Help, perch to housing angle front axle (1 Viewer)

[gmayer]

My old perches were too rusted to give me a good baseline. What is the stock relationship between perch angle and the housing if the housing is plumb.

I supposedly have 3.5" alcan 2400lb front springs for my 45lv with an aluminum block ls hooked to a 6l80e. I am a long way from being able to put weight on the front end. 33" tires. I am assuming I want a stock perch angle. Not planning on any cut and turn.
I am guessing about 1 degree?

Thanks for your response!

 

[watrob]

Make sure you have positive castor, 1 degree positive should be ok?

 

[pb4ugo]

Removing and installing new perches is a big job. I'd hate to weld them on with a guess on the proper angle. What I've done in the past is to install the axle without welding the perches on yet. If you tighten the U bolts the perch won't move. Then when you get your build to the point where you have the weight of vehicle on the suspension you can loosen the U bolts and rotate the axle to the proper castor angle, tighten the Ubolts, tack the perch on, then either pull the axle, or rotate it so you can finish weld it. You will find you will probably have to compromise between a good castor angle and pinion angle.

 

[47coeman]

Get real busy and do cut and turn and get it perfect on both angles

 

[lcwizard]

Why would you want a stock perch angle. The face of the diff housing is 90 degrees to the perch. Even a modest lift adds stress to the u-joint .
Toyota's later designs ( fj60 for example ) had about 6 deg. of lift to the pinion. If you went that route, with a cut and turn you could add 2~4 caster to improve straight line stability . Toyota's original design was great for stock height and manual steering. It's intended purpose was dirt roads...lots of them

 

[gmayer]

Thanks, so I will do some searching on cut and turn. Do I have this right, I will be cutting and turning 8-9 degrees, then stick the perches such that I have 6 degrees of pinon lift, the rest will be caster

 

[White Stripe]

Basically set your pinion angle first and then tack the mounts. Then do the cut and turn. Aim for around 2-6 degrees of caster with no more than a .50 degree difference between sides. I did mine in the truck with the suspension loaded and it worked well for me. Once you are happy with the final product do the final welds.