda346pk]

Ok, couple more questions now that I have gotten started. Should the shims go above or below the factory rear sway bar plate? Also it appears the shims come with different diameter holes for the center pins probably depending on brand. I am planning to install the 6* shims and it looks like I will need longer pins. If I drill my shim center hole to fit over current size pins, there will barely be enough left to center into the rear end holes. If they go below the sway bar plate then I just need longer center pins, which I have to get either way as one of mine broke trying to remove the nut.

[Chryco Psycho]

Either way will work ,  so whatever is easier , it may change the angle of the sway bar if the mount is angled but that will not affect the way it works

[cuda346pk]

Gonna have to get longer centering pins and put shims under sway bar plate or else the larger heads will not go into the rear end perch plates. I am temporarily putting it together with the 6* shims to see how it works out and see if I need longer u bolts too.

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[cuda346pk]

Ok so now I am at 1.6* down at pinion. I need 3" long centering bolts however everything I am seeing has a standard allen head on it, not near long enough to go through the sway bar plate and still have enough to securely locate the rear end too. Where can get factory style centering pins in longer lengths? Possibly the Rancho suspension ones will have a thick enough head but not sure from pictures. Maybe I can get correct length grade 5 bolts, install from below and use 2 nuts locked together on other end to center in plate and rear end? Might have to grind nuts to fit right but may be an option?
Looks like I will only be able to get the tranny to around 2 - 2 1/2* down with shimming it. Will this be an ok setup? I know nothing is matching however I checked the pinion angle at multiple spots and got alot of different readings including 2.7* across the bosses for the pinion snubber mount. I used the 1.6* figure as 2 of the spots came up with that. I am now using a digital level for my measurements.

[jordan]

I don't have my car running yet.  I took the winter off because of too much stuff going on.  I know I will regret it when the ground thaws.   That being said, I don't know if I will have a vibration. 

     I have my trans at a 5* down angle.  I cut my perches off of my axle housing, and set new ones in place and lightly tightened my u-bolts.  I put the angle finder on the pinion and located the pinion 5* or 6* down and tightened the u-bolt.  After a few tack welds, I removed the rear, and finished welding the perches on.  I did have a bit of welding issues with contamination of the weld, so I heated up the housing at the perch mount to burn off the oil contaminates and rewelded the perches with no problems. 

      Hopefully I can get my car going in the next couple of months and report back with my multiple issues that will come up.  Hopefully no vibrations. 

[Chryco Psycho]

typically youwant the nose down so the pinion will climb the ring gear& straighten the angle for the driveshaft but as the lideo shows you need the diff & trans angle to be equal so the shaft is running at a constant speed , indicating trans down 1 * would need diff up 1*

[cuda346pk]

So should it ideally be set so the angles are the same sitting static or put the pinion down some to compensate for it climbing under power?  There is no way I could get my tranny pointing up to match a downward pointing pinion without major cutting.

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[Chryco Psycho]

I would drop it 2-3* down so it will climb even .