I need some chassis specs for suspension (1 Viewer)

[WrenchMonkey]

I"ve got an 81 BJ42 and am planning a spring over but with different springs so I just have a few simple questions well simple for you gurus anyways

1) the spring hanger and the shackle eye are these supposed to be parralel with each other?? in other words the spring perfectly horizontal??

2) what do you use as a referance for your caster I have a guage but am just wondering where you get your reference zero from for the cut and turn?? I was thinking a long bar thru the knuckle and getting it straight vertical and considering that zero

Thaks for your replies in advance

 

[Eskimo]

For #2, I always referenced the third member mating surface..

 

[FLYINGLOW]

1) the spring hanger and the shackle eye are these supposed to be parralel with each other?? in other words the spring perfectly horizontal??

2) what do you use as a referance for your caster I have a guage but am just wondering where you get your reference zero from for the cut and turn?? I was thinking a long bar thru the knuckle and getting it straight vertical and considering that zero

#1, do you mean the spring eyes be perfectly horizontal? This would be changing with spring compression. The mount points on the frame are not horizontal.

#2, for cut and turn, mount the housing in the truck with the pinion lined up where you want it. Then put you gauge on the trunion bearing race or a bar if you want. Don't worry about zero, you just want it set where it will provide good performance (I think 4 or 5 degrees, but do a search or look in tech). If you end up at zero, it will handle like crap. Do this after you have done your springs.

 

[WrenchMonkey]

okay I don't think I'm being clear with the first one or the second

OK first one geometry wise do I want both eyes of the spring to be the same distance from the ground when the vehicle is at reston a level surface?? hopefully this is clearer. is a stock 60 is it at least like that stock??

2nd If I have a housing that is bare no spring perches nothing and cut knuckles where do I put them so they are at zero to start with? Can I put a bar thru the knuckle with a level on it and put it at level vertically and that will be zero??then stick my guage on the knuckle and set caster from there?

 

[FLYINGLOW]

okay I don't think I'm being clear with the first one or the second

OK first one geometry wise do I want both eyes of the spring to be the same distance from the ground when the vehicle is at reston a level surface?? hopefully this is clearer. is a stock 60 is it at least like that stock??

2nd If I have a housing that is bare no spring perches nothing and cut knuckles where do I put them so they are at zero to start with? Can I put a bar thru the knuckle with a level on it and put it at level vertically and that will be zero??then stick my guage on the knuckle and set caster from there?

When it comes to geometry, it is best if the spring eyes are close to level. This is more important on the front and is an issue with shackle reversal. It will cause wierd dive characteristics if it is wrong. I think as long as your in the ball park you will be OK.

The whole reason for cut and turn is to set a better pinion angle and maintain the propper caster. I would call "zero" the stock setting, but it is all just a base line for beginning. Aim your pinion, tack on the perches, install u-bolts and rotate your knuckles to specified caster. I don't know what else to say.