Penion Angle Help

[chevyman 68 C/10]

I am welding a f@rd rear disc brake 9 inch rear in my 68 short wide truck. The width is exactly 66 inches like the stock rear and the bolt pattern is correct for the Bell Tech spindles and front discs that will follow.
I need to know what angle to set the rear end up on. The rear has been lowered 5 inches and it may get bags later.
Is there a standard degree that you set it on or how do you go about determining this.
I have a angle tool for checking the penion, just don't know what to set it on.

['72 Shorty]

Never had todo one in a lowered truck(my rear is stock), but in lifted rigs, I always set them up to the angle at the trans and at the axle are exactly the same. On my Trooper any more than 2* of difference between the 2 will cause nasty vibes. If you're leaving the 2 peice DL in, I'm not sure what to do.

[phantom dually]

I have talked to several shops on this and they say set it between 4-6 degrees. If you set the rear at 6 positive make sure your tranny sits at 6 negative. This can also be set the other way around. They say to never set them both at the same neg or positive. One must be a positive degree and the other a negative. The reason being is that if the are both positive or neg they will not have enough preload on the u joint and therfore will break easily under minumum torque loads.

[chevyman 68 C/10]

Wow I am confused now!! is positive up and negative down?
I am having a aluminum one piece drive shaft built as soon as I can get the rear end welded in and can get the right measurement on the shaft with the new tranny , engine and rear end.
I need to be sure so that there will be no problems after everything is welded up.

[phantom dually]

Zero degrees is level. Up would be positive and yes down would be negative. It really does not matter which is negative or positive. Measure your tranny as it sits and see what the degree is. Say it is 4 degree positive. You would want to make the rear end the opposite at 4 degree negative.

[CustomChevy]

hi, this ought to help you some.

http://www.streetrodderweb.com/tech/...ing/index.html


good luck!

[chevyman 68 C/10]

Wow, That is dangerous in my hands Custom Chevy!!!!!

I think I can get it right now, thanks a million.
If I can get the welder and a case of beer I will be set , thanks again.

[CustomChevy]

good luck!!

[crazy4chevs]

chevyman,
Im dooing the same swap do you have any pics?
Does it look like the rear of your driveline will sit to the pass about 1"from being straight in line? How did you measure for your mounts?

[chevyman 68 C/10]

Hey I have just ran up against that brick wall and stoped to make sure what to do.
I have been told that the off set will not be adverse to anything but I want to check it out before I weld any thing up.
To line it up I simply cut old saddle mount from the original rear end (may it rest in peace ). I destrored it but carefully salvaged the mount with the correct angle.The F@rd rear housing is a slightly different shape from the Chevy but that was corrected by slowly grinding material from the out side edges of the mounts untill they fit nice, this takes a little patients but it retains the angle for your controll arms and looks like it came stock in the truck, also should make welding a snap.

[chevyman 68 C/10]

ttt

[crazy4chevs]

Got the rear done, I set the pinnion angle at 4 deg. I'll try to get a camera an post some pics.